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6 Small-Molecule Motion

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classes in polymer dynamic based on
George Phillies book phenomenology of polymer solution dynamics Cambridge University Press 2011 ends today this
lecture is lectures 6 small
small-molecule motion In any event by
Professor felonies this is physics 597 the phenomenology of polymer dynamics and then we're going to discuss the rest of Chapter 4 my book on white skin and we're going to discuss chance to Fox and because the class compositions or materials and physics I'm not going to to discuss it very much of the very issues of how light light-scattering works or how you calculate College the calculation is important and will show up in Chestertown because we will demonstrate we can actually calculate for spherical particles how the diffusion coefficient depends on concentration and we get a more the right answer and the fact that we get more or less the right answer gives us good reason to believe that we are actually seeing a phenomenon that we understand so let us go back to where we were last time as will trot formed what the races the therefore I was briefly go for a walk so as sketch how scary works and what I am going to sketch works equally well for X-ray static X-ray scattering for electrons together for TransCanada and for once again we have coming in across 1 Toronto claims of constant faces life has gone that way pulsating light because that's what I and there are instances the Honourable light and the widest get the French them and actually had a hole in the wall corrections however some friends often reaches In a real experiment scary this distance is very small holes gathering sellers the laser beam is focused say 100 microns across the unit we collect this way is the same size he had this distance the followed multiplier to might be needed to do so in fact the light rays going to the detectors have to be traveling very nearly parallel to each other to get the detail if you are worried about whether they actually get the detector at the same time the same direction you look takes violent th he advised George Canada and this is a late 60's early seventies papers and he worries about questions
the answers were good as long as the object itself however this and this is their land are not the same therefore if we consider these 2 lightweights yet the detector at the same time they had to start here at different times this for a guest star offer the laser earlier than this 1 and since they started 2 different times they have 2 different phases now I'm going to assume you get some freshman physics that sometimes when you've seen an interference experiment with lasers yes yes vote I'm so what happens is that to libraries the detector and if the EU phase with each other the light is bright and if there are 180 degrees out of phase the light waves cancel there's no light at all now in fact the salt water into scattering particles loads and loads of solution and you have to get up for all of do not 1st approximation is the light shows up with all different phases equally and goes to 0 but that's only an approximation and if there were fluctuations and so sometimes I have drawn things so used particles continuity of life that is scary in phase and other way waste trunk lines like this for a reason ,comma hurdles that lie along these lines scattered light but also gets to the detector particles that here scattered light that is 180 degrees out of phase so quite scary from these particles and coherently the light scattered from these particles and on-site coherently there were hurdles here here than there are in there and therefore working in next there is some scattered light if you were ever seen this phenomenon yes this is why the glows in the daytime namely light scattering from the era because the area is part of the atomic scale is not the universe and say that what we are looking at here he is a density fluctuations that have solved concentration fluctuations that has solid helpful to their local area and that varies in space has become Steinway yet come this way there is a great deal of man that just got so stressed the important issue tho is you were looking at my hands microscopic fluctuations that occur because of particles move around at random and by random chance produced density fluctuations that look like co-signed the rest of this year the and that is perpendicular to the the outlines of the useful feature is this he said K is a factor going back this is the factory making their way not for our position the ad the system and how we define well the light it is my honor to overwhelmed this way factor light and the way factor going out and playing the direction that the human factor going there -minus entitled Islam light is the same color actors gatherings for but it was initially going in the direction high-end is and going to the director and the change in the way of the factor of 1 just change direction is changing called scattering them you good and since I'm demanding a greater infinite amount of of time to tell you about this I'm going to refer you to terrorist proposals was on and there is a book by Ferdinand and his only there are many believe now controlled by Don Shula was working just retired Stony Brook very nice cell carriers will follow the there were 2 collections by In end there are 2 Major advances in science the collection those go back about said and if you referred to these you can get a much more detailed description what is the important issue here all 1st of all I said you get scattering because the particles give you density fluctuations looks like ,comma sideways you should realize that every possible goes sideways is being driven by the fluctuations in the same time each different coincided waved his you scattering in different directions some weakness sample 1 of them and so on we planted concentration versus access and ignoring the fact that there are all these other things going on at the the same time we would see a fluctuation of the concentrated around his equilibrium balance that looks like that this distance is microscopic sort of all moreover the square root of the number of molecules system it's very that's and what is this thing to do if you watch it and measures and to use a function of time on the average she you wait for a role the lives March the currency fluctuations the cases he minus exponentially this page his this distance is due by the wait scaring away on a case where the future co-author of the analysts said will face the same simply relax exponentially this the article suggested would be huge and therefore if you look at the scattered light at the time evolution of these fluctuations in scaring you can measuring fusion of that section now there's something else you could do little more solid many molecules were the
fall of modernizations are not spheres as a result if you send life In 1 polarization when it strikes the molecule what happened well it's an electric field it's striking molecular he creates an electrical fire the letter and the dipole it's not parallel to the original electric field because this isn't here and when the light comes out to the side is coming out straight words you the light was originally polarized light this burden of playing last word but while light comes out words you some of light in the polarized come out not with the original vertical polarization with horizontal polarization In however is molecules it hopes it rotates as a result as time goes on the required time nanoseconds Pico said something very sure Mica said the time these things rotation and the amount of light going out words used in the polarized changes if we can characterize timescale on which the polarization curves we can measure how long it takes work all the fuel to rotate or how long it takes for a settlement of a long haul change rooms and you can actually do this experiment that's the polarized I think the rest the polarized yeah now you can get to the other ways of getting the polarized staring simply scatter light from rough surface some of comes along but we're talking about molecular scale the polarization is often quite weak and you may have to work very hard to isolate people realize that you can't questions at least assumption that the whole world yes like actually has to be polarized to make the experiment work now fact if you were to win the 1983 scaring tourists from map details things canceled but in general you have to stop of polarized light source in the ladies room and you have to sat right out of the polarized area which is very weak from the polarized the area which is very strong and there are optical devices that this and we intend expose polarized staring gives you more reorientation OK what else do discussed chapter waters 1 last thing we're talking about the diffusion goldfish now for sale isolated severe water there is a result stops "quotation mark detailed models would be known as Einstein would be the important part of stock I'm that was and politicians in the thermal and you think the over a drag coefficient death resists motion what is well if I pulled clear to water source this is the worst songs here which is going backwards to the direction of velocity from my son as proportionality constant is that the of the 1st 2 years in water so small that response from using athletes 6 5 8 8 is the soul of of the staff is Brady's is sphere there's an OK Gators Stokes Einstein's equation now suppose however you have a solution that is not dime what happens Will it would actually happens is fairly complicated section of chair world not reading all however there are people who will say that life I the In this case the by 6 times a year and they would again that is a Greek letter what is called a dynamic scandalous 1 this equation comes from critical phenomena theory if you take a liquid and you heated up and compressor there is a temperature and the density because we were the only heightens there is a temperature and density which the liquid phase in the gas phase prompting distinguishes critical .period 10 and as you go there critical point and measured disillusioned with diffusion of or binary liquid diffusion of the 2 components through each other in started diffusion becomes very slow and you just if you look at the composition density here you discover regarding former regions size side I'm being very interesting here and oxide gets bigger and bigger as you get very close to the critical and embrace the assertion is the reason the slows down Is that side gets very moreish here looking at the diffusion of a collective object the size becomes very big .period so it doesn't affect now we are not going to talk about critical points more cost you should be aware of critical phenomena because the budget materials processing methods were critical fluids turned out to be useful effect on my part the users critical carbon-dioxide instead our organic solvents the rods are however having said that on people have taken this result tried to carry it over a user tries to use it describe mutual diffusion diffusion and relaxes concentration fluctuations in policy as we will
see when we get the right chapter this approach is completely wrong but you should be aware that there are people who do this question do dynamics can I think there was a lot of ideas that because you want to work it is the the Europe will be assigned plays the same role it's a leg and face the same almost 100 union rates and so what happens if the proposal is that if you have lots of Oracle's instead of the individual radius of all oils instead of the individual radius governing how what governs how they do it this way that's gives the distance over which called emotions are calling and so siren places or a survey of men the Monday was shot in the chest and find we're not actually going to start discussing motions that there is going to verify discussing there are mostly single particle and we are going to start by discussing small status which I the result all we will eventually push on from solvent molecules to Chapter 6 and we will discuss a little bit polymer chains we have to start sampling so account instead of going to discuss how solvent molecules from homeowners have or other small molecules on the 1st question is what you might ask well problems on the political I can't imagine with various techniques how fast small molecules through and suppose I what's going to happen the lake where and how is this going to affect the ability of small most of the killings the small simple-minded answer is that if you can increase the concentration of Baltimore will you might expect viscosity of the solution will go up the resistance to motion will go up and therefore diffusion slowing down best at least vaguely reasonable-sounding think so let's start with the simplest questions posed holding a solvent molecules or sodium ions or something diffusing through a simple way there stock Minister of the incident where that undermines terms the symbol and I'm going to change the discusses how 1 change the viscosity of the simple label ideas the concentration the well we want we were starting with no :colon solution well the number 1 we can change the temperature please the increase or decrease head you may actually seen this effect suppose you have a glass of ice water and a glass full of water trust brought to boiling point to shake each of the hot water seems to sloshing back and forth on that's because there's a factor of 3 changes viscosity between ice cold water and boil water notice vector 3 changes viscosity is just barely perceptible in the sense that it's not something the other thing you can do that with the actual receipt or what have you been enhanced solutes and is you take for example water and stir in sugar were you Sir Ian offer you take hydrocarbon solvent you at some other molecules and you can change the viscosity of a lake with a great deal looking at solutions rather than simple way and we can go back results of the birds in the region australia the work of the last century paper references urged about 1 his own and what he did was to measure the latter Ferretti mobility of small islands and other people since measured diffusion of under similar conditions and the question is how does the solution viscosity is changed the effect that the fusion small yes it going to kill somebody going you would be entirely possible to to take hold melted and measured diffusion of small students through column about he said the addition of the Our too now action well in my the sheriff thinning shares taken in substance but we're just going to be talking about small the liquids start with the small molecule and rare animals OK so we're going to have a small and we measure the electorate for mobility welfare asked the ions the solution that conduct it we measured diffusion coefficient has the compartment versus discussing and what we find is that not very justices all solutions moreover the diffusion coefficient is proportional to the into the 1st tower that is good he is White Water overseas ties the
think the over-65 age a little long overdue is proportional to the viscosity says so and we are liquids to this because that's exactly what we find out there's a limit down here because there are a lot of really low viscosity liquids and not the liquids that unless this is the water get out here and the charge here of pure water everywhere and temperatures .period home .period 90 cents to license at the stars and we just had to get out about 5 cents to end at some point near 5 always there is a sudden change and hired discussing we find that the University of Hong Kong and that's without two-thirds power and so if you look at the diffusion through viscous liquid doesn't behave like this at all there are going to make an extensive series of papers people who study this in different systems using several different experiments vary on the cross of the location in the hands of being molecular system me if I started head of organic solvents and stories things that sold and there's no reason for 5 cents poised to be the main Nova but is fairly small but the crossover behavior is the same as a strong dependence on viscosity and the larger viscosity is much weaker Wisconsin now 1 thing you must OK so that's not quite what we expected but now you know what happens if you just change the viscosity and it's small suppose however this is all the more for example Soviet-style or sold suppose you instead a polystyrene latex I have savory briefly with polystyrene latex namely their procedures for synthesizing polystyrene and they are running in water and surfactant where they and same water surface and little balls of polystyrene there have either been coated with surfactant where service modified that's carboxyl late and because the surface the modified the serious charge and because the object is charged this service modified effect Indiana something these little polystyrene drops in this all the waters of course Polish areas water soluble it stays the little drop and the trip is if you were very clever the census make these things and they all identical to within 1 per cent and size they're all very satirical so they're very nice object to use of Red a crown when you read the papers they're talking about the and we all measure diffusion coefficient the lights against the only area and there are 2 ways to change the viscosity and change the temperature at least over moderate range and you can change the viscosity for example instead of working in water use work in the water was glycerol and so back about 1 in 7 and I believe this show of these very nicely you you know what that is the next report to the UN thousands of forms and that's exactly what you would expect from Stoke size however few alert but you those for these things which are quite large is just letting in the over out here for the small objects above I said moreover the is linear in viscosity only at 1st and then there's a crossover so this peculiar crossover effect small little detail here does not repeat itself me so Scott Boras now let us watch out and we will push ahead the year 5 . 1 and because we we've pushed ahead Figure 5 . 1 What I do there's plot the diffusion coefficient versus the concentration Paul as we are now going to charge ahead and are going to look at at how fast the salt actually moves through policy and we are on in the book page 116 so we're looking at the emotional for example all of the solvent were looking at the tracer diffusion of a small fuel in the solvent as we are all over increased Wisconsin we have what happens the answer is we have to worry about former branch of the year there is a decrease the diffusion coefficient idea at polymer and this decrease is approximately the quietest songs constant concentration the 1st part and therein lies on
line the bottom of people on the experiment you see the same thing and then at higher concentrations than isn't all over measurements to a lot of schools worry that this is a smooth Turkey -minus some of the constant some power to move and this case was greater than that of the euro and 1 there is there is long behavior out to about 400 grams year and there is another behavior at higher concentrations at the time the Irish bookmaker described as there was no good explanation for it and I wasn't sure what the explanation was that I described that when we get the last chapter there are a whole bunch of information but there are a number of intellectual properties always solutions change vaguely at this concentration does not work each system the crossover is a sharp line not send concentration and call us all the things that I said look upon should be easy to find someplace the phrase 355 pre-emptively that's approximately right and if you look at subsequent figures and people will see more examples of the same her so what happens if we ate that increase the viscosity of Paul of a solution by adding Paul we see this rather odd concentration because it's their concentration dependence is not from various close to being concentration dependence of the viscosity of which get their he's as you at all so I look at this and you wonder what's happening and there is a very recent favorite tied tired at all it's macromolecules 2002 when it's late last year and they discussed various conditions concentrations and then make an observation that make predictions observation which can be translated as what look carefully watched on where we're looking at Holloman solutions from the side of things and if we were all the way to balance the symbolic change many of the BBC and there's quite close together is a cross section of the park small adherence solve all of you will have some sort of astronomy ex-cons who controls Mosul and if there were an e-mail the space between the Kalmar changed this small and the solvent molecules can get through the gaps but if we don't lose the Paula was sold at some concentration as well there is this sense that I will hold side it's that was the CSI it which is the distance between Bolton and at some point the technical side our is such that they can slip between polymer chains consistent and so far the solvent can flow between the spoils of solids liquid as opposed to isolated molecules that have look for holes and songs and U.S. hardly is this concentration well realistically speaking ,comma cross sections for March the size of an average solve all all but a human estimating what sort of concentration this transition from space space security it's something like 350 year 500 grams per liter talk now it's not exactly that but it's not obvious criterion should be the basis of the same size as all their molecular arguments involved and details this basically back-of-the-envelope estimate that the answer is that that change insolvent behavior appears to take place with the gaps between the fall of boils seen from the side are now no longer marching off on the average for solving all of these things through the accident would only chains that's a very approximate statement but it appears to be roughly correct in terms of giving correct concentration of crossover I just for someone that is the motion of small the translational motion of small molecules through Paul reports and you can there are lots of measurements of the same things and in most systems you see the same effect now to make the molecule only slightly larger figure 5 . 7 shows florist seen small-molecule society something like that happened at the end of refusing to hydroxy from cellulose so here is the future involving over the years the concentration of hydroxy programs cellulose is at center of plot which straight line and the diffusion coefficient goes even -minus helpless the new This is our polymer concentration that's the 1st thing you just see if an exponential drop a lot of diffusion coefficient now there's 1 interesting feature hydroxy probes Seles hydroxy probe syllables hasn't liquid crystal phase transition about halfway across that bridge but hydroxy from cellulose is a really Paul I'm quite as rigid as these things short pieces are and there is a concentration of which concentrate the meaning of polymers long line of work these sentiments lined parallel to each other so they can work with the florist seen diffusing through mediation PC doesn't notice that this is purchased diffuses but there's just a straight line straight through the face trends question of what to do the years that we've been doing that would rather be a correct what has been done in Figure 5 points that I do this very often the case in the future so that identified by the diffusion television before your solvents and therefore all the hot diffusion coefficient now you couldn't you if you didn't do the division you simply have different numbers on the side scale but this is just division by constant and if you're interference 7 a lot lot will provide constant you just change the way that some scientists you don't change in him so that is diffusion yet a poll except there is this 1 of the few years feature it is possible to do measurements and all sorts of salt and 1 of the soul of prevented him it is hard for fell 1 which is very polychlorinated by also in terms of chemical safety issues is material you treated with respect but it's been used industrially on a large scale although there have been issues when people have terrible not this particular 1 polychlorinated I think it's in general dollars the PCB problem however interesting feature is supposed put something on the small of England and inventor diffusion coefficient small as a function of the past 3 years and particularly the folly of is particularly material which is being used very systematically experimenting studies sort is a very viscous liquid and there are a number of policy that at the in the same year they're talking about namely diffusion coefficient small falls off exponentially with increasing concentrations however you
can also find poetry and all and absolutely it happens and most particularly if you are calling you dining Paula the diffusion coefficient of the rest of the probe goes up instead of down and what we can say on this is that the polymer appears to be modifying behavior sold well that's not reason where Crowley said we have a solution the column solvent modifies the behavior of a pall over the Paula and dilute solution doesn't behave the way melt and therefore why should we surprised that the pallbearers changing the soul and the same time and in a certain sense you should want people to think that this 1st there was nice work pilots the large animal and various other people sorted out the fact you where Polish was solution and procures household there is a somewhat more dramatic demonstration of this when we get to Section 5 . 4 1 and in Section 5 . at war look at soldiers from the founding of the presentation Wellington inconsolable at the start of the year and the polarizes the Arab light and then you can measurements determine the time scale on which tolerable solvent molecules to use all of you can determine the time scale on which changed the direction tastes and if you do this in a simple way would get some very small numbers of people not Pecos actions but nanoseconds and but if you solvent In discover but there are 2 populations of some of the smaller 1 with vary greatly from 1 of which at least in part rotates very slowly now we have to be a little more careful what I say fast slow you don't actually know that it's song molecules called free rotate fans and some molecules that rotates slowly it might be that you you have a molecule for example it can rotate rapidly around this axis at least moment but inherited from rotating around this excess as you increase the polymer concentration the fast-moving models have this year and the slow-moving molecules dominate and the inferences ,comma these technical polymer is inhibiting the rotation of smaller as well how to do this 1 answer is here blackboard records and bring their races are progressing on represents all of and here is the soul of old people near polishing his black work backwards surface represents polishing always follow rules you rotate like this but it can't rotate into the plight of the warrant any festive Blackwater 1st of all over doesn't move in quite slowly relative to solvency and therefore the polymer is doing something somebody to affect Paul how fast the local sold the question case so what is the effective range of followed .period Is it simply affecting the whole solution uniformly is only affecting molecules close to the polymer changed since the mechanism is specified United hypothesized mechanisms see what might be happening all the questions might ask is well what is going on and the experimental data I just talked to you about on Caracol leads to solution of the new experiment called the fact In all the program said Wallace we are fortunate to
have a pulse of couples polymers that influence solvent motion in opposite ways once-peaceful motion of the undisclosed sold motion so we make block copolymers In 1 choices after the fall of rules capital quality the another choices the slogan make a and B. that is not uniform as you can get and if the choice is moving out Brandon Oklahoma organization and we will have to pay the right next to each other now the Rangers it's extremely long all of these will do about the same pace as each solvent molecules because they know it's amazing but if the Rangers very sure these will tend to cancel each other and these will not cancel each other results fast of the slope of it here once during April they asked what you're being the slow and by looking at these we can infer the range over which of the following facts collected motion the answer would be it to sold that I have heard so molecules irritating rotational motion pure and solvent molecules that are way out of this fall Chania way out 3 informal diameters 20 Angstrom that's way out there are not and that was the analysis of logic chronicled the occasional fusion it's a very clever experiment and you can read about yourselves I see however are out of time we will continue this discussion next Monday was the 1st writing project is doomed and you each have a description of what you should call a reasonable thing to do is to have some tables at the end of her someplace which mentioned what each year researchers found and then 3 to 5 pages written on papers she found that in some sense use electrophoresis to give measurements that like the barrel and robbery from Bach papers could be used to study with polymers students solution were gone
Schaft <Waffe>
Magnetisches Dipolmoment
Konzentrator <Nachrichtentechnik>
Elektronisches Bauelement
Differentieller Wirkungsquerschnitt
Flüssiger Brennstoff
Kritische Temperatur
Walken <Textilveredelung>
Maßstab <Messtechnik>
Interferenz <Physik>
Pfadfinder <Flugzeug>
Basis <Elektrotechnik>
Elektrische Ladung
Schwarzes Loch
Haspel <Textiltechnik>
Stoff <Textilien>
Cross over <Teilchenoptik>
Zelle <Mikroelektronik>
Kette <Zugmittel>
Direkte Messung
Buick Century
Mark <Maßeinheit>
Proof <Graphische Technik>


Formale Metadaten

Titel 6 Small-Molecule Motion
Serientitel Classes in Polymer Dynamics
Teil 6
Anzahl der Teile 30 (Lecture 2 missing)
Autor Phillies, George
Lizenz CC-Namensnennung 3.0 Unported:
Sie dürfen das Werk bzw. den Inhalt zu jedem legalen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen.
DOI 10.5446/16232
Herausgeber Phillies, George
Erscheinungsjahr 2012
Sprache Englisch

Inhaltliche Metadaten

Fachgebiet Physik
Abstract Lecture 6 - small-molecule motion. George Phillies lectures on polymer dynamics based on his book "Phenomenology of Polymer Solution Dynamics".

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