https://wiki.chemika.be/api.php?action=feedcontributions&feedformat=atom&user=R0804230 2026-07-28T09:07:36Z Gebruikersbijdragen MediaWiki 1.43.0 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=4160 2024-07-16T13:19:21Z

<p>R0804230: /* 2024 */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> =Examenvragen=<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> ==2024==<br /> <br /> ===Exam 07/06/2024 08h30 and 09h30===<br /> '''Question one:'''<br /> * How can you make a gold surface hydrophobic or hydrophilic? <br /> * How can you change the hydrophobicity/hydrophilicity of the surface?<br /> * How would you determine this macroscopically? <br /> * How can you detect this microscopically? <br /> '''Question two:''' Si nanowire n-type semiconductor, DNA absorbed to it to detect positively charged proteins. <br /> * Explain the mechanism used for protein sensing.<br /> * Right/wrong: The thicker the diameter, the more sensitive. (Ignore band gap)<br /> * What is the function of PEG on this wire? <br /> * Photo's shown, what kind of visualization technique would you use? <br /> '''Question three:''' hybrid-LBL with Au and Fe<br /> * How can you simple separate Fe and Au? <br /> * Explain how to make water-soluble Au NPs<br /> * Protocol given for iron oxide particles, draw molecule/structure of Fe NPs<br /> * When the LBL is assembled, a red-shift is observed, how come? <br /> <br /> ===Exam 06/06/2024 14h00 and 15h00===<br /> <br /> '''Question one''': Description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle.<br /> #Na ions are selectively absorbed by this dendrimer. Why? (heterocycle is specific for Na)<br /> #Discuss an approach to synthesize this dendrimer. (I explained the actual organic synthesis, but apparently he was after convergent and divergent synthesis and what the (dis)advantages of each method are)<br /> #Discuss the change in viscosity of this dendrimer type upon going from low to high generations.<br /> <br /> '''Question two''': Both carbon NTs and graphene have some disadvantages, in terms of their properties, when it comes to electronic applications. Why?<br /> <br /> '''Question three''': Why is it sometimes observed that upon diluting a solution of ligand-shell protected NPs, based on non-covalent chemistry, the particles aggregate?<br /> <br /> '''Question four''': Again discription of a paper (see slide 34 of chapter 16!)<br /> #Suggest a way to make the &quot;chemical contrast&quot; lines. There is almost no difference in topography between the lines. What is the purpose of the chemical contrast lines?<br /> #What is the surface property of the darkes lines in the figure (specific for this paper but analogous to silde 34) if you know that the PMMA blocks of the PMMA-PS block-copolymer preferentially absorb here?<br /> #What Scanning Probe Technology would you use to reveal the topography and nanostructuring?<br /> <br /> ==2021==<br /> <br /> ===Exam 4 June 2021===<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> ==2016==<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> ==2015==<br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> ==2014==<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3950 2024-06-06T18:09:18Z

<p>R0804230: /* Examenvragen */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> ===6th of June 2024===<br /> <br /> '''Question one''': Description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle.<br /> #Na ions are selectively absorbed by this dendrimer. Why? (heterocycle is specific for Na)<br /> #Discuss an approach to synthesize this dendrimer. (I explained the actual organic synthesis, but apparently he was after convergent and divergent synthesis and what the (dis)advantages of each method are)<br /> #Discuss the change in viscosity of this dendrimer type upon going from low to high generations.<br /> <br /> '''Question two''': Both carbon NTs and graphene have some disadvantages, in terms of their properties, when it comes to electronic applications. Why?<br /> <br /> '''Question three''': Why is it sometimes observed that upon diluting a solution of ligand-shell protected NPs, based on non-covalent chemistry, the particles aggregate?<br /> <br /> '''Question four''': Again discription of a paper (see slide 34 of chapter 16!)<br /> #Suggest a way to make the &quot;chemical contrast&quot; lines. There is almost no difference in topography between the lines. What is the purpose of the chemical contrast lines?<br /> #What is the surface property of the darkes lines in the figure (specific for this paper but analogous to silde 34) if you know that the PMMA blocks of the PMMA-PS block-copolymer preferentially absorb here?<br /> #What Scanning Probe Technology would you use to reveal the topography and nanostructuring?<br /> <br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3949 2024-06-06T18:03:50Z

<p>R0804230: /* 6th of June 2024 */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> ====6th of June 2024====<br /> <br /> '''Question one''': Description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle.<br /> #Na ions are selectively absorbed by this dendrimer. Why? (heterocycle is specific for Na)<br /> #Discuss an approach to synthesize this dendrimer. (I explained the actual organic synthesis, but apparently he was after convergent and divergent synthesis and what the (dis)advantages of each method are)<br /> #Discuss the change in viscosity of this dendrimer type upon going from low to high generations.<br /> <br /> '''Question two''': Both carbon NTs and graphene have some disadvantages, in terms of their properties, when it comes to electronic applications. Why?<br /> <br /> '''Question three''': Why is it sometimes observed that upon diluting a solution of ligand-shell protected NPs, based on non-covalent chemistry, the particles aggregate?<br /> <br /> '''Question four''': Again discription of a paper (see slide 34 of chapter 16!)<br /> #Suggest a way to make the &quot;chemical contrast&quot; lines. There is almost no difference in topography between the lines. What is the purpose of the chemical contrast lines?<br /> #What is the surface property of the darkes lines in the figure (specific for this paper but analogous to silde 34) if you know that the PMMA blocks of the PMMA-PS block-copolymer preferentially absorb here?<br /> #What Scanning Probe Technology would you use to reveal the topography and nanostructuring?<br /> <br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3948 2024-06-06T18:03:31Z

<p>R0804230: /* 6th of June 2024 */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> ====6th of June 2024====<br /> <br /> '''Question one''': Description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle<br /> #Na ions are selectively absorbed by this dendrimer. Why? (heterocycle is specific for Na)<br /> #Discuss an approach to synthesize this dendrimer. (I explained the actual organic synthesis, but apparently he was after convergent and divergent synthesis and what the (dis)advantages of each method are)<br /> #Discuss the change in viscosity of this dendrimer type upon going from low to high generations.<br /> <br /> '''Question two''': Both carbon NTs and graphene have some disadvantages, in terms of their properties, when it comes to electronic applications. Why?<br /> <br /> '''Question three''': Why is it sometimes observed that upon diluting a solution of ligand-shell protected NPs, based on non-covalent chemistry, the particles aggregate?<br /> <br /> '''Question four''': Again discription of a paper (see slide 34 of chapter 16!)<br /> #Suggest a way to make the &quot;chemical contrast&quot; lines. There is almost no difference in topography between the lines. What is the purpose of the chemical contrast lines?<br /> #What is the surface property of the darkes lines in the figure (specific for this paper but analogous to silde 34) if you know that the PMMA blocks of the PMMA-PS block-copolymer preferentially absorb here?<br /> #What Scanning Probe Technology would you use to reveal the topography and nanostructuring?<br /> <br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3947 2024-06-06T18:03:18Z

<p>R0804230: /* Examenvragen */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> ====6th of June 2024====<br /> <br /> '''Question one''': description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle<br /> #Na ions are selectively absorbed by this dendrimer. Why? (heterocycle is specific for Na)<br /> #Discuss an approach to synthesize this dendrimer. (I explained the actual organic synthesis, but apparently he was after convergent and divergent synthesis and what the (dis)advantages of each method are)<br /> #Discuss the change in viscosity of this dendrimer type upon going from low to high generations.<br /> <br /> '''Question two''': Both carbon NTs and graphene have some disadvantages, in terms of their properties, when it comes to electronic applications. Why?<br /> <br /> '''Question three''': Why is it sometimes observed that upon diluting a solution of ligand-shell protected NPs, based on non-covalent chemistry, the particles aggregate?<br /> <br /> '''Question four''': Again discription of a paper (see slide 34 of chapter 16!)<br /> #Suggest a way to make the &quot;chemical contrast&quot; lines. There is almost no difference in topography between the lines. What is the purpose of the chemical contrast lines?<br /> #What is the surface property of the darkes lines in the figure (specific for this paper but analogous to silde 34) if you know that the PMMA blocks of the PMMA-PS block-copolymer preferentially absorb here?<br /> #What Scanning Probe Technology would you use to reveal the topography and nanostructuring?<br /> <br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3946 2024-06-06T18:02:17Z

<p>R0804230: /* Examenvragen */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> ====6th of June 2024====<br /> <br /> '''Question one''': description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle<br /> #Na ions are selectively absorbed by this dendrimer. Why? (heterocycle is specific for Na)<br /> #Discuss an approach to synthesize this dendrimer. (I explained the actual organic synthesis, but apparently he was after convergent and divergent synthesis and what the (dis)advantages of each method are)<br /> #Discuss the change in viscosity of this dendrimer type upon going from low to high generations.<br /> <br /> '''Question two''': Both carbon NTs and graphene have some disadvantages, in terms of their properties, when it comes to electronic applications. Why?<br /> <br /> '''Question three''': Why is it sometimes observed that upon diluting a solution of ligand-shell protected NPs, based on non-covalent chemistry, the particles aggregate?<br /> <br /> '''Question four''': Again discription of a paper (see slide 34 of chapter 16!)<br /> #Suggest a way to make the &quot;chemical contrast&quot; lines. There is almost no difference in topography between the lines. What is the purpose of the chemical contrast lines?<br /> #What is the surface property of the darkes lines in the figure (specific for this paper but analogous to silde 34) if you know that the PMMA blocks of the PMMA-PS block-copolymer preferentially absorb here?<br /> #What Scanning Probe Technology would you use to reveal the topography and nanostructuring?<br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3945 2024-06-06T18:02:06Z

<p>R0804230: /* Examenvragen */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> ====6th of June 2024====<br /> <br /> '''Question one''': description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle<br /> #Na ions are selectively absorbed by this dendrimer. Why? (heterocycle is specific for Na)<br /> #Discuss an approach to synthesize this dendrimer. (I explained the actual organic synthesis, but apparently he was after convergent and divergent synthesis and what the (dis)advantages of each method are)<br /> #Discuss the change in viscosity of this dendrimer type upon going from low to high generations.<br /> <br /> '''Question two''': Both carbon NTs and graphene have some disadvantages, in terms of their properties, when it comes to electronic applications. Why?<br /> <br /> '''Question three''': Why is it sometimes observed that upon diluting a solution of ligand-shell protected NPs, based on non-covalent chemistry, the particles aggregate?<br /> <br /> '''Question 4''': Again discription of a paper (see slide 34 of chapter 16!)<br /> #Suggest a way to make the &quot;chemical contrast&quot; lines. There is almost no difference in topography between the lines. What is the purpose of the chemical contrast lines?<br /> #What is the surface property of the darkes lines in the figure (specific for this paper but analogous to silde 34) if you know that the PMMA blocks of the PMMA-PS block-copolymer preferentially absorb here?<br /> #What Scanning Probe Technology would you use to reveal the topography and nanostructuring?<br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3944 2024-06-06T18:01:16Z

<p>R0804230: /* Examenvragen */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> '''6th of June 2024'''<br /> <br /> Question one: description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle<br /> #Na ions are selectively absorbed by this dendrimer. Why? (heterocycle is specific for Na)<br /> #Discuss an approach to synthesize this dendrimer. (I explained the actual organic synthesis, but apparently he was after convergent and divergent synthesis and what the (dis)advantages of each method are)<br /> #Discuss the change in viscosity of this dendrimer type upon going from low to high generations.<br /> <br /> Question two: Both carbon NTs and graphene have some disadvantages, in terms of their properties, when it comes to electronic applications. Why?<br /> <br /> Question three: Why is it sometimes observed that upon diluting a solution of ligand-shell protected NPs, based on non-covalent chemistry, the particles aggregate?<br /> <br /> Question 4: Again discription of a paper (see slide 34 of chapter 16!)<br /> #Suggest a way to make the &quot;chemical contrast&quot; lines. There is almost no difference in topography between the lines. What is the purpose of the chemical contrast lines?<br /> #What is the surface property of the darkes lines in the figure (specific for this paper but analogous to silde 34) if you know that the PMMA blocks of the PMMA-PS block-copolymer preferentially absorb here?<br /> #What Scanning Probe Technology would you use to reveal the topography and nanostructuring?<br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3943 2024-06-06T18:00:57Z

<p>R0804230: /* Examenvragen */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> '''6th of June 2024'''<br /> <br /> ====Question one====: description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle<br /> #Na ions are selectively absorbed by this dendrimer. Why? (heterocycle is specific for Na)<br /> #Discuss an approach to synthesize this dendrimer. (I explained the actual organic synthesis, but apparently he was after convergent and divergent synthesis and what the (dis)advantages of each method are)<br /> #Discuss the change in viscosity of this dendrimer type upon going from low to high generations.<br /> <br /> Question two: Both carbon NTs and graphene have some disadvantages, in terms of their properties, when it comes to electronic applications. Why?<br /> <br /> Question three: Why is it sometimes observed that upon diluting a solution of ligand-shell protected NPs, based on non-covalent chemistry, the particles aggregate?<br /> <br /> Question 4: Again discription of a paper (see slide 34 of chapter 16!)<br /> #Suggest a way to make the &quot;chemical contrast&quot; lines. There is almost no difference in topography between the lines. What is the purpose of the chemical contrast lines?<br /> #What is the surface property of the darkes lines in the figure (specific for this paper but analogous to silde 34) if you know that the PMMA blocks of the PMMA-PS block-copolymer preferentially absorb here?<br /> #What Scanning Probe Technology would you use to reveal the topography and nanostructuring?<br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3942 2024-06-06T18:00:29Z

<p>R0804230: /* Examenvragen */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> '''6th of June 2024'''<br /> <br /> Question one: description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle<br /> #Na ions are selectively absorbed by this dendrimer. Why? (heterocycle is specific for Na)<br /> #Discuss an approach to synthesize this dendrimer. (I explained the actual organic synthesis, but apparently he was after convergent and divergent synthesis and what the (dis)advantages of each method are)<br /> #Discuss the change in viscosity of this dendrimer type upon going from low to high generations.<br /> <br /> Question two: Both carbon NTs and graphene have some disadvantages, in terms of their properties, when it comes to electronic applications. Why?<br /> <br /> Question three: Why is it sometimes observed that upon diluting a solution of ligand-shell protected NPs, based on non-covalent chemistry, the particles aggregate?<br /> <br /> Question 4: Again discription of a paper (see slide 34 of chapter 16!)<br /> #Suggest a way to make the &quot;chemical contrast&quot; lines. There is almost no difference in topography between the lines. What is the purpose of the chemical contrast lines?<br /> #What is the surface property of the darkes lines in the figure (specific for this paper but analogous to silde 34) if you know that the PMMA blocks of the PMMA-PS block-copolymer preferentially absorb here?<br /> #What Scanning Probe Technology would you use to reveal the topography and nanostructuring?<br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3941 2024-06-06T17:57:29Z

<p>R0804230: /* Examenvragen */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> '''6th of June 2024'''<br /> <br /> Question one: description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle<br /> #Na ions are selectively absorbed by this dendrimer. Why (heterocycle is specific for Na)<br /> #Discuss an approach to synthesize this dendrimer. (I explained the actual organic synthesis, but apparently he was after convergent and divergent synthesis and what the (dis)advantages of each method are)<br /> #Discuss the change in viscosity of this dendrimer type upon going from low to high generations<br /> <br /> Question two: Both carbon NTs and graphene have some disadvantages, in terms of their properties, when it comes to electronic applications. Why?<br /> <br /> Question three: Why is it sometimes observed that upon diluting a solution of ligand-shell protected NPs, based on non-covalent chemistry, the particles aggregate?<br /> <br /> Question 4: Again discription of a paper (see slide 34 of chapter 16!)<br /> #Suggest a way to make the &quot;chemical contrast&quot; lines. There is almost no difference in topography between the lines. What is the purpose of the chemical contrast lines?<br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3940 2024-06-06T17:57:03Z

<p>R0804230: /* Examenvragen */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> '''6th of June 2024'''<br /> <br /> Question one: description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle<br /> #Na ions are selectively absorbed by this dendrimer. Why (heterocycle is specific for Na)<br /> #Discuss an approach to synthesize this dendrimer. (I explained the actual organic synthesis, but apparently he was after convergent and divergent synthesis and what the (dis)advantages of each method are)<br /> #Discuss the change in viscosity of this dendrimer type upon going from low to high generations<br /> Question two: Both carbon NTs and graphene have some disadvantages, in terms of their properties, when it comes to electronic applications. Why?<br /> Question three: Why is it sometimes observed that upon diluting a solution of ligand-shell protected NPs, based on non-covalent chemistry, the particles aggregate?<br /> Question 4: Again discription of a paper (see slide 34 of chapter 16!)<br /> #Suggest a way to make the &quot;chemical contrast&quot; lines. There is almost no difference in topography between the lines. What is the purpose of the chemical contrast lines?<br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3939 2024-06-06T17:55:47Z

<p>R0804230: /* Examenvragen */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> '''6th of June 2024'''<br /> <br /> Question one: description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle<br /> #Na ions are selectively absorbed by this dendrimer. Why (heterocycle is specific for Na)<br /> #Discuss an approach to synthesize this dendrimer. (I explained the actual organic synthesis, but apparently he was after convergent and divergent synthesis and what the (dis)advantages of each method are)<br /> #Discuss the change in viscosity of this dendrimer type upon going from low to high generations<br /> Question two: Both carbon NTs and graphene have some disadvantages, in terms of their properties, when it comes to electronic applications. Why?<br /> Question three: Why is it sometimes observed that upon diluting a solution of ligand-shell protected NPs, based on non-covalent chemistry, the particles aggregate?<br /> Question 4: Again discription of a paper (see slide 34 of chapter 16!)<br /> #<br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3938 2024-06-06T17:55:29Z

<p>R0804230: /* Examenvragen */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> '''6th of June 2024'''<br /> Question one: description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle<br /> #Na ions are selectively absorbed by this dendrimer. Why (heterocycle is specific for Na)<br /> #Discuss an approach to synthesize this dendrimer. (I explained the actual organic synthesis, but apparently he was after convergent and divergent synthesis and what the (dis)advantages of each method are)<br /> #Discuss the change in viscosity of this dendrimer type upon going from low to high generations<br /> Question two: Both carbon NTs and graphene have some disadvantages, in terms of their properties, when it comes to electronic applications. Why?<br /> Question three: Why is it sometimes observed that upon diluting a solution of ligand-shell protected NPs, based on non-covalent chemistry, the particles aggregate?<br /> Question 4: Again discription of a paper (see slide 34 of chapter 16!)<br /> #<br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3937 2024-06-06T17:43:59Z

<p>R0804230: /* Examenvragen */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> '''6th of June 2024'''<br /> ====Question one: description of a paper with a picture of a dendrimer encapsulating a chromophore with a heterocycle====<br /> <br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_at_nanometer_scale&diff=3936 2024-06-06T17:42:19Z

<p>R0804230: /* Vakinformatie */</p> <hr /> <div>[[Categorie:Machemie]]<br /> =Vakinformatie= <br /> Chemistry at nanometer scale, taught by Prof. De Feyter<br /> ==Examenvragen==<br /> Also check vtk wiki: https://wiki.vtk.be/Chemistry_at_Nanometre_Scale_(H06A6A)<br /> <br /> '''6th of June 2024'''<br /> <br /> <br /> '''4 June 2021'''<br /> <br /> 1.Give the optimal way to make a gold surface:<br /> <br /> <br /> a. Hydrophobic<br /> <br /> b. Hydrophilic<br /> <br /> c. To tune hydrophobicity and hydrophilicity<br /> <br /> d. What kind of technique would u use to measure the tickness<br /> <br /> e. Explain this technique<br /> <br /> f. Right/Wrong: I don't remember<br /> <br /> <br /> 2. A silicon nanowire bind a negative charged protein.<br /> <br /> a. How would u make the silicon nanowire<br /> <br /> b. Explain the principle of an N-type silicon nanowire and the set-up<br /> <br /> c. How can you read out the binding of the negative charged protein<br /> <br /> d. How can you improve the binding of the protein<br /> <br /> e. Eight/Wrong: a larger diameter gives a better readout<br /> <br /> <br /> 3. Something with gold nanoparticles and iron-oxide that bind in ordered structure or layer<br /> <br /> a. How would you produce a gold NP, which is soluble in H2O<br /> <br /> b. Draw the structure of iron in n-octylamine and ethyleenglycol<br /> <br /> c. Draw the structure and explain the chemistry of b) in APTMS and methanol<br /> <br /> d. Right/Wrong: ch9emical force microscopy is designed to measure these structures and is the best technique <br /> <br /> <br /> 4. The UV-Vis and fluorescence spectra of a semiconductor NP of 6 nm with a 1.2 nm organic coat in solution shifts (I don't remember to which side) upon evaporation of the solvent. Comment on al the concepts and explain (right/wrong)<br /> <br /> '''14 June 2016 8:00'''<br /> (of course I only notice they're the same questions as 15th june 2015 after I typed all this)<br /> <br /> 1. Give the optimal way to create:<br /> <br /> a) A thiol monolayer on a graphene substrate (extra question: what does this layer look like?)<br /> b) A thiol layer on a gold substrate with a certain alkyn chain length but at five locations at positions you can control with a diameter of a couple tens of nanometers, place thiols with a longer chain<br /> c) A thiol layer on a gold substrate in a regular band structure, bands have a width of several micrometer (extra questions: what is PDMS? what is the ink composed of?)<br /> d) A thiol layer on a gold substrate with the thiol in an array of regular sized dots (about 3 nm in diameter) spaced 1.5 - 2 nm apart<br /> e) A thiol &quot;drawing&quot; on gold substrate, the drawing lines have a width of about 70 nm<br /> f) Gold nanoparticles (d = 10 nm) on a silicon substrate in a regular but noncrystalline array, spaced 60 nm apart<br /> g) What probing method would you use to visualise d)? Can you use the same method to visualise f)? (extra questions: how does feedback work in AFM? what is the resonant frequency of the tip?)<br /> <br /> 2. Correct/wrong and why?<br /> <br /> a) It does not matter what type of amphiphiles you add to a solution (positively charged, negatively charged or neutral), the surface tension decreases at increasing concentration<br /> b) Gold nanoparticles have the major drawback of having a much smaller quantum yield than semiconducting nanoparticles for fluorescence spectroscopy purposes<br /> <br /> '''13 June 2016 10:00'''<br /> <br /> Same questions as 05 June 2015 10:00<br /> <br /> <br /> '''22 June 2015'''<br /> <br /> 1. Dendirmers PAMAM(chap 5) take me a lot of time to find where it is...<br /> <br /> (1) Na+ adsorption why?<br /> (2) structure<br /> (3) how to synthesis?<br /> (4) viscosity change with higher generation<br /> (5) difference between dendrimer and micelle is dendrimer needs lower concentration, right?<br /> <br /> 2.copolymer, epitaxial SA on Si(chap 15) only two slides but you need to know the whole process and the mechanism. also about AFM i think so go over chap 19 AFM!<br /> <br /> (1) how to make chemical contrast?<br /> (2) how copolymer ordered on that?<br /> (3) how to characterise this pattern?<br /> 3.LbL pH sensor just like exercise 1.<br /> <br /> '''23 June 2015'''<br /> <br /> 1) <br /> <br /> a. how to change hidrophilicity/phobicity of a surface<br /> b. how to tune it (not completely philic or phobic but also with different degrees)<br /> c. how to detect polarity of surface macro and nanoscopically<br /> <br /> 2) n-siNW sensor for positively charged protein: how it works<br /> <br /> a. reaction with PEG<br /> b. how to characterize it<br /> c. something else I dont remember<br /> <br /> 3) LbL of iron and gold nanoparticles linked by covalently-bonded crosslink<br /> <br /> a) how to separate the different np<br /> b) how to synthetize np in water.<br /> c) he provides you the protocol for the synthesis of iron oxide NPs with different agents. then they are mixed with APTMS and someother molecule with COOH.<br /> write what happens chemically and draw the composition of NPs<br /> d) red shift in absorption of the nps: what does it mean?<br /> <br /> 4)(true false) mie theory explains fluorescence of semiconductor nps at higher energies.<br /> <br /> '''15th June 2015'''<br /> <br /> 1. Many small questions about patterning, monolayers, etc, almost everything with alkyl thiols.<br /> <br /> a) How would you make a monolayer in graphene?<br /> b) How would you make a monolayer in gold and then substitute some islands of nm size with another alkyl thiol of longer tail?<br /> c) How would you make stripes of alkyl thiol in gold that are micrometer sized?<br /> d) How would you create small islands of aklyl thiols that are 2-3 nm sized and separated also by very few nanometers?<br /> e) How would you make an irregular pattern (like a drawing) of alkyl thiols in gold with precision?<br /> f) How would you deposit gold nanoparticles in Si forming small island in a regular but not crystalline pattern that are separated by 60 nm or so?<br /> g) Which techniques would you use to measure that pattern in Si and the one of the small islands in gold?<br /> <br /> 2. True/False<br /> <br /> a) Something like: the surface energy is independent of the amphiphile you use: positively charged, negatively charged or neutral. (it was something a little bit different but more or less)<br /> b) GNPs are not really used as biolabels because they have low quantum yield in comparison to QDs of the same size.<br /> <br /> '''19th June 2015'''<br /> <br /> 1. Diagram of a DNA functionalised gold NP designed to detect Ascorbic acid. An explanation of how the device work is provided. Basically It fluoresces after the DNA gets cleaved because of a radical produced by the ascorbic acid.<br /> <br /> a) describe how one can prepare gold nanoparticles<br /> b) describe how one can functionalise the NPs with the DNA strands<br /> c) which spectroscopic technique would you use to determine the concentration of gold NP<br /> d) What do you think is the reason why the sensitivty is 100x better with the Gold NP than in a device without gold NPs?<br /> <br /> 2. True or false and why: Keeping a low precursor concentration when synthesising gold NPs results in a broad spectrum of the fluorescence curve <br /> <br /> 3. He gives you a diagram of a molecule with three fused aromaticc rings, a number of C=O bonds, some N atoms and an alkyl chain. He says some researchers showed this can be useful for dispersing SWCNTS.<br /> <br /> a) why is it hard to disperse SWCNTS?<br /> b) Describe a possible mechanism of how this molecule achieves dispersion<br /> <br /> '''5 June 2015 10:00'''<br /> For a given application it is necessary to make a silicon wafer, with its natural oxide layer, hypdrophobic. Looking into the scientific literature, I found the following recipe:<br /> &quot;After dissolving trichlorooctylsilane molecule in a new glass beaker with ethanol, at rather low concentrations, a gold substrate is dipped into the solution for a few seconds, followed by a rinsing step with water.'&quot;'<br /> Analyse this statement, and discuss in terms of chemistry, indicating what's correct/wrong/nonsense and why.<br /> Comment on this statement (correct/wrong and why?):<br /> &quot;Metal nanoparticle synthesis is governed by kinetics, rather than thermodynamics.&quot;<br /> On top of this multilayered substrate, shown below (so with the chromium top layers), a photoresist polymer is coated. The sample is irradiated through a square-shaped mask, and the irradiated area (so having the shape of a square) is washed away. Then the following manipulations were done: gold is deposited via electrodeposition on top of the substrate; a chromium layer is deposited; then the sample is subsequently treated with 1) acetone, 2) nitric acid (dissolves the silver layer), 3) sonicated in a hexadecanethiol solution, though not necessarily in the order indicated. Figure with this top-to-down structure: chromium-silver-chromium-Si/SiO2. Draw the object formed and describe its chemical nature (bulk and surface)<br /> What is the role of acetone, an organic solvent sonication in hexadecanethiol solution in ethanol. Define the order of the different steps in the treatment<br /> Describe two methods you would use to evaluate the degree of polarity of surfaces:<br /> a macroscopic technique and<br /> a technique which operates at the nano to micro scale<br /> <br /> A mixture of oppositely charged spheres (diameter not defined) forms a highly ordered phase (see figure below). The red particles are negatively charged and the green ones positively charged.<br /> Discuss the different aspects of the energetics involved in this self-assembly process (in terms of Gibbs free energy)<br /> Alt<br /> <br /> +/- Charged spheres assembled lattice<br /> In another experiment, rod like objects of identical length, carrying no charge, and with only minimal interrod interactions, were found to self-assemble. Draw the outcome of the self-assembly process. Explain in terms of the energetics of the process.<br /> [edit]Old NanoForum questions<br /> These questions are copied from the old nano forum so the format might not be ideal.<br /> <br /> '''Unknown date'''<br /> <br /> 1. How to make a gold surface hydrophobic or hydrophylic? How to switch the hydrophobicity / hydrophylicity of the gold surface by electrochemical stimuli?<br /> <br /> 2. Comment (right/wrong and why)<br /> <br /> a ) The most important motivation for the development of field-effect-transistors and<br /> solar cells based upon organic molecules isthe improved efficiency compared to inorganic semiconductor materials.<br /> <br /> What are the requirements in order to use low molecular weight organic molecules as active components in organic field-effect-transistors?<br /> <br /> b) The formation of 'objects' with a well-defined size and shape on the basis of selfassembly is an impossible task.<br /> c) A continuous flux of energy into the 'system' is bad for the formation of ordered<br /> patterns.<br /> <br /> d) The Mie-theory explains why the fluorescence of nanometer-sized semiconductor<br /> particles is observed at lower energy upon increasing the size of the particles.<br /> <br /> 3. How does the surface tension of an aquous solution evolve if the concentration of the solute increases?<br /> <br /> 4. Mixing the calixarene (left) and the barbiturate (right) in the appropriate stoichiometric conditions leads to the formation of a complex (see picture).<br /> <br /> a) What's the driving force for the formation of these complexes?<br /> b) What structure will be formed: the (P)-enantiomer, the (M)-enantiomer or both?<br /> Explain by using an energy diagram.<br /> <br /> c) What will happen if one adds to the existing solution a new barbiturate with a chiral<br /> side chain?<br /> <br /> d) These complexes have also been visualised on graphite by a scanning probe<br /> microscopy method. Which technique has been used and why? Give a short description how this technique works.<br /> <br /> 5. How to make an ultrasmall pH sensorbased upon conductivity measurements. How does it work?<br /> <br /> '''Unknown date'''<br /> <br /> 1. Nanowire<br /> <br /> a) A silicion nanowire is made using 20nm nanocluster of gold. Explain which technique is used and how it works (really know how it works and what it needs and different changes in the process).<br /> the nanowire is mixed into a solution of 1%functionalizing thing that I can’t remember and ethanol, write down the product.<br /> <br /> c) You want to use the nanowire as a sensor for viruses in a ‘device’, Explain how to make this device? (explain and really know what parts are needed and how it works, but not how it is produced)<br /> d) There are many long 1 micron wires and you want to order them (picture similar to logs in a pond). Explain how you can do this using a bottom-up technique. (Basically what technique???)<br /> e) How can you image the ‘device’ that you explained on c) Which technique is the best for this and how does it work? Why are the other techniques worse??<br /> <br /> 2. True or false:<br /> <br /> a) Sometimes a constant energy flux is needed to make ordered patterns.<br /> Adding surfactants to water makes the surface tension higher<br /> <br /> c) Can’t remember the other ones!!! But you get the style basically write down why it is write/wrong and really know and explain why.<br /> <br /> 3. “self-healing” There is a thermoreversible polymer that when you cut or break it is only necessary to bring these parts together and the parts reattach themselves. This is done at room temperature. (Wording in this question is key to recognizing what we are working with in this question, since I am an oversimplifying person I do not remember all the exact wording: Basically it dealt with supramolecular polymers)<br /> <br /> a) What is the ‘principle’ behind this?<br /> What interactions are behind this and how can we tune them? (Really know which ones and how we can lower/increase them)<br /> c) Mention a similar material that has becomes useful because of it temperature dependance properties that are not common for regular polymers (basically difference between supramolecular polymers and regular ones)<br /> <br /> '''June 14th 2014, afternoon'''<br /> <br /> 1.<br /> <br /> You get a picture of a new photovoltaic cell. It is made from CdSe nanorods and organic semiconductor. HOMO and LUMO for both materials are given. and also a graph with the absorbency for each wavelength of the photovoltaic cell for CdSe quantum dots, short nanorods, and a bit longer nano rods.<br /> <br /> a) What are the function of the materials and how does this device work<br /> How do you change the bandgap of the CdSe nanorods<br /> c) why is the efficiency of the device bigger for nanorods then for quantum dots<br /> d) How do you make nanorods in stead of quantum dots<br /> e) How would you study the structure of this device<br /> <br /> 2.<br /> <br /> a) How can you make a sensor for for instance negatively charged proteins by using nanowires? ?<br /> c) What are the benefits of this kind of device.<br /> <br /> 3.<br /> <br /> The structure of a molecule to that could dispense CNTs in organic solvents was given, it contained a aromatic group and an alkyl chain.<br /> <br /> a) Why is it not so easy to dispense CNTs in a solven<br /> b) How does the molecule dispence the CNT<br /> c) What molecular interactions are involved in this mechanism<br /> <br /> 4.<br /> <br /> True are false questions<br /> <br /> a) Is the Mie therory valid for semiconductor nanoparticles with a diameter of 10 nm<br /> b and c) can't remember<br /> d) are all molecular interactions for self assembly where entropic forces are involved only possible in water?<br /> 5th: a question about the layer by layer method, can't remember it exactly<br /> <br /> <br /> '''Unknown date'''<br /> answers are not all exactly correct, but gives you a thinking in the right way<br /> <br /> 1. detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) how is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution<br /> --&gt; Chapter 16, metal nanoparticles in aqueous solution, it is with the citrate (that gives also stability)<br /> <br /> detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?<br /> --&gt; something with the gold: if the flour is too close to the gold, the gold inhibits the fluorescence<br /> <br /> c) how are the oglionucleotides bounded to the gold nano particle? explain<br /> --&gt; receptor ligand, (receptor is the thiol) and this binding is stronger than the one of the citrate<br /> <br /> d) wich spectroscopy? eg: UV/Vis<br /> e) what is the (chemical) role of Au particle here?<br /> --&gt; catalysation of breaking the dna enzyme and the dna<br /> <br /> <br /> 2.goldnanoparticles are grown like the classical nucleation model, have broad spectrum plasman resonance. --&gt; explain everything of SPR, explain everything of (de)focussing, so the growth procedure of a nano particle, and finally: you have different nanoparticles with diff sizes and all together they result in a broad SPR<br /> <br /> 3. picture of molecule with aromatic part en alkyl part this molecule helps to dispersce SWCNT a) give a posible mechanism (draw) it was something with H-bonding of the N en =O from the aromatic part wat are the reactions of the alkyl and the aromatic part (alkyl will disolve in the organic solution..)<br /> <br /> 4. a rod goes to an ordered structure, explain the energetics something with delta G = detla H - T*delta S and look to chapter LC, similar to Onsager hard-rod model)<br /> <br /> 5. how would you make a drawing of 70 nm width form thiols on gold substrate en how do you change the witdt? - dip pen nano lithography<br /> <br /> <br /> '''Unknown date'''<br /> Similar like previous years:<br /> <br /> - How do you make a n-type siliconwire from gold particles (VLS) - It is covered with some alkyls, draw the chemistry and how would you do that (SAM) - It is used as protein sensor, how does it work? - How would we measure this? AFM - How can we prevent non-specific interactions with proteins?<br /> <br /> True/false:<br /> <br /> 20nm gold particles are chosed for their better quantum yield then semicondutors when used as fluorescence sensor --&gt; wrong, no fluorescence, particle is too large<br /> <br /> A wire like above is better for sensing lower concentration proteins when it has a larger diameter. --&gt; wrong i think, not sure. Smaller diameter = lower conduction --&gt; bigger effect from proteins, more sensitive.<br /> <br /> LBL question like in excercise session 1, in fact it is the exact same question but he uses polymer X and polymer Y and he reversed the question, asking when polymer X would have the thinnest layer. You have to make a table with = ~ &gt; &lt; in.<br /> <br /> <br /> He does go pretty deep into it with extra questions during the oral examination, for instance he asked me how many times the AFM tip will tap per second in tapping mode... (had no idea)<br /> <br /> '''Unknown date'''<br /> <br /> Right or Wrong<br /> Discuss the chemistry of a silane agent ( trichlorooctylsilane) in a ethanol solution, when a gold substrate is dipped into the solution. Or something like that.<br /> <br /> So the silane hydrolises and forms a SAM on the surface, but since you're using gold and gold forms no oxide , this doesn't work. So the answer was wrong<br /> <br /> Right or wrong<br /> Nanoparticle formation is driven by kinetics instead of thermodynamics<br /> <br /> Question about soft lithography,<br /> Substrate is given and drawn, then photo-resist is spun unto it and a square is etched out, gold is deposited and then chromium layer is deposited,after this acetone is used, HNO3 and then some surface layer draw the new substrate, so after al these steps.add what is what so surface and bulk materials than he asks why you use acetone ( remove Photo-resist) HNO3 ( oxidize chromium) and then the surface layer .<br /> <br /> give two methods for evaluating polarity of a surface on macro scale and on nano scale<br /> I said AFM for nano ,the AFM with the chemically modified tip don't remember the name and contact angle measurements for the macro<br /> <br /> last question was a picture of + and - charged ballz and then they self assemble and you had to sum up all the energetics involved.<br /> <br /> So the questions are quit easy when you have your book, but as stated above, he does go into a lot of detail when asking smaller questions.<br /> <br /> <br /> '''Unknown date'''<br /> <br /> 1. Contained several part. All were related to forming patterns with Alkyl thiols on substrate except for one. Need to explain the approach that will be taken to form the following patterns and motivation for the same<br /> <br /> a. Monolayer on top of gold substrate b. First, Monolayer on top of gold substrate. After this, the height of alkyl thiols have to be changed at certain islands (diameter ~ 10 nm) c. Stripes of alkyl thiols (dimensions in um) d. Alkyl thiol islands at certain positions of gold (dimensions in nm) e. A drawing made of alkyl-thiol f. Pattern made of naked Au clusters on top of Si g. How do you visualize the structures made in d? Provide the Best method<br /> <br /> 2. True/False<br /> <br /> a. +ve/-ve amphiphiles reduce the surface tension. Neutral ones dont reduce it. b. Gold nanoparticles have less quantum yield than semiconducting ones and so not used for fluorescent labeling of cells.<br /> <br /> <br /> '''27/06 exam'''<br /> 1. from paper: hybrid polymer-CdSe solar cells.. there are pics of the device and efficiency of solar cells vs length of CdSe nanorods (positive relation)<br /> <br /> a. explain how it works and state the function of each in the device (there are Al, PEDOT:PSS, polymer-CdSe blend, ITO, Substrate)<br /> <br /> b. how to play with bandgap?<br /> <br /> c. why longer nanorods is more efficient?<br /> <br /> d. how you make nanorods instead of nanodot?<br /> <br /> e. how you measure the topography and composition?<br /> <br /> <br /> 2. a. explain nanowire-based protein detection<br /> <br /> b. draw the output<br /> <br /> c. what is the advantage?<br /> <br /> <br /> 3. a. why CNT can't be dispersed?<br /> <br /> b. what is ur suggested solution?<br /> <br /> c. (pic is shown consist of benzene) why this molecules can disperse the CNT?<br /> <br /> <br /> 4. T/F<br /> <br /> a. mie theory explains flouroscense of CdSe at 10nm<br /> <br /> b. entropy-driven self assembly can only happen in water<br /> <br /> '''Unknown date'''<br /> <br /> 1) A solar cell built from an organic donor and a CdSe nanorod blend acceptor: -explain the working principle -why nanorods? do they have a better efficiency than quantumdots? (shape is better, rods are electronic highways (that's what he said to me )) -how would you examine the structure at nm scale (i just explained stm and it seemed fine for him)<br /> <br /> <br /> 2) true/false -a solution of CdSe nanoparticles has a broad absorption spectrum. when we evaporate the solute, the remaining nanoparticles must have a broad spectrum too, as a result of ostwald ripening. (ostwald has nothing to do here, the particles are allready stable and won't grow) -the insolubility of benzene (and aromats in general) is an enthalpic effect<br /> <br /> <br /> 3)-You want to make a uniform monolayer of an alkyl thiol on gold, how? -&gt; he asked me to give the reaction of the S on AU releasing H2 -You want to make specific islands with thyiols that have a longer alkyl chain -You want to make &quot;trench-shaped&quot; structures of 5µm width -&gt; pdms stamping can go to 50nm -&gt; he asked the chemical structure of PDMS and how the thiols bind to it and how long you would have to press (wtf?)<br /> <br /> <br /> 4) Something about layer by layer deposition and linear charge distrubution vs surface charge distribution. We had to make a table and compare LCD and SCD in several dippings.<br /> <br /> <br /> '''20 June 2014'''<br /> <br /> Q#1: Detection of adsorbic acid in for instance fruit juice you get a picture and I'll try to give an explanation. Sensing goes via functionalized nano particle. A gold nanoparticle has 4 DNAenzymes, with a fluor atom in the middle of enzyme (DNAenzyme: SH-ATTC...G-fluor-AGGGTCC....) and there is a DNA strand with complementary nucleotides of the dna enzyme, and it has a loop (on the place were the fluor is) with Ca2+ in the loop. if this sensor detect AA, then you have left the gold nano-particles, still with some dnaenzyme (just only a little part), 4 fluor atoms still bounded on the other half of the enzyme, en 4 dnastrands with Ca2+. The intensity of the fluor is enhanced.<br /> <br /> a) How is gold nano particle, not yet functionalized with DNA, prepared knowing that the experiments and synthesis carried out in aqueous solution. b) Detection is based on fluorescence; why does the intensity of the fluorescence increases after adsorption of AA?. c) How are the oglionucleotides bounded to the gold nano particle? explain. d) Which spectroscopy technique can you use to detect gold nanoparticles concentration in solution?. e) Why does using gold nanoparticles in solution gives you 2X better results that using ordinary techniques... Explain the methods and comparisons for both techniqes in detail.<br /> <br /> Q#2 Gold nanoparticles are grown like the classical nucleation model, have broad spectrum plasmon resonance. a) What is the effect on emission spectrum if low precursor concentration in used to make gold nanoparticles ?<br /> <br /> Q#3 Picture of molecule with aromatic part and alkyl part this molecule helps to dispersce SWCNT. a) Give a possible mechanism for this molecule interation with SWCNT(draw). Also explain the details about this molecule b) What are the reactions of the alkyl and the aromatic part? c) Why is it difficult to separate these SWCNTs ?<br /> <br /> '''June 23rd 2014 8:00'''<br /> <br /> Q#1 There is a picture of organic molecule given that self-assembles into conductive rod. It has N atom in the middle with 2 extra elextrons and 3 single bonds with 3 benzene rings and then hydro-carbon chains. On second picture there are these rods aligned between two electrodes perpendicular to their surface |----| a) what drives that to assemble b) what makes it align between electrodes<br /> <br /> Q#2 There is picture of lamellar and pillars structure. In the middle of one of the materials there are CdSe nano-particles a) what compound and how can form these structures b) assume the surface of structure is perfectly flat, how can you visualize what material is where on nanoscale c) particles start to aggregate, haw will it affect florescence spectra (with and shift)<br /> <br /> Q#3 There is a picture of rods that are positively charged. When concentration increases they form LC phase. What is the driving force?<br /> <br /> Q#4 There is picture from the paper showing a new way of forming a monocrystal. First there is an amorphous phase formed on a surface, then there are crystal domains that with help of this surface merge into one crystal that then continue to grow. What is the difference between that and classical crystallisation theory?<br /> <br /> b)<br /> <br /> '''June 24th 2014 10.00'''<br /> Q#1<br /> <br /> How do you make a gold surface hydrophilic/hydrophobic?<br /> How do you tune the hydrophobicity (he doesnt want the switching mechanisms but a 'continuous' tuning by adding a certain ratio of different molecules to the SAM)<br /> How would you detect the macroscopic hydrophobicity? Explain the method.<br /> The hydrophobicity varies on the micrometer scale. What method do you use to measure local hydrophobicity?<br /> <br /> Q#2<br /> <br /> An n-type SiNW is used for the detection of a positively charged protein<br /> <br /> Describe the operation (not the fabrication) of this device.<br /> Right/Wrong: The sensitivity of this device increases when the SiNW diameter increases<br /> Describe the characterization method (full AFM description)<br /> <br /> Q#3<br /> <br /> Researchers have made an aggregate of gold NP and ironoxide NP, so-called NP hyperclusters. This method is proposed as an alternative to the electrostatic polymer LBL method to create alternating layers. The researchers added linker molecules to stabilize the aggregate and to give the film a more homogeneous thickness.<br /> <br /> Give a method to separate gold and ironoxide NP in solution (you can give a variety of methods but he says magnetism is the simplest)<br /> Describe a protocol to make a solution of gold NP in water (straight from the course)<br /> Ironoxide NP are made using an inhouse method and functionalized using octylamine. The NP themselves are formed using FeCl3 and PEG (polyethyleneglycol) as reductans and solvent. Afterwards the functionalization is modified by substituting APTMS (aminopropyl-trimethoxysilane) using trace amounts of CH3COOH. Write down the chemistry and give a cartoon diagram of the result.<br /> <br /> Q#4<br /> <br /> Right/wrong and explain: Mie theory describes the significant shift of plasmon frequency (540--&gt;650nm) upon aggregation.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3917 2024-02-01T21:08:32Z

<p>R0804230: /* Prof. Goderis&#039; part: */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===1st of February 2024===<br /> ====Prof. Goderis' part:====<br /> These questions are always based on one or more papers. It's therefore a bit difficult and cumbersome trying to solve questions without the paper... Normally, Prof Goderis should make questions of this examination period available somewhere in November. By all means, feel free to then submit the file to this page!<br /> <br /> ====Prof. Van Meervelts part:====<br /> Are the following statements true or false for each specific case? Explain why and provide a detailed description of the subjects in '''bold'''.<br /> <br /> When unveiling the crystal structure of a ''protein'':<br /> #'''Vapor diffusion''' can be used to obtain a protein crystal.<br /> #'''Solvent flattening''' solves the phase problem.<br /> When using single crystal crystallography to obtain the structure of a ''small organic molecule'':<br /> #'''The normalized structure factor''' enables the crystallographer to determine the absolute configuration.<br /> #ConQuest is useful during '''model refinement'''.<br /> <br /> ===13th of January 2023===<br /> ====Prof. Goderis' part:====<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link.<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing<br /> ====Prof. Van Meervelts part:====<br /> Not available for this examination.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3916 2024-02-01T21:07:29Z

<p>R0804230: /* Prof. Van Meervelts part: */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===1st of February 2024===<br /> ====Prof. Goderis' part:====<br /> These questions are always based on one or more papers. It's therefore a bit difficult and cumbersome trying to solve questions without the paper... Normally, Prof Goderis should make the exam of this examination period available somewhere in November. By all means, feel free to then submit the file to this page! <br /> ====Prof. Van Meervelts part:====<br /> Are the following statements true or false for each specific case? Explain why and provide a detailed description of the subjects in '''bold'''.<br /> <br /> When unveiling the crystal structure of a ''protein'':<br /> #'''Vapor diffusion''' can be used to obtain a protein crystal.<br /> #'''Solvent flattening''' solves the phase problem.<br /> When using single crystal crystallography to obtain the structure of a ''small organic molecule'':<br /> #'''The normalized structure factor''' enables the crystallographer to determine the absolute configuration.<br /> #ConQuest is useful during '''model refinement'''.<br /> <br /> ===13th of January 2023===<br /> ====Prof. Goderis' part:====<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link.<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing<br /> ====Prof. Van Meervelts part:====<br /> Not available for this examination.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3915 2024-02-01T21:07:07Z

<p>R0804230: /* Prof. Van Meervelts part: */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===1st of February 2024===<br /> ====Prof. Goderis' part:====<br /> These questions are always based on one or more papers. It's therefore a bit difficult and cumbersome trying to solve questions without the paper... Normally, Prof Goderis should make the exam of this examination period available somewhere in November. By all means, feel free to then submit the file to this page! <br /> ====Prof. Van Meervelts part:====<br /> Are the following statements true or false for each specific case? Explain why and provide a detailed description of the subjects in '''bold'''.<br /> When unveiling the crystal structure of a ''protein'':<br /> #'''Vapor diffusion''' can be used to obtain a protein crystal.<br /> #'''Solvent flattening''' solves the phase problem.<br /> When using single crystal crystallography to obtain the structure of a ''small organic molecule'':<br /> #'''The normalized structure factor''' enables the crystallographer to determine the absolute configuration.<br /> #ConQuest is useful during '''model refinement'''.<br /> <br /> ===13th of January 2023===<br /> ====Prof. Goderis' part:====<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link.<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing<br /> ====Prof. Van Meervelts part:====<br /> Not available for this examination.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3914 2024-02-01T21:06:27Z

<p>R0804230: /* Exam questions */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===1st of February 2024===<br /> ====Prof. Goderis' part:====<br /> These questions are always based on one or more papers. It's therefore a bit difficult and cumbersome trying to solve questions without the paper... Normally, Prof Goderis should make the exam of this examination period available somewhere in November. By all means, feel free to then submit the file to this page! <br /> ====Prof. Van Meervelts part:====<br /> Are the following statements true or false for, in each specific case? Explain why and provide a detailed description of the subjects in '''bold'''.<br /> When unveiling the crystal structure of a ''protein'':<br /> #'''Vapor diffusion''' can be used to obtain a protein crystal.<br /> #'''Solvent flattening''' solves the phase problem.<br /> When using single crystal crystallography to obtain the structure of a ''small organic molecule'':<br /> #'''The normalized structure factor''' enables the crystallographer to determine the absolute configuration.<br /> #ConQuest is useful during '''model refinement'''.<br /> <br /> ===13th of January 2023===<br /> ====Prof. Goderis' part:====<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link.<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing<br /> ====Prof. Van Meervelts part:====<br /> Not available for this examination.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3913 2024-02-01T21:05:55Z

<p>R0804230: /* Prof. Van Meervelts part: */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===1st of February 2024===<br /> ====Prof. Goderis' part:====<br /> These questions are always based on one or more papers. It's therefore a bit difficult and cumbersome trying to solve questions without the paper... Normally, Prof Goderis should make the exam of this examination period available somewhere in November. By all means, feel free to then submit the file to this page! <br /> ====Prof. Van Meervelts part:====<br /> Are the following statements true or false for, in each specific case? Explain why and provide a detailed description of the subjects in '''bold'''.<br /> When unveiling the crystal structure of a ''protein'':<br /> #'''Vapor diffusion''' can be used to obtain a protein crystal.<br /> #'''Solvent flattening''' solves the phase problem.<br /> When using single crystal crystallography to obtain the structure of a ''small organic molecule'':<br /> #'''The normalized structure factor''' enables the crystallographer to determine the absolute configuration.<br /> #ConQuest is useful during '''model refinement'''.<br /> <br /> <br /> ===13th of January 2023===<br /> ====Prof. Goderis' part:====<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link.<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing<br /> ====Prof. Van Meervelts part:====<br /> Not available for this examination.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3912 2024-02-01T21:05:18Z

<p>R0804230: /* 13th of January 2023 */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===1st of February 2024===<br /> ====Prof. Goderis' part:====<br /> These questions are always based on one or more papers. It's therefore a bit difficult and cumbersome trying to solve questions without the paper... Normally, Prof Goderis should make the exam of this examination period available somewhere in November. By all means, feel free to then submit the file to this page! <br /> ====Prof. Van Meervelts part:====<br /> Are the following statements true or false for, in each specific case? Explain why and provide a detailed description of the subjects in '''bold'''.<br /> When unveiling the crystal structure of a ''protein'':<br /> #'''Vapor diffusion''' can be used to obtain a protein crystal.<br /> #'''Solvent flattening''' solves the phase problem.<br /> When using single crystal crystallography to obtain the structure of a ''small organic molecule'':<br /> #'''The normalized structure factor''' enables the crystallographer to determine the absolute configuration.<br /> #ConQuest is useful during '''model refinement'''.<br /> <br /> <br /> ===13th of January 2023===<br /> ====Prof. Goderis' part:====<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link.<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing<br /> ====Prof. Van Meervelts part:====<br /> Not available for examination.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3911 2024-02-01T21:04:23Z

<p>R0804230: /* Exam questions */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===1st of February 2024===<br /> ====Prof. Goderis' part:====<br /> These questions are always based on one or more papers. It's therefore a bit difficult and cumbersome trying to solve questions without the paper... Normally, Prof Goderis should make the exam of this examination period available somewhere in November. By all means, feel free to then submit the file to this page! <br /> ====Prof. Van Meervelts part:====<br /> Are the following statements true or false for, in each specific case? Explain why and provide a detailed description of the subjects in '''bold'''.<br /> When unveiling the crystal structure of a ''protein'':<br /> #'''Vapor diffusion''' can be used to obtain a protein crystal.<br /> #'''Solvent flattening''' solves the phase problem.<br /> When using single crystal crystallography to obtain the structure of a ''small organic molecule'':<br /> #'''The normalized structure factor''' enables the crystallographer to determine the absolute configuration.<br /> #ConQuest is useful during '''model refinement'''.<br /> <br /> <br /> ===13th of January 2023===<br /> ====Prof. Goderis' part:====<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing<br /> ====Prof. Van Meervelts part:====<br /> Not available for examination.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3910 2024-02-01T20:58:04Z

<p>R0804230: /* Exam questions */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===1st of February 2024===<br /> ====Prof. Goderis' part:====<br /> These questions are always based on one or more papers. It's therefore a bit difficult and cumbersome trying to solve questions without the paper... Normally, Prof Goderis should make the exam of this examination period available somewhere in November. By all means, feel free to then submit the file to this page! <br /> ====Prof. Van Meervelts part:====<br /> Are the following statements true or false for, in each specific case? Explain why and provide a detailed description of the subjects in '''bold'''.<br /> When unveiling the crystal structure of a ''protein'':<br /> #'''Vapor diffusion''' can be used to obtain a protein crystal<br /> #'''Solvent flattening''' solves the phase problem<br /> <br /> <br /> ===13th of January 2023===<br /> ====Prof. Goderis' part:====<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing<br /> ====Prof. Van Meervelts part:====<br /> Not available for examination.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3909 2024-02-01T20:54:19Z

<p>R0804230: /* Exam questions */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===1st of February 2024===<br /> ====Prof. Goderis' part:====<br /> These questions are always based on one or more papers. It's therefore a bit difficult and cumbersome trying to solve questions without the paper... Normally, Prof Goderis should make the exam of this examination period available somewhere in November. By all means, feel free to then submit the file to this page! <br /> ====Prof. Van Meervelts part:====<br /> Are the following statements true or false for, in each specific case? Explain why and provide a detailed description of the subjects in '''bold'''.<br /> When unveiling the structure of a ''protein'':<br /> <br /> ===13th of January 2023===<br /> ====Prof. Goderis' part:====<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing<br /> ====Prof. Van Meervelts part:====<br /> Not available for examination.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3908 2024-02-01T20:54:09Z

<p>R0804230: /* Exam questions */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===1st of February 2024===<br /> ====Prof. Goderis' part:====<br /> These questions are always based on one or more papers. It's therefore a bit difficult and cumbersome trying to solve questions without the paper... Normally, Prof Goderis should make the exam of this examination period available somewhere in November. By all means, feel free to then submit the file to this page! <br /> ====Prof. Van Meervelts part:====<br /> Are the following statements true or false for, in each specific case? Explain why and provide a detailed description of the subjects in '''bold'''.<br /> When unveiling the structure of a 'protein':<br /> <br /> ===13th of January 2023===<br /> ====Prof. Goderis' part:====<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing<br /> ====Prof. Van Meervelts part:====<br /> Not available for examination.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3907 2024-02-01T20:53:24Z

<p>R0804230: /* Exam questions */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===1st of February 2024===<br /> ====Prof. Goderis' part:====<br /> These questions are always based on one or more papers. It's therefore a bit difficult and cumbersome trying to solve questions without the paper... Normally, Prof Goderis should make the exam of this examination period available somewhere in November. By all means, feel free to then submit the file to this page! <br /> ====Prof. Van Meervelts part:====<br /> Are the following statements true or false for, in each specific case? Explain why and provide a detailed description of the subjects in '''bold'''.<br /> When unveiling the structure of a &lt;protein&gt; :<br /> <br /> ===13th of January 2023===<br /> ====Prof. Goderis' part:====<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing<br /> ====Prof. Van Meervelts part:====<br /> Not available for examination.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3906 2024-02-01T20:53:14Z

<p>R0804230: /* Exam questions */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===1st of February 2024===<br /> ====Prof. Goderis' part:====<br /> These questions are always based on one or more papers. It's therefore a bit difficult and cumbersome trying to solve questions without the paper... Normally, Prof Goderis should make the exam of this examination period available somewhere in November. By all means, feel free to then submit the file to this page! <br /> ====Prof. Van Meervelts part:====<br /> Are the following statements true or false for, in each specific case? Explain why and provide a detailed description of the subjects in '''bold'''.<br /> When unveiling the structure of a &lt;protein&gt;:<br /> <br /> ===13th of January 2023===<br /> ====Prof. Goderis' part:====<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing<br /> ====Prof. Van Meervelts part:====<br /> Not available for examination.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3905 2024-02-01T20:51:46Z

<p>R0804230: /* Exam questions */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===1st of February 2024===<br /> ====Prof. Goderis' part:====<br /> These questions are always based on one or more papers. It's therefore a bit difficult and cumbersome trying to solve questions without the paper... Normally, Prof Goderis should make the exam of this examination period available somewhere in November. By all means, feel free to then submit the file to this page! <br /> ====Prof. Van Meervelts part:====<br /> Are the following statements true or false for, in each specific case? Explain why and provide a detailed description of the subjects in '''bold'''.<br /> <br /> ===13th of January 2023===<br /> ====Prof. Goderis' part:====<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing<br /> ====Prof. Van Meervelts part:====<br /> Not available for examination.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3904 2024-02-01T20:32:26Z

<p>R0804230: /* Exam questions */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===1st of February 2024===<br /> <br /> <br /> ===13th of January 2023===<br /> ====Prof. Goderis' part:====<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3903 2024-02-01T20:31:32Z

<p>R0804230: /* 13th of January 2023 */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===13th of January 2023===<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link<br /> And here you'll find my solutions for this particular exam. By all means, if you want to add additional information, or you're absolutely convinced something is wrong: just add it in a comment below (or post your own solutions).<br /> https://drive.google.com/file/d/1xgrCvfQ73Lcc0ZqjDz7YVQrRC-nM-WmW/view?usp=sharing</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3902 2024-02-01T20:15:55Z

<p>R0804230: /* Exam questions */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===13th of January 2023===<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link<br /> And here you'll find my solutions for this particular e</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3893 2024-02-01T15:33:28Z

<p>R0804230: /* Examenvragen */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Exam questions==<br /> ===13th of January 2023===<br /> Via the link, you'll see the exam questions from Prof Goderis' part:<br /> https://drive.google.com/file/d/1mTCEOwZ2v-OtT0TGrcmfofLGQEtQHpD-/view?usp=drive_link<br /> And here you'll find my solutions for this particular e</div>

R0804230 https://wiki.chemika.be/index.php?title=Polymer_Sciences:_from_Synthesis_to_Polymer_Material&diff=3892 2024-02-01T15:20:57Z

<p>R0804230: /* Vakinformatie */</p> <hr /> <div>[[Categorie:Machemie]]<br /> <br /> ==Vakinformatie==<br /> Sinds 2023-2024 heeft professor Nies dit vak langs zich gelegd. Het deel Physical Chemistry is nu verdeeld tussen professor Ianiro (deel Physical Chemistry) en professor Goderis (deel Crystallization).<br /> We gaan er daarom vanuit dat alle voorgaande vragen van professor Nies waardeloos zijn voor reference. Ianiro heeft delen van de leerstof ook aangepast. Dus je zal moeten zien welke vragen goede oefeningen zijn.<br /> Professor Koeckelberghs zijn deel Polymer Chemistry is nog steeds hetzelfde. <br /> Dezelfde cesuur is nog steeds van kracht. Haal minimaal 9/20 voor deel Physics (2/3 totaal punt) en 9/20 op deel Chemistry (1/3 totaal punt), of haal maximum een 9/20 in totaal.<br /> <br /> (Voor '23-'24: Gedoceerd door Professor Nies en Professor Koeckelberghs. Lessen zijn altijd in het Engels. De verdeling is 2/3 op het deel van Nies en 1/3 op het deel van Koeckelberghs. Bij Nies zijn er ook verplichte assignments tijdens het jaar, die meetellen voor een fractie 4/(12-N) van de punten van zijn deel (met N aantal assignments, doorgaans 2). Nies zijn examen is gesloten boek en er moet maar één vraag bij hem mondeling besproken worden (deze wordt op voorhand aangeduid). Bij Koeckelberghs zijn alle vragen mondeling te bespreken.)<br /> <br /> ==Examenvragen==<br /> ===19th of January 2024 Afternoon===<br /> ====Prof. Ianiro====<br /> # 8 Multiple choice questions, half a point each. No GIS-correction:<br /> #*formula Mn, formula Rrms, formula spinodal curve, definition counterion condensation, formula CHIcritical of long poly chain, density of brush layer (densely grafted, flat, good solvent),...<br /> #Keeping in mind that volume fractions and probabilities are connected, derive the Flory-Huggins enthalpy of mixing in a lattice with number of nearest neighbors 𝑧 and with interaction energies 𝜀AB, 𝜀AA, 𝜀BB.<br /> #Explain how polymers behave in the bulk and discuss the concept of relaxation time remembering that the diffusion coefficient is defined by Stokes-Einstein relation 𝐷 = 𝑘B𝑇/𝜁. Where 𝜁 is the friction coefficient, and that the time needed to diffuse of a distance 𝑥 is 𝑡 = 𝑥^2/6𝐷. Link the relaxation time to the rheological behavior of polymers and to the different viscosity (scaling) regimes that can be observed as a function of the chain length 𝑁.<br /> <br /> ====Prof. Koeckelberghs====<br /> #Compare free radical, anionic and cationic vinyl polymerization concerning the monomers used, termination and the possibility and way to turn the polymerization into a living polymerization.<br /> #Explain difference chain- and step-growth. How do we demonstrate which one we have?<br /> #Discuss ROMP.<br /> <br /> ====Prof. Goderis====<br /> #Lamella with surface X,Y, depth l. How is Tm related to l (derivation). Image given.<br /> #Explain shortly how the thickness of a lamella can be measures using X-ray christallography.<br /> #The image in exercise 1 is an ideal respresentation of a polymer crystal. What does it actually look like in a polymer melt?<br /> <br /> ===19th of January 2024 Morning===<br /> ====Prof. Ianiro====<br /> #8 multiple choice questions, half a point each. No GIS-correction.<br /> #Given the entropy: S = -kb(3→R.→R/(2*l^2*N)). For a generic vector: →v^2 = vx^2 + vy^2 + vz^2. Derive the entropy change when a chain is deformed in an arbitrary direction. Describe how to use this to calculate the entropy change upon deformation of a network of k randomly oriented polymer strands.<br /> #What is excl. Volume? How to calculate it, how does it relate to interaction between monomers of real chain? What is the FH-interaction parameter ChiAB and how is it defined? What is the relationship between excl vol and FH-interaction parameter?<br /> <br /> ====Prof. Koeckelberghs====<br /> #What is living/controlled polymerisation? How to experimentally test if a polymer is living controlled? How can a Free Radical Polymerisation become controlled?<br /> #Vinyl monomer. What are the requirements to be able to polymerise? What kind of polymerisations are there? How does the structure affect the polymerisation rate?<br /> #Explain emulsion polymerisation briefly.<br /> <br /> ====Prof. Goderis====<br /> #Lamella with surface X,Y, depth l. How is Tm related to l (derivation). [This is slide 73-74 of prof Goderis.] Image given.<br /> #Explain shortly how the thickness of a lamella can be measures using X-ray christallography.<br /> #The image in exercise 1 is an ideal respresentation of a polymer crystal. What does it actually look like in a polymer melt?<br /> <br /> ===20th of January 2023===<br /> ====Prof. Nies====<br /> #Eq. 1.40 is given. Discuss the limiting behavior for L&lt;&lt;lp and L&gt;&gt;lp. The Kuhn length was defined by two equations. Write them down and give a qualitative description. Based on this, give the relationship between lK and lp. Can a chain with L&lt;&lt;lp also be seen as Kuhn chain? Explain.<br /> #Scientist claim that a polymer in solution shows a Phi(2)-T diagram with a closed loop miscibility hole. Chi(crit,1-2) are given as are T(crit,1-2). The values of Chi(0), Chi(1) and Chi(2) are provided too (Eq. 2.19). From this, calculate s2 and Phi(crit,1-2). Show either qualitatively of quantitatively if their reasoning for a closed loop miscibility hole is justified. Make a sketch of the Phi(2)-T diagram containing Phi(crit,2), T(crit,1-2), the binodals and spinodals.<br /> #Figure 3.27 is given and a graph that demonstrates the linear behavior between 1/l and Tm. In several steps you are guided towards deriving the Gibbs-Thomson-Tammann equation.<br /> <br /> ====Prof. Koeckelberghs====<br /> #Compare anionic and cationic ROP in terms of: monomers, initiators, propagation, transfer, termination and their ceiling temperature.<br /> #Discuss, based on the structure of vinyl monomers, in what way they can be polymerized. Relate the stability of the active species to Rp and discuss retardation and inhibition.<br /> #Discuss briefly how conversion and molar mass relate to each other in step-growth polymerization.<br /> <br /> ===27 augustus 2022===<br /> ====Prof. Nies====<br /> #Grafiek van specific volume relaxation uitleggen<br /> #Gibbs-Thomson equation afleiden<br /> #Polymer in solvent is cooled, binodal/spinodal and Tg curves zijn gegeven. 1) Leg uit wat je denkt dat er zal gebeuren, 2) welke morphology denk je dat gevormd wordt voor trage vs snelle cooling? <br /> ====Prof. Koeckelberghs====<br /> #free radical, anionic and cationic polymerization vergelijken op vlak van a) monomers b) termination reaction c) possibility for living polymerization<br /> #ring opening metathesis polymerization bespreken<br /> ===20 januari 2022===<br /> ====Prof. Nies====<br /> #Afleiding maken van de end to end distance van de freely rotating chain + uitleggen waarom er ⟨ .... ⟩ haakjes worden gebruikt + uitleggen wat L voor de FRC is<br /> #Gegeven formule van de gibbs vrije energie van menging (FH)Flory huggins<br /> #*Wat is de thermodynamische voorwaarde voor spinodaal gedrag? + Wat is de thermodynamische voorwaarde voor kritische toestand?<br /> #*Leid ook verder af wat chi kritisch en phi kritisch zijn hieruit (opnieuw afleiden!)<br /> #*Bepaal of de gegeven Tcritisch op een UCST of LCST systeem wijst <br /> #*Geef UCST en LCST namen voluit<br /> #*Teken een phi T diagram waar je de UCST of LCST van in de oefening uitlegt en uittekend<br /> #Avrami equation gegeven en eveneens een avrami plot<br /> #*Leg uit wat m en k zijn in deze vergelijking<br /> #*Leg uit wat we in deze plot zien ivm de equation, over de volledige tijdsinterval<br /> #*Teken zelf een plot volgens Avrami, waar hetzelfde polymeer (syndiotactic polystyrene) bij andere Tc was: Tc oorspronkelijke plot was 110°C, de 3 anderen waren -30°C, 105°C, 175°C --&gt; Tm en Tg van polystyreen waren gegeven!<br /> <br /> ====Prof. Koeckelberghs====<br /> #Definieer en bespreek living/controlled polymerization. Welke experimenten kan je uitvoeren om aan te tonen dat het gaat om een living/controlled polymerization. Bespreek de algemene methode waarop een free-radical polymerization omgezet wordt in een controlled polymerization. <br /> #Bespreek emulsion polymerization <br /> <br /> ===13 januari 2021===<br /> Verkorte examenduur omwille van corona<br /> ====Prof. Koeckelberghs====<br /> #Definieer en bespreek living/controlled polymerization. Welke experimenten kan je uitvoeren om aan te tonen dat het gaat om een living/controlled polymerization. Bespreek de algemene methode waarop een free-radical polymerization omgezet wordt in een controlled polymerization. <br /> #Bespreek emulsion polymerization <br /> <br /> ====Prof. Nies====<br /> #Gegeven formule van de gibbs vrije energie van menging (FH)<br /> #*Geef de betekenis van ieder symbool in de formule en de eenheid <br /> #*Wat is de thermodynamische voorwaarde voor spinodaal gedrag? <br /> #*Wat is de thermodynamische voorwaarde voor kritische toestand? <br /> #*Schrijf UCST en LCST languit <br /> #*Leidt de vergelijking van chikritisch en phikritisch af<br /> #*Oefening: berekenen Chikritisch, UCST of LCST gedrag? Tekenen fasediagram en verloop van chi in functie van de temperatuur <br /> #Leidt de vergelijking voor de average squared end-to-end distance af voor een WLC met de vergelijking voor een FRC gegeven. <br /> ===16 januari 2020===<br /> ====Prof. Koeckelberghs====<br /> #Anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #Step growth en chain growth vergelijken en hoe je kan bepalen wanneer je welke hebt<br /> #Metathese kort uitleggen<br /> <br /> ====Prof. Nies====<br /> #Taak uitleggen (mondeling).<br /> #Gibs-Thomson-Tammann afleiden voor lamellar crystal, vergelijking voor Gibbs fusie is gegeven<br /> #Derive expression for deltaG = G(deformed) - G(undeformed). Expressions for the squared end-to-end distance for FJC and P(R)dR are given<br /> <br /> ===17 januari 2019===<br /> ====Prof. Koeckelberghs====<br /> #Anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #Step growth en chain growth vergelijken en hoe je kan bepalen wanneer je welke hebt<br /> #Metathese kort uitleggen<br /> <br /> ====Prof. Nies====<br /> #Taak uitleggen (mondeling).<br /> #Grafiek over Tg afhankelijkheid van de cooling rate, uitleggen op moleculair niveau (met betrekking tot mobiliteit)<br /> #Afleiding radius of gyration geven (fjc), toon aan dat &lt;s²&gt;= lb² (N+1)(N-1)/6N en of de uitdrukking verandert als er interacties zijn tussen de massa's met Lennard Jones interactie potentiaal?<br /> <br /> ===14 januari 2019===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #plot van volumeverandering i.f.v. de tijd (case2-figuur 25) gegeven, bespreek ... (physical ageing)<br /> #afleiding voor de Thomson-Tammann smelttemperatuur van een eindig sfeer kristal, met de fusie Gibbs vrij energie van een oneindig groot kristal gegeven<br /> <br /> ===31 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #Anionic versus cationic ring opening polymerization:<br /> #*monomeer<br /> #*intiator<br /> #*general polymerization mechanism<br /> #*termination + transfer<br /> #*ceiling temperature<br /> #Influence of the molecular structure of vinyl monomers on possibility to polymerize. Correlate the molecular structure with:<br /> #*the way monomers can be polymerized<br /> #*rate of polymerization<br /> #*retardation + inhibition<br /> #Influence of conversion on molar mass in step growth polymerization<br /> <br /> ====Prof. Nies====<br /> #Formula growth rate given (case 3 eq. 1.28)<br /> #*discuss the origin of the exponential facors and the front factor in the given equation.<br /> #*discuss dependence of the growth rate on the size of the crystal at a chosen crystallization temperature. Make a schematic plot of the predicted growth rate versus the crystal size for the chosen crystallization temperature.<br /> #*what are the consequences for the predicted growth rate for crystallization behaviour at a particular crystallization temperature?<br /> #Figure volume relaxation (case 2 figure 27)<br /> #Rubbers<br /> #*Define an ideal rubber<br /> #*Derive expression for deltaG = G(deformed) - G(undeformed)<br /> Expressions for the squared end-to-end distance for FJC and P(R)dR are given<br /> <br /> ===25 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #ceiling temperature vergelijken bij vinyl polymerization en ring opening polymerization + kleine bijvragen daarover<br /> #controlled radical polymerization (NMP en ATRP)<br /> #living cationic polymerization<br /> <br /> ====Prof. Nies====<br /> #grafiek spinodal, binodal (die met Berghman's point) toegepast op PDLC, vorming van PDLC uitleggen aan de hand van grafiek<br /> #physical ageing<br /> #avrami plot<br /> <br /> ===19 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #step growth en chain growth vergelijken en hoe ge kunt bepalen wanneer ge wa hebt<br /> #ROMP uitleggen<br /> <br /> ====Prof. Nies====<br /> #taak bespreken (mondeling)<br /> #Gibs-Thomson-Tammann afleiden voor lamellar crystal, vergelijking voor Gibbs fusie is gegeven<br /> #spinodal en critical condition geven + afleiden helemaal en berekenen wat de critische waarden zijn voor 'chi' en 'fi-2', vergelijking Gibbs gegeven<br /> Huggings formule gegeven (niet in boek) is een uitbreiding van Flory-huggings vergelijking, wanneer zijn die aan elkaar gelijk en wat is de betekenis dan<br /> <br /> ===15 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #plot van volumeverandering i.f.v. de tijd (case2-figuur 25) gegeven, bespreek ... (physical ageing)<br /> #afleiding voor de Thomson-Tammann smelttemperatuur van een eindig sfeer kristal, met de fusie Gibbs vrij energie van een oneindig groot kristal gegeven<br /> <br /> ===25 augustus 2017===<br /> ====Prof. Koeckelberghs====<br /> #Vergelijk anionische ring opening polymerizatie met kationische ring opening polymerizatie op vlak van<br /> #*monomeer<br /> #*intiator<br /> #*mechanisme<br /> #*terminatie/recombinatie<br /> #*ceiling temperature<br /> #Lewis Mayo en die R ratio's daar in. Welke dingen invloed daar op hebben en hoe + voorbeeld<br /> #Welk invloed heeft de vorderingsgraad op molaire massa in step growth polymerizatie?<br /> <br /> ====Prof. Nies====<br /> #(mondelinge vraag) bespreek grafiek en waarom dat dit gebeurt (uitleggen op moleculair niveau), grafiek van physical ageing<br /> #Afleiding van hoofdstuk 4 Gibbs vrije energie wanneer een ideaal rubber deformatie ondergaat<br /> #vanalles van UCST en LCST, iets vaags.<br /> <br /> <br /> ===20 januari 2017===<br /> ====Prof. Koeckelberghs====<br /> #Anionische, kationische en frp uitleggen obv monomeer, terminatie en hoe ge het levend kunt maken<br /> #Step growth en chain growth<br /> #Ringopening methatese<br /> <br /> ====Prof. Nies====<br /> Vraag 1:<br /> #Wat is de definitie van een FRC?<br /> #Bij welke condities is de FRC gelijk aan de FJC<br /> #Bereken Lk en Nk voor de limiet van een enorm lange FRC (&lt;R2&gt;frc gegeven)<br /> #Leidt een vergelijking af voor de mean squared end-to-end distance van een ideaal lineair diblock copolymeer bestaande uit Nk1 Kuhn monomeren met lengte lk dat vasthangt via 1 einde aan Nk2 Kuhn monomeren met lengte lk2<br /> Vraag 2:<br /> #Mengsel van PS in methylcyclohexaan (Mw = 355kg/mol)<br /> Bij T=350K bestaat het mengsel uit 1 homogene vloeibare fase. Deze T is 6K boven de flory T. Polymeer volume fractie in de homogene fase is O,2<br /> Bij T=335K: twee vloeibare fases, de polymeer volume fracties van de coexistant fases zijn 0,003 en 0,435<br /> In de compositie range {0,002-0,044} en {0,336-0,435} is de structuur van de initiele fase scheiding kleine druppels in een matrix fase<br /> #*Schets het verloop van delta Gmix ifv de volledige compositierange bij T=333K<br /> #*Duid de points of interest in deze curve aan en leg ze uit.<br /> #*Leg tot he point uit waarom je vraag a zo geschetst hebt<br /> #*Wat zal de morfologie zijn in de initiële fase van scheiding?<br /> <br /> <br /> ===19 Januari 2017===<br /> ====Prof. Koekcelberghs====<br /> #Vergelijken ven anionische en kationische ringopeningpolymerisatie op vlak van<br /> #*Initiatie/Initiatoren<br /> #*Terminatie/transfer<br /> #*Mechanisme<br /> #*Mogelijke monomeren<br /> #*Ceiling temperature<br /> #Geef de factoren die een copolymerisatie beïnvloeden <br /> #Geef de invloed van de conversie bij een step-growth polymerisatie<br /> <br /> ====Prof. Nies====<br /> #Vraag 1: bespreek je taak helemaal (mondeling)<br /> #Vraag 2: Leid het verschil in Gibbs vrije energie voor een vervormd en onvervormd ideaal rubber af. End-to-end distance van een ideaal rubber en de Gaussische distributie zijn gegeven.<br /> #Vraag 3: Gegeven een stelling die zegt dat er een closed-gap miscibility gap plaatsvindt, met een formule voor chi in functie van T. 2 kritische waarden voor de temperatuur zijn gegeven. De vraag is: kan deze stelling kloppen? <br /> <br /> <br /> ===16 januari 2017===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #zie theoretical questions doc case 3 vraag 13, maar alleen de excess Gibbs energy en de chemical potentials waren gegeven<br /> #Vraag 3:<br /> #*thermodynamische uitdrukking voor spinodal en critical conditions afleiden.<br /> #*zie theoretical questions doc case 2 vraag 4 en de uitdrukking voor de Gibbs energy is gegeven<br /> #*de verbeterde Huggins uitdrukking voor de Gibbs energy is gegeven en daarvoor de enthalipsche en entropische bijdragen bepalen.<br /> #*De FH uitdrukking is een speciaal geval van de Huggins uitdrukking: bepaal de conditie van y waarvoor dit geld + geef de fysische betekenis van die conditie<br /> <br /> ===14 januari 2016===<br /> ====Prof. Koeckelberghs====<br /> #Vergelijk chemisch geïnitieerde FRP en ATR op vlak van:<br /> #*Algemeen protocol<br /> #*Snelheidsvergelijkingen<br /> #*Invloed van de moleculaire structuur op de snelheid van polymerisatie<br /> #Leg uit: step growth en chain growth polymerisatie. Hoe kan je experimenteel onderscheid maken tussen beide?<br /> #Leg kort uit: Ziegler-Nattakatalysator<br /> <br /> ====Prof. Nies====<br /> #Gegeven: Tg in functie van cooling rate. Verklaar de moleculaire oorsprong van dit fenomeen. (oral)<br /> #*Mondelinge bijvraag: wat bepaalt, naast de kinetische energie, ook mee het vrije volume?<br /> #Leid een formule af voor het smeltpunt van een eindig sferisch kristal.<br /> #Vrije energie van mengen volgens Flory-Huggins gegeven:<br /> #*Wat zijn de spinodale en kristische voorwaarden?<br /> #*Geef de betekenis en eenheiden van elke parameter in de vergelijking.<br /> #*Geef een concrete uitdrukking voor de kritische en spinodale voorwaarden afgeleid uit de bovenstaande vergelijking.<br /> #*Geef een concrete uitdrukking voor de kritische phi en chi.<br /> #*Gegeven een uitgebreide variant van de vergelijking van Flory en Huggins. Wat zijn de enthalpische en entropische bijdragen?<br /> #*De oorspronkelijke formule van Flory en Huggins is een bijzonder geval van de bovenstaande vergelijking. Onder welke voorwaarde is dit en waarmee komt dit fysisch overeen?<br /> <br /> ===11 januari 2016===<br /> ====Prof. Koeckelberghs====<br /> #Define living/controlled polymerisation. Hoe neem je dit experimenteel waar? Hoe maak je free radical controlled?<br /> #Wat is de invloed van moleculaire structuur van monomeer op manier vinylpolymerisatie, snelheid en retardation/inhibition?<br /> #Bespreek emulsiepolymerisatie.<br /> <br /> ====Prof. Nies====<br /> #Case 2, figuur 27 uitleggen (specifiek volume in functie van tijd) (oral)<br /> #Leid Gibbs Thomson uitdrukking af voor smelttemperatuur van sferisch kristal.<br /> #Uitdrukking s^2 en massacentrum gegeven:<br /> #*Leid average radius of gyration af met alles massa's = m.<br /> #*Toon aan dat average radius of gyration = lb^2 (N+1)(N-1)/6N als i=1,2,3,...,N-1.<br /> #*Veranderen de uitdrukking als er interacties zijn tussen de massa's met Lennard Jones interactie potentiaal?<br /> <br /> ===24 januari 2013===<br /> ====Prof. Koeckelberghs====<br /> #Discuss the ceiling temperature and apply it on both the vinyl polymerization and ring opening polymerization. Is the ceiling temperature of a particular monomer dependent on the way it's polymerized?<br /> Is it possible that a particular monomer, of which the ceiling temperature is such that only low-molar mass oligomers can be obtained via a living anionic polymerization at a certain temperature, can be polymerized into high-molar mass polymer using a free radical polymerization at the same temperature? Motivate your anwer.<br /> #Explain the principle of a controlled radical polymerization and apply it on NMP and ATRP.<br /> #Discuss briefly the living cationic vinyl polymerization.<br /> ====Prof. Nies====<br /> Zie onderstaande afbeelding.<br /> [ <br /> #Assignment 1 (oral)<br /> #The &amp;lt;i&amp;gt;free rotating chain&amp;lt;/i&amp;gt; (FRC) consists of N bonding vectors l&amp;lt;sub&amp;gt;i&amp;lt;/sub&amp;gt;, i=1,...,N with constant bond length |l&amp;lt;sub&amp;gt;i&amp;lt;/sub&amp;gt;| = l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt; and constant bond angles Ï´&amp;lt;sub&amp;gt;ii+1&amp;lt;/sub&amp;gt;=Ï´, i=1,...,N between the successive bonding vectors. The average quadratic end-to-end distance &amp;lt;R²&amp;gt;, valid for all physically sensible values of N, l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt; and Ï´, is given by [[Bestand:R-FRC.JPG]]<br /> #*Show that the average quadratic end-to-end distance &amp;lt;R²&amp;gt; of the FRC chain with very small bond angles also can be written in the Kratky-Porod chain form: &amp;lt;R²&amp;gt; = 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;L-2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;²(1-exp(-L/l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;),<br /> with l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;=l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt;L/(1-cosÏ´) the perstistence length and L the contour length.<br /> #Derive from the general thermodynamic equilibrium conditions the melting point of a polymer crystal in equilibrium with a solution of the polymer.<br /> For the polymer solution you can use the Flory-Huggins excess Gibbs-energy of mixing.<br /> [[Bestand:G(mix).JPG]]<br /> <br /> The chemical potentials of the components are given by:<br /> [[Bestand:Chempot.JPG]] ]<br /> <br /> [[Bestand:240113nies.png]]<br /> <br /> ===18 januari 2013===<br /> ====Prof. Koeckelberghs====<br /> #Compare chemically initiated free radical polymerization and ATRP, for the following aspects:<br /> #*general concept<br /> #*rate of polymerization<br /> #*influence of molecule structure on polymerization rate<br /> #Discuss the differences in mechanism of chain growth and step growth polymerization. How can one investigate which type of polymerization he is dealing with?<br /> #Explain briefly: Ziegler-Natta catalyst<br /> ====Prof. Nies====<br /> #Discussion of assignment 1 (oral)<br /> <br /> Zie onderstaande afbeelding.<br /> <br /> #The expression of average squared end-to-end distance of the Kratky-Porod chain is given: &amp;lt;R²&amp;gt; = 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;L - 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;²(1-exp(-L/l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;)<br /> #*Derive expressions for the Kuhn segment length and the number of Kuhn segments for this chain.<br /> #*Discuss your results. For instance, did you make any assumptions? Mention them explicitly.<br /> #The excess Gibbs ebergy of mixing in the Flory-Huggins model is given: ΔG/N&amp;lt;sub&amp;gt;l&amp;lt;/sub&amp;gt;kT = Δg/kT = (φ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;/s&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;)lnφ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt; + (φ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;/s&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;)lnφ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; + χφ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;φ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;<br /> #*Derive expressions for the spinodal and critical conditions.<br /> #*Derive from these expressions the formulae for the critical composition φ&amp;lt;sub&amp;gt;2,cr&amp;lt;/sub&amp;gt; and critical value of χ.<br /> #*What is the relevance of the spinodal for material behaviour?<br /> [[Bestand:180113nies.png]]<br /> <br /> ===20 januari 2012===<br /> ====Professor Nies====<br /> #Gegeven een fase-diagram uit Case II. Wat gebeurt er als er vanuit punt A (dat links van de critical point lag):<br /> #* traag wordt afgekoeld<br /> #* wordt gequenched (1000K/min)<br /> #* Hoe ziet de oplossing er na koelen uit voor beide gevallen<br /> #5 begrippen uitleggen:<br /> #*Thermo-elastische inversie<br /> #*Physical ageing<br /> #*Second order transition<br /> #*Effective pair potential<br /> #*Nucleation &amp;amp; growth<br /> #Leidt de spinodal en critical conditions af en ook de waarden voor Fi(2,crit) en Chi(krit).<br /> <br /> ====Professor Koeckelberghs====<br /> #Wat is de ceiling temperatuur en correleer dit met vinylpolymerisatie en Ring opening polymerisatie. Is de ceiling temperatuur afhankelijk van hoe we polymeriseren? Stel we polymeriseren via een living anionische polymerisatie. Het monomeer heeft een lage ceiling temperatuur, wat ervoor zorgt dat er geen lange polymeerketens worden gevormd. Kan men dan langere ketens verkrijgen als men bij dezelfde temperatuur via een radicale polymerisatie polymeriseert?<br /> #M1 en M2 worden gecopolymeriseerd. Geef de parameters voor beide monomeren en leg uit waarvan deze afhangen.<br /> # Leg uit: (radicalaire) emulsiepolymerisatie<br /> <br /> ===21 januari 2011===<br /> ====Professor Nies====<br /> # Teken het verloop van de de gibssvrij-energie in functie van volumefractie bij een temperatuur van 300K. Volumefracties = 0,2. Coexistence points en spinodal points gegeven. Ook de verschillende punten aanduiden en kort uitleggen. (deze vraag was mondeling)<br /> # Formule p 50 case 1 gegeven (zonder 4e term)<br /> #* leg de symbolen uit + dimensies + eenheden<br /> #* wat bedoelt men met &amp;quot;volgens de Flory benadering...&amp;quot;<br /> #* leg de twee verschillende termen uit<br /> #* Bereken end-to-end distance in evenwicht bij een flory-solvent<br /> #* Bereken end-to-end distance in evenwicht bij een goed solvent<br /> # Avramiplot+vergelijking gegeven<br /> #*leg de parameters uit<br /> #*hoe kan je volumefractie kristallijne fase meten, leg kort techniek uit.<br /> #*geef een kwalitatieve bespreking van de grafiek<br /> #*wat kan je uit de parameters afleiden<br /> <br /> ====Professor Koeckelberghs====<br /> # zie vragen vorig jaar<br /> <br /> ===15 januari 2010===<br /> ====Professor Nies====<br /> #Er was de grafiek gegeven met daarop de binodal, spinodal en Tg curve. Met daarop 3 punten aangegeven, telkens in het homogene gebied boven de binodal en boven Tg. Punt A: Links van kritische punt, punt B tussen kritische punt en Berghmans punt en punt C rechts van Berghmanspunt. (Alleen deze vraag mondeling)<br /> #*Wat vindt plaats als je in punt A traag afkoelt?<br /> #*Wat vindt plaats als je in punt A afkoelt met 1000K/min<br /> #*Wat vindt plaats als je in punt B traag afkoelt<br /> #*Wat vindt plaats als je in punt B afkoelt met 1000K/min<br /> #*Wat vindt plaats als je in punt C traag afkoelt?<br /> #*Wat vindt plaats als je in punt C afkoelt met 1000K/min<br /> #Vergelijking van Groeisnelheid bij kristallisatie (U) gegeven: U=Fexp(A)exp(B)exp(C) Zowel F,A,B,C waren gegeven in symbolen(vergelijking onder 7.B case III)<br /> #*Geef waarvoor de symbolen staan en wat hun eenheden zijn.<br /> #*Verklaar waar de Frontfactor (F) en de drie exp's vandaan komen<br /> #*Bespreek temperatuursafhankelijkheid en geef een schets<br /> #Geef de definitie van een ideale Rubber<br /> #* Leid de uitdrukking voor af voor S bij een willekeurige verandering. P(R) gegeven<br /> <br /> ====Koeckelberghs====<br /> #Vergelijk radicalaire, anionische en kationische vinylpolymerisatie<br /> #*Mogelijke monomere deeltjes (stabiliteit)<br /> #*Terminatie reacties<br /> #*Invloed van verschillende voorkomende deeltjes op sneldheid (hiermee bedoelde hij de associated ion pairs etc)<br /> #*Mogelijke manier om ze 'levend' te maken. (of quasi levend)<br /> #*? dacht dat er nog 1 was<br /> #Je wil een ideaal, perfect blockcopolymeer maken van MMA en MA op anionische wijze. Welk monomeer moet je eerst polymeriseren? Blijft indien je dit met ATRP wil doen de volgorde dezelfde?<br /> #Bespreek kort Ring Opening Metathesis Polymerisatie.</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3891 2024-02-01T15:17:19Z

<p>R0804230: /* Vakinformatie */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Course information==<br /> <br /> Course taught by professors Bart Goderis and Luc Van Meervelt. The first and latter part respectively account for three and two credits. The last credit will be earned at the submission of a report of the excursion, taking place in the second semester (ESRF and CERN). All the further information can be found via this link:<br /> https://onderwijsaanbod.kuleuven.be/2023/syllabi/e/G0G99AE.htm#activetab=doelstellingen_idp1523248<br /> <br /> Lecture attendance is strongly recommended, so that additional information can be noted on the provided slides. This increases the chances of passing the exam.<br /> <br /> ==Examenvragen==</div>

R0804230 https://wiki.chemika.be/index.php?title=Nanostructure_Determination_via_Electromagnetic_Radiation&diff=3890 2024-02-01T14:52:24Z

<p>R0804230: /* Vakinformatie */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Vakinformatie==<br /> <br /> Vak gedoceerd door professoren Bart Goderis en Luv Van Meervelt.<br /> <br /> ==Examenvragen==</div>

R0804230 https://wiki.chemika.be/index.php?title=Advanced_Organic_Chemistry&diff=3681 2024-01-11T19:46:01Z

<p>R0804230: /* 26 January 2023 */</p> <hr /> <div>[[Categorie:Machemie]]<br /> <br /> ==Examenvragen==<br /> ===26 January 2023===<br /> IMPORTANT NOTE: The following exercise assignments contain a number of errors. In this drive, you can find everything without structural mistakes for this specific exam. https://docs.google.com/document/d/1mfHLVkxhkN63DB88_RoDP4fWwyL5m0VA/edit?usp=sharing&amp;ouid=101486339872913430382&amp;rtpof=true&amp;sd=true<br /> #Devise a strategy to obtain following molecule using Tosylazide and Rhodium salt and any other reagent. No stereochemistry needs to be explained. (I drew the endproduct wrongly, one of the substituents is acetate not a ketone)[[Bestand:Exam_Question_1.png]]<br /> #Both products have a common intermediate. Explain in detail how these products are formed [[Bestand:Exam_Question_2.png]]<br /> #Discuss the mechanism to obtain following products [[Bestand:Exam_Question_3.png]]<br /> #Discuss the mechanism of this reaction. No stereochemistry has to be explained (It's PPh3=CH2 btw, another mistake) [[Bestand:Exam_Question_4.png]]<br /> #Explain the following reaction. [[Bestand:Exam_Question_5.png]]<br /> <br /> PS: I might be wrong on questions 3b and 5. I'm going off of memory here.<br /> <br /> ===27 januari 2022===<br /> Door Corona was er dit jaar geen mondeling. Hierdoor was de moeilijkheidsgraad van de vragen iets lager. Professor Dehaen stuurt immers normaal gezien veel bij tijdens het mondeling. Indien er dus wel terug mondelinge examens kunnen plaatsvinden zijn de examenvragen van eerdere jaren representatiever. <br /> <br /> [[Bestand:Organiccc1.jpg]]<br /> [[Bestand:Organiccc2.jpg]]<br /> <br /> ===30 augustus 2021===<br /> Door Corona was er dit jaar geen mondeling. Hierdoor was de moeilijkheidsgraad van de vragen iets lager. Professor Dehaen stuurt immers normaal gezien veel bij tijdens het mondeling. Indien er dus wel terug mondelinge examens kunnen plaatsvinden zijn de examenvragen van eerdere jaren representatiever. <br /> <br /> [[Bestand:Organic-30-8-2021 oef 1-4.png]]<br /> [[Bestand:Organic-30-8-2021 oef 5-6.png]]<br /> <br /> <br /> ===20 januari 2021===<br /> Door Corona was er dit jaar geen mondeling. Hierdoor was de moeilijkheidsgraad van de vragen iets lager. Professor Dehaen stuurt immers normaal gezien veel bij tijdens het mondeling. Indien er dus wel terug mondelinge examens kunnen plaatsvinden zijn de examenvragen van eerdere jaren representatiever. <br /> # 6 punten [[Bestand:Oefening_1.png]]<br /> # 3 punten [[Bestand:Oefening_2.png]]<br /> # 3 punten [[Bestand:Oefening_3.png]]<br /> # 4 punten [[Bestand:Oefening_4.png]]<br /> # 4 punten [[Bestand:Oefening_5.png]]<br /> <br /> ===6 januari 2021===<br /> Door Corona was er dit jaar geen mondeling. <br /> # In de synthese van een product reageert het gegeven diketon met 2 equivalenten van een een ylide. Geeft de structuur van dit ylide, de structuur van intermediairen A en B en bespreek kort het mechanisme. De laatste stap is een rearrangement met een zuur. [[Media:Oganic 6-1-2021 oef 1.png]] (/6)<br /> # Geef het mechanisme van de reactie [[Media:Organic 6-1-2021 oef 2 .png]] (/3)<br /> # Geef het mechanisme van de reactie [[Media:Organic 6-1-2021 oef 3.jpg]] (/3)<br /> # Gegeven: een lijst van 8 reagentia, waaronder een H2SO4, acetonitrille, Na, NH2OH, t-BuONa, TiCl4, Me3SiCl en 2-broompropaan. Slechts 6 van de 8 moeten worden gebruikt. Geef de intermediairen X en Y en het mechanisme. De laatste stap is een fragmentatiereactie. [[Media:Organic 6-1-2021 oef 4.PNG]] (het kan zijn dat er een klein foutje zit in de structuur van het eindproduct) (/6)<br /> # Geef het mechanisme van de reactie. In de eerste stap reageert het startproduct met een bromopropaan-derivaat. De laatste stap is een pericyclische reactie. Verloopt de cyclisatie thermisch of fotochemisch? [[Media:Organic 6-1-2021 oef 5.PNG]] (/3)<br /> <br /> <br /> <br /> ===20 januari 2020===<br /> WERKEND BESTAND: [[Media:Organic examen 2020 deel 1.jpg]] en [[Media:Organic examen 2020 deel 2.jpg]]<br /> <br /> <br /> <br /> <br /> [[Categorie:Machemie]]<br /> <br /> ===22 januari 2019===<br /> <br /> [[Media:Vragen_Advanced_Organic_22-01-19_VM_Deel_1.jpg]]<br /> [[Media:Vragen_Advanced_Organic_22-01-19_VM_Deel_2.jpg]]<br /> <br /> ===21 januari 2019 VM===<br /> <br /> ====Examen====<br /> <br /> [[Bestand:ExamAdvOrg21jan2019.png|800px]]<br /> <br /> ====Oplossingen====<br /> [[Media:SolutionsAdvOrg21jan2019jpg.jpg]]<br /> <br /> <br /> ===28 januari 2013 NM===<br /> <br /> [[Media:Examen organische chemie 23-01-2017.jpeg]]<br /> <br /> #Explain the following reaction. [[Bestand:org1.png]]<br /> #How is given cyclopropane synthesized from diethyl malonate in several steps? Choose reagents such that a maximal yield is obtained. [[Bestand:org2.png]]<br /> #This reaction scheme is an example of a benzannelation reaction. Upon heating, several consecutive steps happen so that the given end product is obtained. Among these steps are three electrocyclic reactions (two 4-electron and one 6-electron), a tautomerization, and a cycloaddition (not necessarily in this order). [[Bestand:org3.png]]<br /> #Explain formation of this product in presence of base. [[Bestand:org4.png]]<br /> #Give product A and explain how this reaction occurs. [[Bestand:org5.png]]<br /> #What products will be formed in following reactions? [[Bestand:org6.png]]</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_in_Motion&diff=3680 2024-01-11T19:40:26Z

<p>R0804230: /* 29th August 2023 */</p> <hr /> <div>[[Categorie:Machemie]]<br /> <br /> ==Vakinformatie==<br /> Vak van 6 stp gedoceerd door Koen Clays en Jérôme Loreau. Bestaat uit 2 delen: Advanced Chemical Kinetics en Dynamics of Chemical and Biochemical Systems, het laatste deel wordt gedoceerd door Clays en was voordien een vak op zichzelf (kijk naar die examenwikipagina voor oudere vragen).<br /> Dynamics of Chemical and Biochemical Systems is een mondeling examen, bevattende hoofdstukken over (1) stabiliteit, (2) fluctuaties, (3) diffusie, (4) Langevin, (5) relaxatie, (6) evolutie. Het laatste hoofdstuk werd de laatste 2 jaar weggelaten.<br /> <br /> ==Examenvragen==<br /> ===29th August 2023===<br /> ====Advanced Chemical Kinetics====<br /> =====First question=====<br /> Given a Diels-Alder reaction of A+B-&gt;C, elementary, exothermic.<br /> * H2C=CH-CH=CH2 (1,3-butadiene) + H2C=CH2 (ethylene) -&gt; H2C=CH-CH2-CH2-CH=CH2 (cyclohexene)<br /> # Give the order of the reaction, and the unit of the rate coefficient.<br /> # Describe entropy and enthalpy profile of this reaction.<br /> # Would you expect the transition state to be more like the reactants or the product?<br /> # Based on your answer of the previous question, which type of energy is more suitable before the transition state?<br /> # What methods could be used to describe the rate coefficient? What information do we need to know for each method?<br /> # If the product further undergoes isomerization or fragmentation, what method should we use for it?<br /> =====Second question=====<br /> Lindemann’s theory about unimolecular reaction.<br /> # Describe this theory, write the expression of rate coefficient.<br /> # What is the problem of this theory and how to fix it?<br /> ====Dynamics of Chemical and Biochemical Systems====<br /> # Prove that for stability conditions in terms of entropy can be related to a minimum in &quot;energy&quot;.<br /> # Explain the relation between Fick's laws, Langevin equation and the Einstein equation.<br /> <br /> ===13th January 2023===<br /> ====Advanced Chemical Kinetics====<br /> =====First question=====<br /> # Give the rate constant described by TST and explain the different elements.<br /> # Given are the expressions for Qrot and Qtrans. Qelec and Qvib can be neglected. Describe the temperature dependence for the following reactions:<br /> #* F + H2 --&gt; HF + H<br /> #* C2H4 + HCl --&gt; C2H5Cl<br /> # What becomes the temperature dependence if we include Qvib.<br /> # Compare with the result obtained from the Arrhenius equation (A in Arrhenius equation is obtained via experiment whereas with TST the pre-exp. factor is obtained via direct calculation)<br /> # Can we do quantum calculations for these reactions. Explain<br /> <br /> =====Second question=====<br /> # Unimolecular reaction that shows first order behavior at high pressure and second order behavior at low pressure. Write down the reaction rates and the dimensions of the rate constants for these two cases.<br /> # Prove qualitatively and quantitative the rates at high and low pressure.<br /> <br /> ====Dynamics of Chemical and Biochemical Systems====<br /> # Given is the Master Equation of Fluctuation Theory, for both P(delta P, delta S) and P(delta T, delta V). Derive the amplitude of fluctuations for one of the four possible fluctuations.<br /> # The reaction is: A+B &lt;-&gt; C+D. Derive and describe the relaxation for an instantaneous T-jump. What are the minimal conditions/requirements and which ones are optimal? (see page 10 of the relaxation pdf)<br /> <br /> ===29th August 2022===<br /> ====Advanced Chemical Kinetics====<br /> # Given the ozone reaction that happens in the earths stratosphere. What method would be the most accurate to describe the rate constant? (justify)<br /> # Question about TST<br /> 1) Write down the expression for the rate constant in TST. Explain the different elements.<br /> 2) Given are Qtrans and Qrot equations (Qel and Qvib can be neglected). Describe the temperature dependency of the rate constant for the following reactions (both have non-linear TS):<br /> *F + H2 --&gt; HF + H<br /> *non-linear molecule + linear molecule --&gt; non-linear molecule (Was specific, but don't remember the molecules)<br /> 3. Exercise 2.3<br /> <br /> ====Dynamics of Chemical and Biochemical Systems====<br /> # Explain how we get from the entropy maximum of the second law of thermodynamics to the minimum in energy. Explain what role fluctuations play here and explain the probability.<br /> # Explain the relation between Fick's laws, Langevin equation and the einstein equation. (He said no derivation was necessary) Explain correlation between the diffusion constant and temperature and friction.<br /> <br /> ===14 januari 2022 - Voormiddag===<br /> ====Advanced Chemical Kinetics====<br /> 1. [NO3] + [CO] --(fast)-&gt; [NO2] + [CO2] bij T hoger dan 255°C; [NO2] + [NO2] --(slow)-&gt; [NO3] + [NO] en [NO3] + [CO] --(fast)-&gt; [NO2] + [CO2] bij T lager dan 255°C (exotherme reacties)<br /> 1) Leid voor beide reacties de reactie rate af (tweede met steady state approximation)<br /> 2) Wat is de orde van elke reactie en de bijboherende units (2de orde; unit = cm^-3/s)<br /> 3) Teken het energieprofiel ifv reactie coordinaat<br /> 4) Welke quantum dynamische techniek verkies je: time independent of time dependent? (Time dependent wegens reacties met meer dan 4 atomen. Dit is niet doenbaar voor time independent)<br /> 5) Welke technieken zou je nog kunnen gebruiken voor de k te berekenen? (hard sphere, tst, capture theory, classical)<br /> 6) Stel de reactie, die exotherm is, heeft een late barrière. Welke energie is nodig voor deze te overbruggen? (Polanyi's rules, E(vibratie) nodig) <br /> 2. Oefening 3 van Chapter 2 met als extra vraag de delen van de k(hard sphere) uit te leggen.<br /> <br /> ==== Dynamics of Chemical and Biochemical Systems====<br /> # Gegeven de Master Equation of Fluctuation Theory, voor zowel P(delta P, delta S) als P(delta T, delta V). Leid de amplitude van de fluctuaties van een van deze 2 vergelijkingen af.<br /> # Reactie A+B &lt;-&gt; C+D. Leid de relaxatieformule af. Wat zijn de minimale condities/voorwaarden en wat zijn de optimale?</div>

R0804230 https://wiki.chemika.be/index.php?title=Grondslagen_van_de_Chemie&diff=3679 2024-01-11T19:39:13Z

<p>R0804230: /* Vakinformatie */</p> <hr /> <div>[[Categorie:Bachelor Chemie]]<br /> [[Categorie:Bachelor Biochemie]]<br /> <br /> ==Vakinformatie==<br /> Basisvak chemie voor 1e bachelor chemie, biochemie, biologie en geologie.<br /> Gedoceerd door professor Koen Clays (sinds academiejaar 2013-2014, daarvoor door Prof. Bart Goderis). Het examen is deels mondeling, deels schriftelijk.<br /> <br /> ''academiejaar 2022-2023''<br /> * Aanpak vak<br /> ** Gegeven door Prof. Koen Clays<br /> *** Werkt vaak dingen uit op het bord die zeer nuttig/noodzakelijk zijn op een examen te vermelden, lessen volgen zijn dus wel zeker sterk aan te raden!<br /> ** Examen volledig schriftelijk<br /> ** Examen + practica<br /> * Kwaliteit cursus<br /> ** Er zijn geen slides, boek is zeker voldoende om te slagen<br /> * Examenvragen<br /> ** Theorievragen komen vaak terug<br /> ** Oefeningen zijn zeer vergelijkend met die van de oefenzittingen, maak ook zeker de makkelijke oefeningen opnieuw want deze kunnen ook voorkomen<br /> ** Vooral deel E is enorm belangrijk!!<br /> * Practica<br /> ** Griet Depotter, beste practica-assistent van het eerste jaar!<br /> ** Is goed te doen<br /> * Oefenzittingen<br /> ** Op de website van bios staan de oplossingen van enkele jaren geleden, zijn niet exact hetzelfde, maar het principe komt steeds op hetzelfde neer<br /> <br /> ==Examenvragen==<br /> <br /> === 17 januari 2023===<br /> <br /> Theorie:<br /> # Bij welke reacties gebruik je een katalysator en bij welke is quenchen van toepassing? (bij elk een voorbeeld geven + afleidingen formules en verduidelijking hierbij + grafieken)<br /> # Halfreacties autoaccu (functies chemische elementen geven, welke richting oplaad en welke ontlaad, waarom die fasetoestand bij lood)<br /> <br /> Oefeningen:<br /> # Geometrie, hybridisatie, polair/apolair (uitleggen waarom) van SO3(2-)<br /> # pH bepalen van 0.4M Na2SO3<br /> # Oplosbaarheid van PbI2 berekenen + hoeveel KCl toevoegen ter vorming van Pb(Cl)4(-) bij een bepaalde concentratie aan PbI2 + wordt er nog neerslag gevormd<br /> <br /> === 23 augustus 2022===<br /> Theorie: <br /> # Schrijf uit hoe je bekomt tot reactie 7 (pagina 119 BOD) en leg je redeneringen uit. (reductie half reacties- reactie uitgeschreven op bord in de les)<br /> # Leg de relevantie van de ladingsdichthied (niet electronendichtheid) in de scheikunde uit. [antw.: complexatie en neerslag reacties, in zuur als protontransfer van Hˆ+ (te grote ladingsdichtheid om te bestaan), electrontransfer reacties]<br /> <br /> Oefeningen:<br /> # HCN toevoegen om Co(OH)2 beter op te lossen. Welke HCN-concentratie nodig om 6,79 g Co(OH)2 in oplossing te brengen in 250 mL water? (Analoog oefening 8 E4)<br /> # Is volgende reactie aflopend bij 40 graden celcius? 2NH4NO3 &lt;--&gt; 2N2 + 4H2O + O2 (zie o.a. oef 4/6/7/E5 deel D)<br /> <br /> === 18 januari 2022 ===<br /> Theorie:<br /> 1. Hoe kan je de snelheid van een reactie verhogen, wat gebeurt er met het evenwicht?<br /> 2. Buffers: vuistregels + afleiding, verband met titratie, is bloed een goede buffer?<br /> <br /> Oefeningen:<br /> <br /> oefening 1:<br /> a. molaire oplosbaarheid van Ag2Cr2O7 in zuiver water<br /> b. hoeveel NH3 nodig om 0,100 mol AgI op te lossen in 0,500L (Ag(NH3)2^+ wordt gevormd)<br /> c. toon aan dat er geen AgOH neerslag gevormd wordt<br /> <br /> oefening 2:<br /> a. redoxreactie opstellen voor N2/NH2OH en Al(OH)4^-/Al<br /> b. toon aan dat de reactie aflopend is bij 25°C<br /> <br /> === 16 augustus 2021 ===<br /> Theorie:<br /> #Op welke manieren kan je de snelheid van een reactie vergroten, leg uit wat er dan ook met de evenwichtsconstante gebeurt. Verandert hierbij de ligging van het evenwicht? Gebruik formules of figuren om dit aan te tonen<br /> #Op welke manier beïnvloedt complexatie het redoxpotentiaal van een metaal? Leg uit, geef een voorbeeld. In de natuur wordt Fe gebruikt voor reversibele redoxreacties. Waarom?<br /> <br /> Oefeningen: <br /> #Boven of onder welke temperatuur gaat deze reactie spontaan op: O2 (g) + N2 (g) —&gt; 2NO (g)<br /> #HCN verhoogt de oplosbaarheid van Fe(OH)2, hoe groot is de concentratie van HCN die je nodig hebt om 250 ml 3,37g Fe(OH)2 in oplossing te brengen?”<br /> <br /> === 6 januari 2021 ===<br /> Theorie 1:<br /> #Bespreek alle K’s die we hebben gezien in de cursus en geef een voorbeeld waarin hun definitie duidelijk wordt. Indien je iets kan zeggen over K&gt;&gt;1 K=1 en K&lt;&lt;1, voeg je dit hieraan toe.<br /> #Gebruik een voorbeeld uit 1a en leg uit hoe je K puur theoretisch kunt vinden.<br /> #Geef een mogelijk verband tussen K en k indien er een is.<br /> <br /> Theorie 2:<br /> Bespreek de elektrolyse van water zonder NaCl, met een beetje NaCl en met veel NaCl.<br /> <br /> Oefening 1:<br /> Bewijs dat dankzij de complexvorming, PbCl2 niet neerslaat, wanneer we 50ml Pb(NO3)2 (0,4M) bij 50ml BaCl2 (0,6M)doen.<br /> <br /> Oefening 2:<br /> 0,700M NaHSO3 en 0,450M Na2SO3<br /> #Bereken de pH.<br /> #Bereken de pH bij het toevoegen van 20ml KOH.<br /> #Bij welke concentratie aan NaOH de buffer (100mL) niet meer werkt.<br /> <br /> === 13 augustus 2020 ===<br /> Theorie:<br /> 1) Leg homogene, heterogene en enzymatische katalyse uit. Geef ook telkens een voorbeeld. Leg de gelijkenis tussen heterogene en enzymatische katalyse uit. Leg de gelijkenis tussen homogene en enzymatische katalyse uit. /4<br /> 2) Vergelijk chroomvocht (dichromaat in zwavelzuur), piranhazuur (waterstofperoxide in zwavelzuur), koningswater en cyanide in base als oplosmiddelen voor (edel)metalen. /6<br /> <br /> Oefeningen:<br /> 1) Bereken de oplosbaarheid van AgBr in een 0.053M NH3 oplossing. Ag(NH3)2- wordt gevormd.<br /> 2) Is volgende reactie (reactie gegeven) aflopend bij 68 graden C? Toon aan met berekeningen.<br /> <br /> === 15 januari 2020 voormiddag ===<br /> Theorie:<br /> 1) Hoe evenwicht verschuiven naar kant van producten, verandert er iets aan de snelheid?<br /> 2) De ruimtelijke structuur van de covalente binding, 4 relevante voorbeelden geven en bespreken.<br /> <br /> Oefeningen:<br /> 1) Bereken Kd van complex Ag(CN)2 adhv thermodynamische eigenschap bij 25°C<br /> 2) Na3PO4 0.045 M: bereken werkelijke concentraties van PO43-, Na+, HPO42-, H2PO4-, H3PO4, H3O+, OH- en bereken de pH.<br /> <br /> === 14 januari 2020 namiddag ===<br /> theorie:<br /> #Hoe verklaar je de werking van een &quot;hoog-rendements&quot; brander voor een centrale verwarming? Welke aanpassingen dienen er te gebeuren in vergelijking met een klassieke brander<br /> #Bespreek de dissociatie van HgCl2. Waarmee is dit te vergelijken?<br /> <br /> oefeningen:<br /> #Je voegt 50 mL van een 0.0200M AgNO3 - oplossing toe aan 50 mL van een 0.0300M NaCN-oplossing. Zal AgCN neerslaan, ondanks de complexvorming (Kst Ag(CN)2- = 2.5 x 10^20). Verwaarloos de basische eigenschappen van CN-<br /> #Bepaal grafisch orde van de reactie, de snelheidsconstante en halfwaardetijd. Je krijgt de beginconcentratie van het reagens gegeven, en het verloop van de concentratie van een product. (Dus je moet nog berekenen, hoe het verloop van de concentratie van het reagens gaat)<br /> <br /> === 13 januari 2020 namiddag ===<br /> theorie:<br /> 1) bespreek de elektrolyse van water of in een waterige oplossing van zeezout (NaCl) voor volgende situaties: zonder toevoeging van zout, bij toevoeging van een beetje NaCl, bij toevoeging van veel NaCl<br /> 2) Bespreek homogene, heterogene en enzymatische katalyse: geef verschillen en gelijkenissen. Geef telkens een relevant voorbeeld ter illustratie.<br /> <br /> oefeningen:<br /> 1) reactie N2 + O2 --&gt; 2NO gegeven en berekenen boven/onder welke temperatuur de reactie spontaan is<br /> 2) Berekenen hoeveel gram NaCl je moet toevoegen aan 0,448g Cu(OH)2 om dit volledig te kunnen oplossen in 100 ml water als je weet dat het complex [CuCl4]2- wordt gevormd<br /> <br /> === 13 januari 2020 voormiddag ===<br /> theorie<br /> # Buffer<br /> # Reactiemechanisme van Broom<br /> <br /> ===?===<br /> Theorie:<br /> 1) hoe kan men de snelheid van een chemische reactie vergroten? Verandert dit ook iets aan het evenwicht?<br /> 2) chemische eigenschappen ammoniak, hebben ze dan een zwakke of sterke functie? Geef voorbeeldreacties<br /> 3) bespreek de thermodynamische eigenschappen van de autoprotolyse van water. Zie hiervoor tabel 6.9 BOD<br /> <br /> Oefeningen:<br /> 1) bereken of neerslag wordt gevormd bij samenvoegen 2 stoffen<br /> 2) bereken potentiaal galvanische cel<br /> <br /> === 1 februari 2019 namiddag===<br /> theorie<br /> #Leg uit hoe een biprotisch zuur dissocieert en geef een voorbeeld. Vergelijk deze dissociatie met die van HgCl&lt;sub&gt;2&lt;/sub&gt;<br /> #Broom in base<br /> oefeningen<br /> <br /> #Bepaal de standaardreductiepotentiaal van het koppel Zn(OH)&lt;sub&gt;2 (s)&lt;/sub&gt;\ Zn&lt;sub&gt;(s)&lt;/sub&gt; met het oplosbaarheidsproduct van Zn(OH)&lt;sub&gt;2&lt;/sub&gt; en de standaardreductiepotentiaal van het koppel Zn&lt;sup&gt;2+&lt;/sup&gt;\ Zn&lt;sub&gt;(s)&lt;/sub&gt; <br /> #Een klontje vast ethanol met een massa van 50 g wordt bij 155.80 K overgoten met 2.22 L (1 L = 0.79 kg) vloeibaar ethanol waardoor het klontje zal smelten. Wat is de begintemperatuur van het vloeibaar ethanol als je weet dat het systeem een eindtemperatuur van 287.80 K bereikt en als je weet dat er geen energie verloren gaat aan de omgeving?<br /> <br /> === 21 januari 2019 namiddag===<br /> theorie<br /> #vervolledig de reactievergelijking ClO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; + Cl&lt;sup&gt;-&lt;/sup&gt; -&gt; Cl&lt;sub&gt;2&lt;/sub&gt; + H&lt;sub&gt;2&lt;/sub&gt;O en geef een plausibel reactiemechanisme.<br /> #bespreek de elektrolyse van water of in een waterig milieu zonder toevoeging van zout, bij toevoeging van een beetje NaCl, bij toevoeging van veel NaCl. <br /> <br /> oefeningen<br /> #hoeveel natriumthiosulfaat is er nodig om 0,025 mol AgBr op te lossen in 500 ml? Het complex zilverthiosulfaat wordt gevormd. <br /> #een ijsklontje met massa 56 gram wordt in 150 g water gedaan om dit af te koelen. Het ijsklontje heeft een begintemperatuur van 0°C en het geheel heeft een eindtemperatuur van 14°C. Bereken de begintemperatuur van het water.<br /> <br /> === 16 januari 2019 voormiddag===<br /> Theorie<br /> #Bespreek de spontane ontbinding van waterstofperoxide. Welke parameters dragen bij tot de ontbinding en hoe kan je dit tegen gaan?<br /> #De ruimtelijke structuur van de covalente binding, 4 relevante voorbeelden geven en bespreken.<br /> Oefeningen<br /> <br /> #0,040 M 100 mL H&lt;sub&gt;3&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt; bij 100 ml 4M Ca&lt;sup&gt;2+&lt;/sup&gt;-ionen. Wordt er neerslag gevormd?<br /> #Een orde oefening met grafisch de halfwaarde tijd en k bepalen<br /> <br /> === 15 januari 2019===<br /> Theorie<br /> #Hoe kan je het evenwicht naar de kant van de producten krijgen. Heeft dit ook invloed op de snelheid van de reactie? /6<br /> #Stel een chemisch mechanisme op zodat citroenzuur (wat een bestandsdeel is van citroensap) kan ontgiften. /4<br /> <br /> Oefeningen<br /> #Bepaal de K&lt;sub&gt;b&lt;/sub&gt; uit de gegeven redoxkoppels (H&lt;sub&gt;2&lt;/sub&gt;O/H&lt;sub&gt;2&lt;/sub&gt;O (E&lt;sup&gt;0&lt;/sup&gt;=1.76V) en HO&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt;/OH&lt;sup&gt;−&lt;/sup&gt;) (E&lt;sup&gt;0&lt;/sup&gt;=0.87V). Met welke andere 2 koppels kan je dit nog doen? /3<br /> # Geef de lewisstructuur, hybridisatie, polariteit (+ uitleg), en geometrie van XeF&lt;sub&gt;2&lt;/sub&gt; en PBr&lt;sub&gt;3&lt;/sub&gt;. /3<br /> <br /> === 14 januari 2019===<br /> Theorie<br /> #Geef de twee vuistregels voor een goede buffer en leg ze uit adhv neutralisatiegraad en buffercapaciteit. Leg uit bloed als buffer en waarom het geen ideale buffer is. Geef de relatie tussen een buffer en een pH- titratie(curve). /6<br /> #Vervolledig deze reactie, BrO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; + Br&lt;sup&gt;-&lt;/sup&gt; → Br&lt;sub&gt;2&lt;/sub&gt; + H&lt;sub&gt;2&lt;/sub&gt;O, en geef een plausibel reactiemechanisme voor deze reactie (Staat niet in de cursus maar wel gezien als een extra voorbeeld). BOD Tabel 6.2 n.7 /4<br /> <br /> === 30 januari 2018 namiddag===<br /> Theorie<br /> #Welke verbindingen zijn zelf niet zuur of basisch, maar vertonen wel zure of basische eigenschappen als ze in water gebracht worden? /6<br /> # Bespreek de voorwaarden en de gevolgen van het stationariteitsprincipe. Geef een duidelijk en relevant voorbeeld. /4<br /> <br /> Oefeningen<br /> #De stabiliteitsconstante voor de vorming van het complex Pb(OH)&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt; is 1,0.1016. De standaardreductiepotentiaal voor het koppel Pb&lt;sup&gt;2+&lt;/sup&gt;(aq)/Pb(s) is -0,12V. Bereken aan de hand van deze gegevens de standaardreductiepotentiaal voor het koppel Pb(OH)&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;(aq)/Pb(s). / 3<br /> #Er wordt een buffer met pH = 6,90 gemaakt uitgaande van NaH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt; en Na&lt;sub&gt;2&lt;/sub&gt;HPO&lt;sub&gt;4&lt;/sub&gt;. De eindconcentratie van NaH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt; in 400 mL van deze oplossing is 0,020 M. Bereken hoeveel gram dinatriumwaterstoffosfaat er in deze oplossing moet zitten om de beoogde pH te realiseren. Aan deze oplossing wordt 100 mL 0,0080 M HI toegevoegd. Bereken ook de pH na toevoeging hiervan. Vanaf hoeveel mol NaOH toegevoegd zou de startbuffer niet meer werkzaam zijn? Licht kort toe. /3<br /> &lt;sup&gt;&lt;/sup&gt;<br /> <br /> === 23 januari 2018 namiddag===<br /> Theorie<br /> #Stel een mogelijk reactiemechanisme voor bij reactie 7 BOD tabel 6.2. /4<br /> #Waarom mag men geen ontkalker bij javel doen? Geef alle relevante reacties. /6<br /> <br /> Oefeningen<br /> #Bepaal de baseconstante van NH&lt;sub&gt;3&lt;/sub&gt; aan de hand van de standaardreductiepotentialen van de redoxkoppels. /3<br /> #Geef de Lewisstructuur, hybridisatie en polariteit van XeF&lt;sub&gt;2&lt;/sub&gt; en HClO&lt;sub&gt;2&lt;/sub&gt;. /3<br /> <br /> === 22 januari 2018 namiddag===<br /> Theorie <br /> # Hoe kan men het evenwicht naar de producten doen verschuiven? Heeft dit dan ook gevolgen voor de reactiesnelheid? /4<br /> # Vergelijk chroomvocht (dichromaat in zwavelzuur), piranhazuur (waterstofperoxide in zwavelzuur), koningswater en cyanide in base als oplosmiddelen voor (edel)metalen. /6<br /> <br /> Oefeningen<br /> # Je wilt 0.488 g Cu(OH)&lt;sub&gt;2&lt;/sub&gt; oplossen in water tot een eindvolume van 100 mL. Bereken hoeveel gram NaCl er nodig is om ervoor te zorgen dat Cu(OH)&lt;sub&gt;2&lt;/sub&gt; niet neerslaat. Het CuCl&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt; complex wordt gevormd. /3<br /> # Bepaal grafisch de activeringsenergie van de reactie (tabel met temperatuur en snelheidsconstantes gegeven). Bepaal ook de snelheidsconstante bij 37°C. Kan je hiermee iets zeggen over de orde van de reactie? /3<br /> <br /> === 17 januari 2018 ===<br /> Theorie <br /> # Hoe kan de snelheid van de reactie beïnvloed worden? Verandert dan ook de ligging van het evenwicht van de reactie? /6<br /> # Welke factoren bepalen of een molecule al dan niet een permanent dipoolmoment bezit? Geef duidelijke voorbeelden. /4<br /> <br /> Oefeningen<br /> # Je wilt 42.72 g Fe(OH)&lt;sub&gt;3&lt;/sub&gt; oplossen in water tot een eindvolume van 500 mL. Bereken welke concentratie waterstoffluoride (HF) er nodig is om ervoor te zorgen dat Fe(OH)&lt;sub&gt;3&lt;/sub&gt; niet neerslaat. /3<br /> # Stel de correcte redoxreactie op van de koppels Br&lt;sub&gt;2&lt;/sub&gt;/Br&lt;sup&gt;-&lt;/sup&gt; en AsO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;3-&lt;/sup&gt;/AsO&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;. Toon aan met berekeningen dat het over een aflopende reactie gaat bij kamertemperatuur (25°C) /3<br /> <br /> === 16 januari 2018 ===<br /> Theorie<br /> # Bespreek de reactie van chloor in base. Geef een belangrijke toepassing.<br /> # Vergelijk de ideale gaswet met de van der Waalsvergelijking voor reële gassen en bespreek de trend in co-volume b en cohesiedruk a (BOD p.141) voor H&lt;sub&gt;2&lt;/sub&gt;, N&lt;sub&gt;2&lt;/sub&gt;, CO&lt;sub&gt;2&lt;/sub&gt; en C&lt;sub&gt;4&lt;/sub&gt;H&lt;sub&gt;10&lt;/sub&gt;<br /> <br /> === 15 januari 2018 namiddag ===<br /> Theorie<br /> # BOD tabel 6.2, reactie 8: stel een mogelijk reactiemachanisme voor<br /> # Wat zijn de 2 vuistregels van een goeie buffer? Leidt deze af aan de hand van de begrippen neutralisatiegraad en buffercapaciteit. Leg de link met pH-titratie. Leg uit: bloed als buffer<br /> <br /> Oefeningen<br /> # bepaal de baseconstante van MnO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt; aan de hand van de standaardreductiepotentialen van de redoxkoppels<br /> # lewisstructuur, hybridisatie en polariteit van 2 moleculen<br /> <br /> === 15 januari 2018 namiddag ===<br /> (examen voor gedeeltelijke vrijstelling, enkel vragen deel E)<br /> <br /> Theorie<br /> # Wat zijn de drijvende krachten bij een complexatiereactie? Toon aan met goed gekozen voorbeelden, en leg uit aan de hand van de kenmerken van een hoge stabiliteitsconstante. /4<br /> # Wat zijn de 2 vuistregels van een goeie buffer? Leidt deze af aan de hand van de begrippen neutralisatiegraad en buffercapaciteit. Leg de link met pH-titratie. Leg uit: bloed als buffer. /6<br /> <br /> Oefeningen<br /> # Bepaal de baseconstante van MnO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt; aan de hand van de standaardreductiepotentialen van de redoxkoppels /3<br /> # Hoeveel zilverbromide kan je oplossen in een 0.530M ammoniakoplossing. Verwaarloos de basische eigenschappen van NH&lt;sub&gt;3&lt;/sub&gt;. /3 (Toepassing neerslag &amp; complexatie)<br /> <br /> === 1 september 2017 ===<br /> Theorie<br /> #Waarom zijn er diagonaalrelaties? Geef voorbeelden van chemische eigenschappen die gebruikt worden in chemische reacties. /5 <br /> #Geef het verband tussen de redoxpotentiaal van een redoxhalfreactie en de evenwichtconstante van de gehele reactie. Geef ook de gevolgen. /5<br /> <br /> <br /> Oefeningen<br /> #Berekenen of er neerslagvorming optreedt. <br /> #Vrijgekomen warmte en energie uit een reactie berekenen. <br /> === 25 Augustus 2017 ===<br /> Theorie<br /> #Vergelijk het verschil van de invloed van temperatuur op de reactiesnelheid en het evenwicht - zowel in formulevorm als grafisch /6<br /> k &amp; K afleiden en grafisch weergeven met resp. ln k ~ 1/T en ln K ~ 1/T (voor dH&gt;0 en dH&lt;0)<br /> <br /> #Welke chemisch relevante eigenschappen van atomen kan je afleiden van de positie in het periodiek systeem? /4 <br /> Zuur-base; oxidans-reductans (+verband), ... (atomen, niet ionen van het element!)<br /> <br /> <br /> Oefeningen<br /> #Hoeveel zilverbromide kan je oplossen in een 0.53M ammonium oplossing. Verwaarloos de basische eigenschappen van NH&lt;sub&gt;3&lt;/sub&gt;. /3<br /> (Toepassing neerslag &amp; complexatie)<br /> <br /> #Redoxreactie van SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;(aq)/SO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;(aq)- en MnO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;(aq)/MnO(v). /3<br /> <br /> === 21 Augustus 2017 ===<br /> Theorie<br /> #Hoe kan het evenwicht in de richting van de producten worden verschoven? Heeft dit invloed op het evenwicht? /6<br /> '''concentratie wijzigen'''<br /> principe van Le Chatelier<br /> hogere concentratie → meer kans op botsingen → sneller<br /> <br /> '''druk wijzigen'''<br /> bij drukverhoging → daalt volume → c=n/v dus concentratie stijgt (vanaf dan analoog aan Le Chatelier)<br /> bij drukverlaging is gunstig voor reacties waarbij ΔN = (N&lt;sub&gt;producten&lt;/sub&gt; - N&lt;sub&gt;reagentia&lt;/sub&gt;) negatief is(N staat voor de coëfficiënten van de stoffen in de reactie)<br /> <br /> '''temperatuur wijzigen'''<br /> K&lt;sub&gt;ev&lt;/sub&gt; is temperatuursafhankelijk → ΔG =-RTln(K) ↔ ln(k)=-ΔH/RT +ΔS/R (teken grafiek 1/T met ln(k))<br /> endo → hoge T is gunstig<br /> exo → lage T is gunstig<br /> <br /> #Wat is het verband tussen neerslag- en complexatiereacties? /4<br /> ionen met een hoge ladingsdichtheid kunnen niet zoals bijvoorbeeld Na&lt;sup&gt;+&lt;/sup&gt; en Cl&lt;sup&gt;-&lt;/sup&gt; (afkomstig van goed oplosbaar zou NaCl) in oplossing voorkomen,<br /> aangezien dit niet stabiel is.<br /> gaan dus ofwel neerslaan ofwel complexeren<br /> (K&lt;sub&gt;sp&lt;/sub&gt; en 1/K&lt;sub&gt;st&lt;/sub&gt; vergelijken → de stabielste toestand gaat zich dan voordoen)<br /> <br /> <br /> Oefeningen<br /> #Teken de lewis-structuur, geef het sterisch getal, hybridisatie, geometrische en atoomstructuur van HCN en ICl&lt;sub&gt;3&lt;/sub&gt;. Geef ook aan of ze polair zijn of niet. /3<br /> #Leid de K&lt;sub&gt;b&lt;/sub&gt; af van AsO&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; aan de hand van zijn standaarreductiepotentiaal. Kies zelf een goed redoxkoppel. /3<br /> <br /> === 24 januari 2017 ===<br /> Theorie<br /> #Welke verbindingen zijn zelf niet zuur of basisch, maar vertonen wel zure of basische eigenschappen als ze in water gebracht worden? /6<br /> #Hoe kunnen meerdere verschillende kationen die samen in een mengsel voorkomen, van elkaar gescheiden worden? Waarop moet je letten om de scheiding zo volledig mogelijk te laten gebeuren? /4<br /> <br /> Oefeningen<br /> #Berekenen of een reactie neerslaat of niet ondanks complexvorming /3<br /> #correcte redoxreactie van 2 gegeven koppels schrijven en berekenen dat dit een aflopende reactie is. /3<br /> <br /> === 23 januari 2017 ===<br /> Theorie<br /> #Bij welke reacties is quenchen van toepassing? Leg goed uit en geef een voorbeeld. /4<br /> #Vergelijk chroomvocht, piranhazuur, koningswater en cyanide in base als oplossmiddel voor (edel)metalen. /6<br /> <br /> Oefeningen<br /> #Roosterenergie berekenen /2.5<br /> #concentratie zout berekenen die toegevoegd moet worden om gegeven hoeveelheid neerslag op te doen lossen. /3.5<br /> <br /> === 18 januari 2017 ===<br /> VM<br /> Theorie<br /> #Hoe kan je de reactiesnelheid beïnvloeden? Wat betekent dit voor het chemisch evenwicht? /4<br /> #Wat gebeurt er bij de elektrolyse van water voor geen, een weinig en veel NaCL? /6<br /> <br /> Oefeningen<br /> #pH + werkelijke ionenconcentraties van een bioprotisch zuur berekenen /3<br /> #een slecht oplosbaar zout oplossen aan de hand van complexatie door een te berekenen massa NaCl toe te voegen /3<br /> <br /> === 17 januari 2017 ===<br /> Theorie<br /> #Hoe kan je het evenwicht naar de kant van de producten brengen? Heeft dit een invloed op de snelheid?<br /> #Geef het verband tussen protontransferreacties en elektrontransferreacties. Geef voorbeelden die dit verduidelijken.<br /> <br /> Oefeningen<br /> #Berekenen of een reactie neerslaat of niet ondanks complexvorming.<br /> #Bepaal de hybridisatie en geometrie van PCl&lt;sub&gt;3&lt;/sub&gt; en SF&lt;sub&gt;4&lt;/sub&gt;. Teken de atoomstructuur en zijn deze moleculen polair of apolair en een uitleg waarom.<br /> <br /> === 16 januari 2017 ===<br /> Theorie<br /> #Vuistregels met afleiding van buffers geven, dit ook toepassen op pH titraties, bloed als buffer bespreken<br /> #Hebben kationen basische of zure eigenschappen, zijn dit dan zwakke of sterke zuren of basen (voorbeelden kunnen helpen en verduidelijkend zijn)<br /> <br /> Oefeningen <br /> #Aantal mL en molair NiSO&lt;sub&gt;4&lt;/sub&gt;-oplossing samenvoegen met een aantal ml en molair NH&lt;sub&gt;3&lt;/sub&gt;, toon aan dat ondanks het gevormde complex nikkel (II) ammoniak er toch nog neerslag gevormd wordt<br /> #Een tabel gegeven van temperatuur en snelheidsconstante, de opdracht is grafisch de activeringsenergie te berekenen en k te berekenen bij 250°C<br /> <br /> === XX Augustus 2016 ===<br /> Theorie:<br /> #Leg de verschillende soorten isomerie uit + wat is tautomerie?<br /> #Leg uit waarom fluoride in tandpasta zit (alle 6 puntjes geven, dus ook vorming CaF uitleggen)<br /> <br /> Oefeningen<br /> #Random oefening uit oefenzitting<br /> #Berekend de K&lt;sub&gt;w&lt;/sub&gt; vertrekkende vanuit de standaardreductiepotentialen voor water in zuur/basisch milieu<br /> <br /> ===XX januari 2016===<br /> Theorie:<br /> #Leg de elementaire reactiestappen uit adhv voorbeelden (mono,bi,termoleculair, stationariteitsprincipe, vorming ozon)<br /> #Geef de '''essentie''' van een titratie + grafieken<br /> <br /> oefeningen:<br /> #Oplosbaarheid van AgNO&lt;sub&gt;3&lt;/sub&gt; berekenen na toevoegen van een of ander zuur/base<br /> #nog een oefening<br /> <br /> === 11 januari 2016 ===<br /> #Hoe bepaal je de geometrische structuur bij covalent gebonden atomen en geef 3 voorbeelden <br /> #bij welke reactie is quenching van toepassing?<br /> <br /> ===XX januari 2016===<br /> Theorie:<br /> #heterogene en homogene en enzymatische katalysator + alles uitleggen hiervan<br /> #loodbatterij<br /> <br /> ===12 januari 2016===<br /> #Verschillen tussen Co en Fe en zeggen waarom Fe gebruikt wordt voor zuurstof transport <br /> #het verschil tussen C dubbel gebonden en enkel gebonden <br /> #bij de oefeningen was eentje E&lt;sup&gt;0&lt;/sup&gt; bepalen ahv K&lt;sub&gt;a&lt;/sub&gt; en een andere E&lt;sup&gt;0&lt;/sup&gt; <br /> #andere grafisch de orde enzo bepalen<br /> <br /> ===10 JAN 2014===<br /> Theorie:<br /> #Roosterenergie van 2 roosters (NaCl en MgO) berekenen met de formule, zeggen of er nog een andere manier was om die te vinden (Hess) en of er een verschil in uitkomst te verwachten was tussen de twee manieren. Vergelijken van de pH van de twee oplossingen.<br /> #Uitleggen waarom termoleculaire reactiestappen omwaarschijnlijk zijn. Reactiemechanisme van 2HI + H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; → I&lt;sub&gt;2&lt;/sub&gt; + H&lt;sub&gt;2&lt;/sub&gt;O geven. Stationariteitsprincipe uitleggen en zeggen of het op die reactie van toepassing was. <br /> #Waar/soms waar/niet waar: Een proces is spontaan als de entropie in het systeem toeneemt. <br /> #Uitleggen wat een buffer is en de vuistregels voor een goede buffer uitleggen zonder de hele wiskundige berekening te doen.<br /> <br /> Oefeningen.<br /> #Oplosbaarheid van AgBr, complexatie met thiosulfaat en alternatieve manier geven om oplosbaarheid te verhogen. Uitleggen waarom die laatste manier weinig effect zou hebben.<br /> #Celpotentiaal berekenen van een gegeven schematische voorstelling.<br /> <br /> ===11 JAN 2013===<br /> Theorie:<br /> # Vergelijk de elektronenstructuur van de atomen N en O met die van de moleculen N&lt;sub&gt;2&lt;/sub&gt; en O&lt;sub&gt;2&lt;/sub&gt;. Licht de hierbij essentiële principes toe.<br /> # Geef de chemische functies van water. Geef bij iedere functie een voorbeeld in de vorm van een reactievergelijking. Is water sterk of zwak in deze functie?<br /> <br /> Oefeningen:<br /> # CuSO&lt;sub&gt;4&lt;/sub&gt; oplossing met NH&lt;sub&gt;3&lt;/sub&gt; oplossing (grootheden gegeven). Laat zien dat er ondanks de complexatie toch nog neerslagvorming optreedt.<br /> # Gegeven concentraties (van reactieproduct) in functie van de tijd. Bepaal grafisch de orde en de halfwaardetijd.<br /> <br /> ===3 FEB 2012 NM===<br /> # Geef twee vuistregels voor een goede buffer en toon ze aan aan de hand van de neutralisatiegraad en de buffer capaciteit. <br /> #* Geef het verband hiervan met pH- titratie <br /> #* Is bloed een goede buffer ? Verklaar. <br /> # Verklaar waarom men tandpasta fluorideert.<br /> <br /> <br /> ===30 JAN 2012 NM===<br /> # Beschrijf en vergelijk de kinematica en thermodynamica van de methatesereactie en de liganduitwisselingsreactie.<br /> # Broom in base.<br /> <br /> <br /> ===30 JAN 2012 VM===<br /> # Welke reacties kunnen optreden als katalysator bij redoxreacties?<br /> # Leidt de halfreacties van een zwavelzure loodbatterij af<br /> <br /> <br /> ===24 JAN 2012 VM===<br /> # hoe bepaal je de elektronenconfiguratie van diatomaire moleculen en geef twee duidelijk verschillende voorbeelden<br /> # vergelijk Al en Li voor batterijen, geef voor en nadelen en verklaar waarom er Li batterijen zijn en geen Al<br /> <br /> <br /> ===23 JAN 2012 NM===<br /> # staaf met enkele goed gekoze voorbeelden het belang van de ladingsdichtheid in de chemie<br /> # welke reacties hebben er baat bij quenching toe te passen<br /> <br /> <br /> ===23 JAN 2012 VM===<br /> Theorie:<br /> # Beschrijf en vergelijk de kinematica en thermodynamica van de methatesereactie en de liganduitwisselingsreactie. <br /> # Leg de elektrolyse van water uit in de volgende omstandigheden:1. zonder zout, 2. met een beetje zout en 3. met oplossing van veel zeezout. <br /> <br /> <br /> ===20 JAN 2012 NM===<br /> Theorie :<br /> # geef de vuistregels voor bufferoplossing + afleiden buffercapaciteit en neutralisatiegraad. link met pH-titratie. vertellen over bloed als buffer, goede/slechte buffer?<br /> # iets van Fe complexatie, waarom de natuur is aangepast aan ademhaling door complexvorming van Fe met zuurstof<br /> Oefeningen :<br /> # van deel C met een tabel met waarden, orde van reactie afleiden + grafisch k en t&lt;sub&gt;1/2&lt;/sub&gt; bepalen<br /> # berekenen of PbOH&lt;sub&gt;2&lt;/sub&gt; neerslaat, uit een mengsel van PbSO&lt;sub&gt;4&lt;/sub&gt; met NaOH geloof ik<br /> <br /> ===20 JAN 2012 VM===<br /> Theorie:<br /> # Vergelijk de bindingssterkte en reactiviteit van C=C en C - C (enkelvoudige binding) op 4 ptn<br /> # Vergelijk de afhankelijkheid van de temperatuur voor de snelheidsconstante en de evenwichtsconstante<br /> <br /> <br /> ===1 FEB 2011=== <br /> Theorie:<br /> # Bespreek: Chroomvocht, Piranhazuur , koningswater en cyanide in base en hun werking op (edel)metalen. (/6)<br /> # Wat is een indicator en hoe werkt het? (/4)<br /> Oefeningen:<br /> # P&lt;sub&gt;4&lt;/sub&gt; + BR&lt;sub&gt;2&lt;/sub&gt; =&amp;gt; PBR&lt;sub&gt;3&lt;/sub&gt; vul aan met coefficienten en bereken de temperatuur waarvoor deze reactie spontaan zal verlopen. (/2.5)<br /> # en een oefening over de combinatie van complexvorming van AlOH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; en de neerslag van AlOH&lt;sub&gt;3&lt;/sub&gt;. (/3.5)<br /> <br /> === 1 sep 2010 ===<br /> Theorie:<br /> # Verschillen en gelijkenissen tussen homogene, heterogene en enzymatische katalyse geven. Verduidelijken met vb.<br /> # Bindingssterkte en reactiviteit vergelijken tussen C-C en C=C. Welke reacties ondergaan ze.<br /> Oefingen:<br /> # Oplosbaarheid<br /> # Enthalpie &amp;amp; Entropie<br /> <br /> <br /> ===28 jan 2010===<br /> # bespreek de oplosbaarheid van metalen in zuur en basisch milieu (/6) <br /> # bespreek &amp;quot;quenching&amp;quot; en voor welke reacties is dit toepasbaar? (/4) <br /> <br /> oefeningen: <br /> # bepaal de oplosbaarheid van AgBr in een molaire NH&lt;sub&gt;3&lt;/sub&gt; oplossing (complexvorming) <br /> # een reactie difluor en diwaterstof -&amp;gt; 2HF. Gaat deze reactie op bij 500K ?<br /> <br /> ===26 jan 2010===<br /> # vergelijk piranhazuur, koningswater, dichromaat en cyanide voor het oplossen van edelmetalen. (.../6)<br /> # welke reacties kunnen als katalysator optreden bij een redoxreactie? (.../4)<br /> oefeningen:<br /> # Een oplossing van Ti(II)-ionen wordt in zuur midden getitreerd met een dichromaatoplossing (K&lt;sub&gt;2&lt;/sub&gt;Cr&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7-&lt;/sub&gt;oplossing). Hierbij worden het Cr(III)-ion en het Ti(III)-ion gevormd. Toon aan dat het gaat om een aflopende reactie.Het verloop van de titratie wordt potentiometrisch gevolgd en ook de pH wordt constant gemeten. In de oplossing zit nog een kalomelelektrode (E&lt;sup&gt;0&lt;/sup&gt;=0.25V) die aan de anode gekoppeld is en een platina-elektrode. Op zeker ogenblik - na het passeren van het equivalentiepunt - wordt een celpotentiaal van 0.95V gemeten en een pH van 1.2. Bereken de concentratie aan Cr&lt;sup&gt;3+&lt;/sup&gt; ionen, als je weet dat deze concentratie vier maal hoger ligt dan die van de dichromaationen. (.../3)<br /> # Aan een oplossing van 70 ml 0.20 M nikkelsulfaat wordt 30 ml 0.60 M ammoniak toegevoegd. Toon aan dat er - ondanks de complexvorming - toch hydroxideneerslag gevormd zal worden. (.../3)<br /> <br /> === jan 2010 ===<br /> Mondeling:<br /> # Toon het belang aan van ladingsdichtheid in de scheikunde. Geef telkens duidelijk verschillende voorbeelden als het over verschillende soorten reacties gaat.<br /> # Bespreek de reactie van broom in base. Geef een relevante toepassing.<br /> Schriftelijk:<br /> # Bij 298 K gaat onderstaande reactie op. Men maakt een oplossing van 35,5 g van Cl&lt;sub&gt;2&lt;/sub&gt; en 0,1 g van H&lt;sub&gt;2&lt;/sub&gt; in een totaal volume van 200 ml. Wat zijn de evenwichtsconcentraties van H&lt;sub&gt;2&lt;/sub&gt;, Cl&lt;sub&gt;2&lt;/sub&gt; en HCl ?<br /> #*H&lt;sub&gt;2&lt;/sub&gt;(g) + Cl&lt;sub&gt;2&lt;/sub&gt;(g) &amp;lt;=&amp;gt; 2HCl(g) <br /> # Bereken de Kb van IO-, uitgaande van<br /> #*IO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;(aq) / HIO(l) E&lt;sup&gt;0&lt;/sup&gt; = 1,13V<br /> #*IO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;(aq) / IO&lt;sup&gt;-&lt;/sup&gt;(aq) E&lt;sup&gt;0&lt;/sup&gt; = 0,15V<br /> <br /> === jan 2009 ===<br /> Mondeling:<br /> # Wat is een dipoolmoment?<br /> # Vroeger werd kaliumpermanganaat e.a. veel gebruikt als goede oxidator. Tegenwoordig wordt pirhanazuur (mengsel waterstofperoxide/zwavelzuur) gebruikt. Waarom?<br /> Schriftelijk:<br /> # Temperatuurverandering berekenen van ijs (faseverandering,...)<br /> # Nog zo'n oefening in die aard.<br /> <br /> <br /> === jan 2009 ===<br /> Mondeling:<br /> # Vergelijk de temperatuursafhankelijkheid van de evenwichtsconstante en de snelheidsconstante.<br /> # Waarom is een stof goed of slecht oplosbaar in water? En hoe kan je een slecht oplosbare stof beter oplosbaar maken?<br /> # Maak een vergelijking tussen thermodinamica en kinetica van metathesereacties versus complexatiereacties.<br /> # Geef de 2 hoofdregels voor het maken van een buffer en leid ze wiskundig af.<br /> Schriftelijk:<br /> #* Evenwichtsconstante berekenen bij 45°C (je krijgt de reactie)<br /> #* Evenwichtsdruk berekenen als druk in het begin gegeven is<br /> # K&lt;sub&gt;b&lt;/sub&gt; geven als je redoxkoppel krijgt (in zuur en in basisch midden)<br /> <br /> === 1 feb 2008 ===<br /> Mondeling:<br /> # Welke reacties kunnen een redoxreactie katalyseren?<br /> # Geef het verband tussen neerslagreacties en complexatiereacties en geef een goed gevonden voorbeeld.<br /> Schriftelijk:<br /> #* Evenwichtsconstante berekenen bij 45°C (je krijgt de reactie)<br /> #* Evenwichtsdruk berekenen als druk in het begin gegeven is<br /> # K&lt;sub&gt;b&lt;/sub&gt; geven als je redoxkoppel krijgt (in zuur en in basisch midden)<br /> <br /> === 25 jan 2008 ===<br /> Mondeling:<br /> # Leg uit wat tautomerie is + vb.<br /> # Voor het oxideren werden vroeger vaak de klassieke sterke oxidanten permanaat of dichromaat in zwavelzuur gebruikt, waarom is het gebruik van &amp;quot;piranaha-zuur&amp;quot; (waterstofperoxide in zwavelzuur) aan een opmars bezig?<br /> Schriftelijk:<br /> # men wil 200 ml maken van een oplossing die 3,81g magnesiumcloride en 0,8g natriumhydroxide bevat. Hoeveel gram ammoniumbromide moet er ook in deze oplossing zitter, opdat er geen neerslag is?<br /> # Boven/onder welke temperatuur gaat deze reactie spontaan op? <br /> #* N&lt;sub&gt;2&lt;/sub&gt; (g) + O&lt;sub&gt;2&lt;/sub&gt;(g) = 2NO (g)<br /> #* Bereken ook de evenwichtsconstante bij 68°C.<br /> <br /> === 15 jan 2007 ===<br /> Mondeling:<br /> # geef verband van de ionbinding en de covalente binding + verklaar<br /> # geef verband pH en redoxpotentiaal<br /> Schriftelijk:<br /> # bereken kb van een stof aan hand van 2 redoxpotentialen <br /> # oefenening waar je een eind temperatuur moest berekenen met warmtecapaciteit en latente verdampingswarmte (aangezien er een faseovergang is)</div>

R0804230 https://wiki.chemika.be/index.php?title=Grondslagen_van_de_Chemie&diff=3678 2024-01-11T19:38:50Z

<p>R0804230: /* Vakinformatie */</p> <hr /> <div>[[Categorie:Bachelor Chemie]]<br /> [[Categorie:Bachelor Biochemie]]<br /> <br /> ==Vakinformatie==<br /> Basisvak chemie voor 1e bachelor chemie, biochemie, biologie en geologie.<br /> Gedoceerd door professor Koen Clays (sinds academiejaar 2013-2014, daarvoor dor Prof. Bart Goderis). Het examen is deels mondeling, deels schriftelijk.<br /> <br /> ''academiejaar 2022-2023''<br /> * Aanpak vak<br /> ** Gegeven door Prof. Koen Clays<br /> *** Werkt vaak dingen uit op het bord die zeer nuttig/noodzakelijk zijn op een examen te vermelden, lessen volgen zijn dus wel zeker sterk aan te raden!<br /> ** Examen volledig schriftelijk<br /> ** Examen + practica<br /> * Kwaliteit cursus<br /> ** Er zijn geen slides, boek is zeker voldoende om te slagen<br /> * Examenvragen<br /> ** Theorievragen komen vaak terug<br /> ** Oefeningen zijn zeer vergelijkend met die van de oefenzittingen, maak ook zeker de makkelijke oefeningen opnieuw want deze kunnen ook voorkomen<br /> ** Vooral deel E is enorm belangrijk!!<br /> * Practica<br /> ** Griet Depotter, beste practica-assistent van het eerste jaar!<br /> ** Is goed te doen<br /> * Oefenzittingen<br /> ** Op de website van bios staan de oplossingen van enkele jaren geleden, zijn niet exact hetzelfde, maar het principe komt steeds op hetzelfde neer<br /> <br /> ==Examenvragen==<br /> <br /> === 17 januari 2023===<br /> <br /> Theorie:<br /> # Bij welke reacties gebruik je een katalysator en bij welke is quenchen van toepassing? (bij elk een voorbeeld geven + afleidingen formules en verduidelijking hierbij + grafieken)<br /> # Halfreacties autoaccu (functies chemische elementen geven, welke richting oplaad en welke ontlaad, waarom die fasetoestand bij lood)<br /> <br /> Oefeningen:<br /> # Geometrie, hybridisatie, polair/apolair (uitleggen waarom) van SO3(2-)<br /> # pH bepalen van 0.4M Na2SO3<br /> # Oplosbaarheid van PbI2 berekenen + hoeveel KCl toevoegen ter vorming van Pb(Cl)4(-) bij een bepaalde concentratie aan PbI2 + wordt er nog neerslag gevormd<br /> <br /> === 23 augustus 2022===<br /> Theorie: <br /> # Schrijf uit hoe je bekomt tot reactie 7 (pagina 119 BOD) en leg je redeneringen uit. (reductie half reacties- reactie uitgeschreven op bord in de les)<br /> # Leg de relevantie van de ladingsdichthied (niet electronendichtheid) in de scheikunde uit. [antw.: complexatie en neerslag reacties, in zuur als protontransfer van Hˆ+ (te grote ladingsdichtheid om te bestaan), electrontransfer reacties]<br /> <br /> Oefeningen:<br /> # HCN toevoegen om Co(OH)2 beter op te lossen. Welke HCN-concentratie nodig om 6,79 g Co(OH)2 in oplossing te brengen in 250 mL water? (Analoog oefening 8 E4)<br /> # Is volgende reactie aflopend bij 40 graden celcius? 2NH4NO3 &lt;--&gt; 2N2 + 4H2O + O2 (zie o.a. oef 4/6/7/E5 deel D)<br /> <br /> === 18 januari 2022 ===<br /> Theorie:<br /> 1. Hoe kan je de snelheid van een reactie verhogen, wat gebeurt er met het evenwicht?<br /> 2. Buffers: vuistregels + afleiding, verband met titratie, is bloed een goede buffer?<br /> <br /> Oefeningen:<br /> <br /> oefening 1:<br /> a. molaire oplosbaarheid van Ag2Cr2O7 in zuiver water<br /> b. hoeveel NH3 nodig om 0,100 mol AgI op te lossen in 0,500L (Ag(NH3)2^+ wordt gevormd)<br /> c. toon aan dat er geen AgOH neerslag gevormd wordt<br /> <br /> oefening 2:<br /> a. redoxreactie opstellen voor N2/NH2OH en Al(OH)4^-/Al<br /> b. toon aan dat de reactie aflopend is bij 25°C<br /> <br /> === 16 augustus 2021 ===<br /> Theorie:<br /> #Op welke manieren kan je de snelheid van een reactie vergroten, leg uit wat er dan ook met de evenwichtsconstante gebeurt. Verandert hierbij de ligging van het evenwicht? Gebruik formules of figuren om dit aan te tonen<br /> #Op welke manier beïnvloedt complexatie het redoxpotentiaal van een metaal? Leg uit, geef een voorbeeld. In de natuur wordt Fe gebruikt voor reversibele redoxreacties. Waarom?<br /> <br /> Oefeningen: <br /> #Boven of onder welke temperatuur gaat deze reactie spontaan op: O2 (g) + N2 (g) —&gt; 2NO (g)<br /> #HCN verhoogt de oplosbaarheid van Fe(OH)2, hoe groot is de concentratie van HCN die je nodig hebt om 250 ml 3,37g Fe(OH)2 in oplossing te brengen?”<br /> <br /> === 6 januari 2021 ===<br /> Theorie 1:<br /> #Bespreek alle K’s die we hebben gezien in de cursus en geef een voorbeeld waarin hun definitie duidelijk wordt. Indien je iets kan zeggen over K&gt;&gt;1 K=1 en K&lt;&lt;1, voeg je dit hieraan toe.<br /> #Gebruik een voorbeeld uit 1a en leg uit hoe je K puur theoretisch kunt vinden.<br /> #Geef een mogelijk verband tussen K en k indien er een is.<br /> <br /> Theorie 2:<br /> Bespreek de elektrolyse van water zonder NaCl, met een beetje NaCl en met veel NaCl.<br /> <br /> Oefening 1:<br /> Bewijs dat dankzij de complexvorming, PbCl2 niet neerslaat, wanneer we 50ml Pb(NO3)2 (0,4M) bij 50ml BaCl2 (0,6M)doen.<br /> <br /> Oefening 2:<br /> 0,700M NaHSO3 en 0,450M Na2SO3<br /> #Bereken de pH.<br /> #Bereken de pH bij het toevoegen van 20ml KOH.<br /> #Bij welke concentratie aan NaOH de buffer (100mL) niet meer werkt.<br /> <br /> === 13 augustus 2020 ===<br /> Theorie:<br /> 1) Leg homogene, heterogene en enzymatische katalyse uit. Geef ook telkens een voorbeeld. Leg de gelijkenis tussen heterogene en enzymatische katalyse uit. Leg de gelijkenis tussen homogene en enzymatische katalyse uit. /4<br /> 2) Vergelijk chroomvocht (dichromaat in zwavelzuur), piranhazuur (waterstofperoxide in zwavelzuur), koningswater en cyanide in base als oplosmiddelen voor (edel)metalen. /6<br /> <br /> Oefeningen:<br /> 1) Bereken de oplosbaarheid van AgBr in een 0.053M NH3 oplossing. Ag(NH3)2- wordt gevormd.<br /> 2) Is volgende reactie (reactie gegeven) aflopend bij 68 graden C? Toon aan met berekeningen.<br /> <br /> === 15 januari 2020 voormiddag ===<br /> Theorie:<br /> 1) Hoe evenwicht verschuiven naar kant van producten, verandert er iets aan de snelheid?<br /> 2) De ruimtelijke structuur van de covalente binding, 4 relevante voorbeelden geven en bespreken.<br /> <br /> Oefeningen:<br /> 1) Bereken Kd van complex Ag(CN)2 adhv thermodynamische eigenschap bij 25°C<br /> 2) Na3PO4 0.045 M: bereken werkelijke concentraties van PO43-, Na+, HPO42-, H2PO4-, H3PO4, H3O+, OH- en bereken de pH.<br /> <br /> === 14 januari 2020 namiddag ===<br /> theorie:<br /> #Hoe verklaar je de werking van een &quot;hoog-rendements&quot; brander voor een centrale verwarming? Welke aanpassingen dienen er te gebeuren in vergelijking met een klassieke brander<br /> #Bespreek de dissociatie van HgCl2. Waarmee is dit te vergelijken?<br /> <br /> oefeningen:<br /> #Je voegt 50 mL van een 0.0200M AgNO3 - oplossing toe aan 50 mL van een 0.0300M NaCN-oplossing. Zal AgCN neerslaan, ondanks de complexvorming (Kst Ag(CN)2- = 2.5 x 10^20). Verwaarloos de basische eigenschappen van CN-<br /> #Bepaal grafisch orde van de reactie, de snelheidsconstante en halfwaardetijd. Je krijgt de beginconcentratie van het reagens gegeven, en het verloop van de concentratie van een product. (Dus je moet nog berekenen, hoe het verloop van de concentratie van het reagens gaat)<br /> <br /> === 13 januari 2020 namiddag ===<br /> theorie:<br /> 1) bespreek de elektrolyse van water of in een waterige oplossing van zeezout (NaCl) voor volgende situaties: zonder toevoeging van zout, bij toevoeging van een beetje NaCl, bij toevoeging van veel NaCl<br /> 2) Bespreek homogene, heterogene en enzymatische katalyse: geef verschillen en gelijkenissen. Geef telkens een relevant voorbeeld ter illustratie.<br /> <br /> oefeningen:<br /> 1) reactie N2 + O2 --&gt; 2NO gegeven en berekenen boven/onder welke temperatuur de reactie spontaan is<br /> 2) Berekenen hoeveel gram NaCl je moet toevoegen aan 0,448g Cu(OH)2 om dit volledig te kunnen oplossen in 100 ml water als je weet dat het complex [CuCl4]2- wordt gevormd<br /> <br /> === 13 januari 2020 voormiddag ===<br /> theorie<br /> # Buffer<br /> # Reactiemechanisme van Broom<br /> <br /> ===?===<br /> Theorie:<br /> 1) hoe kan men de snelheid van een chemische reactie vergroten? Verandert dit ook iets aan het evenwicht?<br /> 2) chemische eigenschappen ammoniak, hebben ze dan een zwakke of sterke functie? Geef voorbeeldreacties<br /> 3) bespreek de thermodynamische eigenschappen van de autoprotolyse van water. Zie hiervoor tabel 6.9 BOD<br /> <br /> Oefeningen:<br /> 1) bereken of neerslag wordt gevormd bij samenvoegen 2 stoffen<br /> 2) bereken potentiaal galvanische cel<br /> <br /> === 1 februari 2019 namiddag===<br /> theorie<br /> #Leg uit hoe een biprotisch zuur dissocieert en geef een voorbeeld. Vergelijk deze dissociatie met die van HgCl&lt;sub&gt;2&lt;/sub&gt;<br /> #Broom in base<br /> oefeningen<br /> <br /> #Bepaal de standaardreductiepotentiaal van het koppel Zn(OH)&lt;sub&gt;2 (s)&lt;/sub&gt;\ Zn&lt;sub&gt;(s)&lt;/sub&gt; met het oplosbaarheidsproduct van Zn(OH)&lt;sub&gt;2&lt;/sub&gt; en de standaardreductiepotentiaal van het koppel Zn&lt;sup&gt;2+&lt;/sup&gt;\ Zn&lt;sub&gt;(s)&lt;/sub&gt; <br /> #Een klontje vast ethanol met een massa van 50 g wordt bij 155.80 K overgoten met 2.22 L (1 L = 0.79 kg) vloeibaar ethanol waardoor het klontje zal smelten. Wat is de begintemperatuur van het vloeibaar ethanol als je weet dat het systeem een eindtemperatuur van 287.80 K bereikt en als je weet dat er geen energie verloren gaat aan de omgeving?<br /> <br /> === 21 januari 2019 namiddag===<br /> theorie<br /> #vervolledig de reactievergelijking ClO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; + Cl&lt;sup&gt;-&lt;/sup&gt; -&gt; Cl&lt;sub&gt;2&lt;/sub&gt; + H&lt;sub&gt;2&lt;/sub&gt;O en geef een plausibel reactiemechanisme.<br /> #bespreek de elektrolyse van water of in een waterig milieu zonder toevoeging van zout, bij toevoeging van een beetje NaCl, bij toevoeging van veel NaCl. <br /> <br /> oefeningen<br /> #hoeveel natriumthiosulfaat is er nodig om 0,025 mol AgBr op te lossen in 500 ml? Het complex zilverthiosulfaat wordt gevormd. <br /> #een ijsklontje met massa 56 gram wordt in 150 g water gedaan om dit af te koelen. Het ijsklontje heeft een begintemperatuur van 0°C en het geheel heeft een eindtemperatuur van 14°C. Bereken de begintemperatuur van het water.<br /> <br /> === 16 januari 2019 voormiddag===<br /> Theorie<br /> #Bespreek de spontane ontbinding van waterstofperoxide. Welke parameters dragen bij tot de ontbinding en hoe kan je dit tegen gaan?<br /> #De ruimtelijke structuur van de covalente binding, 4 relevante voorbeelden geven en bespreken.<br /> Oefeningen<br /> <br /> #0,040 M 100 mL H&lt;sub&gt;3&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt; bij 100 ml 4M Ca&lt;sup&gt;2+&lt;/sup&gt;-ionen. Wordt er neerslag gevormd?<br /> #Een orde oefening met grafisch de halfwaarde tijd en k bepalen<br /> <br /> === 15 januari 2019===<br /> Theorie<br /> #Hoe kan je het evenwicht naar de kant van de producten krijgen. Heeft dit ook invloed op de snelheid van de reactie? /6<br /> #Stel een chemisch mechanisme op zodat citroenzuur (wat een bestandsdeel is van citroensap) kan ontgiften. /4<br /> <br /> Oefeningen<br /> #Bepaal de K&lt;sub&gt;b&lt;/sub&gt; uit de gegeven redoxkoppels (H&lt;sub&gt;2&lt;/sub&gt;O/H&lt;sub&gt;2&lt;/sub&gt;O (E&lt;sup&gt;0&lt;/sup&gt;=1.76V) en HO&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt;/OH&lt;sup&gt;−&lt;/sup&gt;) (E&lt;sup&gt;0&lt;/sup&gt;=0.87V). Met welke andere 2 koppels kan je dit nog doen? /3<br /> # Geef de lewisstructuur, hybridisatie, polariteit (+ uitleg), en geometrie van XeF&lt;sub&gt;2&lt;/sub&gt; en PBr&lt;sub&gt;3&lt;/sub&gt;. /3<br /> <br /> === 14 januari 2019===<br /> Theorie<br /> #Geef de twee vuistregels voor een goede buffer en leg ze uit adhv neutralisatiegraad en buffercapaciteit. Leg uit bloed als buffer en waarom het geen ideale buffer is. Geef de relatie tussen een buffer en een pH- titratie(curve). /6<br /> #Vervolledig deze reactie, BrO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; + Br&lt;sup&gt;-&lt;/sup&gt; → Br&lt;sub&gt;2&lt;/sub&gt; + H&lt;sub&gt;2&lt;/sub&gt;O, en geef een plausibel reactiemechanisme voor deze reactie (Staat niet in de cursus maar wel gezien als een extra voorbeeld). BOD Tabel 6.2 n.7 /4<br /> <br /> === 30 januari 2018 namiddag===<br /> Theorie<br /> #Welke verbindingen zijn zelf niet zuur of basisch, maar vertonen wel zure of basische eigenschappen als ze in water gebracht worden? /6<br /> # Bespreek de voorwaarden en de gevolgen van het stationariteitsprincipe. Geef een duidelijk en relevant voorbeeld. /4<br /> <br /> Oefeningen<br /> #De stabiliteitsconstante voor de vorming van het complex Pb(OH)&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt; is 1,0.1016. De standaardreductiepotentiaal voor het koppel Pb&lt;sup&gt;2+&lt;/sup&gt;(aq)/Pb(s) is -0,12V. Bereken aan de hand van deze gegevens de standaardreductiepotentiaal voor het koppel Pb(OH)&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;(aq)/Pb(s). / 3<br /> #Er wordt een buffer met pH = 6,90 gemaakt uitgaande van NaH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt; en Na&lt;sub&gt;2&lt;/sub&gt;HPO&lt;sub&gt;4&lt;/sub&gt;. De eindconcentratie van NaH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt; in 400 mL van deze oplossing is 0,020 M. Bereken hoeveel gram dinatriumwaterstoffosfaat er in deze oplossing moet zitten om de beoogde pH te realiseren. Aan deze oplossing wordt 100 mL 0,0080 M HI toegevoegd. Bereken ook de pH na toevoeging hiervan. Vanaf hoeveel mol NaOH toegevoegd zou de startbuffer niet meer werkzaam zijn? Licht kort toe. /3<br /> &lt;sup&gt;&lt;/sup&gt;<br /> <br /> === 23 januari 2018 namiddag===<br /> Theorie<br /> #Stel een mogelijk reactiemechanisme voor bij reactie 7 BOD tabel 6.2. /4<br /> #Waarom mag men geen ontkalker bij javel doen? Geef alle relevante reacties. /6<br /> <br /> Oefeningen<br /> #Bepaal de baseconstante van NH&lt;sub&gt;3&lt;/sub&gt; aan de hand van de standaardreductiepotentialen van de redoxkoppels. /3<br /> #Geef de Lewisstructuur, hybridisatie en polariteit van XeF&lt;sub&gt;2&lt;/sub&gt; en HClO&lt;sub&gt;2&lt;/sub&gt;. /3<br /> <br /> === 22 januari 2018 namiddag===<br /> Theorie <br /> # Hoe kan men het evenwicht naar de producten doen verschuiven? Heeft dit dan ook gevolgen voor de reactiesnelheid? /4<br /> # Vergelijk chroomvocht (dichromaat in zwavelzuur), piranhazuur (waterstofperoxide in zwavelzuur), koningswater en cyanide in base als oplosmiddelen voor (edel)metalen. /6<br /> <br /> Oefeningen<br /> # Je wilt 0.488 g Cu(OH)&lt;sub&gt;2&lt;/sub&gt; oplossen in water tot een eindvolume van 100 mL. Bereken hoeveel gram NaCl er nodig is om ervoor te zorgen dat Cu(OH)&lt;sub&gt;2&lt;/sub&gt; niet neerslaat. Het CuCl&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt; complex wordt gevormd. /3<br /> # Bepaal grafisch de activeringsenergie van de reactie (tabel met temperatuur en snelheidsconstantes gegeven). Bepaal ook de snelheidsconstante bij 37°C. Kan je hiermee iets zeggen over de orde van de reactie? /3<br /> <br /> === 17 januari 2018 ===<br /> Theorie <br /> # Hoe kan de snelheid van de reactie beïnvloed worden? Verandert dan ook de ligging van het evenwicht van de reactie? /6<br /> # Welke factoren bepalen of een molecule al dan niet een permanent dipoolmoment bezit? Geef duidelijke voorbeelden. /4<br /> <br /> Oefeningen<br /> # Je wilt 42.72 g Fe(OH)&lt;sub&gt;3&lt;/sub&gt; oplossen in water tot een eindvolume van 500 mL. Bereken welke concentratie waterstoffluoride (HF) er nodig is om ervoor te zorgen dat Fe(OH)&lt;sub&gt;3&lt;/sub&gt; niet neerslaat. /3<br /> # Stel de correcte redoxreactie op van de koppels Br&lt;sub&gt;2&lt;/sub&gt;/Br&lt;sup&gt;-&lt;/sup&gt; en AsO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;3-&lt;/sup&gt;/AsO&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;. Toon aan met berekeningen dat het over een aflopende reactie gaat bij kamertemperatuur (25°C) /3<br /> <br /> === 16 januari 2018 ===<br /> Theorie<br /> # Bespreek de reactie van chloor in base. Geef een belangrijke toepassing.<br /> # Vergelijk de ideale gaswet met de van der Waalsvergelijking voor reële gassen en bespreek de trend in co-volume b en cohesiedruk a (BOD p.141) voor H&lt;sub&gt;2&lt;/sub&gt;, N&lt;sub&gt;2&lt;/sub&gt;, CO&lt;sub&gt;2&lt;/sub&gt; en C&lt;sub&gt;4&lt;/sub&gt;H&lt;sub&gt;10&lt;/sub&gt;<br /> <br /> === 15 januari 2018 namiddag ===<br /> Theorie<br /> # BOD tabel 6.2, reactie 8: stel een mogelijk reactiemachanisme voor<br /> # Wat zijn de 2 vuistregels van een goeie buffer? Leidt deze af aan de hand van de begrippen neutralisatiegraad en buffercapaciteit. Leg de link met pH-titratie. Leg uit: bloed als buffer<br /> <br /> Oefeningen<br /> # bepaal de baseconstante van MnO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt; aan de hand van de standaardreductiepotentialen van de redoxkoppels<br /> # lewisstructuur, hybridisatie en polariteit van 2 moleculen<br /> <br /> === 15 januari 2018 namiddag ===<br /> (examen voor gedeeltelijke vrijstelling, enkel vragen deel E)<br /> <br /> Theorie<br /> # Wat zijn de drijvende krachten bij een complexatiereactie? Toon aan met goed gekozen voorbeelden, en leg uit aan de hand van de kenmerken van een hoge stabiliteitsconstante. /4<br /> # Wat zijn de 2 vuistregels van een goeie buffer? Leidt deze af aan de hand van de begrippen neutralisatiegraad en buffercapaciteit. Leg de link met pH-titratie. Leg uit: bloed als buffer. /6<br /> <br /> Oefeningen<br /> # Bepaal de baseconstante van MnO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt; aan de hand van de standaardreductiepotentialen van de redoxkoppels /3<br /> # Hoeveel zilverbromide kan je oplossen in een 0.530M ammoniakoplossing. Verwaarloos de basische eigenschappen van NH&lt;sub&gt;3&lt;/sub&gt;. /3 (Toepassing neerslag &amp; complexatie)<br /> <br /> === 1 september 2017 ===<br /> Theorie<br /> #Waarom zijn er diagonaalrelaties? Geef voorbeelden van chemische eigenschappen die gebruikt worden in chemische reacties. /5 <br /> #Geef het verband tussen de redoxpotentiaal van een redoxhalfreactie en de evenwichtconstante van de gehele reactie. Geef ook de gevolgen. /5<br /> <br /> <br /> Oefeningen<br /> #Berekenen of er neerslagvorming optreedt. <br /> #Vrijgekomen warmte en energie uit een reactie berekenen. <br /> === 25 Augustus 2017 ===<br /> Theorie<br /> #Vergelijk het verschil van de invloed van temperatuur op de reactiesnelheid en het evenwicht - zowel in formulevorm als grafisch /6<br /> k &amp; K afleiden en grafisch weergeven met resp. ln k ~ 1/T en ln K ~ 1/T (voor dH&gt;0 en dH&lt;0)<br /> <br /> #Welke chemisch relevante eigenschappen van atomen kan je afleiden van de positie in het periodiek systeem? /4 <br /> Zuur-base; oxidans-reductans (+verband), ... (atomen, niet ionen van het element!)<br /> <br /> <br /> Oefeningen<br /> #Hoeveel zilverbromide kan je oplossen in een 0.53M ammonium oplossing. Verwaarloos de basische eigenschappen van NH&lt;sub&gt;3&lt;/sub&gt;. /3<br /> (Toepassing neerslag &amp; complexatie)<br /> <br /> #Redoxreactie van SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;(aq)/SO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;(aq)- en MnO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;(aq)/MnO(v). /3<br /> <br /> === 21 Augustus 2017 ===<br /> Theorie<br /> #Hoe kan het evenwicht in de richting van de producten worden verschoven? Heeft dit invloed op het evenwicht? /6<br /> '''concentratie wijzigen'''<br /> principe van Le Chatelier<br /> hogere concentratie → meer kans op botsingen → sneller<br /> <br /> '''druk wijzigen'''<br /> bij drukverhoging → daalt volume → c=n/v dus concentratie stijgt (vanaf dan analoog aan Le Chatelier)<br /> bij drukverlaging is gunstig voor reacties waarbij ΔN = (N&lt;sub&gt;producten&lt;/sub&gt; - N&lt;sub&gt;reagentia&lt;/sub&gt;) negatief is(N staat voor de coëfficiënten van de stoffen in de reactie)<br /> <br /> '''temperatuur wijzigen'''<br /> K&lt;sub&gt;ev&lt;/sub&gt; is temperatuursafhankelijk → ΔG =-RTln(K) ↔ ln(k)=-ΔH/RT +ΔS/R (teken grafiek 1/T met ln(k))<br /> endo → hoge T is gunstig<br /> exo → lage T is gunstig<br /> <br /> #Wat is het verband tussen neerslag- en complexatiereacties? /4<br /> ionen met een hoge ladingsdichtheid kunnen niet zoals bijvoorbeeld Na&lt;sup&gt;+&lt;/sup&gt; en Cl&lt;sup&gt;-&lt;/sup&gt; (afkomstig van goed oplosbaar zou NaCl) in oplossing voorkomen,<br /> aangezien dit niet stabiel is.<br /> gaan dus ofwel neerslaan ofwel complexeren<br /> (K&lt;sub&gt;sp&lt;/sub&gt; en 1/K&lt;sub&gt;st&lt;/sub&gt; vergelijken → de stabielste toestand gaat zich dan voordoen)<br /> <br /> <br /> Oefeningen<br /> #Teken de lewis-structuur, geef het sterisch getal, hybridisatie, geometrische en atoomstructuur van HCN en ICl&lt;sub&gt;3&lt;/sub&gt;. Geef ook aan of ze polair zijn of niet. /3<br /> #Leid de K&lt;sub&gt;b&lt;/sub&gt; af van AsO&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; aan de hand van zijn standaarreductiepotentiaal. Kies zelf een goed redoxkoppel. /3<br /> <br /> === 24 januari 2017 ===<br /> Theorie<br /> #Welke verbindingen zijn zelf niet zuur of basisch, maar vertonen wel zure of basische eigenschappen als ze in water gebracht worden? /6<br /> #Hoe kunnen meerdere verschillende kationen die samen in een mengsel voorkomen, van elkaar gescheiden worden? Waarop moet je letten om de scheiding zo volledig mogelijk te laten gebeuren? /4<br /> <br /> Oefeningen<br /> #Berekenen of een reactie neerslaat of niet ondanks complexvorming /3<br /> #correcte redoxreactie van 2 gegeven koppels schrijven en berekenen dat dit een aflopende reactie is. /3<br /> <br /> === 23 januari 2017 ===<br /> Theorie<br /> #Bij welke reacties is quenchen van toepassing? Leg goed uit en geef een voorbeeld. /4<br /> #Vergelijk chroomvocht, piranhazuur, koningswater en cyanide in base als oplossmiddel voor (edel)metalen. /6<br /> <br /> Oefeningen<br /> #Roosterenergie berekenen /2.5<br /> #concentratie zout berekenen die toegevoegd moet worden om gegeven hoeveelheid neerslag op te doen lossen. /3.5<br /> <br /> === 18 januari 2017 ===<br /> VM<br /> Theorie<br /> #Hoe kan je de reactiesnelheid beïnvloeden? Wat betekent dit voor het chemisch evenwicht? /4<br /> #Wat gebeurt er bij de elektrolyse van water voor geen, een weinig en veel NaCL? /6<br /> <br /> Oefeningen<br /> #pH + werkelijke ionenconcentraties van een bioprotisch zuur berekenen /3<br /> #een slecht oplosbaar zout oplossen aan de hand van complexatie door een te berekenen massa NaCl toe te voegen /3<br /> <br /> === 17 januari 2017 ===<br /> Theorie<br /> #Hoe kan je het evenwicht naar de kant van de producten brengen? Heeft dit een invloed op de snelheid?<br /> #Geef het verband tussen protontransferreacties en elektrontransferreacties. Geef voorbeelden die dit verduidelijken.<br /> <br /> Oefeningen<br /> #Berekenen of een reactie neerslaat of niet ondanks complexvorming.<br /> #Bepaal de hybridisatie en geometrie van PCl&lt;sub&gt;3&lt;/sub&gt; en SF&lt;sub&gt;4&lt;/sub&gt;. Teken de atoomstructuur en zijn deze moleculen polair of apolair en een uitleg waarom.<br /> <br /> === 16 januari 2017 ===<br /> Theorie<br /> #Vuistregels met afleiding van buffers geven, dit ook toepassen op pH titraties, bloed als buffer bespreken<br /> #Hebben kationen basische of zure eigenschappen, zijn dit dan zwakke of sterke zuren of basen (voorbeelden kunnen helpen en verduidelijkend zijn)<br /> <br /> Oefeningen <br /> #Aantal mL en molair NiSO&lt;sub&gt;4&lt;/sub&gt;-oplossing samenvoegen met een aantal ml en molair NH&lt;sub&gt;3&lt;/sub&gt;, toon aan dat ondanks het gevormde complex nikkel (II) ammoniak er toch nog neerslag gevormd wordt<br /> #Een tabel gegeven van temperatuur en snelheidsconstante, de opdracht is grafisch de activeringsenergie te berekenen en k te berekenen bij 250°C<br /> <br /> === XX Augustus 2016 ===<br /> Theorie:<br /> #Leg de verschillende soorten isomerie uit + wat is tautomerie?<br /> #Leg uit waarom fluoride in tandpasta zit (alle 6 puntjes geven, dus ook vorming CaF uitleggen)<br /> <br /> Oefeningen<br /> #Random oefening uit oefenzitting<br /> #Berekend de K&lt;sub&gt;w&lt;/sub&gt; vertrekkende vanuit de standaardreductiepotentialen voor water in zuur/basisch milieu<br /> <br /> ===XX januari 2016===<br /> Theorie:<br /> #Leg de elementaire reactiestappen uit adhv voorbeelden (mono,bi,termoleculair, stationariteitsprincipe, vorming ozon)<br /> #Geef de '''essentie''' van een titratie + grafieken<br /> <br /> oefeningen:<br /> #Oplosbaarheid van AgNO&lt;sub&gt;3&lt;/sub&gt; berekenen na toevoegen van een of ander zuur/base<br /> #nog een oefening<br /> <br /> === 11 januari 2016 ===<br /> #Hoe bepaal je de geometrische structuur bij covalent gebonden atomen en geef 3 voorbeelden <br /> #bij welke reactie is quenching van toepassing?<br /> <br /> ===XX januari 2016===<br /> Theorie:<br /> #heterogene en homogene en enzymatische katalysator + alles uitleggen hiervan<br /> #loodbatterij<br /> <br /> ===12 januari 2016===<br /> #Verschillen tussen Co en Fe en zeggen waarom Fe gebruikt wordt voor zuurstof transport <br /> #het verschil tussen C dubbel gebonden en enkel gebonden <br /> #bij de oefeningen was eentje E&lt;sup&gt;0&lt;/sup&gt; bepalen ahv K&lt;sub&gt;a&lt;/sub&gt; en een andere E&lt;sup&gt;0&lt;/sup&gt; <br /> #andere grafisch de orde enzo bepalen<br /> <br /> ===10 JAN 2014===<br /> Theorie:<br /> #Roosterenergie van 2 roosters (NaCl en MgO) berekenen met de formule, zeggen of er nog een andere manier was om die te vinden (Hess) en of er een verschil in uitkomst te verwachten was tussen de twee manieren. Vergelijken van de pH van de twee oplossingen.<br /> #Uitleggen waarom termoleculaire reactiestappen omwaarschijnlijk zijn. Reactiemechanisme van 2HI + H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; → I&lt;sub&gt;2&lt;/sub&gt; + H&lt;sub&gt;2&lt;/sub&gt;O geven. Stationariteitsprincipe uitleggen en zeggen of het op die reactie van toepassing was. <br /> #Waar/soms waar/niet waar: Een proces is spontaan als de entropie in het systeem toeneemt. <br /> #Uitleggen wat een buffer is en de vuistregels voor een goede buffer uitleggen zonder de hele wiskundige berekening te doen.<br /> <br /> Oefeningen.<br /> #Oplosbaarheid van AgBr, complexatie met thiosulfaat en alternatieve manier geven om oplosbaarheid te verhogen. Uitleggen waarom die laatste manier weinig effect zou hebben.<br /> #Celpotentiaal berekenen van een gegeven schematische voorstelling.<br /> <br /> ===11 JAN 2013===<br /> Theorie:<br /> # Vergelijk de elektronenstructuur van de atomen N en O met die van de moleculen N&lt;sub&gt;2&lt;/sub&gt; en O&lt;sub&gt;2&lt;/sub&gt;. Licht de hierbij essentiële principes toe.<br /> # Geef de chemische functies van water. Geef bij iedere functie een voorbeeld in de vorm van een reactievergelijking. Is water sterk of zwak in deze functie?<br /> <br /> Oefeningen:<br /> # CuSO&lt;sub&gt;4&lt;/sub&gt; oplossing met NH&lt;sub&gt;3&lt;/sub&gt; oplossing (grootheden gegeven). Laat zien dat er ondanks de complexatie toch nog neerslagvorming optreedt.<br /> # Gegeven concentraties (van reactieproduct) in functie van de tijd. Bepaal grafisch de orde en de halfwaardetijd.<br /> <br /> ===3 FEB 2012 NM===<br /> # Geef twee vuistregels voor een goede buffer en toon ze aan aan de hand van de neutralisatiegraad en de buffer capaciteit. <br /> #* Geef het verband hiervan met pH- titratie <br /> #* Is bloed een goede buffer ? Verklaar. <br /> # Verklaar waarom men tandpasta fluorideert.<br /> <br /> <br /> ===30 JAN 2012 NM===<br /> # Beschrijf en vergelijk de kinematica en thermodynamica van de methatesereactie en de liganduitwisselingsreactie.<br /> # Broom in base.<br /> <br /> <br /> ===30 JAN 2012 VM===<br /> # Welke reacties kunnen optreden als katalysator bij redoxreacties?<br /> # Leidt de halfreacties van een zwavelzure loodbatterij af<br /> <br /> <br /> ===24 JAN 2012 VM===<br /> # hoe bepaal je de elektronenconfiguratie van diatomaire moleculen en geef twee duidelijk verschillende voorbeelden<br /> # vergelijk Al en Li voor batterijen, geef voor en nadelen en verklaar waarom er Li batterijen zijn en geen Al<br /> <br /> <br /> ===23 JAN 2012 NM===<br /> # staaf met enkele goed gekoze voorbeelden het belang van de ladingsdichtheid in de chemie<br /> # welke reacties hebben er baat bij quenching toe te passen<br /> <br /> <br /> ===23 JAN 2012 VM===<br /> Theorie:<br /> # Beschrijf en vergelijk de kinematica en thermodynamica van de methatesereactie en de liganduitwisselingsreactie. <br /> # Leg de elektrolyse van water uit in de volgende omstandigheden:1. zonder zout, 2. met een beetje zout en 3. met oplossing van veel zeezout. <br /> <br /> <br /> ===20 JAN 2012 NM===<br /> Theorie :<br /> # geef de vuistregels voor bufferoplossing + afleiden buffercapaciteit en neutralisatiegraad. link met pH-titratie. vertellen over bloed als buffer, goede/slechte buffer?<br /> # iets van Fe complexatie, waarom de natuur is aangepast aan ademhaling door complexvorming van Fe met zuurstof<br /> Oefeningen :<br /> # van deel C met een tabel met waarden, orde van reactie afleiden + grafisch k en t&lt;sub&gt;1/2&lt;/sub&gt; bepalen<br /> # berekenen of PbOH&lt;sub&gt;2&lt;/sub&gt; neerslaat, uit een mengsel van PbSO&lt;sub&gt;4&lt;/sub&gt; met NaOH geloof ik<br /> <br /> ===20 JAN 2012 VM===<br /> Theorie:<br /> # Vergelijk de bindingssterkte en reactiviteit van C=C en C - C (enkelvoudige binding) op 4 ptn<br /> # Vergelijk de afhankelijkheid van de temperatuur voor de snelheidsconstante en de evenwichtsconstante<br /> <br /> <br /> ===1 FEB 2011=== <br /> Theorie:<br /> # Bespreek: Chroomvocht, Piranhazuur , koningswater en cyanide in base en hun werking op (edel)metalen. (/6)<br /> # Wat is een indicator en hoe werkt het? (/4)<br /> Oefeningen:<br /> # P&lt;sub&gt;4&lt;/sub&gt; + BR&lt;sub&gt;2&lt;/sub&gt; =&amp;gt; PBR&lt;sub&gt;3&lt;/sub&gt; vul aan met coefficienten en bereken de temperatuur waarvoor deze reactie spontaan zal verlopen. (/2.5)<br /> # en een oefening over de combinatie van complexvorming van AlOH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; en de neerslag van AlOH&lt;sub&gt;3&lt;/sub&gt;. (/3.5)<br /> <br /> === 1 sep 2010 ===<br /> Theorie:<br /> # Verschillen en gelijkenissen tussen homogene, heterogene en enzymatische katalyse geven. Verduidelijken met vb.<br /> # Bindingssterkte en reactiviteit vergelijken tussen C-C en C=C. Welke reacties ondergaan ze.<br /> Oefingen:<br /> # Oplosbaarheid<br /> # Enthalpie &amp;amp; Entropie<br /> <br /> <br /> ===28 jan 2010===<br /> # bespreek de oplosbaarheid van metalen in zuur en basisch milieu (/6) <br /> # bespreek &amp;quot;quenching&amp;quot; en voor welke reacties is dit toepasbaar? (/4) <br /> <br /> oefeningen: <br /> # bepaal de oplosbaarheid van AgBr in een molaire NH&lt;sub&gt;3&lt;/sub&gt; oplossing (complexvorming) <br /> # een reactie difluor en diwaterstof -&amp;gt; 2HF. Gaat deze reactie op bij 500K ?<br /> <br /> ===26 jan 2010===<br /> # vergelijk piranhazuur, koningswater, dichromaat en cyanide voor het oplossen van edelmetalen. (.../6)<br /> # welke reacties kunnen als katalysator optreden bij een redoxreactie? (.../4)<br /> oefeningen:<br /> # Een oplossing van Ti(II)-ionen wordt in zuur midden getitreerd met een dichromaatoplossing (K&lt;sub&gt;2&lt;/sub&gt;Cr&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7-&lt;/sub&gt;oplossing). Hierbij worden het Cr(III)-ion en het Ti(III)-ion gevormd. Toon aan dat het gaat om een aflopende reactie.Het verloop van de titratie wordt potentiometrisch gevolgd en ook de pH wordt constant gemeten. In de oplossing zit nog een kalomelelektrode (E&lt;sup&gt;0&lt;/sup&gt;=0.25V) die aan de anode gekoppeld is en een platina-elektrode. Op zeker ogenblik - na het passeren van het equivalentiepunt - wordt een celpotentiaal van 0.95V gemeten en een pH van 1.2. Bereken de concentratie aan Cr&lt;sup&gt;3+&lt;/sup&gt; ionen, als je weet dat deze concentratie vier maal hoger ligt dan die van de dichromaationen. (.../3)<br /> # Aan een oplossing van 70 ml 0.20 M nikkelsulfaat wordt 30 ml 0.60 M ammoniak toegevoegd. Toon aan dat er - ondanks de complexvorming - toch hydroxideneerslag gevormd zal worden. (.../3)<br /> <br /> === jan 2010 ===<br /> Mondeling:<br /> # Toon het belang aan van ladingsdichtheid in de scheikunde. Geef telkens duidelijk verschillende voorbeelden als het over verschillende soorten reacties gaat.<br /> # Bespreek de reactie van broom in base. Geef een relevante toepassing.<br /> Schriftelijk:<br /> # Bij 298 K gaat onderstaande reactie op. Men maakt een oplossing van 35,5 g van Cl&lt;sub&gt;2&lt;/sub&gt; en 0,1 g van H&lt;sub&gt;2&lt;/sub&gt; in een totaal volume van 200 ml. Wat zijn de evenwichtsconcentraties van H&lt;sub&gt;2&lt;/sub&gt;, Cl&lt;sub&gt;2&lt;/sub&gt; en HCl ?<br /> #*H&lt;sub&gt;2&lt;/sub&gt;(g) + Cl&lt;sub&gt;2&lt;/sub&gt;(g) &amp;lt;=&amp;gt; 2HCl(g) <br /> # Bereken de Kb van IO-, uitgaande van<br /> #*IO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;(aq) / HIO(l) E&lt;sup&gt;0&lt;/sup&gt; = 1,13V<br /> #*IO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;(aq) / IO&lt;sup&gt;-&lt;/sup&gt;(aq) E&lt;sup&gt;0&lt;/sup&gt; = 0,15V<br /> <br /> === jan 2009 ===<br /> Mondeling:<br /> # Wat is een dipoolmoment?<br /> # Vroeger werd kaliumpermanganaat e.a. veel gebruikt als goede oxidator. Tegenwoordig wordt pirhanazuur (mengsel waterstofperoxide/zwavelzuur) gebruikt. Waarom?<br /> Schriftelijk:<br /> # Temperatuurverandering berekenen van ijs (faseverandering,...)<br /> # Nog zo'n oefening in die aard.<br /> <br /> <br /> === jan 2009 ===<br /> Mondeling:<br /> # Vergelijk de temperatuursafhankelijkheid van de evenwichtsconstante en de snelheidsconstante.<br /> # Waarom is een stof goed of slecht oplosbaar in water? En hoe kan je een slecht oplosbare stof beter oplosbaar maken?<br /> # Maak een vergelijking tussen thermodinamica en kinetica van metathesereacties versus complexatiereacties.<br /> # Geef de 2 hoofdregels voor het maken van een buffer en leid ze wiskundig af.<br /> Schriftelijk:<br /> #* Evenwichtsconstante berekenen bij 45°C (je krijgt de reactie)<br /> #* Evenwichtsdruk berekenen als druk in het begin gegeven is<br /> # K&lt;sub&gt;b&lt;/sub&gt; geven als je redoxkoppel krijgt (in zuur en in basisch midden)<br /> <br /> === 1 feb 2008 ===<br /> Mondeling:<br /> # Welke reacties kunnen een redoxreactie katalyseren?<br /> # Geef het verband tussen neerslagreacties en complexatiereacties en geef een goed gevonden voorbeeld.<br /> Schriftelijk:<br /> #* Evenwichtsconstante berekenen bij 45°C (je krijgt de reactie)<br /> #* Evenwichtsdruk berekenen als druk in het begin gegeven is<br /> # K&lt;sub&gt;b&lt;/sub&gt; geven als je redoxkoppel krijgt (in zuur en in basisch midden)<br /> <br /> === 25 jan 2008 ===<br /> Mondeling:<br /> # Leg uit wat tautomerie is + vb.<br /> # Voor het oxideren werden vroeger vaak de klassieke sterke oxidanten permanaat of dichromaat in zwavelzuur gebruikt, waarom is het gebruik van &amp;quot;piranaha-zuur&amp;quot; (waterstofperoxide in zwavelzuur) aan een opmars bezig?<br /> Schriftelijk:<br /> # men wil 200 ml maken van een oplossing die 3,81g magnesiumcloride en 0,8g natriumhydroxide bevat. Hoeveel gram ammoniumbromide moet er ook in deze oplossing zitter, opdat er geen neerslag is?<br /> # Boven/onder welke temperatuur gaat deze reactie spontaan op? <br /> #* N&lt;sub&gt;2&lt;/sub&gt; (g) + O&lt;sub&gt;2&lt;/sub&gt;(g) = 2NO (g)<br /> #* Bereken ook de evenwichtsconstante bij 68°C.<br /> <br /> === 15 jan 2007 ===<br /> Mondeling:<br /> # geef verband van de ionbinding en de covalente binding + verklaar<br /> # geef verband pH en redoxpotentiaal<br /> Schriftelijk:<br /> # bereken kb van een stof aan hand van 2 redoxpotentialen <br /> # oefenening waar je een eind temperatuur moest berekenen met warmtecapaciteit en latente verdampingswarmte (aangezien er een faseovergang is)</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemistry_in_Motion&diff=3617 2023-07-28T14:10:28Z

<p>R0804230: /* First question */</p> <hr /> <div>[[Categorie:Machemie]]<br /> <br /> ==Vakinformatie==<br /> Vak van 6 stp gedoceerd door Koen Clays en Jérôme Loreau. Bestaat uit 2 delen: Advanced Chemical Kinetics en Dynamics of Chemical and Biochemical Systems, het laatste deel wordt gedoceerd door Clays en was voordien een vak op zichzelf (kijk naar die examenwikipagina voor oudere vragen).<br /> Dynamics of Chemical and Biochemical Systems is een mondeling examen, bevattende hoofdstukken over (1) stabiliteit, (2) fluctuaties, (3) diffusie, (4) Langevin, (5) relaxatie, (6) evolutie. Het laatste hoofdstuk werd de laatste 2 jaar weggelaten.<br /> <br /> ==Examenvragen==<br /> ===13th January 2023===<br /> ====Advanced Chemical Kinetics====<br /> =====First question=====<br /> # Give the rate constant described by TST and explain the different elements.<br /> # Given are the expressions for Qrot and Qtrans. Qelec and Qvib can be neglected. Describe the temperature dependence for the following reactions:<br /> #* F + H2 --&gt; HF + H<br /> #* C2H4 + HCl --&gt; C2H5Cl<br /> # What becomes the temperature dependence if we include Qvib.<br /> # Compare with the result obtained from the Arrhenius equation (A in Arrhenius equation is obtained via experiment whereas with TST the pre-exp. factor is obtained via direct calculation)<br /> # Can we do quantum calculations for these reactions. Explain<br /> <br /> =====Second question=====<br /> # Unimolecular reaction that shows first order behavior at high pressure and second order behavior at low pressure. Write down the reaction rates and the dimensions of the rate constants for these two cases.<br /> # Prove qualitatively and quantitative the rates at high and low pressure.<br /> <br /> ====Dynamics of Chemical and Biochemical Systems====<br /> # Given is the Master Equation of Fluctuation Theory, for both P(delta P, delta S) and P(delta T, delta V). Derive the amplitude of fluctuations for one of the four possible fluctuations.<br /> # The reaction is: A+B &lt;-&gt; C+D. Derive and describe the relaxation for an instantaneous T-jump. What are the minimal conditions/requirements and which ones are optimal? (see page 10 of the relaxation pdf)<br /> <br /> ===29th August 2022===<br /> ====Advanced Chemical Kinetics====<br /> # Given the ozone reaction that happens in the earths stratosphere. What method would be the most accurate to describe the rate constant? (justify)<br /> # Question about TST<br /> 1) Write down the expression for the rate constant in TST. Explain the different elements.<br /> 2) Given are Qtrans and Qrot equations (Qel and Qvib can be neglected). Describe the temperature dependency of the rate constant for the following reactions (both have non-linear TS):<br /> *F + H2 --&gt; HF + H<br /> *non-linear molecule + linear molecule --&gt; non-linear molecule (Was specific, but don't remember the molecules)<br /> 3. Exercise 2.3<br /> <br /> ====Dynamics of Chemical and Biochemical Systems====<br /> # Explain how we get from the entropy maximum of the second law of thermodynamics to the minimum in energy. Explain what role fluctuations play here and explain the probability.<br /> # Explain the relation between Fick's laws, Langevin equation and the einstein equation. (He said no derivation was necessary) Explain correlation between the diffusion constant and temperature and friction.<br /> <br /> ===14 januari 2022 - Voormiddag===<br /> ====Advanced Chemical Kinetics====<br /> 1. [NO3] + [CO] --(fast)-&gt; [NO2] + [CO2] bij T hoger dan 255°C; [NO2] + [NO2] --(slow)-&gt; [NO3] + [NO] en [NO3] + [CO] --(fast)-&gt; [NO2] + [CO2] bij T lager dan 255°C (exotherme reacties)<br /> 1) Leid voor beide reacties de reactie rate af (tweede met steady state approximation)<br /> 2) Wat is de orde van elke reactie en de bijboherende units (2de orde; unit = cm^-3/s)<br /> 3) Teken het energieprofiel ifv reactie coordinaat<br /> 4) Welke quantum dynamische techniek verkies je: time independent of time dependent? (Time dependent wegens reacties met meer dan 4 atomen. Dit is niet doenbaar voor time independent)<br /> 5) Welke technieken zou je nog kunnen gebruiken voor de k te berekenen? (hard sphere, tst, capture theory, classical)<br /> 6) Stel de reactie, die exotherm is, heeft een late barrière. Welke energie is nodig voor deze te overbruggen? (Polanyi's rules, E(vibratie) nodig) <br /> 2. Oefening 3 van Chapter 2 met als extra vraag de delen van de k(hard sphere) uit te leggen.<br /> <br /> ==== Dynamics of Chemical and Biochemical Systems====<br /> # Gegeven de Master Equation of Fluctuation Theory, voor zowel P(delta P, delta S) als P(delta T, delta V). Leid de amplitude van de fluctuaties van een van deze 2 vergelijkingen af.<br /> # Reactie A+B &lt;-&gt; C+D. Leid de relaxatieformule af. Wat zijn de minimale condities/voorwaarden en wat zijn de optimale?</div>

R0804230 https://wiki.chemika.be/index.php?title=Polymer_Sciences:_from_Synthesis_to_Polymer_Material&diff=3310 2023-02-10T13:01:38Z

<p>R0804230: /* Prof. Nies */</p> <hr /> <div>[[Categorie:Machemie]]<br /> <br /> ==Vakinformatie==<br /> Gedoceerd door Professor Nies en Professor Koeckelberghs. Lessen zijn altijd in het Engels. De verdeling is 2/3 op het deel van Nies en 1/3 op het deel van Koeckelberghs. Bij Nies zijn er ook verplichte assignments tijdens het jaar, die meetellen voor een fractie 4/(12-N) van de punten van zijn deel (met N aantal assignments, doorgaans 2). Nies zijn examen is gesloten boek en er moet maar één vraag bij hem mondeling besproken worden (deze wordt op voorhand aangeduid). Bij Koeckelberghs zijn alle vragen mondeling te bespreken.<br /> <br /> ==Examenvragen==<br /> ===20th of January 2023===<br /> ====Prof. Nies====<br /> #Eq. 1.40 is given. Discuss the limiting behavior for L&lt;&lt;lp and L&gt;&gt;lp. The Kuhn length was defined by two equations. Write them down and give a qualitative description. Based on this, give the relationship between lK and lp. Can a chain with L&lt;&lt;lp also be seen as Kuhn chain? Explain.<br /> #Scientist claim that a polymer in solution shows a Phi(2)-T diagram with a closed loop miscibility hole. Chi(crit,1-2) are given as are T(crit,1-2). The values of Chi(0), Chi(1) and Chi(2) are provided too (Eq. 2.19). From this, calculate s2 and Phi(crit,1-2). Show either qualitatively of quantitatively if their reasoning for a closed loop miscibility hole is justified. Make a sketch of the Phi(2)-T diagram containing Phi(crit,2), T(crit,1-2), the binodals and spinodals.<br /> #Figure 3.27 is given and a graph that demonstrates the linear behavior between 1/l and Tm. In several steps you are guided towards deriving the Gibbs-Thomson-Tammann equation.<br /> <br /> ====Prof. Koeckelberghs====<br /> #Compare anionic and cationic ROP in terms of: monomers, initiators, propagation, transfer, termination and their ceiling temperature.<br /> #Discuss, based on the structure of vinyl monomers, in what way they can be polymerized. Relate the stability of the active species to Rp and discuss retardation and inhibition.<br /> #Discuss briefly how conversion and molar mass relate to each other in step-growth polymerization.<br /> <br /> ===27 augustus 2022===<br /> ====Prof. Nies====<br /> #Grafiek van specific volume relaxation uitleggen<br /> #Gibbs-Thomson equation afleiden<br /> #Polymer in solvent is cooled, binodal/spinodal and Tg curves zijn gegeven. 1) Leg uit wat je denkt dat er zal gebeuren, 2) welke morphology denk je dat gevormd wordt voor trage vs snelle cooling? <br /> ====Prof. Koeckelberghs====<br /> #free radical, anionic and cationic polymerization vergelijken op vlak van a) monomers b) termination reaction c) possibility for living polymerization<br /> #ring opening metathesis polymerization bespreken<br /> ===20 januari 2022===<br /> ====Prof. Nies====<br /> #Afleiding maken van de end to end distance van de freely rotating chain + uitleggen waarom er ⟨ .... ⟩ haakjes worden gebruikt + uitleggen wat L voor de FRC is<br /> #Gegeven formule van de gibbs vrije energie van menging (FH)Flory huggins<br /> #*Wat is de thermodynamische voorwaarde voor spinodaal gedrag? + Wat is de thermodynamische voorwaarde voor kritische toestand?<br /> #*Leid ook verder af wat chi kritisch en phi kritisch zijn hieruit (opnieuw afleiden!)<br /> #*Bepaal of de gegeven Tcritisch op een UCST of LCST systeem wijst <br /> #*Geef UCST en LCST namen voluit<br /> #*Teken een phi T diagram waar je de UCST of LCST van in de oefening uitlegt en uittekend<br /> #Avrami equation gegeven en eveneens een avrami plot<br /> #*Leg uit wat m en k zijn in deze vergelijking<br /> #*Leg uit wat we in deze plot zien ivm de equation, over de volledige tijdsinterval<br /> #*Teken zelf een plot volgens Avrami, waar hetzelfde polymeer (syndiotactic polystyrene) bij andere Tc was: Tc oorspronkelijke plot was 110°C, de 3 anderen waren -30°C, 105°C, 175°C --&gt; Tm en Tg van polystyreen waren gegeven!<br /> <br /> ====Prof. Koeckelberghs====<br /> #Definieer en bespreek living/controlled polymerization. Welke experimenten kan je uitvoeren om aan te tonen dat het gaat om een living/controlled polymerization. Bespreek de algemene methode waarop een free-radical polymerization omgezet wordt in een controlled polymerization. <br /> #Bespreek emulsion polymerization <br /> <br /> ===13 januari 2021===<br /> Verkorte examenduur omwille van corona<br /> ====Prof. Koeckelberghs====<br /> #Definieer en bespreek living/controlled polymerization. Welke experimenten kan je uitvoeren om aan te tonen dat het gaat om een living/controlled polymerization. Bespreek de algemene methode waarop een free-radical polymerization omgezet wordt in een controlled polymerization. <br /> #Bespreek emulsion polymerization <br /> <br /> ====Prof. Nies====<br /> #Gegeven formule van de gibbs vrije energie van menging (FH)<br /> #*Geef de betekenis van ieder symbool in de formule en de eenheid <br /> #*Wat is de thermodynamische voorwaarde voor spinodaal gedrag? <br /> #*Wat is de thermodynamische voorwaarde voor kritische toestand? <br /> #*Schrijf UCST en LCST languit <br /> #*Leidt de vergelijking van chikritisch en phikritisch af<br /> #*Oefening: berekenen Chikritisch, UCST of LCST gedrag? Tekenen fasediagram en verloop van chi in functie van de temperatuur <br /> #Leidt de vergelijking voor de average squared end-to-end distance af voor een WLC met de vergelijking voor een FRC gegeven. <br /> ===16 januari 2020===<br /> ====Prof. Koeckelberghs====<br /> #Anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #Step growth en chain growth vergelijken en hoe je kan bepalen wanneer je welke hebt<br /> #Metathese kort uitleggen<br /> <br /> ====Prof. Nies====<br /> #Taak uitleggen (mondeling).<br /> #Gibs-Thomson-Tammann afleiden voor lamellar crystal, vergelijking voor Gibbs fusie is gegeven<br /> #Derive expression for deltaG = G(deformed) - G(undeformed). Expressions for the squared end-to-end distance for FJC and P(R)dR are given<br /> <br /> ===17 januari 2019===<br /> ====Prof. Koeckelberghs====<br /> #Anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #Step growth en chain growth vergelijken en hoe je kan bepalen wanneer je welke hebt<br /> #Metathese kort uitleggen<br /> <br /> ====Prof. Nies====<br /> #Taak uitleggen (mondeling).<br /> #Grafiek over Tg afhankelijkheid van de cooling rate, uitleggen op moleculair niveau (met betrekking tot mobiliteit)<br /> #Afleiding radius of gyration geven (fjc), toon aan dat &lt;s²&gt;= lb² (N+1)(N-1)/6N en of de uitdrukking verandert als er interacties zijn tussen de massa's met Lennard Jones interactie potentiaal?<br /> <br /> ===14 januari 2019===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #plot van volumeverandering i.f.v. de tijd (case2-figuur 25) gegeven, bespreek ... (physical ageing)<br /> #afleiding voor de Thomson-Tammann smelttemperatuur van een eindig sfeer kristal, met de fusie Gibbs vrij energie van een oneindig groot kristal gegeven<br /> <br /> ===31 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #Anionic versus cationic ring opening polymerization:<br /> #*monomeer<br /> #*intiator<br /> #*general polymerization mechanism<br /> #*termination + transfer<br /> #*ceiling temperature<br /> #Influence of the molecular structure of vinyl monomers on possibility to polymerize. Correlate the molecular structure with:<br /> #*the way monomers can be polymerized<br /> #*rate of polymerization<br /> #*retardation + inhibition<br /> #Influence of conversion on molar mass in step growth polymerization<br /> <br /> ====Prof. Nies====<br /> #Formula growth rate given (case 3 eq. 1.28)<br /> #*discuss the origin of the exponential facors and the front factor in the given equation.<br /> #*discuss dependence of the growth rate on the size of the crystal at a chosen crystallization temperature. Make a schematic plot of the predicted growth rate versus the crystal size for the chosen crystallization temperature.<br /> #*what are the consequences for the predicted growth rate for crystallization behaviour at a particular crystallization temperature?<br /> #Figure volume relaxation (case 2 figure 27)<br /> #Rubbers<br /> #*Define an ideal rubber<br /> #*Derive expression for deltaG = G(deformed) - G(undeformed)<br /> Expressions for the squared end-to-end distance for FJC and P(R)dR are given<br /> <br /> ===25 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #ceiling temperature vergelijken bij vinyl polymerization en ring opening polymerization + kleine bijvragen daarover<br /> #controlled radical polymerization (NMP en ATRP)<br /> #living cationic polymerization<br /> <br /> ====Prof. Nies====<br /> #grafiek spinodal, binodal (die met Berghman's point) toegepast op PDLC, vorming van PDLC uitleggen aan de hand van grafiek<br /> #physical ageing<br /> #avrami plot<br /> <br /> ===19 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #step growth en chain growth vergelijken en hoe ge kunt bepalen wanneer ge wa hebt<br /> #ROMP uitleggen<br /> <br /> ====Prof. Nies====<br /> #taak bespreken (mondeling)<br /> #Gibs-Thomson-Tammann afleiden voor lamellar crystal, vergelijking voor Gibbs fusie is gegeven<br /> #spinodal en critical condition geven + afleiden helemaal en berekenen wat de critische waarden zijn voor 'chi' en 'fi-2', vergelijking Gibbs gegeven<br /> Huggings formule gegeven (niet in boek) is een uitbreiding van Flory-huggings vergelijking, wanneer zijn die aan elkaar gelijk en wat is de betekenis dan<br /> <br /> ===15 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #plot van volumeverandering i.f.v. de tijd (case2-figuur 25) gegeven, bespreek ... (physical ageing)<br /> #afleiding voor de Thomson-Tammann smelttemperatuur van een eindig sfeer kristal, met de fusie Gibbs vrij energie van een oneindig groot kristal gegeven<br /> <br /> ===25 augustus 2017===<br /> ====Prof. Koeckelberghs====<br /> #Vergelijk anionische ring opening polymerizatie met kationische ring opening polymerizatie op vlak van<br /> #*monomeer<br /> #*intiator<br /> #*mechanisme<br /> #*terminatie/recombinatie<br /> #*ceiling temperature<br /> #Lewis Mayo en die R ratio's daar in. Welke dingen invloed daar op hebben en hoe + voorbeeld<br /> #Welk invloed heeft de vorderingsgraad op molaire massa in step growth polymerizatie?<br /> <br /> ====Prof. Nies====<br /> #(mondelinge vraag) bespreek grafiek en waarom dat dit gebeurt (uitleggen op moleculair niveau), grafiek van physical ageing<br /> #Afleiding van hoofdstuk 4 Gibbs vrije energie wanneer een ideaal rubber deformatie ondergaat<br /> #vanalles van UCST en LCST, iets vaags.<br /> <br /> <br /> ===20 januari 2017===<br /> ====Prof. Koeckelberghs====<br /> #Anionische, kationische en frp uitleggen obv monomeer, terminatie en hoe ge het levend kunt maken<br /> #Step growth en chain growth<br /> #Ringopening methatese<br /> <br /> ====Prof. Nies====<br /> Vraag 1:<br /> #Wat is de definitie van een FRC?<br /> #Bij welke condities is de FRC gelijk aan de FJC<br /> #Bereken Lk en Nk voor de limiet van een enorm lange FRC (&lt;R2&gt;frc gegeven)<br /> #Leidt een vergelijking af voor de mean squared end-to-end distance van een ideaal lineair diblock copolymeer bestaande uit Nk1 Kuhn monomeren met lengte lk dat vasthangt via 1 einde aan Nk2 Kuhn monomeren met lengte lk2<br /> Vraag 2:<br /> #Mengsel van PS in methylcyclohexaan (Mw = 355kg/mol)<br /> Bij T=350K bestaat het mengsel uit 1 homogene vloeibare fase. Deze T is 6K boven de flory T. Polymeer volume fractie in de homogene fase is O,2<br /> Bij T=335K: twee vloeibare fases, de polymeer volume fracties van de coexistant fases zijn 0,003 en 0,435<br /> In de compositie range {0,002-0,044} en {0,336-0,435} is de structuur van de initiele fase scheiding kleine druppels in een matrix fase<br /> #*Schets het verloop van delta Gmix ifv de volledige compositierange bij T=333K<br /> #*Duid de points of interest in deze curve aan en leg ze uit.<br /> #*Leg tot he point uit waarom je vraag a zo geschetst hebt<br /> #*Wat zal de morfologie zijn in de initiële fase van scheiding?<br /> <br /> <br /> ===19 Januari 2017===<br /> ====Prof. Koekcelberghs====<br /> #Vergelijken ven anionische en kationische ringopeningpolymerisatie op vlak van<br /> #*Initiatie/Initiatoren<br /> #*Terminatie/transfer<br /> #*Mechanisme<br /> #*Mogelijke monomeren<br /> #*Ceiling temperature<br /> #Geef de factoren die een copolymerisatie beïnvloeden <br /> #Geef de invloed van de conversie bij een step-growth polymerisatie<br /> <br /> ====Prof. Nies====<br /> #Vraag 1: bespreek je taak helemaal (mondeling)<br /> #Vraag 2: Leid het verschil in Gibbs vrije energie voor een vervormd en onvervormd ideaal rubber af. End-to-end distance van een ideaal rubber en de Gaussische distributie zijn gegeven.<br /> #Vraag 3: Gegeven een stelling die zegt dat er een closed-gap miscibility gap plaatsvindt, met een formule voor chi in functie van T. 2 kritische waarden voor de temperatuur zijn gegeven. De vraag is: kan deze stelling kloppen? <br /> <br /> <br /> ===16 januari 2017===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #zie theoretical questions doc case 3 vraag 13, maar alleen de excess Gibbs energy en de chemical potentials waren gegeven<br /> #Vraag 3:<br /> #*thermodynamische uitdrukking voor spinodal en critical conditions afleiden.<br /> #*zie theoretical questions doc case 2 vraag 4 en de uitdrukking voor de Gibbs energy is gegeven<br /> #*de verbeterde Huggins uitdrukking voor de Gibbs energy is gegeven en daarvoor de enthalipsche en entropische bijdragen bepalen.<br /> #*De FH uitdrukking is een speciaal geval van de Huggins uitdrukking: bepaal de conditie van y waarvoor dit geld + geef de fysische betekenis van die conditie<br /> <br /> ===14 januari 2016===<br /> ====Prof. Koeckelberghs====<br /> #Vergelijk chemisch geïnitieerde FRP en ATR op vlak van:<br /> #*Algemeen protocol<br /> #*Snelheidsvergelijkingen<br /> #*Invloed van de moleculaire structuur op de snelheid van polymerisatie<br /> #Leg uit: step growth en chain growth polymerisatie. Hoe kan je experimenteel onderscheid maken tussen beide?<br /> #Leg kort uit: Ziegler-Nattakatalysator<br /> <br /> ====Prof. Nies====<br /> #Gegeven: Tg in functie van cooling rate. Verklaar de moleculaire oorsprong van dit fenomeen. (oral)<br /> #*Mondelinge bijvraag: wat bepaalt, naast de kinetische energie, ook mee het vrije volume?<br /> #Leid een formule af voor het smeltpunt van een eindig sferisch kristal.<br /> #Vrije energie van mengen volgens Flory-Huggins gegeven:<br /> #*Wat zijn de spinodale en kristische voorwaarden?<br /> #*Geef de betekenis en eenheiden van elke parameter in de vergelijking.<br /> #*Geef een concrete uitdrukking voor de kritische en spinodale voorwaarden afgeleid uit de bovenstaande vergelijking.<br /> #*Geef een concrete uitdrukking voor de kritische phi en chi.<br /> #*Gegeven een uitgebreide variant van de vergelijking van Flory en Huggins. Wat zijn de enthalpische en entropische bijdragen?<br /> #*De oorspronkelijke formule van Flory en Huggins is een bijzonder geval van de bovenstaande vergelijking. Onder welke voorwaarde is dit en waarmee komt dit fysisch overeen?<br /> <br /> ===11 januari 2016===<br /> ====Prof. Koeckelberghs====<br /> #Define living/controlled polymerisation. Hoe neem je dit experimenteel waar? Hoe maak je free radical controlled?<br /> #Wat is de invloed van moleculaire structuur van monomeer op manier vinylpolymerisatie, snelheid en retardation/inhibition?<br /> #Bespreek emulsiepolymerisatie.<br /> <br /> ====Prof. Nies====<br /> #Case 2, figuur 27 uitleggen (specifiek volume in functie van tijd) (oral)<br /> #Leid Gibbs Thomson uitdrukking af voor smelttemperatuur van sferisch kristal.<br /> #Uitdrukking s^2 en massacentrum gegeven:<br /> #*Leid average radius of gyration af met alles massa's = m.<br /> #*Toon aan dat average radius of gyration = lb^2 (N+1)(N-1)/6N als i=1,2,3,...,N-1.<br /> #*Veranderen de uitdrukking als er interacties zijn tussen de massa's met Lennard Jones interactie potentiaal?<br /> <br /> ===24 januari 2013===<br /> ====Prof. Koeckelberghs====<br /> #Discuss the ceiling temperature and apply it on both the vinyl polymerization and ring opening polymerization. Is the ceiling temperature of a particular monomer dependent on the way it's polymerized?<br /> Is it possible that a particular monomer, of which the ceiling temperature is such that only low-molar mass oligomers can be obtained via a living anionic polymerization at a certain temperature, can be polymerized into high-molar mass polymer using a free radical polymerization at the same temperature? Motivate your anwer.<br /> #Explain the principle of a controlled radical polymerization and apply it on NMP and ATRP.<br /> #Discuss briefly the living cationic vinyl polymerization.<br /> ====Prof. Nies====<br /> Zie onderstaande afbeelding.<br /> [ <br /> #Assignment 1 (oral)<br /> #The &amp;lt;i&amp;gt;free rotating chain&amp;lt;/i&amp;gt; (FRC) consists of N bonding vectors l&amp;lt;sub&amp;gt;i&amp;lt;/sub&amp;gt;, i=1,...,N with constant bond length |l&amp;lt;sub&amp;gt;i&amp;lt;/sub&amp;gt;| = l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt; and constant bond angles Ï´&amp;lt;sub&amp;gt;ii+1&amp;lt;/sub&amp;gt;=Ï´, i=1,...,N between the successive bonding vectors. The average quadratic end-to-end distance &amp;lt;R²&amp;gt;, valid for all physically sensible values of N, l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt; and Ï´, is given by [[Bestand:R-FRC.JPG]]<br /> #*Show that the average quadratic end-to-end distance &amp;lt;R²&amp;gt; of the FRC chain with very small bond angles also can be written in the Kratky-Porod chain form: &amp;lt;R²&amp;gt; = 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;L-2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;²(1-exp(-L/l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;),<br /> with l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;=l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt;L/(1-cosÏ´) the perstistence length and L the contour length.<br /> #Derive from the general thermodynamic equilibrium conditions the melting point of a polymer crystal in equilibrium with a solution of the polymer.<br /> For the polymer solution you can use the Flory-Huggins excess Gibbs-energy of mixing.<br /> [[Bestand:G(mix).JPG]]<br /> <br /> The chemical potentials of the components are given by:<br /> [[Bestand:Chempot.JPG]] ]<br /> <br /> [[Bestand:240113nies.png]]<br /> <br /> ===18 januari 2013===<br /> ====Prof. Koeckelberghs====<br /> #Compare chemically initiated free radical polymerization and ATRP, for the following aspects:<br /> #*general concept<br /> #*rate of polymerization<br /> #*influence of molecule structure on polymerization rate<br /> #Discuss the differences in mechanism of chain growth and step growth polymerization. How can one investigate which type of polymerization he is dealing with?<br /> #Explain briefly: Ziegler-Natta catalyst<br /> ====Prof. Nies====<br /> #Discussion of assignment 1 (oral)<br /> <br /> Zie onderstaande afbeelding.<br /> <br /> #The expression of average squared end-to-end distance of the Kratky-Porod chain is given: &amp;lt;R²&amp;gt; = 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;L - 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;²(1-exp(-L/l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;)<br /> #*Derive expressions for the Kuhn segment length and the number of Kuhn segments for this chain.<br /> #*Discuss your results. For instance, did you make any assumptions? Mention them explicitly.<br /> #The excess Gibbs ebergy of mixing in the Flory-Huggins model is given: ΔG/N&amp;lt;sub&amp;gt;l&amp;lt;/sub&amp;gt;kT = Δg/kT = (φ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;/s&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;)lnφ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt; + (φ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;/s&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;)lnφ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; + χφ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;φ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;<br /> #*Derive expressions for the spinodal and critical conditions.<br /> #*Derive from these expressions the formulae for the critical composition φ&amp;lt;sub&amp;gt;2,cr&amp;lt;/sub&amp;gt; and critical value of χ.<br /> #*What is the relevance of the spinodal for material behaviour?<br /> [[Bestand:180113nies.png]]<br /> <br /> ===20 januari 2012===<br /> ====Professor Nies====<br /> #Gegeven een fase-diagram uit Case II. Wat gebeurt er als er vanuit punt A (dat links van de critical point lag):<br /> #* traag wordt afgekoeld<br /> #* wordt gequenched (1000K/min)<br /> #* Hoe ziet de oplossing er na koelen uit voor beide gevallen<br /> #5 begrippen uitleggen:<br /> #*Thermo-elastische inversie<br /> #*Physical ageing<br /> #*Second order transition<br /> #*Effective pair potential<br /> #*Nucleation &amp;amp; growth<br /> #Leidt de spinodal en critical conditions af en ook de waarden voor Fi(2,crit) en Chi(krit).<br /> <br /> ====Professor Koeckelberghs====<br /> #Wat is de ceiling temperatuur en correleer dit met vinylpolymerisatie en Ring opening polymerisatie. Is de ceiling temperatuur afhankelijk van hoe we polymeriseren? Stel we polymeriseren via een living anionische polymerisatie. Het monomeer heeft een lage ceiling temperatuur, wat ervoor zorgt dat er geen lange polymeerketens worden gevormd. Kan men dan langere ketens verkrijgen als men bij dezelfde temperatuur via een radicale polymerisatie polymeriseert?<br /> #M1 en M2 worden gecopolymeriseerd. Geef de parameters voor beide monomeren en leg uit waarvan deze afhangen.<br /> # Leg uit: (radicalaire) emulsiepolymerisatie<br /> <br /> ===21 januari 2011===<br /> ====Professor Nies====<br /> # Teken het verloop van de de gibssvrij-energie in functie van volumefractie bij een temperatuur van 300K. Volumefracties = 0,2. Coexistence points en spinodal points gegeven. Ook de verschillende punten aanduiden en kort uitleggen. (deze vraag was mondeling)<br /> # Formule p 50 case 1 gegeven (zonder 4e term)<br /> #* leg de symbolen uit + dimensies + eenheden<br /> #* wat bedoelt men met &amp;quot;volgens de Flory benadering...&amp;quot;<br /> #* leg de twee verschillende termen uit<br /> #* Bereken end-to-end distance in evenwicht bij een flory-solvent<br /> #* Bereken end-to-end distance in evenwicht bij een goed solvent<br /> # Avramiplot+vergelijking gegeven<br /> #*leg de parameters uit<br /> #*hoe kan je volumefractie kristallijne fase meten, leg kort techniek uit.<br /> #*geef een kwalitatieve bespreking van de grafiek<br /> #*wat kan je uit de parameters afleiden<br /> <br /> ====Professor Koeckelberghs====<br /> # zie vragen vorig jaar<br /> <br /> ===15 januari 2010===<br /> ====Professor Nies====<br /> #Er was de grafiek gegeven met daarop de binodal, spinodal en Tg curve. Met daarop 3 punten aangegeven, telkens in het homogene gebied boven de binodal en boven Tg. Punt A: Links van kritische punt, punt B tussen kritische punt en Berghmans punt en punt C rechts van Berghmanspunt. (Alleen deze vraag mondeling)<br /> #*Wat vindt plaats als je in punt A traag afkoelt?<br /> #*Wat vindt plaats als je in punt A afkoelt met 1000K/min<br /> #*Wat vindt plaats als je in punt B traag afkoelt<br /> #*Wat vindt plaats als je in punt B afkoelt met 1000K/min<br /> #*Wat vindt plaats als je in punt C traag afkoelt?<br /> #*Wat vindt plaats als je in punt C afkoelt met 1000K/min<br /> #Vergelijking van Groeisnelheid bij kristallisatie (U) gegeven: U=Fexp(A)exp(B)exp(C) Zowel F,A,B,C waren gegeven in symbolen(vergelijking onder 7.B case III)<br /> #*Geef waarvoor de symbolen staan en wat hun eenheden zijn.<br /> #*Verklaar waar de Frontfactor (F) en de drie exp's vandaan komen<br /> #*Bespreek temperatuursafhankelijkheid en geef een schets<br /> #Geef de definitie van een ideale Rubber<br /> #* Leid de uitdrukking voor af voor S bij een willekeurige verandering. P(R) gegeven<br /> <br /> ====Koeckelberghs====<br /> #Vergelijk radicalaire, anionische en kationische vinylpolymerisatie<br /> #*Mogelijke monomere deeltjes (stabiliteit)<br /> #*Terminatie reacties<br /> #*Invloed van verschillende voorkomende deeltjes op sneldheid (hiermee bedoelde hij de associated ion pairs etc)<br /> #*Mogelijke manier om ze 'levend' te maken. (of quasi levend)<br /> #*? dacht dat er nog 1 was<br /> #Je wil een ideaal, perfect blockcopolymeer maken van MMA en MA op anionische wijze. Welk monomeer moet je eerst polymeriseren? Blijft indien je dit met ATRP wil doen de volgorde dezelfde?<br /> #Bespreek kort Ring Opening Metathesis Polymerisatie.</div>

R0804230 https://wiki.chemika.be/index.php?title=Advanced_Organic_Chemistry&diff=3267 2023-01-27T17:45:40Z

<p>R0804230: /* 26 January 2023 */</p> <hr /> <div>[[Categorie:Machemie]]<br /> <br /> ==Examenvragen==<br /> ===26 January 2023===<br /> IMPORTANT NOTE: The following exercise assignments contain a number of errors. In this drive you can find everything correctly. https://docs.google.com/document/d/1mfHLVkxhkN63DB88_RoDP4fWwyL5m0VA/edit?usp=sharing&amp;ouid=101486339872913430382&amp;rtpof=true&amp;sd=true<br /> #Devise a strategy to obtain following molecule using Tosylazide and Rhodium salt and any other reagent. No stereochemistry needs to be explained. (I drew the endproduct wrongly, one of the substituents is acetate not a ketone)[[Bestand:Exam_Question_1.png]]<br /> #Both products have a common intermediate. Explain in detail how these products are formed [[Bestand:Exam_Question_2.png]]<br /> #Discuss the mechanism to obtain following products [[Bestand:Exam_Question_3.png]]<br /> #Discuss the mechanism of this reaction. No stereochemistry has to be explained (It's PPh3=CH2 btw, another mistake) [[Bestand:Exam_Question_4.png]]<br /> #Explain the following reaction. [[Bestand:Exam_Question_5.png]]<br /> <br /> PS: I might be wrong on questions 3b and 5. I'm going off of memory here.<br /> <br /> ===27 januari 2022===<br /> Door Corona was er dit jaar geen mondeling. Hierdoor was de moeilijkheidsgraad van de vragen iets lager. Professor Dehaen stuurt immers normaal gezien veel bij tijdens het mondeling. Indien er dus wel terug mondelinge examens kunnen plaatsvinden zijn de examenvragen van eerdere jaren representatiever. <br /> <br /> [[Bestand:Organiccc1.jpg]]<br /> [[Bestand:Organiccc2.jpg]]<br /> <br /> ===30 augustus 2021===<br /> Door Corona was er dit jaar geen mondeling. Hierdoor was de moeilijkheidsgraad van de vragen iets lager. Professor Dehaen stuurt immers normaal gezien veel bij tijdens het mondeling. Indien er dus wel terug mondelinge examens kunnen plaatsvinden zijn de examenvragen van eerdere jaren representatiever. <br /> <br /> [[Bestand:Organic-30-8-2021 oef 1-4.png]]<br /> [[Bestand:Organic-30-8-2021 oef 5-6.png]]<br /> <br /> <br /> ===20 januari 2021===<br /> Door Corona was er dit jaar geen mondeling. Hierdoor was de moeilijkheidsgraad van de vragen iets lager. Professor Dehaen stuurt immers normaal gezien veel bij tijdens het mondeling. Indien er dus wel terug mondelinge examens kunnen plaatsvinden zijn de examenvragen van eerdere jaren representatiever. <br /> # 6 punten [[Bestand:Oefening_1.png]]<br /> # 3 punten [[Bestand:Oefening_2.png]]<br /> # 3 punten [[Bestand:Oefening_3.png]]<br /> # 4 punten [[Bestand:Oefening_4.png]]<br /> # 4 punten [[Bestand:Oefening_5.png]]<br /> <br /> ===6 januari 2021===<br /> Door Corona was er dit jaar geen mondeling. <br /> # In de synthese van een product reageert het gegeven diketon met 2 equivalenten van een een ylide. Geeft de structuur van dit ylide, de structuur van intermediairen A en B en bespreek kort het mechanisme. De laatste stap is een rearrangement met een zuur. [[Media:Oganic 6-1-2021 oef 1.png]] (/6)<br /> # Geef het mechanisme van de reactie [[Media:Organic 6-1-2021 oef 2 .png]] (/3)<br /> # Geef het mechanisme van de reactie [[Media:Organic 6-1-2021 oef 3.jpg]] (/3)<br /> # Gegeven: een lijst van 8 reagentia, waaronder een H2SO4, acetonitrille, Na, NH2OH, t-BuONa, TiCl4, Me3SiCl en 2-broompropaan. Slechts 6 van de 8 moeten worden gebruikt. Geef de intermediairen X en Y en het mechanisme. De laatste stap is een fragmentatiereactie. [[Media:Organic 6-1-2021 oef 4.PNG]] (het kan zijn dat er een klein foutje zit in de structuur van het eindproduct) (/6)<br /> # Geef het mechanisme van de reactie. In de eerste stap reageert het startproduct met een bromopropaan-derivaat. De laatste stap is een pericyclische reactie. Verloopt de cyclisatie thermisch of fotochemisch? [[Media:Organic 6-1-2021 oef 5.PNG]] (/3)<br /> <br /> <br /> <br /> ===20 januari 2020===<br /> WERKEND BESTAND: [[Media:Organic examen 2020 deel 1.jpg]] en [[Media:Organic examen 2020 deel 2.jpg]]<br /> <br /> <br /> <br /> <br /> [[Categorie:Machemie]]<br /> <br /> ===22 januari 2019===<br /> <br /> [[Media:Vragen_Advanced_Organic_22-01-19_VM_Deel_1.jpg]]<br /> [[Media:Vragen_Advanced_Organic_22-01-19_VM_Deel_2.jpg]]<br /> <br /> ===21 januari 2019 VM===<br /> <br /> ====Examen====<br /> <br /> [[Bestand:ExamAdvOrg21jan2019.png|800px]]<br /> <br /> ====Oplossingen====<br /> [[Media:SolutionsAdvOrg21jan2019jpg.jpg]]<br /> <br /> <br /> ===28 januari 2013 NM===<br /> <br /> [[Media:Examen organische chemie 23-01-2017.jpeg]]<br /> <br /> #Explain the following reaction. [[Bestand:org1.png]]<br /> #How is given cyclopropane synthesized from diethyl malonate in several steps? Choose reagents such that a maximal yield is obtained. [[Bestand:org2.png]]<br /> #This reaction scheme is an example of a benzannelation reaction. Upon heating, several consecutive steps happen so that the given end product is obtained. Among these steps are three electrocyclic reactions (two 4-electron and one 6-electron), a tautomerization, and a cycloaddition (not necessarily in this order). [[Bestand:org3.png]]<br /> #Explain formation of this product in presence of base. [[Bestand:org4.png]]<br /> #Give product A and explain how this reaction occurs. [[Bestand:org5.png]]<br /> #What products will be formed in following reactions? [[Bestand:org6.png]]</div>

R0804230 https://wiki.chemika.be/index.php?title=Advanced_Organic_Chemistry&diff=3266 2023-01-27T16:43:02Z

<p>R0804230: /* 26 January 2023 */</p> <hr /> <div>[[Categorie:Machemie]]<br /> <br /> ==Examenvragen==<br /> ===26 January 2023===<br /> IMPORTANT NOTE: The following exercise assignments contain a number of errors. In this drive you can find everything correctly. https://docs.google.com/document/d/1076KR86PdTwE4jakAgw2e8KvuAksebex/edit?usp=sharing&amp;ouid=101486339872913430382&amp;rtpof=true&amp;sd=true<br /> #Devise a strategy to obtain following molecule using Tosylazide and Rhodium salt and any other reagent. No stereochemistry needs to be explained. (I drew the endproduct wrongly, one of the substituents is acetate not a ketone)[[Bestand:Exam_Question_1.png]]<br /> #Both products have a common intermediate. Explain in detail how these products are formed [[Bestand:Exam_Question_2.png]]<br /> #Discuss the mechanism to obtain following products [[Bestand:Exam_Question_3.png]]<br /> #Discuss the mechanism of this reaction. No stereochemistry has to be explained (It's PPh3=CH2 btw, another mistake) [[Bestand:Exam_Question_4.png]]<br /> #Explain the following reaction. [[Bestand:Exam_Question_5.png]]<br /> <br /> PS: I might be wrong on questions 3b and 5. I'm going off of memory here.<br /> <br /> ===27 januari 2022===<br /> Door Corona was er dit jaar geen mondeling. Hierdoor was de moeilijkheidsgraad van de vragen iets lager. Professor Dehaen stuurt immers normaal gezien veel bij tijdens het mondeling. Indien er dus wel terug mondelinge examens kunnen plaatsvinden zijn de examenvragen van eerdere jaren representatiever. <br /> <br /> [[Bestand:Organiccc1.jpg]]<br /> [[Bestand:Organiccc2.jpg]]<br /> <br /> ===30 augustus 2021===<br /> Door Corona was er dit jaar geen mondeling. Hierdoor was de moeilijkheidsgraad van de vragen iets lager. Professor Dehaen stuurt immers normaal gezien veel bij tijdens het mondeling. Indien er dus wel terug mondelinge examens kunnen plaatsvinden zijn de examenvragen van eerdere jaren representatiever. <br /> <br /> [[Bestand:Organic-30-8-2021 oef 1-4.png]]<br /> [[Bestand:Organic-30-8-2021 oef 5-6.png]]<br /> <br /> <br /> ===20 januari 2021===<br /> Door Corona was er dit jaar geen mondeling. Hierdoor was de moeilijkheidsgraad van de vragen iets lager. Professor Dehaen stuurt immers normaal gezien veel bij tijdens het mondeling. Indien er dus wel terug mondelinge examens kunnen plaatsvinden zijn de examenvragen van eerdere jaren representatiever. <br /> # 6 punten [[Bestand:Oefening_1.png]]<br /> # 3 punten [[Bestand:Oefening_2.png]]<br /> # 3 punten [[Bestand:Oefening_3.png]]<br /> # 4 punten [[Bestand:Oefening_4.png]]<br /> # 4 punten [[Bestand:Oefening_5.png]]<br /> <br /> ===6 januari 2021===<br /> Door Corona was er dit jaar geen mondeling. <br /> # In de synthese van een product reageert het gegeven diketon met 2 equivalenten van een een ylide. Geeft de structuur van dit ylide, de structuur van intermediairen A en B en bespreek kort het mechanisme. De laatste stap is een rearrangement met een zuur. [[Media:Oganic 6-1-2021 oef 1.png]] (/6)<br /> # Geef het mechanisme van de reactie [[Media:Organic 6-1-2021 oef 2 .png]] (/3)<br /> # Geef het mechanisme van de reactie [[Media:Organic 6-1-2021 oef 3.jpg]] (/3)<br /> # Gegeven: een lijst van 8 reagentia, waaronder een H2SO4, acetonitrille, Na, NH2OH, t-BuONa, TiCl4, Me3SiCl en 2-broompropaan. Slechts 6 van de 8 moeten worden gebruikt. Geef de intermediairen X en Y en het mechanisme. De laatste stap is een fragmentatiereactie. [[Media:Organic 6-1-2021 oef 4.PNG]] (het kan zijn dat er een klein foutje zit in de structuur van het eindproduct) (/6)<br /> # Geef het mechanisme van de reactie. In de eerste stap reageert het startproduct met een bromopropaan-derivaat. De laatste stap is een pericyclische reactie. Verloopt de cyclisatie thermisch of fotochemisch? [[Media:Organic 6-1-2021 oef 5.PNG]] (/3)<br /> <br /> <br /> <br /> ===20 januari 2020===<br /> WERKEND BESTAND: [[Media:Organic examen 2020 deel 1.jpg]] en [[Media:Organic examen 2020 deel 2.jpg]]<br /> <br /> <br /> <br /> <br /> [[Categorie:Machemie]]<br /> <br /> ===22 januari 2019===<br /> <br /> [[Media:Vragen_Advanced_Organic_22-01-19_VM_Deel_1.jpg]]<br /> [[Media:Vragen_Advanced_Organic_22-01-19_VM_Deel_2.jpg]]<br /> <br /> ===21 januari 2019 VM===<br /> <br /> ====Examen====<br /> <br /> [[Bestand:ExamAdvOrg21jan2019.png|800px]]<br /> <br /> ====Oplossingen====<br /> [[Media:SolutionsAdvOrg21jan2019jpg.jpg]]<br /> <br /> <br /> ===28 januari 2013 NM===<br /> <br /> [[Media:Examen organische chemie 23-01-2017.jpeg]]<br /> <br /> #Explain the following reaction. [[Bestand:org1.png]]<br /> #How is given cyclopropane synthesized from diethyl malonate in several steps? Choose reagents such that a maximal yield is obtained. [[Bestand:org2.png]]<br /> #This reaction scheme is an example of a benzannelation reaction. Upon heating, several consecutive steps happen so that the given end product is obtained. Among these steps are three electrocyclic reactions (two 4-electron and one 6-electron), a tautomerization, and a cycloaddition (not necessarily in this order). [[Bestand:org3.png]]<br /> #Explain formation of this product in presence of base. [[Bestand:org4.png]]<br /> #Give product A and explain how this reaction occurs. [[Bestand:org5.png]]<br /> #What products will be formed in following reactions? [[Bestand:org6.png]]</div>

R0804230 https://wiki.chemika.be/index.php?title=Advanced_Organic_Chemistry&diff=3265 2023-01-27T16:41:26Z

<p>R0804230: /* 26 January 2023 */</p> <hr /> <div>[[Categorie:Machemie]]<br /> <br /> ==Examenvragen==<br /> ===26 January 2023===<br /> IMPORTANT NOTE: The following statements contain a number of errors. In this drive you can find everything correctly. https://docs.google.com/document/d/1076KR86PdTwE4jakAgw2e8KvuAksebex/edit?usp=sharing&amp;ouid=101486339872913430382&amp;rtpof=true&amp;sd=true<br /> #Devise a strategy to obtain following molecule using Tosylazide and Rhodium salt and any other reagent. No stereochemistry needs to be explained. (I drew the endproduct wrongly, one of the substituents is acetate not a ketone)[[Bestand:Exam_Question_1.png]]<br /> #Both products have a common intermediate. Explain in detail how these products are formed [[Bestand:Exam_Question_2.png]]<br /> #Discuss the mechanism to obtain following products [[Bestand:Exam_Question_3.png]]<br /> #Discuss the mechanism of this reaction. No stereochemistry has to be explained (It's PPh3=CH2 btw, another mistake) [[Bestand:Exam_Question_4.png]]<br /> #Explain the following reaction. [[Bestand:Exam_Question_5.png]]<br /> <br /> PS: I might be wrong on questions 3b and 5. I'm going off of memory here.<br /> <br /> ===27 januari 2022===<br /> Door Corona was er dit jaar geen mondeling. Hierdoor was de moeilijkheidsgraad van de vragen iets lager. Professor Dehaen stuurt immers normaal gezien veel bij tijdens het mondeling. Indien er dus wel terug mondelinge examens kunnen plaatsvinden zijn de examenvragen van eerdere jaren representatiever. <br /> <br /> [[Bestand:Organiccc1.jpg]]<br /> [[Bestand:Organiccc2.jpg]]<br /> <br /> ===30 augustus 2021===<br /> Door Corona was er dit jaar geen mondeling. Hierdoor was de moeilijkheidsgraad van de vragen iets lager. Professor Dehaen stuurt immers normaal gezien veel bij tijdens het mondeling. Indien er dus wel terug mondelinge examens kunnen plaatsvinden zijn de examenvragen van eerdere jaren representatiever. <br /> <br /> [[Bestand:Organic-30-8-2021 oef 1-4.png]]<br /> [[Bestand:Organic-30-8-2021 oef 5-6.png]]<br /> <br /> <br /> ===20 januari 2021===<br /> Door Corona was er dit jaar geen mondeling. Hierdoor was de moeilijkheidsgraad van de vragen iets lager. Professor Dehaen stuurt immers normaal gezien veel bij tijdens het mondeling. Indien er dus wel terug mondelinge examens kunnen plaatsvinden zijn de examenvragen van eerdere jaren representatiever. <br /> # 6 punten [[Bestand:Oefening_1.png]]<br /> # 3 punten [[Bestand:Oefening_2.png]]<br /> # 3 punten [[Bestand:Oefening_3.png]]<br /> # 4 punten [[Bestand:Oefening_4.png]]<br /> # 4 punten [[Bestand:Oefening_5.png]]<br /> <br /> ===6 januari 2021===<br /> Door Corona was er dit jaar geen mondeling. <br /> # In de synthese van een product reageert het gegeven diketon met 2 equivalenten van een een ylide. Geeft de structuur van dit ylide, de structuur van intermediairen A en B en bespreek kort het mechanisme. De laatste stap is een rearrangement met een zuur. [[Media:Oganic 6-1-2021 oef 1.png]] (/6)<br /> # Geef het mechanisme van de reactie [[Media:Organic 6-1-2021 oef 2 .png]] (/3)<br /> # Geef het mechanisme van de reactie [[Media:Organic 6-1-2021 oef 3.jpg]] (/3)<br /> # Gegeven: een lijst van 8 reagentia, waaronder een H2SO4, acetonitrille, Na, NH2OH, t-BuONa, TiCl4, Me3SiCl en 2-broompropaan. Slechts 6 van de 8 moeten worden gebruikt. Geef de intermediairen X en Y en het mechanisme. De laatste stap is een fragmentatiereactie. [[Media:Organic 6-1-2021 oef 4.PNG]] (het kan zijn dat er een klein foutje zit in de structuur van het eindproduct) (/6)<br /> # Geef het mechanisme van de reactie. In de eerste stap reageert het startproduct met een bromopropaan-derivaat. De laatste stap is een pericyclische reactie. Verloopt de cyclisatie thermisch of fotochemisch? [[Media:Organic 6-1-2021 oef 5.PNG]] (/3)<br /> <br /> <br /> <br /> ===20 januari 2020===<br /> WERKEND BESTAND: [[Media:Organic examen 2020 deel 1.jpg]] en [[Media:Organic examen 2020 deel 2.jpg]]<br /> <br /> <br /> <br /> <br /> [[Categorie:Machemie]]<br /> <br /> ===22 januari 2019===<br /> <br /> [[Media:Vragen_Advanced_Organic_22-01-19_VM_Deel_1.jpg]]<br /> [[Media:Vragen_Advanced_Organic_22-01-19_VM_Deel_2.jpg]]<br /> <br /> ===21 januari 2019 VM===<br /> <br /> ====Examen====<br /> <br /> [[Bestand:ExamAdvOrg21jan2019.png|800px]]<br /> <br /> ====Oplossingen====<br /> [[Media:SolutionsAdvOrg21jan2019jpg.jpg]]<br /> <br /> <br /> ===28 januari 2013 NM===<br /> <br /> [[Media:Examen organische chemie 23-01-2017.jpeg]]<br /> <br /> #Explain the following reaction. [[Bestand:org1.png]]<br /> #How is given cyclopropane synthesized from diethyl malonate in several steps? Choose reagents such that a maximal yield is obtained. [[Bestand:org2.png]]<br /> #This reaction scheme is an example of a benzannelation reaction. Upon heating, several consecutive steps happen so that the given end product is obtained. Among these steps are three electrocyclic reactions (two 4-electron and one 6-electron), a tautomerization, and a cycloaddition (not necessarily in this order). [[Bestand:org3.png]]<br /> #Explain formation of this product in presence of base. [[Bestand:org4.png]]<br /> #Give product A and explain how this reaction occurs. [[Bestand:org5.png]]<br /> #What products will be formed in following reactions? [[Bestand:org6.png]]</div>

R0804230 https://wiki.chemika.be/index.php?title=Chemical_Statistical_Mechanics&diff=3199 2023-01-21T20:09:48Z

<p>R0804230: /* Harvey */</p> <hr /> <div>[[Categorie:Machemie]]<br /> ==Vakinformatie==<br /> Vak gegeven door Harvey en Nies. Er zijn 3 of 4 vragen op het examen, waarvan telkens 1 van nies voor 1/3de van de punten, en de rest is van Harvey.<br /> Harvey geeft altijd 1 artikel waaruit je allerlei vragen moet gaan oplossen (na het lezen). Achteraf is er nog een soort oefening die een halve mengeling is met de theorie. De oefeningen van nies (PC) worden nooit gevraagd. <br /> LET OP: het is open boek, maar niet voor niets, het boek is niet echt echt nodig. Je moet eigelijk bewijzen dat je dingen fundamenteel begrijpt op het examen.<br /> Examen is schriftelijk (niet mondeling zoals op ECTS staat) + open boek voor beide proffen.<br /> <br /> ==Examenvragen==<br /> <br /> ===Augustus (herexamen) 2022===<br /> <br /> ====Harvey====<br /> #Artikel over gouden nanopartikels die via binding met Cu, 2 anionen (- - lading) toch op elkaar konden laten binden. Hierbij moesten we uitleg geven waarom dit beter ging met hulp van NaCl en KCl (en waarom het bij een van de 2 beter ging dan bij de andere). Ook nog een paar vragen maar best oplosbaar met open boek. (over de transl en vibr partitiefunctie was er ook een vraag).<br /> #Weet ik niet meer concreet, maar ging over de partitiefunctie en ensembles<br /> <br /> ====Nies====<br /> <br /> #Vraag over Flory Huggins lattice theory (aangepast in vloei) en we moesten phi en chi berekenen bij critische toestand (uit polymer science phi en chi kritisch bij het deel van flory huggins!). Ook nog extra vragen waar we een p,T, chi diagram moesten tekenen (dit kon ik echt niet)</div>

R0804230 https://wiki.chemika.be/index.php?title=Polymer_Sciences:_from_Synthesis_to_Polymer_Material&diff=3198 2023-01-21T15:44:33Z

<p>R0804230: /* Prof. Nies */</p> <hr /> <div>[[Categorie:Machemie]]<br /> <br /> ==Vakinformatie==<br /> Gedoceerd door Professor Nies en Professor Koeckelberghs. Lessen zijn altijd in het Engels. De verdeling is 2/3 op het deel van Nies en 1/3 op het deel van Koeckelberghs. Bij Nies zijn er ook verplichte assignments tijdens het jaar, die meetellen voor een fractie 4/(12-N) van de punten van zijn deel (met N aantal assignments, doorgaans 2). Nies zijn examen is gesloten boek en er moet maar één vraag bij hem mondeling besproken worden (deze wordt op voorhand aangeduid). Bij Koeckelberghs zijn alle vragen mondeling te bespreken.<br /> <br /> ==Examenvragen==<br /> ===20th of January 2023===<br /> ====Prof. Nies====<br /> #Eq. 1.40 is given. Discuss the limiting behavior for L&lt;&lt;lp and L&gt;&gt;lp. The Kuhn length was defined by two equations. Write them down and give a qualitative description. Based on this, give the relationship between lK and lp. Can a chain with L&lt;&lt;lp also be seen as Kuhn chain? Explain.<br /> #Scientist claim that a polymer in solution shows a Phi(2)-T diagram with a closed loop miscibility hole. Chi(crit,1-2) are given as are T(crit,1-2). The values of Chi(0), Chi(1) and Chi(2) are provided too (Eq. 2.19). From this, calculate s2 and Phi(crit,1-2). Show ether qualitatively of quantitatively if their reasoning for a closed loop miscibility hole is justified. Make a sketch of the Phi(2)-T diagram containing Phi(crit,2), T(crit,1-2), the binodals and spinodals.<br /> #Figure 3.27 is given and a graph that demonstrates the linear behavior between 1/l and Tm. In several steps you are guided towards deriving the Gibbs-Thomson-Tammann equation.<br /> <br /> ====Prof. Koeckelberghs====<br /> #Compare anionic and cationic ROP in terms of: monomers, initiators, propagation, transfer, termination and their ceiling temperature.<br /> #Discuss, based on the structure of vinyl monomers, in what way they can be polymerized. Relate the stability of the active species to Rp and discuss retardation and inhibition.<br /> #Discuss briefly how conversion and molar mass relate to each other in step-growth polymerization.<br /> <br /> ===27 augustus 2022===<br /> ====Prof. Nies====<br /> #Grafiek van specific volume relaxation uitleggen<br /> #Gibbs-Thomson equation afleiden<br /> #Polymer in solvent is cooled, binodal/spinodal and Tg curves zijn gegeven. 1) Leg uit wat je denkt dat er zal gebeuren, 2) welke morphology denk je dat gevormd wordt voor trage vs snelle cooling? <br /> ====Prof. Koeckelberghs====<br /> #free radical, anionic and cationic polymerization vergelijken op vlak van a) monomers b) termination reaction c) possibility for living polymerization<br /> #ring opening metathesis polymerization bespreken<br /> ===20 januari 2022===<br /> ====Prof. Nies====<br /> #Afleiding maken van de end to end distance van de freely rotating chain + uitleggen waarom er ⟨ .... ⟩ haakjes worden gebruikt + uitleggen wat L voor de FRC is<br /> #Gegeven formule van de gibbs vrije energie van menging (FH)Flory huggins<br /> #*Wat is de thermodynamische voorwaarde voor spinodaal gedrag? + Wat is de thermodynamische voorwaarde voor kritische toestand?<br /> #*Leid ook verder af wat chi kritisch en phi kritisch zijn hieruit (opnieuw afleiden!)<br /> #*Bepaal of de gegeven Tcritisch op een UCST of LCST systeem wijst <br /> #*Geef UCST en LCST namen voluit<br /> #*Teken een phi T diagram waar je de UCST of LCST van in de oefening uitlegt en uittekend<br /> #Avrami equation gegeven en eveneens een avrami plot<br /> #*Leg uit wat m en k zijn in deze vergelijking<br /> #*Leg uit wat we in deze plot zien ivm de equation, over de volledige tijdsinterval<br /> #*Teken zelf een plot volgens Avrami, waar hetzelfde polymeer (syndiotactic polystyrene) bij andere Tc was: Tc oorspronkelijke plot was 110°C, de 3 anderen waren -30°C, 105°C, 175°C --&gt; Tm en Tg van polystyreen waren gegeven!<br /> <br /> ====Prof. Koeckelberghs====<br /> #Definieer en bespreek living/controlled polymerization. Welke experimenten kan je uitvoeren om aan te tonen dat het gaat om een living/controlled polymerization. Bespreek de algemene methode waarop een free-radical polymerization omgezet wordt in een controlled polymerization. <br /> #Bespreek emulsion polymerization <br /> <br /> ===13 januari 2021===<br /> Verkorte examenduur omwille van corona<br /> ====Prof. Koeckelberghs====<br /> #Definieer en bespreek living/controlled polymerization. Welke experimenten kan je uitvoeren om aan te tonen dat het gaat om een living/controlled polymerization. Bespreek de algemene methode waarop een free-radical polymerization omgezet wordt in een controlled polymerization. <br /> #Bespreek emulsion polymerization <br /> <br /> ====Prof. Nies====<br /> #Gegeven formule van de gibbs vrije energie van menging (FH)<br /> #*Geef de betekenis van ieder symbool in de formule en de eenheid <br /> #*Wat is de thermodynamische voorwaarde voor spinodaal gedrag? <br /> #*Wat is de thermodynamische voorwaarde voor kritische toestand? <br /> #*Schrijf UCST en LCST languit <br /> #*Leidt de vergelijking van chikritisch en phikritisch af<br /> #*Oefening: berekenen Chikritisch, UCST of LCST gedrag? Tekenen fasediagram en verloop van chi in functie van de temperatuur <br /> #Leidt de vergelijking voor de average squared end-to-end distance af voor een WLC met de vergelijking voor een FRC gegeven. <br /> ===16 januari 2020===<br /> ====Prof. Koeckelberghs====<br /> #Anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #Step growth en chain growth vergelijken en hoe je kan bepalen wanneer je welke hebt<br /> #Metathese kort uitleggen<br /> <br /> ====Prof. Nies====<br /> #Taak uitleggen (mondeling).<br /> #Gibs-Thomson-Tammann afleiden voor lamellar crystal, vergelijking voor Gibbs fusie is gegeven<br /> #Derive expression for deltaG = G(deformed) - G(undeformed). Expressions for the squared end-to-end distance for FJC and P(R)dR are given<br /> <br /> ===17 januari 2019===<br /> ====Prof. Koeckelberghs====<br /> #Anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #Step growth en chain growth vergelijken en hoe je kan bepalen wanneer je welke hebt<br /> #Metathese kort uitleggen<br /> <br /> ====Prof. Nies====<br /> #Taak uitleggen (mondeling).<br /> #Grafiek over Tg afhankelijkheid van de cooling rate, uitleggen op moleculair niveau (met betrekking tot mobiliteit)<br /> #Afleiding radius of gyration geven (fjc), toon aan dat &lt;s²&gt;= lb² (N+1)(N-1)/6N en of de uitdrukking verandert als er interacties zijn tussen de massa's met Lennard Jones interactie potentiaal?<br /> <br /> ===14 januari 2019===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #plot van volumeverandering i.f.v. de tijd (case2-figuur 25) gegeven, bespreek ... (physical ageing)<br /> #afleiding voor de Thomson-Tammann smelttemperatuur van een eindig sfeer kristal, met de fusie Gibbs vrij energie van een oneindig groot kristal gegeven<br /> <br /> ===31 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #Anionic versus cationic ring opening polymerization:<br /> #*monomeer<br /> #*intiator<br /> #*general polymerization mechanism<br /> #*termination + transfer<br /> #*ceiling temperature<br /> #Influence of the molecular structure of vinyl monomers on possibility to polymerize. Correlate the molecular structure with:<br /> #*the way monomers can be polymerized<br /> #*rate of polymerization<br /> #*retardation + inhibition<br /> #Influence of conversion on molar mass in step growth polymerization<br /> <br /> ====Prof. Nies====<br /> #Formula growth rate given (case 3 eq. 1.28)<br /> #*discuss the origin of the exponential facors and the front factor in the given equation.<br /> #*discuss dependence of the growth rate on the size of the crystal at a chosen crystallization temperature. Make a schematic plot of the predicted growth rate versus the crystal size for the chosen crystallization temperature.<br /> #*what are the consequences for the predicted growth rate for crystallization behaviour at a particular crystallization temperature?<br /> #Figure volume relaxation (case 2 figure 27)<br /> #Rubbers<br /> #*Define an ideal rubber<br /> #*Derive expression for deltaG = G(deformed) - G(undeformed)<br /> Expressions for the squared end-to-end distance for FJC and P(R)dR are given<br /> <br /> ===25 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #ceiling temperature vergelijken bij vinyl polymerization en ring opening polymerization + kleine bijvragen daarover<br /> #controlled radical polymerization (NMP en ATRP)<br /> #living cationic polymerization<br /> <br /> ====Prof. Nies====<br /> #grafiek spinodal, binodal (die met Berghman's point) toegepast op PDLC, vorming van PDLC uitleggen aan de hand van grafiek<br /> #physical ageing<br /> #avrami plot<br /> <br /> ===19 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #step growth en chain growth vergelijken en hoe ge kunt bepalen wanneer ge wa hebt<br /> #ROMP uitleggen<br /> <br /> ====Prof. Nies====<br /> #taak bespreken (mondeling)<br /> #Gibs-Thomson-Tammann afleiden voor lamellar crystal, vergelijking voor Gibbs fusie is gegeven<br /> #spinodal en critical condition geven + afleiden helemaal en berekenen wat de critische waarden zijn voor 'chi' en 'fi-2', vergelijking Gibbs gegeven<br /> Huggings formule gegeven (niet in boek) is een uitbreiding van Flory-huggings vergelijking, wanneer zijn die aan elkaar gelijk en wat is de betekenis dan<br /> <br /> ===15 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #plot van volumeverandering i.f.v. de tijd (case2-figuur 25) gegeven, bespreek ... (physical ageing)<br /> #afleiding voor de Thomson-Tammann smelttemperatuur van een eindig sfeer kristal, met de fusie Gibbs vrij energie van een oneindig groot kristal gegeven<br /> <br /> ===25 augustus 2017===<br /> ====Prof. Koeckelberghs====<br /> #Vergelijk anionische ring opening polymerizatie met kationische ring opening polymerizatie op vlak van<br /> #*monomeer<br /> #*intiator<br /> #*mechanisme<br /> #*terminatie/recombinatie<br /> #*ceiling temperature<br /> #Lewis Mayo en die R ratio's daar in. Welke dingen invloed daar op hebben en hoe + voorbeeld<br /> #Welk invloed heeft de vorderingsgraad op molaire massa in step growth polymerizatie?<br /> <br /> ====Prof. Nies====<br /> #(mondelinge vraag) bespreek grafiek en waarom dat dit gebeurt (uitleggen op moleculair niveau), grafiek van physical ageing<br /> #Afleiding van hoofdstuk 4 Gibbs vrije energie wanneer een ideaal rubber deformatie ondergaat<br /> #vanalles van UCST en LCST, iets vaags.<br /> <br /> <br /> ===20 januari 2017===<br /> ====Prof. Koeckelberghs====<br /> #Anionische, kationische en frp uitleggen obv monomeer, terminatie en hoe ge het levend kunt maken<br /> #Step growth en chain growth<br /> #Ringopening methatese<br /> <br /> ====Prof. Nies====<br /> Vraag 1:<br /> #Wat is de definitie van een FRC?<br /> #Bij welke condities is de FRC gelijk aan de FJC<br /> #Bereken Lk en Nk voor de limiet van een enorm lange FRC (&lt;R2&gt;frc gegeven)<br /> #Leidt een vergelijking af voor de mean squared end-to-end distance van een ideaal lineair diblock copolymeer bestaande uit Nk1 Kuhn monomeren met lengte lk dat vasthangt via 1 einde aan Nk2 Kuhn monomeren met lengte lk2<br /> Vraag 2:<br /> #Mengsel van PS in methylcyclohexaan (Mw = 355kg/mol)<br /> Bij T=350K bestaat het mengsel uit 1 homogene vloeibare fase. Deze T is 6K boven de flory T. Polymeer volume fractie in de homogene fase is O,2<br /> Bij T=335K: twee vloeibare fases, de polymeer volume fracties van de coexistant fases zijn 0,003 en 0,435<br /> In de compositie range {0,002-0,044} en {0,336-0,435} is de structuur van de initiele fase scheiding kleine druppels in een matrix fase<br /> #*Schets het verloop van delta Gmix ifv de volledige compositierange bij T=333K<br /> #*Duid de points of interest in deze curve aan en leg ze uit.<br /> #*Leg tot he point uit waarom je vraag a zo geschetst hebt<br /> #*Wat zal de morfologie zijn in de initiële fase van scheiding?<br /> <br /> <br /> ===19 Januari 2017===<br /> ====Prof. Koekcelberghs====<br /> #Vergelijken ven anionische en kationische ringopeningpolymerisatie op vlak van<br /> #*Initiatie/Initiatoren<br /> #*Terminatie/transfer<br /> #*Mechanisme<br /> #*Mogelijke monomeren<br /> #*Ceiling temperature<br /> #Geef de factoren die een copolymerisatie beïnvloeden <br /> #Geef de invloed van de conversie bij een step-growth polymerisatie<br /> <br /> ====Prof. Nies====<br /> #Vraag 1: bespreek je taak helemaal (mondeling)<br /> #Vraag 2: Leid het verschil in Gibbs vrije energie voor een vervormd en onvervormd ideaal rubber af. End-to-end distance van een ideaal rubber en de Gaussische distributie zijn gegeven.<br /> #Vraag 3: Gegeven een stelling die zegt dat er een closed-gap miscibility gap plaatsvindt, met een formule voor chi in functie van T. 2 kritische waarden voor de temperatuur zijn gegeven. De vraag is: kan deze stelling kloppen? <br /> <br /> <br /> ===16 januari 2017===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #zie theoretical questions doc case 3 vraag 13, maar alleen de excess Gibbs energy en de chemical potentials waren gegeven<br /> #Vraag 3:<br /> #*thermodynamische uitdrukking voor spinodal en critical conditions afleiden.<br /> #*zie theoretical questions doc case 2 vraag 4 en de uitdrukking voor de Gibbs energy is gegeven<br /> #*de verbeterde Huggins uitdrukking voor de Gibbs energy is gegeven en daarvoor de enthalipsche en entropische bijdragen bepalen.<br /> #*De FH uitdrukking is een speciaal geval van de Huggins uitdrukking: bepaal de conditie van y waarvoor dit geld + geef de fysische betekenis van die conditie<br /> <br /> ===14 januari 2016===<br /> ====Prof. Koeckelberghs====<br /> #Vergelijk chemisch geïnitieerde FRP en ATR op vlak van:<br /> #*Algemeen protocol<br /> #*Snelheidsvergelijkingen<br /> #*Invloed van de moleculaire structuur op de snelheid van polymerisatie<br /> #Leg uit: step growth en chain growth polymerisatie. Hoe kan je experimenteel onderscheid maken tussen beide?<br /> #Leg kort uit: Ziegler-Nattakatalysator<br /> <br /> ====Prof. Nies====<br /> #Gegeven: Tg in functie van cooling rate. Verklaar de moleculaire oorsprong van dit fenomeen. (oral)<br /> #*Mondelinge bijvraag: wat bepaalt, naast de kinetische energie, ook mee het vrije volume?<br /> #Leid een formule af voor het smeltpunt van een eindig sferisch kristal.<br /> #Vrije energie van mengen volgens Flory-Huggins gegeven:<br /> #*Wat zijn de spinodale en kristische voorwaarden?<br /> #*Geef de betekenis en eenheiden van elke parameter in de vergelijking.<br /> #*Geef een concrete uitdrukking voor de kritische en spinodale voorwaarden afgeleid uit de bovenstaande vergelijking.<br /> #*Geef een concrete uitdrukking voor de kritische phi en chi.<br /> #*Gegeven een uitgebreide variant van de vergelijking van Flory en Huggins. Wat zijn de enthalpische en entropische bijdragen?<br /> #*De oorspronkelijke formule van Flory en Huggins is een bijzonder geval van de bovenstaande vergelijking. Onder welke voorwaarde is dit en waarmee komt dit fysisch overeen?<br /> <br /> ===11 januari 2016===<br /> ====Prof. Koeckelberghs====<br /> #Define living/controlled polymerisation. Hoe neem je dit experimenteel waar? Hoe maak je free radical controlled?<br /> #Wat is de invloed van moleculaire structuur van monomeer op manier vinylpolymerisatie, snelheid en retardation/inhibition?<br /> #Bespreek emulsiepolymerisatie.<br /> <br /> ====Prof. Nies====<br /> #Case 2, figuur 27 uitleggen (specifiek volume in functie van tijd) (oral)<br /> #Leid Gibbs Thomson uitdrukking af voor smelttemperatuur van sferisch kristal.<br /> #Uitdrukking s^2 en massacentrum gegeven:<br /> #*Leid average radius of gyration af met alles massa's = m.<br /> #*Toon aan dat average radius of gyration = lb^2 (N+1)(N-1)/6N als i=1,2,3,...,N-1.<br /> #*Veranderen de uitdrukking als er interacties zijn tussen de massa's met Lennard Jones interactie potentiaal?<br /> <br /> ===24 januari 2013===<br /> ====Prof. Koeckelberghs====<br /> #Discuss the ceiling temperature and apply it on both the vinyl polymerization and ring opening polymerization. Is the ceiling temperature of a particular monomer dependent on the way it's polymerized?<br /> Is it possible that a particular monomer, of which the ceiling temperature is such that only low-molar mass oligomers can be obtained via a living anionic polymerization at a certain temperature, can be polymerized into high-molar mass polymer using a free radical polymerization at the same temperature? Motivate your anwer.<br /> #Explain the principle of a controlled radical polymerization and apply it on NMP and ATRP.<br /> #Discuss briefly the living cationic vinyl polymerization.<br /> ====Prof. Nies====<br /> Zie onderstaande afbeelding.<br /> [ <br /> #Assignment 1 (oral)<br /> #The &amp;lt;i&amp;gt;free rotating chain&amp;lt;/i&amp;gt; (FRC) consists of N bonding vectors l&amp;lt;sub&amp;gt;i&amp;lt;/sub&amp;gt;, i=1,...,N with constant bond length |l&amp;lt;sub&amp;gt;i&amp;lt;/sub&amp;gt;| = l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt; and constant bond angles Ï´&amp;lt;sub&amp;gt;ii+1&amp;lt;/sub&amp;gt;=Ï´, i=1,...,N between the successive bonding vectors. The average quadratic end-to-end distance &amp;lt;R²&amp;gt;, valid for all physically sensible values of N, l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt; and Ï´, is given by [[Bestand:R-FRC.JPG]]<br /> #*Show that the average quadratic end-to-end distance &amp;lt;R²&amp;gt; of the FRC chain with very small bond angles also can be written in the Kratky-Porod chain form: &amp;lt;R²&amp;gt; = 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;L-2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;²(1-exp(-L/l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;),<br /> with l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;=l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt;L/(1-cosÏ´) the perstistence length and L the contour length.<br /> #Derive from the general thermodynamic equilibrium conditions the melting point of a polymer crystal in equilibrium with a solution of the polymer.<br /> For the polymer solution you can use the Flory-Huggins excess Gibbs-energy of mixing.<br /> [[Bestand:G(mix).JPG]]<br /> <br /> The chemical potentials of the components are given by:<br /> [[Bestand:Chempot.JPG]] ]<br /> <br /> [[Bestand:240113nies.png]]<br /> <br /> ===18 januari 2013===<br /> ====Prof. Koeckelberghs====<br /> #Compare chemically initiated free radical polymerization and ATRP, for the following aspects:<br /> #*general concept<br /> #*rate of polymerization<br /> #*influence of molecule structure on polymerization rate<br /> #Discuss the differences in mechanism of chain growth and step growth polymerization. How can one investigate which type of polymerization he is dealing with?<br /> #Explain briefly: Ziegler-Natta catalyst<br /> ====Prof. Nies====<br /> #Discussion of assignment 1 (oral)<br /> <br /> Zie onderstaande afbeelding.<br /> <br /> #The expression of average squared end-to-end distance of the Kratky-Porod chain is given: &amp;lt;R²&amp;gt; = 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;L - 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;²(1-exp(-L/l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;)<br /> #*Derive expressions for the Kuhn segment length and the number of Kuhn segments for this chain.<br /> #*Discuss your results. For instance, did you make any assumptions? Mention them explicitly.<br /> #The excess Gibbs ebergy of mixing in the Flory-Huggins model is given: ΔG/N&amp;lt;sub&amp;gt;l&amp;lt;/sub&amp;gt;kT = Δg/kT = (φ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;/s&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;)lnφ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt; + (φ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;/s&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;)lnφ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; + χφ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;φ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;<br /> #*Derive expressions for the spinodal and critical conditions.<br /> #*Derive from these expressions the formulae for the critical composition φ&amp;lt;sub&amp;gt;2,cr&amp;lt;/sub&amp;gt; and critical value of χ.<br /> #*What is the relevance of the spinodal for material behaviour?<br /> [[Bestand:180113nies.png]]<br /> <br /> ===20 januari 2012===<br /> ====Professor Nies====<br /> #Gegeven een fase-diagram uit Case II. Wat gebeurt er als er vanuit punt A (dat links van de critical point lag):<br /> #* traag wordt afgekoeld<br /> #* wordt gequenched (1000K/min)<br /> #* Hoe ziet de oplossing er na koelen uit voor beide gevallen<br /> #5 begrippen uitleggen:<br /> #*Thermo-elastische inversie<br /> #*Physical ageing<br /> #*Second order transition<br /> #*Effective pair potential<br /> #*Nucleation &amp;amp; growth<br /> #Leidt de spinodal en critical conditions af en ook de waarden voor Fi(2,crit) en Chi(krit).<br /> <br /> ====Professor Koeckelberghs====<br /> #Wat is de ceiling temperatuur en correleer dit met vinylpolymerisatie en Ring opening polymerisatie. Is de ceiling temperatuur afhankelijk van hoe we polymeriseren? Stel we polymeriseren via een living anionische polymerisatie. Het monomeer heeft een lage ceiling temperatuur, wat ervoor zorgt dat er geen lange polymeerketens worden gevormd. Kan men dan langere ketens verkrijgen als men bij dezelfde temperatuur via een radicale polymerisatie polymeriseert?<br /> #M1 en M2 worden gecopolymeriseerd. Geef de parameters voor beide monomeren en leg uit waarvan deze afhangen.<br /> # Leg uit: (radicalaire) emulsiepolymerisatie<br /> <br /> ===21 januari 2011===<br /> ====Professor Nies====<br /> # Teken het verloop van de de gibssvrij-energie in functie van volumefractie bij een temperatuur van 300K. Volumefracties = 0,2. Coexistence points en spinodal points gegeven. Ook de verschillende punten aanduiden en kort uitleggen. (deze vraag was mondeling)<br /> # Formule p 50 case 1 gegeven (zonder 4e term)<br /> #* leg de symbolen uit + dimensies + eenheden<br /> #* wat bedoelt men met &amp;quot;volgens de Flory benadering...&amp;quot;<br /> #* leg de twee verschillende termen uit<br /> #* Bereken end-to-end distance in evenwicht bij een flory-solvent<br /> #* Bereken end-to-end distance in evenwicht bij een goed solvent<br /> # Avramiplot+vergelijking gegeven<br /> #*leg de parameters uit<br /> #*hoe kan je volumefractie kristallijne fase meten, leg kort techniek uit.<br /> #*geef een kwalitatieve bespreking van de grafiek<br /> #*wat kan je uit de parameters afleiden<br /> <br /> ====Professor Koeckelberghs====<br /> # zie vragen vorig jaar<br /> <br /> ===15 januari 2010===<br /> ====Professor Nies====<br /> #Er was de grafiek gegeven met daarop de binodal, spinodal en Tg curve. Met daarop 3 punten aangegeven, telkens in het homogene gebied boven de binodal en boven Tg. Punt A: Links van kritische punt, punt B tussen kritische punt en Berghmans punt en punt C rechts van Berghmanspunt. (Alleen deze vraag mondeling)<br /> #*Wat vindt plaats als je in punt A traag afkoelt?<br /> #*Wat vindt plaats als je in punt A afkoelt met 1000K/min<br /> #*Wat vindt plaats als je in punt B traag afkoelt<br /> #*Wat vindt plaats als je in punt B afkoelt met 1000K/min<br /> #*Wat vindt plaats als je in punt C traag afkoelt?<br /> #*Wat vindt plaats als je in punt C afkoelt met 1000K/min<br /> #Vergelijking van Groeisnelheid bij kristallisatie (U) gegeven: U=Fexp(A)exp(B)exp(C) Zowel F,A,B,C waren gegeven in symbolen(vergelijking onder 7.B case III)<br /> #*Geef waarvoor de symbolen staan en wat hun eenheden zijn.<br /> #*Verklaar waar de Frontfactor (F) en de drie exp's vandaan komen<br /> #*Bespreek temperatuursafhankelijkheid en geef een schets<br /> #Geef de definitie van een ideale Rubber<br /> #* Leid de uitdrukking voor af voor S bij een willekeurige verandering. P(R) gegeven<br /> <br /> ====Koeckelberghs====<br /> #Vergelijk radicalaire, anionische en kationische vinylpolymerisatie<br /> #*Mogelijke monomere deeltjes (stabiliteit)<br /> #*Terminatie reacties<br /> #*Invloed van verschillende voorkomende deeltjes op sneldheid (hiermee bedoelde hij de associated ion pairs etc)<br /> #*Mogelijke manier om ze 'levend' te maken. (of quasi levend)<br /> #*? dacht dat er nog 1 was<br /> #Je wil een ideaal, perfect blockcopolymeer maken van MMA en MA op anionische wijze. Welk monomeer moet je eerst polymeriseren? Blijft indien je dit met ATRP wil doen de volgorde dezelfde?<br /> #Bespreek kort Ring Opening Metathesis Polymerisatie.</div>

R0804230 https://wiki.chemika.be/index.php?title=Polymer_Sciences:_from_Synthesis_to_Polymer_Material&diff=3192 2023-01-20T22:27:28Z

<p>R0804230: /* Prof. Koeckelberghs */</p> <hr /> <div>[[Categorie:Machemie]]<br /> <br /> ==Vakinformatie==<br /> Gedoceerd door Professor Nies en Professor Koeckelberghs. Lessen zijn altijd in het Engels. De verdeling is 2/3 op het deel van Nies en 1/3 op het deel van Koeckelberghs. Bij Nies zijn er ook verplichte assignments tijdens het jaar, die meetellen voor een fractie 4/(12-N) van de punten van zijn deel (met N aantal assignments, doorgaans 2). Nies zijn examen is gesloten boek en er moet maar één vraag bij hem mondeling besproken worden (deze wordt op voorhand aangeduid). Bij Koeckelberghs zijn alle vragen mondeling te bespreken.<br /> <br /> ==Examenvragen==<br /> ===20th of January 2022===<br /> ====Prof. Nies====<br /> #Eq. 1.40 is given. Discuss the limiting behavior for L&lt;&lt;lp and L&gt;&gt;lp. The Kuhn length was defined by two equations. Write them down and give a qualitative description. Even a wormlike chain with high but not infinite stiffness will behave like an ideal flexible chain under certain conditions. Explain.<br /> #Scientist claim that a polymer in solution shows a Phi(2)-T diagram with a closed loop miscibility hole. Chi(crit,1-2) are given as are T(crit,1-2). The values of Chi(0), Chi(1) and Chi(2) are provided too (Eq. 2.19). From this, calculate s2 and Phi(crit,1-2). Show ether qualitatively of quantitatively if their reasoning for a closed loop miscibility hole is justified. Make a sketch of the Phi(2)-T diagram containing Phi(crit,2), T(crit,1-2), the binodals and spinodals.<br /> #Figure 3.27 is given and a graph that demonstrates the linear behavior between 1/l and Tm. In several steps you are guided towards deriving the Gibbs-Thomson-Tammann equation.<br /> ====Prof. Koeckelberghs====<br /> #Compare anionic and cationic ROP in terms of: monomers, initiators, propagation, transfer, termination and their ceiling temperature.<br /> #Discuss, based on the structure of vinyl monomers, in what way they can be polymerized. Relate the stability of the active species to Rp and discuss retardation and inhibition.<br /> #Discuss briefly how conversion and molar mass relate to each other in step-growth polymerization.<br /> <br /> ===27 augustus 2022===<br /> ====Prof. Nies====<br /> #Grafiek van specific volume relaxation uitleggen<br /> #Gibbs-Thomson equation afleiden<br /> #Polymer in solvent is cooled, binodal/spinodal and Tg curves zijn gegeven. 1) Leg uit wat je denkt dat er zal gebeuren, 2) welke morphology denk je dat gevormd wordt voor trage vs snelle cooling? <br /> ====Prof. Koeckelberghs====<br /> #free radical, anionic and cationic polymerization vergelijken op vlak van a) monomers b) termination reaction c) possibility for living polymerization<br /> #ring opening metathesis polymerization bespreken<br /> ===20 januari 2022===<br /> ====Prof. Nies====<br /> #Afleiding maken van de end to end distance van de freely rotating chain + uitleggen waarom er ⟨ .... ⟩ haakjes worden gebruikt + uitleggen wat L voor de FRC is<br /> #Gegeven formule van de gibbs vrije energie van menging (FH)Flory huggins<br /> #*Wat is de thermodynamische voorwaarde voor spinodaal gedrag? + Wat is de thermodynamische voorwaarde voor kritische toestand?<br /> #*Leid ook verder af wat chi kritisch en phi kritisch zijn hieruit (opnieuw afleiden!)<br /> #*Bepaal of de gegeven Tcritisch op een UCST of LCST systeem wijst <br /> #*Geef UCST en LCST namen voluit<br /> #*Teken een phi T diagram waar je de UCST of LCST van in de oefening uitlegt en uittekend<br /> #Avrami equation gegeven en eveneens een avrami plot<br /> #*Leg uit wat m en k zijn in deze vergelijking<br /> #*Leg uit wat we in deze plot zien ivm de equation, over de volledige tijdsinterval<br /> #*Teken zelf een plot volgens Avrami, waar hetzelfde polymeer (syndiotactic polystyrene) bij andere Tc was: Tc oorspronkelijke plot was 110°C, de 3 anderen waren -30°C, 105°C, 175°C --&gt; Tm en Tg van polystyreen waren gegeven!<br /> <br /> ====Prof. Koeckelberghs====<br /> #Definieer en bespreek living/controlled polymerization. Welke experimenten kan je uitvoeren om aan te tonen dat het gaat om een living/controlled polymerization. Bespreek de algemene methode waarop een free-radical polymerization omgezet wordt in een controlled polymerization. <br /> #Bespreek emulsion polymerization <br /> <br /> ===13 januari 2021===<br /> Verkorte examenduur omwille van corona<br /> ====Prof. Koeckelberghs====<br /> #Definieer en bespreek living/controlled polymerization. Welke experimenten kan je uitvoeren om aan te tonen dat het gaat om een living/controlled polymerization. Bespreek de algemene methode waarop een free-radical polymerization omgezet wordt in een controlled polymerization. <br /> #Bespreek emulsion polymerization <br /> <br /> ====Prof. Nies====<br /> #Gegeven formule van de gibbs vrije energie van menging (FH)<br /> #*Geef de betekenis van ieder symbool in de formule en de eenheid <br /> #*Wat is de thermodynamische voorwaarde voor spinodaal gedrag? <br /> #*Wat is de thermodynamische voorwaarde voor kritische toestand? <br /> #*Schrijf UCST en LCST languit <br /> #*Leidt de vergelijking van chikritisch en phikritisch af<br /> #*Oefening: berekenen Chikritisch, UCST of LCST gedrag? Tekenen fasediagram en verloop van chi in functie van de temperatuur <br /> #Leidt de vergelijking voor de average squared end-to-end distance af voor een WLC met de vergelijking voor een FRC gegeven. <br /> ===16 januari 2020===<br /> ====Prof. Koeckelberghs====<br /> #Anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #Step growth en chain growth vergelijken en hoe je kan bepalen wanneer je welke hebt<br /> #Metathese kort uitleggen<br /> <br /> ====Prof. Nies====<br /> #Taak uitleggen (mondeling).<br /> #Gibs-Thomson-Tammann afleiden voor lamellar crystal, vergelijking voor Gibbs fusie is gegeven<br /> #Derive expression for deltaG = G(deformed) - G(undeformed). Expressions for the squared end-to-end distance for FJC and P(R)dR are given<br /> <br /> ===17 januari 2019===<br /> ====Prof. Koeckelberghs====<br /> #Anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #Step growth en chain growth vergelijken en hoe je kan bepalen wanneer je welke hebt<br /> #Metathese kort uitleggen<br /> <br /> ====Prof. Nies====<br /> #Taak uitleggen (mondeling).<br /> #Grafiek over Tg afhankelijkheid van de cooling rate, uitleggen op moleculair niveau (met betrekking tot mobiliteit)<br /> #Afleiding radius of gyration geven (fjc), toon aan dat &lt;s²&gt;= lb² (N+1)(N-1)/6N en of de uitdrukking verandert als er interacties zijn tussen de massa's met Lennard Jones interactie potentiaal?<br /> <br /> ===14 januari 2019===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #plot van volumeverandering i.f.v. de tijd (case2-figuur 25) gegeven, bespreek ... (physical ageing)<br /> #afleiding voor de Thomson-Tammann smelttemperatuur van een eindig sfeer kristal, met de fusie Gibbs vrij energie van een oneindig groot kristal gegeven<br /> <br /> ===31 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #Anionic versus cationic ring opening polymerization:<br /> #*monomeer<br /> #*intiator<br /> #*general polymerization mechanism<br /> #*termination + transfer<br /> #*ceiling temperature<br /> #Influence of the molecular structure of vinyl monomers on possibility to polymerize. Correlate the molecular structure with:<br /> #*the way monomers can be polymerized<br /> #*rate of polymerization<br /> #*retardation + inhibition<br /> #Influence of conversion on molar mass in step growth polymerization<br /> <br /> ====Prof. Nies====<br /> #Formula growth rate given (case 3 eq. 1.28)<br /> #*discuss the origin of the exponential facors and the front factor in the given equation.<br /> #*discuss dependence of the growth rate on the size of the crystal at a chosen crystallization temperature. Make a schematic plot of the predicted growth rate versus the crystal size for the chosen crystallization temperature.<br /> #*what are the consequences for the predicted growth rate for crystallization behaviour at a particular crystallization temperature?<br /> #Figure volume relaxation (case 2 figure 27)<br /> #Rubbers<br /> #*Define an ideal rubber<br /> #*Derive expression for deltaG = G(deformed) - G(undeformed)<br /> Expressions for the squared end-to-end distance for FJC and P(R)dR are given<br /> <br /> ===25 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #ceiling temperature vergelijken bij vinyl polymerization en ring opening polymerization + kleine bijvragen daarover<br /> #controlled radical polymerization (NMP en ATRP)<br /> #living cationic polymerization<br /> <br /> ====Prof. Nies====<br /> #grafiek spinodal, binodal (die met Berghman's point) toegepast op PDLC, vorming van PDLC uitleggen aan de hand van grafiek<br /> #physical ageing<br /> #avrami plot<br /> <br /> ===19 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #step growth en chain growth vergelijken en hoe ge kunt bepalen wanneer ge wa hebt<br /> #ROMP uitleggen<br /> <br /> ====Prof. Nies====<br /> #taak bespreken (mondeling)<br /> #Gibs-Thomson-Tammann afleiden voor lamellar crystal, vergelijking voor Gibbs fusie is gegeven<br /> #spinodal en critical condition geven + afleiden helemaal en berekenen wat de critische waarden zijn voor 'chi' en 'fi-2', vergelijking Gibbs gegeven<br /> Huggings formule gegeven (niet in boek) is een uitbreiding van Flory-huggings vergelijking, wanneer zijn die aan elkaar gelijk en wat is de betekenis dan<br /> <br /> ===15 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #plot van volumeverandering i.f.v. de tijd (case2-figuur 25) gegeven, bespreek ... (physical ageing)<br /> #afleiding voor de Thomson-Tammann smelttemperatuur van een eindig sfeer kristal, met de fusie Gibbs vrij energie van een oneindig groot kristal gegeven<br /> <br /> ===25 augustus 2017===<br /> ====Prof. Koeckelberghs====<br /> #Vergelijk anionische ring opening polymerizatie met kationische ring opening polymerizatie op vlak van<br /> #*monomeer<br /> #*intiator<br /> #*mechanisme<br /> #*terminatie/recombinatie<br /> #*ceiling temperature<br /> #Lewis Mayo en die R ratio's daar in. Welke dingen invloed daar op hebben en hoe + voorbeeld<br /> #Welk invloed heeft de vorderingsgraad op molaire massa in step growth polymerizatie?<br /> <br /> ====Prof. Nies====<br /> #(mondelinge vraag) bespreek grafiek en waarom dat dit gebeurt (uitleggen op moleculair niveau), grafiek van physical ageing<br /> #Afleiding van hoofdstuk 4 Gibbs vrije energie wanneer een ideaal rubber deformatie ondergaat<br /> #vanalles van UCST en LCST, iets vaags.<br /> <br /> <br /> ===20 januari 2017===<br /> ====Prof. Koeckelberghs====<br /> #Anionische, kationische en frp uitleggen obv monomeer, terminatie en hoe ge het levend kunt maken<br /> #Step growth en chain growth<br /> #Ringopening methatese<br /> <br /> ====Prof. Nies====<br /> Vraag 1:<br /> #Wat is de definitie van een FRC?<br /> #Bij welke condities is de FRC gelijk aan de FJC<br /> #Bereken Lk en Nk voor de limiet van een enorm lange FRC (&lt;R2&gt;frc gegeven)<br /> #Leidt een vergelijking af voor de mean squared end-to-end distance van een ideaal lineair diblock copolymeer bestaande uit Nk1 Kuhn monomeren met lengte lk dat vasthangt via 1 einde aan Nk2 Kuhn monomeren met lengte lk2<br /> Vraag 2:<br /> #Mengsel van PS in methylcyclohexaan (Mw = 355kg/mol)<br /> Bij T=350K bestaat het mengsel uit 1 homogene vloeibare fase. Deze T is 6K boven de flory T. Polymeer volume fractie in de homogene fase is O,2<br /> Bij T=335K: twee vloeibare fases, de polymeer volume fracties van de coexistant fases zijn 0,003 en 0,435<br /> In de compositie range {0,002-0,044} en {0,336-0,435} is de structuur van de initiele fase scheiding kleine druppels in een matrix fase<br /> #*Schets het verloop van delta Gmix ifv de volledige compositierange bij T=333K<br /> #*Duid de points of interest in deze curve aan en leg ze uit.<br /> #*Leg tot he point uit waarom je vraag a zo geschetst hebt<br /> #*Wat zal de morfologie zijn in de initiële fase van scheiding?<br /> <br /> <br /> ===19 Januari 2017===<br /> ====Prof. Koekcelberghs====<br /> #Vergelijken ven anionische en kationische ringopeningpolymerisatie op vlak van<br /> #*Initiatie/Initiatoren<br /> #*Terminatie/transfer<br /> #*Mechanisme<br /> #*Mogelijke monomeren<br /> #*Ceiling temperature<br /> #Geef de factoren die een copolymerisatie beïnvloeden <br /> #Geef de invloed van de conversie bij een step-growth polymerisatie<br /> <br /> ====Prof. Nies====<br /> #Vraag 1: bespreek je taak helemaal (mondeling)<br /> #Vraag 2: Leid het verschil in Gibbs vrije energie voor een vervormd en onvervormd ideaal rubber af. End-to-end distance van een ideaal rubber en de Gaussische distributie zijn gegeven.<br /> #Vraag 3: Gegeven een stelling die zegt dat er een closed-gap miscibility gap plaatsvindt, met een formule voor chi in functie van T. 2 kritische waarden voor de temperatuur zijn gegeven. De vraag is: kan deze stelling kloppen? <br /> <br /> <br /> ===16 januari 2017===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #zie theoretical questions doc case 3 vraag 13, maar alleen de excess Gibbs energy en de chemical potentials waren gegeven<br /> #Vraag 3:<br /> #*thermodynamische uitdrukking voor spinodal en critical conditions afleiden.<br /> #*zie theoretical questions doc case 2 vraag 4 en de uitdrukking voor de Gibbs energy is gegeven<br /> #*de verbeterde Huggins uitdrukking voor de Gibbs energy is gegeven en daarvoor de enthalipsche en entropische bijdragen bepalen.<br /> #*De FH uitdrukking is een speciaal geval van de Huggins uitdrukking: bepaal de conditie van y waarvoor dit geld + geef de fysische betekenis van die conditie<br /> <br /> ===14 januari 2016===<br /> ====Prof. Koeckelberghs====<br /> #Vergelijk chemisch geïnitieerde FRP en ATR op vlak van:<br /> #*Algemeen protocol<br /> #*Snelheidsvergelijkingen<br /> #*Invloed van de moleculaire structuur op de snelheid van polymerisatie<br /> #Leg uit: step growth en chain growth polymerisatie. Hoe kan je experimenteel onderscheid maken tussen beide?<br /> #Leg kort uit: Ziegler-Nattakatalysator<br /> <br /> ====Prof. Nies====<br /> #Gegeven: Tg in functie van cooling rate. Verklaar de moleculaire oorsprong van dit fenomeen. (oral)<br /> #*Mondelinge bijvraag: wat bepaalt, naast de kinetische energie, ook mee het vrije volume?<br /> #Leid een formule af voor het smeltpunt van een eindig sferisch kristal.<br /> #Vrije energie van mengen volgens Flory-Huggins gegeven:<br /> #*Wat zijn de spinodale en kristische voorwaarden?<br /> #*Geef de betekenis en eenheiden van elke parameter in de vergelijking.<br /> #*Geef een concrete uitdrukking voor de kritische en spinodale voorwaarden afgeleid uit de bovenstaande vergelijking.<br /> #*Geef een concrete uitdrukking voor de kritische phi en chi.<br /> #*Gegeven een uitgebreide variant van de vergelijking van Flory en Huggins. Wat zijn de enthalpische en entropische bijdragen?<br /> #*De oorspronkelijke formule van Flory en Huggins is een bijzonder geval van de bovenstaande vergelijking. Onder welke voorwaarde is dit en waarmee komt dit fysisch overeen?<br /> <br /> ===11 januari 2016===<br /> ====Prof. Koeckelberghs====<br /> #Define living/controlled polymerisation. Hoe neem je dit experimenteel waar? Hoe maak je free radical controlled?<br /> #Wat is de invloed van moleculaire structuur van monomeer op manier vinylpolymerisatie, snelheid en retardation/inhibition?<br /> #Bespreek emulsiepolymerisatie.<br /> <br /> ====Prof. Nies====<br /> #Case 2, figuur 27 uitleggen (specifiek volume in functie van tijd) (oral)<br /> #Leid Gibbs Thomson uitdrukking af voor smelttemperatuur van sferisch kristal.<br /> #Uitdrukking s^2 en massacentrum gegeven:<br /> #*Leid average radius of gyration af met alles massa's = m.<br /> #*Toon aan dat average radius of gyration = lb^2 (N+1)(N-1)/6N als i=1,2,3,...,N-1.<br /> #*Veranderen de uitdrukking als er interacties zijn tussen de massa's met Lennard Jones interactie potentiaal?<br /> <br /> ===24 januari 2013===<br /> ====Prof. Koeckelberghs====<br /> #Discuss the ceiling temperature and apply it on both the vinyl polymerization and ring opening polymerization. Is the ceiling temperature of a particular monomer dependent on the way it's polymerized?<br /> Is it possible that a particular monomer, of which the ceiling temperature is such that only low-molar mass oligomers can be obtained via a living anionic polymerization at a certain temperature, can be polymerized into high-molar mass polymer using a free radical polymerization at the same temperature? Motivate your anwer.<br /> #Explain the principle of a controlled radical polymerization and apply it on NMP and ATRP.<br /> #Discuss briefly the living cationic vinyl polymerization.<br /> ====Prof. Nies====<br /> Zie onderstaande afbeelding.<br /> [ <br /> #Assignment 1 (oral)<br /> #The &amp;lt;i&amp;gt;free rotating chain&amp;lt;/i&amp;gt; (FRC) consists of N bonding vectors l&amp;lt;sub&amp;gt;i&amp;lt;/sub&amp;gt;, i=1,...,N with constant bond length |l&amp;lt;sub&amp;gt;i&amp;lt;/sub&amp;gt;| = l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt; and constant bond angles Ï´&amp;lt;sub&amp;gt;ii+1&amp;lt;/sub&amp;gt;=Ï´, i=1,...,N between the successive bonding vectors. The average quadratic end-to-end distance &amp;lt;R²&amp;gt;, valid for all physically sensible values of N, l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt; and Ï´, is given by [[Bestand:R-FRC.JPG]]<br /> #*Show that the average quadratic end-to-end distance &amp;lt;R²&amp;gt; of the FRC chain with very small bond angles also can be written in the Kratky-Porod chain form: &amp;lt;R²&amp;gt; = 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;L-2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;²(1-exp(-L/l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;),<br /> with l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;=l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt;L/(1-cosÏ´) the perstistence length and L the contour length.<br /> #Derive from the general thermodynamic equilibrium conditions the melting point of a polymer crystal in equilibrium with a solution of the polymer.<br /> For the polymer solution you can use the Flory-Huggins excess Gibbs-energy of mixing.<br /> [[Bestand:G(mix).JPG]]<br /> <br /> The chemical potentials of the components are given by:<br /> [[Bestand:Chempot.JPG]] ]<br /> <br /> [[Bestand:240113nies.png]]<br /> <br /> ===18 januari 2013===<br /> ====Prof. Koeckelberghs====<br /> #Compare chemically initiated free radical polymerization and ATRP, for the following aspects:<br /> #*general concept<br /> #*rate of polymerization<br /> #*influence of molecule structure on polymerization rate<br /> #Discuss the differences in mechanism of chain growth and step growth polymerization. How can one investigate which type of polymerization he is dealing with?<br /> #Explain briefly: Ziegler-Natta catalyst<br /> ====Prof. Nies====<br /> #Discussion of assignment 1 (oral)<br /> <br /> Zie onderstaande afbeelding.<br /> <br /> #The expression of average squared end-to-end distance of the Kratky-Porod chain is given: &amp;lt;R²&amp;gt; = 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;L - 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;²(1-exp(-L/l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;)<br /> #*Derive expressions for the Kuhn segment length and the number of Kuhn segments for this chain.<br /> #*Discuss your results. For instance, did you make any assumptions? Mention them explicitly.<br /> #The excess Gibbs ebergy of mixing in the Flory-Huggins model is given: ΔG/N&amp;lt;sub&amp;gt;l&amp;lt;/sub&amp;gt;kT = Δg/kT = (φ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;/s&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;)lnφ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt; + (φ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;/s&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;)lnφ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; + χφ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;φ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;<br /> #*Derive expressions for the spinodal and critical conditions.<br /> #*Derive from these expressions the formulae for the critical composition φ&amp;lt;sub&amp;gt;2,cr&amp;lt;/sub&amp;gt; and critical value of χ.<br /> #*What is the relevance of the spinodal for material behaviour?<br /> [[Bestand:180113nies.png]]<br /> <br /> ===20 januari 2012===<br /> ====Professor Nies====<br /> #Gegeven een fase-diagram uit Case II. Wat gebeurt er als er vanuit punt A (dat links van de critical point lag):<br /> #* traag wordt afgekoeld<br /> #* wordt gequenched (1000K/min)<br /> #* Hoe ziet de oplossing er na koelen uit voor beide gevallen<br /> #5 begrippen uitleggen:<br /> #*Thermo-elastische inversie<br /> #*Physical ageing<br /> #*Second order transition<br /> #*Effective pair potential<br /> #*Nucleation &amp;amp; growth<br /> #Leidt de spinodal en critical conditions af en ook de waarden voor Fi(2,crit) en Chi(krit).<br /> <br /> ====Professor Koeckelberghs====<br /> #Wat is de ceiling temperatuur en correleer dit met vinylpolymerisatie en Ring opening polymerisatie. Is de ceiling temperatuur afhankelijk van hoe we polymeriseren? Stel we polymeriseren via een living anionische polymerisatie. Het monomeer heeft een lage ceiling temperatuur, wat ervoor zorgt dat er geen lange polymeerketens worden gevormd. Kan men dan langere ketens verkrijgen als men bij dezelfde temperatuur via een radicale polymerisatie polymeriseert?<br /> #M1 en M2 worden gecopolymeriseerd. Geef de parameters voor beide monomeren en leg uit waarvan deze afhangen.<br /> # Leg uit: (radicalaire) emulsiepolymerisatie<br /> <br /> ===21 januari 2011===<br /> ====Professor Nies====<br /> # Teken het verloop van de de gibssvrij-energie in functie van volumefractie bij een temperatuur van 300K. Volumefracties = 0,2. Coexistence points en spinodal points gegeven. Ook de verschillende punten aanduiden en kort uitleggen. (deze vraag was mondeling)<br /> # Formule p 50 case 1 gegeven (zonder 4e term)<br /> #* leg de symbolen uit + dimensies + eenheden<br /> #* wat bedoelt men met &amp;quot;volgens de Flory benadering...&amp;quot;<br /> #* leg de twee verschillende termen uit<br /> #* Bereken end-to-end distance in evenwicht bij een flory-solvent<br /> #* Bereken end-to-end distance in evenwicht bij een goed solvent<br /> # Avramiplot+vergelijking gegeven<br /> #*leg de parameters uit<br /> #*hoe kan je volumefractie kristallijne fase meten, leg kort techniek uit.<br /> #*geef een kwalitatieve bespreking van de grafiek<br /> #*wat kan je uit de parameters afleiden<br /> <br /> ====Professor Koeckelberghs====<br /> # zie vragen vorig jaar<br /> <br /> ===15 januari 2010===<br /> ====Professor Nies====<br /> #Er was de grafiek gegeven met daarop de binodal, spinodal en Tg curve. Met daarop 3 punten aangegeven, telkens in het homogene gebied boven de binodal en boven Tg. Punt A: Links van kritische punt, punt B tussen kritische punt en Berghmans punt en punt C rechts van Berghmanspunt. (Alleen deze vraag mondeling)<br /> #*Wat vindt plaats als je in punt A traag afkoelt?<br /> #*Wat vindt plaats als je in punt A afkoelt met 1000K/min<br /> #*Wat vindt plaats als je in punt B traag afkoelt<br /> #*Wat vindt plaats als je in punt B afkoelt met 1000K/min<br /> #*Wat vindt plaats als je in punt C traag afkoelt?<br /> #*Wat vindt plaats als je in punt C afkoelt met 1000K/min<br /> #Vergelijking van Groeisnelheid bij kristallisatie (U) gegeven: U=Fexp(A)exp(B)exp(C) Zowel F,A,B,C waren gegeven in symbolen(vergelijking onder 7.B case III)<br /> #*Geef waarvoor de symbolen staan en wat hun eenheden zijn.<br /> #*Verklaar waar de Frontfactor (F) en de drie exp's vandaan komen<br /> #*Bespreek temperatuursafhankelijkheid en geef een schets<br /> #Geef de definitie van een ideale Rubber<br /> #* Leid de uitdrukking voor af voor S bij een willekeurige verandering. P(R) gegeven<br /> <br /> ====Koeckelberghs====<br /> #Vergelijk radicalaire, anionische en kationische vinylpolymerisatie<br /> #*Mogelijke monomere deeltjes (stabiliteit)<br /> #*Terminatie reacties<br /> #*Invloed van verschillende voorkomende deeltjes op sneldheid (hiermee bedoelde hij de associated ion pairs etc)<br /> #*Mogelijke manier om ze 'levend' te maken. (of quasi levend)<br /> #*? dacht dat er nog 1 was<br /> #Je wil een ideaal, perfect blockcopolymeer maken van MMA en MA op anionische wijze. Welk monomeer moet je eerst polymeriseren? Blijft indien je dit met ATRP wil doen de volgorde dezelfde?<br /> #Bespreek kort Ring Opening Metathesis Polymerisatie.</div>

R0804230 https://wiki.chemika.be/index.php?title=Polymer_Sciences:_from_Synthesis_to_Polymer_Material&diff=3191 2023-01-20T22:26:22Z

<p>R0804230: /* 20th of January 2022 */</p> <hr /> <div>[[Categorie:Machemie]]<br /> <br /> ==Vakinformatie==<br /> Gedoceerd door Professor Nies en Professor Koeckelberghs. Lessen zijn altijd in het Engels. De verdeling is 2/3 op het deel van Nies en 1/3 op het deel van Koeckelberghs. Bij Nies zijn er ook verplichte assignments tijdens het jaar, die meetellen voor een fractie 4/(12-N) van de punten van zijn deel (met N aantal assignments, doorgaans 2). Nies zijn examen is gesloten boek en er moet maar één vraag bij hem mondeling besproken worden (deze wordt op voorhand aangeduid). Bij Koeckelberghs zijn alle vragen mondeling te bespreken.<br /> <br /> ==Examenvragen==<br /> ===20th of January 2022===<br /> ====Prof. Nies====<br /> #Eq. 1.40 is given. Discuss the limiting behavior for L&lt;&lt;lp and L&gt;&gt;lp. The Kuhn length was defined by two equations. Write them down and give a qualitative description. Even a wormlike chain with high but not infinite stiffness will behave like an ideal flexible chain under certain conditions. Explain.<br /> #Scientist claim that a polymer in solution shows a Phi(2)-T diagram with a closed loop miscibility hole. Chi(crit,1-2) are given as are T(crit,1-2). The values of Chi(0), Chi(1) and Chi(2) are provided too (Eq. 2.19). From this, calculate s2 and Phi(crit,1-2). Show ether qualitatively of quantitatively if their reasoning for a closed loop miscibility hole is justified. Make a sketch of the Phi(2)-T diagram containing Phi(crit,2), T(crit,1-2), the binodals and spinodals.<br /> #Figure 3.27 is given and a graph that demonstrates the linear behavior between 1/l and Tm. In several steps you are guided towards deriving the Gibbs-Thomson-Tammann equation.<br /> ====Prof. Koeckelberghs====<br /> #Compare anionic and cationic ROP in terms of: monomers, initiators, propagation, transfer, termination and their ceiling temperature.<br /> #Discuss based on the structure op vinyl monomers in what way they can be polymerized. Relate the stability of the active species to Rp and discuss retardation and inhibition.<br /> #Discuss briefly how conversion and molar mass relate to each other in step-growth polymerization.<br /> <br /> ===27 augustus 2022===<br /> ====Prof. Nies====<br /> #Grafiek van specific volume relaxation uitleggen<br /> #Gibbs-Thomson equation afleiden<br /> #Polymer in solvent is cooled, binodal/spinodal and Tg curves zijn gegeven. 1) Leg uit wat je denkt dat er zal gebeuren, 2) welke morphology denk je dat gevormd wordt voor trage vs snelle cooling? <br /> ====Prof. Koeckelberghs====<br /> #free radical, anionic and cationic polymerization vergelijken op vlak van a) monomers b) termination reaction c) possibility for living polymerization<br /> #ring opening metathesis polymerization bespreken<br /> ===20 januari 2022===<br /> ====Prof. Nies====<br /> #Afleiding maken van de end to end distance van de freely rotating chain + uitleggen waarom er ⟨ .... ⟩ haakjes worden gebruikt + uitleggen wat L voor de FRC is<br /> #Gegeven formule van de gibbs vrije energie van menging (FH)Flory huggins<br /> #*Wat is de thermodynamische voorwaarde voor spinodaal gedrag? + Wat is de thermodynamische voorwaarde voor kritische toestand?<br /> #*Leid ook verder af wat chi kritisch en phi kritisch zijn hieruit (opnieuw afleiden!)<br /> #*Bepaal of de gegeven Tcritisch op een UCST of LCST systeem wijst <br /> #*Geef UCST en LCST namen voluit<br /> #*Teken een phi T diagram waar je de UCST of LCST van in de oefening uitlegt en uittekend<br /> #Avrami equation gegeven en eveneens een avrami plot<br /> #*Leg uit wat m en k zijn in deze vergelijking<br /> #*Leg uit wat we in deze plot zien ivm de equation, over de volledige tijdsinterval<br /> #*Teken zelf een plot volgens Avrami, waar hetzelfde polymeer (syndiotactic polystyrene) bij andere Tc was: Tc oorspronkelijke plot was 110°C, de 3 anderen waren -30°C, 105°C, 175°C --&gt; Tm en Tg van polystyreen waren gegeven!<br /> <br /> ====Prof. Koeckelberghs====<br /> #Definieer en bespreek living/controlled polymerization. Welke experimenten kan je uitvoeren om aan te tonen dat het gaat om een living/controlled polymerization. Bespreek de algemene methode waarop een free-radical polymerization omgezet wordt in een controlled polymerization. <br /> #Bespreek emulsion polymerization <br /> <br /> ===13 januari 2021===<br /> Verkorte examenduur omwille van corona<br /> ====Prof. Koeckelberghs====<br /> #Definieer en bespreek living/controlled polymerization. Welke experimenten kan je uitvoeren om aan te tonen dat het gaat om een living/controlled polymerization. Bespreek de algemene methode waarop een free-radical polymerization omgezet wordt in een controlled polymerization. <br /> #Bespreek emulsion polymerization <br /> <br /> ====Prof. Nies====<br /> #Gegeven formule van de gibbs vrije energie van menging (FH)<br /> #*Geef de betekenis van ieder symbool in de formule en de eenheid <br /> #*Wat is de thermodynamische voorwaarde voor spinodaal gedrag? <br /> #*Wat is de thermodynamische voorwaarde voor kritische toestand? <br /> #*Schrijf UCST en LCST languit <br /> #*Leidt de vergelijking van chikritisch en phikritisch af<br /> #*Oefening: berekenen Chikritisch, UCST of LCST gedrag? Tekenen fasediagram en verloop van chi in functie van de temperatuur <br /> #Leidt de vergelijking voor de average squared end-to-end distance af voor een WLC met de vergelijking voor een FRC gegeven. <br /> ===16 januari 2020===<br /> ====Prof. Koeckelberghs====<br /> #Anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #Step growth en chain growth vergelijken en hoe je kan bepalen wanneer je welke hebt<br /> #Metathese kort uitleggen<br /> <br /> ====Prof. Nies====<br /> #Taak uitleggen (mondeling).<br /> #Gibs-Thomson-Tammann afleiden voor lamellar crystal, vergelijking voor Gibbs fusie is gegeven<br /> #Derive expression for deltaG = G(deformed) - G(undeformed). Expressions for the squared end-to-end distance for FJC and P(R)dR are given<br /> <br /> ===17 januari 2019===<br /> ====Prof. Koeckelberghs====<br /> #Anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #Step growth en chain growth vergelijken en hoe je kan bepalen wanneer je welke hebt<br /> #Metathese kort uitleggen<br /> <br /> ====Prof. Nies====<br /> #Taak uitleggen (mondeling).<br /> #Grafiek over Tg afhankelijkheid van de cooling rate, uitleggen op moleculair niveau (met betrekking tot mobiliteit)<br /> #Afleiding radius of gyration geven (fjc), toon aan dat &lt;s²&gt;= lb² (N+1)(N-1)/6N en of de uitdrukking verandert als er interacties zijn tussen de massa's met Lennard Jones interactie potentiaal?<br /> <br /> ===14 januari 2019===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #plot van volumeverandering i.f.v. de tijd (case2-figuur 25) gegeven, bespreek ... (physical ageing)<br /> #afleiding voor de Thomson-Tammann smelttemperatuur van een eindig sfeer kristal, met de fusie Gibbs vrij energie van een oneindig groot kristal gegeven<br /> <br /> ===31 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #Anionic versus cationic ring opening polymerization:<br /> #*monomeer<br /> #*intiator<br /> #*general polymerization mechanism<br /> #*termination + transfer<br /> #*ceiling temperature<br /> #Influence of the molecular structure of vinyl monomers on possibility to polymerize. Correlate the molecular structure with:<br /> #*the way monomers can be polymerized<br /> #*rate of polymerization<br /> #*retardation + inhibition<br /> #Influence of conversion on molar mass in step growth polymerization<br /> <br /> ====Prof. Nies====<br /> #Formula growth rate given (case 3 eq. 1.28)<br /> #*discuss the origin of the exponential facors and the front factor in the given equation.<br /> #*discuss dependence of the growth rate on the size of the crystal at a chosen crystallization temperature. Make a schematic plot of the predicted growth rate versus the crystal size for the chosen crystallization temperature.<br /> #*what are the consequences for the predicted growth rate for crystallization behaviour at a particular crystallization temperature?<br /> #Figure volume relaxation (case 2 figure 27)<br /> #Rubbers<br /> #*Define an ideal rubber<br /> #*Derive expression for deltaG = G(deformed) - G(undeformed)<br /> Expressions for the squared end-to-end distance for FJC and P(R)dR are given<br /> <br /> ===25 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #ceiling temperature vergelijken bij vinyl polymerization en ring opening polymerization + kleine bijvragen daarover<br /> #controlled radical polymerization (NMP en ATRP)<br /> #living cationic polymerization<br /> <br /> ====Prof. Nies====<br /> #grafiek spinodal, binodal (die met Berghman's point) toegepast op PDLC, vorming van PDLC uitleggen aan de hand van grafiek<br /> #physical ageing<br /> #avrami plot<br /> <br /> ===19 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #step growth en chain growth vergelijken en hoe ge kunt bepalen wanneer ge wa hebt<br /> #ROMP uitleggen<br /> <br /> ====Prof. Nies====<br /> #taak bespreken (mondeling)<br /> #Gibs-Thomson-Tammann afleiden voor lamellar crystal, vergelijking voor Gibbs fusie is gegeven<br /> #spinodal en critical condition geven + afleiden helemaal en berekenen wat de critische waarden zijn voor 'chi' en 'fi-2', vergelijking Gibbs gegeven<br /> Huggings formule gegeven (niet in boek) is een uitbreiding van Flory-huggings vergelijking, wanneer zijn die aan elkaar gelijk en wat is de betekenis dan<br /> <br /> ===15 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #plot van volumeverandering i.f.v. de tijd (case2-figuur 25) gegeven, bespreek ... (physical ageing)<br /> #afleiding voor de Thomson-Tammann smelttemperatuur van een eindig sfeer kristal, met de fusie Gibbs vrij energie van een oneindig groot kristal gegeven<br /> <br /> ===25 augustus 2017===<br /> ====Prof. Koeckelberghs====<br /> #Vergelijk anionische ring opening polymerizatie met kationische ring opening polymerizatie op vlak van<br /> #*monomeer<br /> #*intiator<br /> #*mechanisme<br /> #*terminatie/recombinatie<br /> #*ceiling temperature<br /> #Lewis Mayo en die R ratio's daar in. Welke dingen invloed daar op hebben en hoe + voorbeeld<br /> #Welk invloed heeft de vorderingsgraad op molaire massa in step growth polymerizatie?<br /> <br /> ====Prof. Nies====<br /> #(mondelinge vraag) bespreek grafiek en waarom dat dit gebeurt (uitleggen op moleculair niveau), grafiek van physical ageing<br /> #Afleiding van hoofdstuk 4 Gibbs vrije energie wanneer een ideaal rubber deformatie ondergaat<br /> #vanalles van UCST en LCST, iets vaags.<br /> <br /> <br /> ===20 januari 2017===<br /> ====Prof. Koeckelberghs====<br /> #Anionische, kationische en frp uitleggen obv monomeer, terminatie en hoe ge het levend kunt maken<br /> #Step growth en chain growth<br /> #Ringopening methatese<br /> <br /> ====Prof. Nies====<br /> Vraag 1:<br /> #Wat is de definitie van een FRC?<br /> #Bij welke condities is de FRC gelijk aan de FJC<br /> #Bereken Lk en Nk voor de limiet van een enorm lange FRC (&lt;R2&gt;frc gegeven)<br /> #Leidt een vergelijking af voor de mean squared end-to-end distance van een ideaal lineair diblock copolymeer bestaande uit Nk1 Kuhn monomeren met lengte lk dat vasthangt via 1 einde aan Nk2 Kuhn monomeren met lengte lk2<br /> Vraag 2:<br /> #Mengsel van PS in methylcyclohexaan (Mw = 355kg/mol)<br /> Bij T=350K bestaat het mengsel uit 1 homogene vloeibare fase. Deze T is 6K boven de flory T. Polymeer volume fractie in de homogene fase is O,2<br /> Bij T=335K: twee vloeibare fases, de polymeer volume fracties van de coexistant fases zijn 0,003 en 0,435<br /> In de compositie range {0,002-0,044} en {0,336-0,435} is de structuur van de initiele fase scheiding kleine druppels in een matrix fase<br /> #*Schets het verloop van delta Gmix ifv de volledige compositierange bij T=333K<br /> #*Duid de points of interest in deze curve aan en leg ze uit.<br /> #*Leg tot he point uit waarom je vraag a zo geschetst hebt<br /> #*Wat zal de morfologie zijn in de initiële fase van scheiding?<br /> <br /> <br /> ===19 Januari 2017===<br /> ====Prof. Koekcelberghs====<br /> #Vergelijken ven anionische en kationische ringopeningpolymerisatie op vlak van<br /> #*Initiatie/Initiatoren<br /> #*Terminatie/transfer<br /> #*Mechanisme<br /> #*Mogelijke monomeren<br /> #*Ceiling temperature<br /> #Geef de factoren die een copolymerisatie beïnvloeden <br /> #Geef de invloed van de conversie bij een step-growth polymerisatie<br /> <br /> ====Prof. Nies====<br /> #Vraag 1: bespreek je taak helemaal (mondeling)<br /> #Vraag 2: Leid het verschil in Gibbs vrije energie voor een vervormd en onvervormd ideaal rubber af. End-to-end distance van een ideaal rubber en de Gaussische distributie zijn gegeven.<br /> #Vraag 3: Gegeven een stelling die zegt dat er een closed-gap miscibility gap plaatsvindt, met een formule voor chi in functie van T. 2 kritische waarden voor de temperatuur zijn gegeven. De vraag is: kan deze stelling kloppen? <br /> <br /> <br /> ===16 januari 2017===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #zie theoretical questions doc case 3 vraag 13, maar alleen de excess Gibbs energy en de chemical potentials waren gegeven<br /> #Vraag 3:<br /> #*thermodynamische uitdrukking voor spinodal en critical conditions afleiden.<br /> #*zie theoretical questions doc case 2 vraag 4 en de uitdrukking voor de Gibbs energy is gegeven<br /> #*de verbeterde Huggins uitdrukking voor de Gibbs energy is gegeven en daarvoor de enthalipsche en entropische bijdragen bepalen.<br /> #*De FH uitdrukking is een speciaal geval van de Huggins uitdrukking: bepaal de conditie van y waarvoor dit geld + geef de fysische betekenis van die conditie<br /> <br /> ===14 januari 2016===<br /> ====Prof. Koeckelberghs====<br /> #Vergelijk chemisch geïnitieerde FRP en ATR op vlak van:<br /> #*Algemeen protocol<br /> #*Snelheidsvergelijkingen<br /> #*Invloed van de moleculaire structuur op de snelheid van polymerisatie<br /> #Leg uit: step growth en chain growth polymerisatie. Hoe kan je experimenteel onderscheid maken tussen beide?<br /> #Leg kort uit: Ziegler-Nattakatalysator<br /> <br /> ====Prof. Nies====<br /> #Gegeven: Tg in functie van cooling rate. Verklaar de moleculaire oorsprong van dit fenomeen. (oral)<br /> #*Mondelinge bijvraag: wat bepaalt, naast de kinetische energie, ook mee het vrije volume?<br /> #Leid een formule af voor het smeltpunt van een eindig sferisch kristal.<br /> #Vrije energie van mengen volgens Flory-Huggins gegeven:<br /> #*Wat zijn de spinodale en kristische voorwaarden?<br /> #*Geef de betekenis en eenheiden van elke parameter in de vergelijking.<br /> #*Geef een concrete uitdrukking voor de kritische en spinodale voorwaarden afgeleid uit de bovenstaande vergelijking.<br /> #*Geef een concrete uitdrukking voor de kritische phi en chi.<br /> #*Gegeven een uitgebreide variant van de vergelijking van Flory en Huggins. Wat zijn de enthalpische en entropische bijdragen?<br /> #*De oorspronkelijke formule van Flory en Huggins is een bijzonder geval van de bovenstaande vergelijking. Onder welke voorwaarde is dit en waarmee komt dit fysisch overeen?<br /> <br /> ===11 januari 2016===<br /> ====Prof. Koeckelberghs====<br /> #Define living/controlled polymerisation. Hoe neem je dit experimenteel waar? Hoe maak je free radical controlled?<br /> #Wat is de invloed van moleculaire structuur van monomeer op manier vinylpolymerisatie, snelheid en retardation/inhibition?<br /> #Bespreek emulsiepolymerisatie.<br /> <br /> ====Prof. Nies====<br /> #Case 2, figuur 27 uitleggen (specifiek volume in functie van tijd) (oral)<br /> #Leid Gibbs Thomson uitdrukking af voor smelttemperatuur van sferisch kristal.<br /> #Uitdrukking s^2 en massacentrum gegeven:<br /> #*Leid average radius of gyration af met alles massa's = m.<br /> #*Toon aan dat average radius of gyration = lb^2 (N+1)(N-1)/6N als i=1,2,3,...,N-1.<br /> #*Veranderen de uitdrukking als er interacties zijn tussen de massa's met Lennard Jones interactie potentiaal?<br /> <br /> ===24 januari 2013===<br /> ====Prof. Koeckelberghs====<br /> #Discuss the ceiling temperature and apply it on both the vinyl polymerization and ring opening polymerization. Is the ceiling temperature of a particular monomer dependent on the way it's polymerized?<br /> Is it possible that a particular monomer, of which the ceiling temperature is such that only low-molar mass oligomers can be obtained via a living anionic polymerization at a certain temperature, can be polymerized into high-molar mass polymer using a free radical polymerization at the same temperature? Motivate your anwer.<br /> #Explain the principle of a controlled radical polymerization and apply it on NMP and ATRP.<br /> #Discuss briefly the living cationic vinyl polymerization.<br /> ====Prof. Nies====<br /> Zie onderstaande afbeelding.<br /> [ <br /> #Assignment 1 (oral)<br /> #The &amp;lt;i&amp;gt;free rotating chain&amp;lt;/i&amp;gt; (FRC) consists of N bonding vectors l&amp;lt;sub&amp;gt;i&amp;lt;/sub&amp;gt;, i=1,...,N with constant bond length |l&amp;lt;sub&amp;gt;i&amp;lt;/sub&amp;gt;| = l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt; and constant bond angles Ï´&amp;lt;sub&amp;gt;ii+1&amp;lt;/sub&amp;gt;=Ï´, i=1,...,N between the successive bonding vectors. The average quadratic end-to-end distance &amp;lt;R²&amp;gt;, valid for all physically sensible values of N, l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt; and Ï´, is given by [[Bestand:R-FRC.JPG]]<br /> #*Show that the average quadratic end-to-end distance &amp;lt;R²&amp;gt; of the FRC chain with very small bond angles also can be written in the Kratky-Porod chain form: &amp;lt;R²&amp;gt; = 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;L-2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;²(1-exp(-L/l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;),<br /> with l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;=l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt;L/(1-cosÏ´) the perstistence length and L the contour length.<br /> #Derive from the general thermodynamic equilibrium conditions the melting point of a polymer crystal in equilibrium with a solution of the polymer.<br /> For the polymer solution you can use the Flory-Huggins excess Gibbs-energy of mixing.<br /> [[Bestand:G(mix).JPG]]<br /> <br /> The chemical potentials of the components are given by:<br /> [[Bestand:Chempot.JPG]] ]<br /> <br /> [[Bestand:240113nies.png]]<br /> <br /> ===18 januari 2013===<br /> ====Prof. Koeckelberghs====<br /> #Compare chemically initiated free radical polymerization and ATRP, for the following aspects:<br /> #*general concept<br /> #*rate of polymerization<br /> #*influence of molecule structure on polymerization rate<br /> #Discuss the differences in mechanism of chain growth and step growth polymerization. How can one investigate which type of polymerization he is dealing with?<br /> #Explain briefly: Ziegler-Natta catalyst<br /> ====Prof. Nies====<br /> #Discussion of assignment 1 (oral)<br /> <br /> Zie onderstaande afbeelding.<br /> <br /> #The expression of average squared end-to-end distance of the Kratky-Porod chain is given: &amp;lt;R²&amp;gt; = 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;L - 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;²(1-exp(-L/l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;)<br /> #*Derive expressions for the Kuhn segment length and the number of Kuhn segments for this chain.<br /> #*Discuss your results. For instance, did you make any assumptions? Mention them explicitly.<br /> #The excess Gibbs ebergy of mixing in the Flory-Huggins model is given: ΔG/N&amp;lt;sub&amp;gt;l&amp;lt;/sub&amp;gt;kT = Δg/kT = (φ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;/s&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;)lnφ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt; + (φ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;/s&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;)lnφ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; + χφ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;φ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;<br /> #*Derive expressions for the spinodal and critical conditions.<br /> #*Derive from these expressions the formulae for the critical composition φ&amp;lt;sub&amp;gt;2,cr&amp;lt;/sub&amp;gt; and critical value of χ.<br /> #*What is the relevance of the spinodal for material behaviour?<br /> [[Bestand:180113nies.png]]<br /> <br /> ===20 januari 2012===<br /> ====Professor Nies====<br /> #Gegeven een fase-diagram uit Case II. Wat gebeurt er als er vanuit punt A (dat links van de critical point lag):<br /> #* traag wordt afgekoeld<br /> #* wordt gequenched (1000K/min)<br /> #* Hoe ziet de oplossing er na koelen uit voor beide gevallen<br /> #5 begrippen uitleggen:<br /> #*Thermo-elastische inversie<br /> #*Physical ageing<br /> #*Second order transition<br /> #*Effective pair potential<br /> #*Nucleation &amp;amp; growth<br /> #Leidt de spinodal en critical conditions af en ook de waarden voor Fi(2,crit) en Chi(krit).<br /> <br /> ====Professor Koeckelberghs====<br /> #Wat is de ceiling temperatuur en correleer dit met vinylpolymerisatie en Ring opening polymerisatie. Is de ceiling temperatuur afhankelijk van hoe we polymeriseren? Stel we polymeriseren via een living anionische polymerisatie. Het monomeer heeft een lage ceiling temperatuur, wat ervoor zorgt dat er geen lange polymeerketens worden gevormd. Kan men dan langere ketens verkrijgen als men bij dezelfde temperatuur via een radicale polymerisatie polymeriseert?<br /> #M1 en M2 worden gecopolymeriseerd. Geef de parameters voor beide monomeren en leg uit waarvan deze afhangen.<br /> # Leg uit: (radicalaire) emulsiepolymerisatie<br /> <br /> ===21 januari 2011===<br /> ====Professor Nies====<br /> # Teken het verloop van de de gibssvrij-energie in functie van volumefractie bij een temperatuur van 300K. Volumefracties = 0,2. Coexistence points en spinodal points gegeven. Ook de verschillende punten aanduiden en kort uitleggen. (deze vraag was mondeling)<br /> # Formule p 50 case 1 gegeven (zonder 4e term)<br /> #* leg de symbolen uit + dimensies + eenheden<br /> #* wat bedoelt men met &amp;quot;volgens de Flory benadering...&amp;quot;<br /> #* leg de twee verschillende termen uit<br /> #* Bereken end-to-end distance in evenwicht bij een flory-solvent<br /> #* Bereken end-to-end distance in evenwicht bij een goed solvent<br /> # Avramiplot+vergelijking gegeven<br /> #*leg de parameters uit<br /> #*hoe kan je volumefractie kristallijne fase meten, leg kort techniek uit.<br /> #*geef een kwalitatieve bespreking van de grafiek<br /> #*wat kan je uit de parameters afleiden<br /> <br /> ====Professor Koeckelberghs====<br /> # zie vragen vorig jaar<br /> <br /> ===15 januari 2010===<br /> ====Professor Nies====<br /> #Er was de grafiek gegeven met daarop de binodal, spinodal en Tg curve. Met daarop 3 punten aangegeven, telkens in het homogene gebied boven de binodal en boven Tg. Punt A: Links van kritische punt, punt B tussen kritische punt en Berghmans punt en punt C rechts van Berghmanspunt. (Alleen deze vraag mondeling)<br /> #*Wat vindt plaats als je in punt A traag afkoelt?<br /> #*Wat vindt plaats als je in punt A afkoelt met 1000K/min<br /> #*Wat vindt plaats als je in punt B traag afkoelt<br /> #*Wat vindt plaats als je in punt B afkoelt met 1000K/min<br /> #*Wat vindt plaats als je in punt C traag afkoelt?<br /> #*Wat vindt plaats als je in punt C afkoelt met 1000K/min<br /> #Vergelijking van Groeisnelheid bij kristallisatie (U) gegeven: U=Fexp(A)exp(B)exp(C) Zowel F,A,B,C waren gegeven in symbolen(vergelijking onder 7.B case III)<br /> #*Geef waarvoor de symbolen staan en wat hun eenheden zijn.<br /> #*Verklaar waar de Frontfactor (F) en de drie exp's vandaan komen<br /> #*Bespreek temperatuursafhankelijkheid en geef een schets<br /> #Geef de definitie van een ideale Rubber<br /> #* Leid de uitdrukking voor af voor S bij een willekeurige verandering. P(R) gegeven<br /> <br /> ====Koeckelberghs====<br /> #Vergelijk radicalaire, anionische en kationische vinylpolymerisatie<br /> #*Mogelijke monomere deeltjes (stabiliteit)<br /> #*Terminatie reacties<br /> #*Invloed van verschillende voorkomende deeltjes op sneldheid (hiermee bedoelde hij de associated ion pairs etc)<br /> #*Mogelijke manier om ze 'levend' te maken. (of quasi levend)<br /> #*? dacht dat er nog 1 was<br /> #Je wil een ideaal, perfect blockcopolymeer maken van MMA en MA op anionische wijze. Welk monomeer moet je eerst polymeriseren? Blijft indien je dit met ATRP wil doen de volgorde dezelfde?<br /> #Bespreek kort Ring Opening Metathesis Polymerisatie.</div>

R0804230 https://wiki.chemika.be/index.php?title=Polymer_Sciences:_from_Synthesis_to_Polymer_Material&diff=3190 2023-01-20T22:23:15Z

<p>R0804230: /* 20th of January 2022 */</p> <hr /> <div>[[Categorie:Machemie]]<br /> <br /> ==Vakinformatie==<br /> Gedoceerd door Professor Nies en Professor Koeckelberghs. Lessen zijn altijd in het Engels. De verdeling is 2/3 op het deel van Nies en 1/3 op het deel van Koeckelberghs. Bij Nies zijn er ook verplichte assignments tijdens het jaar, die meetellen voor een fractie 4/(12-N) van de punten van zijn deel (met N aantal assignments, doorgaans 2). Nies zijn examen is gesloten boek en er moet maar één vraag bij hem mondeling besproken worden (deze wordt op voorhand aangeduid). Bij Koeckelberghs zijn alle vragen mondeling te bespreken.<br /> <br /> ==Examenvragen==<br /> ===20th of January 2022===<br /> ====Prof. Nies====<br /> #Eq. 1.40 is given. Discuss the limiting behavior for L&lt;&lt;lp and L&gt;&gt;lp. The Kuhn length was defined by two equations. Write them down and give a qualitative description. Even a wormlike chain with high but not infinite stiffness will behave like an ideal flexible chain under certain conditions. Explain.<br /> #Scientist claim that a polymer in solution shows a Phi(2)-T diagram with a closed loop miscibility hole. Chi(crit,1-2) are given as are T(crit,1-2). The values of Chi(0), Chi(1) and Chi(2) are provided too. From this, calculate s2 and Phi(crit,1-2). Show ether qualitatively of quantitatively if their reasoning for a closed loop miscibility hole is justified. Make a sketch of the Phi(2)-T diagram containing Phi(crit,2), T(crit,1-2), the binodals and spinodals.<br /> #Figure 3.27 is given and a graph that demonstrates the linear behavior between 1/l and Tm. In several steps you are guided towards deriving the Gibbs-Thomson-Tammann equation.<br /> ====Prof. Koeckelberghs====<br /> #Compare anionic and cationic ROP in terms of: monomers, initiators, propagation, transfer, termination and their ceiling temperature.<br /> #Discuss based on the structure op vinyl monomers in what way they can be polymerized. Relate the stability of the active species to Rp and discuss retardation and inhibition.<br /> #Discuss briefly how conversion and molar mass relate to each other in step-growth polymerization.<br /> <br /> ===27 augustus 2022===<br /> ====Prof. Nies====<br /> #Grafiek van specific volume relaxation uitleggen<br /> #Gibbs-Thomson equation afleiden<br /> #Polymer in solvent is cooled, binodal/spinodal and Tg curves zijn gegeven. 1) Leg uit wat je denkt dat er zal gebeuren, 2) welke morphology denk je dat gevormd wordt voor trage vs snelle cooling? <br /> ====Prof. Koeckelberghs====<br /> #free radical, anionic and cationic polymerization vergelijken op vlak van a) monomers b) termination reaction c) possibility for living polymerization<br /> #ring opening metathesis polymerization bespreken<br /> ===20 januari 2022===<br /> ====Prof. Nies====<br /> #Afleiding maken van de end to end distance van de freely rotating chain + uitleggen waarom er ⟨ .... ⟩ haakjes worden gebruikt + uitleggen wat L voor de FRC is<br /> #Gegeven formule van de gibbs vrije energie van menging (FH)Flory huggins<br /> #*Wat is de thermodynamische voorwaarde voor spinodaal gedrag? + Wat is de thermodynamische voorwaarde voor kritische toestand?<br /> #*Leid ook verder af wat chi kritisch en phi kritisch zijn hieruit (opnieuw afleiden!)<br /> #*Bepaal of de gegeven Tcritisch op een UCST of LCST systeem wijst <br /> #*Geef UCST en LCST namen voluit<br /> #*Teken een phi T diagram waar je de UCST of LCST van in de oefening uitlegt en uittekend<br /> #Avrami equation gegeven en eveneens een avrami plot<br /> #*Leg uit wat m en k zijn in deze vergelijking<br /> #*Leg uit wat we in deze plot zien ivm de equation, over de volledige tijdsinterval<br /> #*Teken zelf een plot volgens Avrami, waar hetzelfde polymeer (syndiotactic polystyrene) bij andere Tc was: Tc oorspronkelijke plot was 110°C, de 3 anderen waren -30°C, 105°C, 175°C --&gt; Tm en Tg van polystyreen waren gegeven!<br /> <br /> ====Prof. Koeckelberghs====<br /> #Definieer en bespreek living/controlled polymerization. Welke experimenten kan je uitvoeren om aan te tonen dat het gaat om een living/controlled polymerization. Bespreek de algemene methode waarop een free-radical polymerization omgezet wordt in een controlled polymerization. <br /> #Bespreek emulsion polymerization <br /> <br /> ===13 januari 2021===<br /> Verkorte examenduur omwille van corona<br /> ====Prof. Koeckelberghs====<br /> #Definieer en bespreek living/controlled polymerization. Welke experimenten kan je uitvoeren om aan te tonen dat het gaat om een living/controlled polymerization. Bespreek de algemene methode waarop een free-radical polymerization omgezet wordt in een controlled polymerization. <br /> #Bespreek emulsion polymerization <br /> <br /> ====Prof. Nies====<br /> #Gegeven formule van de gibbs vrije energie van menging (FH)<br /> #*Geef de betekenis van ieder symbool in de formule en de eenheid <br /> #*Wat is de thermodynamische voorwaarde voor spinodaal gedrag? <br /> #*Wat is de thermodynamische voorwaarde voor kritische toestand? <br /> #*Schrijf UCST en LCST languit <br /> #*Leidt de vergelijking van chikritisch en phikritisch af<br /> #*Oefening: berekenen Chikritisch, UCST of LCST gedrag? Tekenen fasediagram en verloop van chi in functie van de temperatuur <br /> #Leidt de vergelijking voor de average squared end-to-end distance af voor een WLC met de vergelijking voor een FRC gegeven. <br /> ===16 januari 2020===<br /> ====Prof. Koeckelberghs====<br /> #Anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #Step growth en chain growth vergelijken en hoe je kan bepalen wanneer je welke hebt<br /> #Metathese kort uitleggen<br /> <br /> ====Prof. Nies====<br /> #Taak uitleggen (mondeling).<br /> #Gibs-Thomson-Tammann afleiden voor lamellar crystal, vergelijking voor Gibbs fusie is gegeven<br /> #Derive expression for deltaG = G(deformed) - G(undeformed). Expressions for the squared end-to-end distance for FJC and P(R)dR are given<br /> <br /> ===17 januari 2019===<br /> ====Prof. Koeckelberghs====<br /> #Anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #Step growth en chain growth vergelijken en hoe je kan bepalen wanneer je welke hebt<br /> #Metathese kort uitleggen<br /> <br /> ====Prof. Nies====<br /> #Taak uitleggen (mondeling).<br /> #Grafiek over Tg afhankelijkheid van de cooling rate, uitleggen op moleculair niveau (met betrekking tot mobiliteit)<br /> #Afleiding radius of gyration geven (fjc), toon aan dat &lt;s²&gt;= lb² (N+1)(N-1)/6N en of de uitdrukking verandert als er interacties zijn tussen de massa's met Lennard Jones interactie potentiaal?<br /> <br /> ===14 januari 2019===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #plot van volumeverandering i.f.v. de tijd (case2-figuur 25) gegeven, bespreek ... (physical ageing)<br /> #afleiding voor de Thomson-Tammann smelttemperatuur van een eindig sfeer kristal, met de fusie Gibbs vrij energie van een oneindig groot kristal gegeven<br /> <br /> ===31 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #Anionic versus cationic ring opening polymerization:<br /> #*monomeer<br /> #*intiator<br /> #*general polymerization mechanism<br /> #*termination + transfer<br /> #*ceiling temperature<br /> #Influence of the molecular structure of vinyl monomers on possibility to polymerize. Correlate the molecular structure with:<br /> #*the way monomers can be polymerized<br /> #*rate of polymerization<br /> #*retardation + inhibition<br /> #Influence of conversion on molar mass in step growth polymerization<br /> <br /> ====Prof. Nies====<br /> #Formula growth rate given (case 3 eq. 1.28)<br /> #*discuss the origin of the exponential facors and the front factor in the given equation.<br /> #*discuss dependence of the growth rate on the size of the crystal at a chosen crystallization temperature. Make a schematic plot of the predicted growth rate versus the crystal size for the chosen crystallization temperature.<br /> #*what are the consequences for the predicted growth rate for crystallization behaviour at a particular crystallization temperature?<br /> #Figure volume relaxation (case 2 figure 27)<br /> #Rubbers<br /> #*Define an ideal rubber<br /> #*Derive expression for deltaG = G(deformed) - G(undeformed)<br /> Expressions for the squared end-to-end distance for FJC and P(R)dR are given<br /> <br /> ===25 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #ceiling temperature vergelijken bij vinyl polymerization en ring opening polymerization + kleine bijvragen daarover<br /> #controlled radical polymerization (NMP en ATRP)<br /> #living cationic polymerization<br /> <br /> ====Prof. Nies====<br /> #grafiek spinodal, binodal (die met Berghman's point) toegepast op PDLC, vorming van PDLC uitleggen aan de hand van grafiek<br /> #physical ageing<br /> #avrami plot<br /> <br /> ===19 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #anionic, cationic en radical vinyl polymerisation vergelijken ivm monomeren, terminatie en mogelijkheid tot controlled/living<br /> #step growth en chain growth vergelijken en hoe ge kunt bepalen wanneer ge wa hebt<br /> #ROMP uitleggen<br /> <br /> ====Prof. Nies====<br /> #taak bespreken (mondeling)<br /> #Gibs-Thomson-Tammann afleiden voor lamellar crystal, vergelijking voor Gibbs fusie is gegeven<br /> #spinodal en critical condition geven + afleiden helemaal en berekenen wat de critische waarden zijn voor 'chi' en 'fi-2', vergelijking Gibbs gegeven<br /> Huggings formule gegeven (niet in boek) is een uitbreiding van Flory-huggings vergelijking, wanneer zijn die aan elkaar gelijk en wat is de betekenis dan<br /> <br /> ===15 januari 2018===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #plot van volumeverandering i.f.v. de tijd (case2-figuur 25) gegeven, bespreek ... (physical ageing)<br /> #afleiding voor de Thomson-Tammann smelttemperatuur van een eindig sfeer kristal, met de fusie Gibbs vrij energie van een oneindig groot kristal gegeven<br /> <br /> ===25 augustus 2017===<br /> ====Prof. Koeckelberghs====<br /> #Vergelijk anionische ring opening polymerizatie met kationische ring opening polymerizatie op vlak van<br /> #*monomeer<br /> #*intiator<br /> #*mechanisme<br /> #*terminatie/recombinatie<br /> #*ceiling temperature<br /> #Lewis Mayo en die R ratio's daar in. Welke dingen invloed daar op hebben en hoe + voorbeeld<br /> #Welk invloed heeft de vorderingsgraad op molaire massa in step growth polymerizatie?<br /> <br /> ====Prof. Nies====<br /> #(mondelinge vraag) bespreek grafiek en waarom dat dit gebeurt (uitleggen op moleculair niveau), grafiek van physical ageing<br /> #Afleiding van hoofdstuk 4 Gibbs vrije energie wanneer een ideaal rubber deformatie ondergaat<br /> #vanalles van UCST en LCST, iets vaags.<br /> <br /> <br /> ===20 januari 2017===<br /> ====Prof. Koeckelberghs====<br /> #Anionische, kationische en frp uitleggen obv monomeer, terminatie en hoe ge het levend kunt maken<br /> #Step growth en chain growth<br /> #Ringopening methatese<br /> <br /> ====Prof. Nies====<br /> Vraag 1:<br /> #Wat is de definitie van een FRC?<br /> #Bij welke condities is de FRC gelijk aan de FJC<br /> #Bereken Lk en Nk voor de limiet van een enorm lange FRC (&lt;R2&gt;frc gegeven)<br /> #Leidt een vergelijking af voor de mean squared end-to-end distance van een ideaal lineair diblock copolymeer bestaande uit Nk1 Kuhn monomeren met lengte lk dat vasthangt via 1 einde aan Nk2 Kuhn monomeren met lengte lk2<br /> Vraag 2:<br /> #Mengsel van PS in methylcyclohexaan (Mw = 355kg/mol)<br /> Bij T=350K bestaat het mengsel uit 1 homogene vloeibare fase. Deze T is 6K boven de flory T. Polymeer volume fractie in de homogene fase is O,2<br /> Bij T=335K: twee vloeibare fases, de polymeer volume fracties van de coexistant fases zijn 0,003 en 0,435<br /> In de compositie range {0,002-0,044} en {0,336-0,435} is de structuur van de initiele fase scheiding kleine druppels in een matrix fase<br /> #*Schets het verloop van delta Gmix ifv de volledige compositierange bij T=333K<br /> #*Duid de points of interest in deze curve aan en leg ze uit.<br /> #*Leg tot he point uit waarom je vraag a zo geschetst hebt<br /> #*Wat zal de morfologie zijn in de initiële fase van scheiding?<br /> <br /> <br /> ===19 Januari 2017===<br /> ====Prof. Koekcelberghs====<br /> #Vergelijken ven anionische en kationische ringopeningpolymerisatie op vlak van<br /> #*Initiatie/Initiatoren<br /> #*Terminatie/transfer<br /> #*Mechanisme<br /> #*Mogelijke monomeren<br /> #*Ceiling temperature<br /> #Geef de factoren die een copolymerisatie beïnvloeden <br /> #Geef de invloed van de conversie bij een step-growth polymerisatie<br /> <br /> ====Prof. Nies====<br /> #Vraag 1: bespreek je taak helemaal (mondeling)<br /> #Vraag 2: Leid het verschil in Gibbs vrije energie voor een vervormd en onvervormd ideaal rubber af. End-to-end distance van een ideaal rubber en de Gaussische distributie zijn gegeven.<br /> #Vraag 3: Gegeven een stelling die zegt dat er een closed-gap miscibility gap plaatsvindt, met een formule voor chi in functie van T. 2 kritische waarden voor de temperatuur zijn gegeven. De vraag is: kan deze stelling kloppen? <br /> <br /> <br /> ===16 januari 2017===<br /> ====Prof. Koeckelberghs====<br /> #living/controlled polymerization: definitie + uitleggen. Hoe kunt ge dat experimenteel kunt nagaan. Principe uitleggen hoe ge van free radical polymerization naar controlled polymerization gaat.<br /> #De invloed van de moleculaire structuur van vinyl polymeren op polymerisatie en op de polymerisation rate en dan ook nog op inhibitie en retardatie<br /> #bespreek emulsion polymerization<br /> <br /> ====Prof. Nies====<br /> #Bespreek uw taak: gewoon uw taak uitleggen aan Nies (mondelinge vraag)<br /> #zie theoretical questions doc case 3 vraag 13, maar alleen de excess Gibbs energy en de chemical potentials waren gegeven<br /> #Vraag 3:<br /> #*thermodynamische uitdrukking voor spinodal en critical conditions afleiden.<br /> #*zie theoretical questions doc case 2 vraag 4 en de uitdrukking voor de Gibbs energy is gegeven<br /> #*de verbeterde Huggins uitdrukking voor de Gibbs energy is gegeven en daarvoor de enthalipsche en entropische bijdragen bepalen.<br /> #*De FH uitdrukking is een speciaal geval van de Huggins uitdrukking: bepaal de conditie van y waarvoor dit geld + geef de fysische betekenis van die conditie<br /> <br /> ===14 januari 2016===<br /> ====Prof. Koeckelberghs====<br /> #Vergelijk chemisch geïnitieerde FRP en ATR op vlak van:<br /> #*Algemeen protocol<br /> #*Snelheidsvergelijkingen<br /> #*Invloed van de moleculaire structuur op de snelheid van polymerisatie<br /> #Leg uit: step growth en chain growth polymerisatie. Hoe kan je experimenteel onderscheid maken tussen beide?<br /> #Leg kort uit: Ziegler-Nattakatalysator<br /> <br /> ====Prof. Nies====<br /> #Gegeven: Tg in functie van cooling rate. Verklaar de moleculaire oorsprong van dit fenomeen. (oral)<br /> #*Mondelinge bijvraag: wat bepaalt, naast de kinetische energie, ook mee het vrije volume?<br /> #Leid een formule af voor het smeltpunt van een eindig sferisch kristal.<br /> #Vrije energie van mengen volgens Flory-Huggins gegeven:<br /> #*Wat zijn de spinodale en kristische voorwaarden?<br /> #*Geef de betekenis en eenheiden van elke parameter in de vergelijking.<br /> #*Geef een concrete uitdrukking voor de kritische en spinodale voorwaarden afgeleid uit de bovenstaande vergelijking.<br /> #*Geef een concrete uitdrukking voor de kritische phi en chi.<br /> #*Gegeven een uitgebreide variant van de vergelijking van Flory en Huggins. Wat zijn de enthalpische en entropische bijdragen?<br /> #*De oorspronkelijke formule van Flory en Huggins is een bijzonder geval van de bovenstaande vergelijking. Onder welke voorwaarde is dit en waarmee komt dit fysisch overeen?<br /> <br /> ===11 januari 2016===<br /> ====Prof. Koeckelberghs====<br /> #Define living/controlled polymerisation. Hoe neem je dit experimenteel waar? Hoe maak je free radical controlled?<br /> #Wat is de invloed van moleculaire structuur van monomeer op manier vinylpolymerisatie, snelheid en retardation/inhibition?<br /> #Bespreek emulsiepolymerisatie.<br /> <br /> ====Prof. Nies====<br /> #Case 2, figuur 27 uitleggen (specifiek volume in functie van tijd) (oral)<br /> #Leid Gibbs Thomson uitdrukking af voor smelttemperatuur van sferisch kristal.<br /> #Uitdrukking s^2 en massacentrum gegeven:<br /> #*Leid average radius of gyration af met alles massa's = m.<br /> #*Toon aan dat average radius of gyration = lb^2 (N+1)(N-1)/6N als i=1,2,3,...,N-1.<br /> #*Veranderen de uitdrukking als er interacties zijn tussen de massa's met Lennard Jones interactie potentiaal?<br /> <br /> ===24 januari 2013===<br /> ====Prof. Koeckelberghs====<br /> #Discuss the ceiling temperature and apply it on both the vinyl polymerization and ring opening polymerization. Is the ceiling temperature of a particular monomer dependent on the way it's polymerized?<br /> Is it possible that a particular monomer, of which the ceiling temperature is such that only low-molar mass oligomers can be obtained via a living anionic polymerization at a certain temperature, can be polymerized into high-molar mass polymer using a free radical polymerization at the same temperature? Motivate your anwer.<br /> #Explain the principle of a controlled radical polymerization and apply it on NMP and ATRP.<br /> #Discuss briefly the living cationic vinyl polymerization.<br /> ====Prof. Nies====<br /> Zie onderstaande afbeelding.<br /> [ <br /> #Assignment 1 (oral)<br /> #The &amp;lt;i&amp;gt;free rotating chain&amp;lt;/i&amp;gt; (FRC) consists of N bonding vectors l&amp;lt;sub&amp;gt;i&amp;lt;/sub&amp;gt;, i=1,...,N with constant bond length |l&amp;lt;sub&amp;gt;i&amp;lt;/sub&amp;gt;| = l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt; and constant bond angles Ï´&amp;lt;sub&amp;gt;ii+1&amp;lt;/sub&amp;gt;=Ï´, i=1,...,N between the successive bonding vectors. The average quadratic end-to-end distance &amp;lt;R²&amp;gt;, valid for all physically sensible values of N, l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt; and Ï´, is given by [[Bestand:R-FRC.JPG]]<br /> #*Show that the average quadratic end-to-end distance &amp;lt;R²&amp;gt; of the FRC chain with very small bond angles also can be written in the Kratky-Porod chain form: &amp;lt;R²&amp;gt; = 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;L-2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;²(1-exp(-L/l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;),<br /> with l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;=l&amp;lt;sub&amp;gt;b&amp;lt;/sub&amp;gt;L/(1-cosÏ´) the perstistence length and L the contour length.<br /> #Derive from the general thermodynamic equilibrium conditions the melting point of a polymer crystal in equilibrium with a solution of the polymer.<br /> For the polymer solution you can use the Flory-Huggins excess Gibbs-energy of mixing.<br /> [[Bestand:G(mix).JPG]]<br /> <br /> The chemical potentials of the components are given by:<br /> [[Bestand:Chempot.JPG]] ]<br /> <br /> [[Bestand:240113nies.png]]<br /> <br /> ===18 januari 2013===<br /> ====Prof. Koeckelberghs====<br /> #Compare chemically initiated free radical polymerization and ATRP, for the following aspects:<br /> #*general concept<br /> #*rate of polymerization<br /> #*influence of molecule structure on polymerization rate<br /> #Discuss the differences in mechanism of chain growth and step growth polymerization. How can one investigate which type of polymerization he is dealing with?<br /> #Explain briefly: Ziegler-Natta catalyst<br /> ====Prof. Nies====<br /> #Discussion of assignment 1 (oral)<br /> <br /> Zie onderstaande afbeelding.<br /> <br /> #The expression of average squared end-to-end distance of the Kratky-Porod chain is given: &amp;lt;R²&amp;gt; = 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;L - 2l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;²(1-exp(-L/l&amp;lt;sub&amp;gt;p&amp;lt;/sub&amp;gt;)<br /> #*Derive expressions for the Kuhn segment length and the number of Kuhn segments for this chain.<br /> #*Discuss your results. For instance, did you make any assumptions? Mention them explicitly.<br /> #The excess Gibbs ebergy of mixing in the Flory-Huggins model is given: ΔG/N&amp;lt;sub&amp;gt;l&amp;lt;/sub&amp;gt;kT = Δg/kT = (φ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;/s&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;)lnφ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt; + (φ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;/s&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;)lnφ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; + χφ&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;φ&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;<br /> #*Derive expressions for the spinodal and critical conditions.<br /> #*Derive from these expressions the formulae for the critical composition φ&amp;lt;sub&amp;gt;2,cr&amp;lt;/sub&amp;gt; and critical value of χ.<br /> #*What is the relevance of the spinodal for material behaviour?<br /> [[Bestand:180113nies.png]]<br /> <br /> ===20 januari 2012===<br /> ====Professor Nies====<br /> #Gegeven een fase-diagram uit Case II. Wat gebeurt er als er vanuit punt A (dat links van de critical point lag):<br /> #* traag wordt afgekoeld<br /> #* wordt gequenched (1000K/min)<br /> #* Hoe ziet de oplossing er na koelen uit voor beide gevallen<br /> #5 begrippen uitleggen:<br /> #*Thermo-elastische inversie<br /> #*Physical ageing<br /> #*Second order transition<br /> #*Effective pair potential<br /> #*Nucleation &amp;amp; growth<br /> #Leidt de spinodal en critical conditions af en ook de waarden voor Fi(2,crit) en Chi(krit).<br /> <br /> ====Professor Koeckelberghs====<br /> #Wat is de ceiling temperatuur en correleer dit met vinylpolymerisatie en Ring opening polymerisatie. Is de ceiling temperatuur afhankelijk van hoe we polymeriseren? Stel we polymeriseren via een living anionische polymerisatie. Het monomeer heeft een lage ceiling temperatuur, wat ervoor zorgt dat er geen lange polymeerketens worden gevormd. Kan men dan langere ketens verkrijgen als men bij dezelfde temperatuur via een radicale polymerisatie polymeriseert?<br /> #M1 en M2 worden gecopolymeriseerd. Geef de parameters voor beide monomeren en leg uit waarvan deze afhangen.<br /> # Leg uit: (radicalaire) emulsiepolymerisatie<br /> <br /> ===21 januari 2011===<br /> ====Professor Nies====<br /> # Teken het verloop van de de gibssvrij-energie in functie van volumefractie bij een temperatuur van 300K. Volumefracties = 0,2. Coexistence points en spinodal points gegeven. Ook de verschillende punten aanduiden en kort uitleggen. (deze vraag was mondeling)<br /> # Formule p 50 case 1 gegeven (zonder 4e term)<br /> #* leg de symbolen uit + dimensies + eenheden<br /> #* wat bedoelt men met &amp;quot;volgens de Flory benadering...&amp;quot;<br /> #* leg de twee verschillende termen uit<br /> #* Bereken end-to-end distance in evenwicht bij een flory-solvent<br /> #* Bereken end-to-end distance in evenwicht bij een goed solvent<br /> # Avramiplot+vergelijking gegeven<br /> #*leg de parameters uit<br /> #*hoe kan je volumefractie kristallijne fase meten, leg kort techniek uit.<br /> #*geef een kwalitatieve bespreking van de grafiek<br /> #*wat kan je uit de parameters afleiden<br /> <br /> ====Professor Koeckelberghs====<br /> # zie vragen vorig jaar<br /> <br /> ===15 januari 2010===<br /> ====Professor Nies====<br /> #Er was de grafiek gegeven met daarop de binodal, spinodal en Tg curve. Met daarop 3 punten aangegeven, telkens in het homogene gebied boven de binodal en boven Tg. Punt A: Links van kritische punt, punt B tussen kritische punt en Berghmans punt en punt C rechts van Berghmanspunt. (Alleen deze vraag mondeling)<br /> #*Wat vindt plaats als je in punt A traag afkoelt?<br /> #*Wat vindt plaats als je in punt A afkoelt met 1000K/min<br /> #*Wat vindt plaats als je in punt B traag afkoelt<br /> #*Wat vindt plaats als je in punt B afkoelt met 1000K/min<br /> #*Wat vindt plaats als je in punt C traag afkoelt?<br /> #*Wat vindt plaats als je in punt C afkoelt met 1000K/min<br /> #Vergelijking van Groeisnelheid bij kristallisatie (U) gegeven: U=Fexp(A)exp(B)exp(C) Zowel F,A,B,C waren gegeven in symbolen(vergelijking onder 7.B case III)<br /> #*Geef waarvoor de symbolen staan en wat hun eenheden zijn.<br /> #*Verklaar waar de Frontfactor (F) en de drie exp's vandaan komen<br /> #*Bespreek temperatuursafhankelijkheid en geef een schets<br /> #Geef de definitie van een ideale Rubber<br /> #* Leid de uitdrukking voor af voor S bij een willekeurige verandering. P(R) gegeven<br /> <br /> ====Koeckelberghs====<br /> #Vergelijk radicalaire, anionische en kationische vinylpolymerisatie<br /> #*Mogelijke monomere deeltjes (stabiliteit)<br /> #*Terminatie reacties<br /> #*Invloed van verschillende voorkomende deeltjes op sneldheid (hiermee bedoelde hij de associated ion pairs etc)<br /> #*Mogelijke manier om ze 'levend' te maken. (of quasi levend)<br /> #*? dacht dat er nog 1 was<br /> #Je wil een ideaal, perfect blockcopolymeer maken van MMA en MA op anionische wijze. Welk monomeer moet je eerst polymeriseren? Blijft indien je dit met ATRP wil doen de volgorde dezelfde?<br /> #Bespreek kort Ring Opening Metathesis Polymerisatie.</div>

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