14 Probe Diffusion, Part 1

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14 Probe Diffusion, Part 1
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30 (Lecture 2 missing)
Phillies, George
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Lecture 14 - Probe diffusion, part 1. George Phillies lectures on polymer solution dynamics, based on his book "Phenomenology of Polymer Solution Dynamics".
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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 E is lecture 14
probe diffusion I'm
professor fillies and this is lecture 14 my discussion on Polish solution I am today will start the discussion program diffusion literature on prohibition extremely large detectives for solutions at least as large as any of the other literatures on any of the other experimental techniques that we're going to discuss however if you do a search of reviews on Polish solution properties you'll find appropriate fusion for various historical reasons Israel underrepresented what is the general idea we have polymer solution we have "quotation mark isn't all that changed and we find some of the measles scuppered probably object and the measles standard for logic spheres the term presented is raised you can change we can change size it just sits there and is the object notice as we've already discussed probe fusion because the smallest probes the woman easily imagine thinking of horror I solvent molecules and if you go back to our 1st chapter on small-molecule diffusion error I have a solvent molecules moving through polymer solution we're going to be focusing here on unsold larger Wyoming this life probe diffusion be interesting technique what does that link between on the 1 hand something that we win talked about the last after the tracer itself future in which the probe object is a random oil polymer just like the matrix poll results on the other hand this is a future rejected we demand the same from part except protocols for refusing to in all 3 cases the basic forces involved artists say you have excluded volume bosses tennis with him macromolecules terms to each other and you may find 1998 reaction between the excluded volume and made a dynamic interactions there are also some shorter-range
forces for example between any to material objects you have better roles forces it could be the case we don't discuss this with the objects a church in 1 case we have Polly electrolytes we have charged grows and we
will then have in addition electrostatic forces get complicated nowhere however the core issues the core forces are explored volume and hired him the 2 forces are somewhat delayed by the shape of the matrix objects from the probe that is we have here a long rally in oil for all we have years here over we have year-round well matrices we have here is here matrices cost college don't have to be spheres but will talk mostly about Spears and therefore we can sort out the effects due to the topology the shape most of the all of the matrix by comparing 1 2 and for 3 recent experiments and actually demonstrated the utility of this look at this and future lectures the core issue in recent experiments is that if you take a solution of Grand Hotel polymers and her very clever canister you can't persuade the polymers to start crosslinking with each other that is to form a permanent covalent bonds that link them together when you do this there and wild colors solution is transformed into the but held and the true gelled crop chemically cross-linked JAL can then be confronted with a brand loyalty from forays 0 these experiments clearly demonstrate the permanently cross-link jails are entirely different physically from Real Quiet always solution namely In a grand while polymer solution fairly large and enron oil for probes are equally however if you insert the across it's wonderful chemical trade if you insert across this year's draft but can't find any holes big enough to move Paul oils are free agent who headed tail 1st through the holes in the polymer mesh and therefore we can say with considerable certainty that random while always solutions for of like gels and scarecrows at ran .period probes can give him different sorts of information conclusive transparent demonstration so we're really talking about proliferation there is a very large literature the large literature can be broken into 3 major segments but the 3 segments are part of the probe into the future team which we have probed classical strong polystyrene theaters and cylinders spheres we have solution and we used 1 of the standard optical methods Aussie elastic light-scattering fluorescence recovery after photo bleaching forced Rayleigh scattering all fluorescence correlation spectroscopy we use any of several methods to measure the diffusion of the probe through matrix a 2nd benefit he is currently drafting the notion of a particle tracking is that we Wimbledon with a microscope we will get this solution and we have done something clever to make pros visible for example we could arrange things so that the fluorescent recital eliminating with the dark background we could arrange things but there is something that is highly reflective in which case the although I alter microscope that mean we literally from the side of the background is black and you can easily see objects that are much smaller than the microscopic Cisco's ability to resolve the shape In a letter to Hurricane Fran in this is you do a video of the part of the objects going anywhere according to the positions of the object that you're interested in as a function of time you could then go in
and computes statistics of the measurements of the past the virtue of this technique is that you are actually seeing the full information about how the article was moving here is seen as something that is for example a statistical average of a single wavelength fluctuations relaxing the limitation of particle trapping is that
you're doing the video measurements and have limited by the frame rate of your video system now technology keeps advancing and there are a variety of tricks however heroes were certainly talking at this time I speak for the most part of times longer than the Millie said on the other hand causing elastic scary it's trivial to get out of the microseconds timescale and there are several tricks involving
the use of multiple voter Wall lawyer whose such and cross-correlation white-skinned missing direction but in to borrow to buy you can easily get down to all 50 nanoseconds I don't myself so you have several different techniques piled on top of this there is a separate literature which goes under the hammer from reality but Micro reality literature in currently uses several other physical methods for example the Southall's interviews ways that crosses the technique which we go over in some detail people of micro reality technique also refers to people who was sour that sense that Texas to squared average is old song titled hasn't diffusion coefficient tea and therefore from the the we can infer this playing at the to the something that is not binding instead of the symbol viscosity aura and of course the time defended viscosity really turns the dynamic model on my salary all literature is last
technique focused it's focused on the idea that while the elastic light skewering were vertical trail or solid thing you can measure the dynamic model Visco elastic properties of the media will discuss this in some detail interesting issues that these claims right OK so as to deliver the goods rather than was actually introduced 1st in the literature was pregnant rabbits because Brown when he discovered Brownian motion had microscope he did observations and he was actually doing particle bracket 1 vertical at the time of serving with the naked eye Brown was an extremely good might cross the best you can find a recent papers were people duplicated period instruments trying to duplicate his measurements and discovered it was astonishingly difficult to get things to work Brown had a bit more time on his hands and he was apparently very good because he got the expected results OK for optical probe diffusion they're trying to hold the this goes back to about 73 and optical produce fusion experiments we took a solution of bovine serum albumin and the idea was to measure the viscosity of the the salute by dropping in polystyrene spheres and measuring their diffusion coefficient I was very simple concessions the answer is charged polystyrene series a church the Polisario's fears went into the solution looked around not for very long at aggregated and fell straight out of solution their just fell straight to the bottom of this will be rock of the 1st people who were actually smart enough to get the experiment to work was with was turned Halla 1974 all hello and several of his students turned gray also I did experiments where they studied the diffusion of pro particles of different sorts in polymer solutions may successfully got measurements to work we're going to be focusing on producing optical probe leased at 1st so let us look at things on old-line aside if you were to win a literature search there is an optical probe diffusion literature probe diffusion literature there is a micro reality literature especially in Haiti using way spectroscopy literature there substantially No communicator not so that if you simply look in lot of the footnotes along the citation searches on water and try to find the other 2 Group of papers you're going to find it's a little more challenging the might innocently had expected because the 2 literature stopover where very well if you're interested in sociology of science you try speculating why I'm simply pointing out there this very limited communication OK so let us consider for all of you the polymer solution to be said C. Paul and were sold on the experiment is that you can see the pall over it's invisible and you can't see any surfactant or anything else you've ever added this is it's invisible to eye you can however see the problems you wouldn't we started polystyrene spheres the reason we started with polystyrene spheres we have a lot in their very intensely ski area so you can easily go about all cancel the highest moral and minus-5 by volume so this year's away far apart from each other and don't injury at all anywhere that observing singles fear diffusion coefficient all the stirring 1 is the sole supplier of scientific data and this was the 1st set point the fight started off as an assistant professor uses both sides signing trade deals you can call vision feared KGB is Bolton's constant canceled temperatures 6 5 viscosity of a radius of try and my general idea just when I was starting out as it would make sense to do a set of parametric tests to see if the assumptions that were being put into Bosnia last light-scattering and so we tried a series of water is a function of temperature were great we've tried it but we tried looking at a series of water glycerol as we vary the temperature in and Stokes Einstein continued to work great for some people reason people were very fond of an experimental system there at least 7 a three-year war papers since then looking at the the same system all with and so
well it b is proportional to the overrated we can say that with great certainty about that .period 1 of the and I just remember this very recently after I wrote the book and are 1 of the graduate students in the former program came through the palace and like I described what I was doing and she suggested Well why don't you change the viscosity by having them all and I hadn't thought of the possibility to be a very good idea although having said that she suggested polyethylene in which from the standpoint of synthetic chemists said I'm not positive features but that would have turned out to be a little challenging because polyethylene in me in water would tend to aggregated spheres we have available there however I instead tried Polly acrylic acid and the Polly acrylic acid even nonviolent relies on a weak shot doesn't tend to stay for the polystyrene spheres area and we went on from there bowlers themselves on Sunday wages you have to rewrite the rules for and long forms I was born on an area of over a year and rearrange everything else 6 times now diesel and the music flight problems Miss Kathy Bates and ferocity in the diffusion coefficients pro I'm also write this down or are made this case T all this 6 times in the 10 our age is in effect the hybridizing and raised this we follow effective rate is because the numbers you get through the radius can be quite different from the size of of particles and while you could imagine aggregation or something in the article looks to be out there is no obvious physical process that gives you a particle which is actually much smaller than a standard top scale and there isn't as effective radius is actually the radius of the part so we started out and we did measurements and after not her along old became apparent that a few seconds mold radius oracle and all viscosity of the liquid he didn't get agreement was measured diffusion coefficient the system was not caving in accord with the stop signs that wages and were getting knowledge of times society and the failure of the existence of nonstops Einstein and behavior occasionally upsets people a great deal because it appears to imply that Stokes Einstein equations wrong with fairly transparent and therefore something is perhaps along with Stokes law Of the actual issue was a bit more complicated than that 1st of all Stokes referring to objects moving in a straight line at a constant speed however diffusing particles do not own straight lines except as the very low probability that they do not know which constant speed except as variable probability that they move on a regular course and if you take an object in water and we through water on an irregular course the drag force on the object is not yet by Sosa along this year by both domestic ways all 35 years ago this became a significant issue briefly in statistical mechanics and the question was why don't we see Stokes slot Stokes Einstein's equations leased from large objects of all viscosity when Woods when the directive was not given by so a lot but is much more complicated equation that has for example America and what can be done was to do the full calculations Sharon objects that simply read arrived the Einstein diffusion equation of what correct words oracle and if you did this when you file is that for the specific topic being calculated to win the diffusion coefficient although the both Celeste Einstein equation the correct diffusion coefficient is essentially the same as the stock signs on the way to the environment as favored by analysts in the shower and promotions for example and there were well so solid and sometimes I really isn't correct but the correct equation gives the same result having if you now have a particle cellulosic liquid and it's going through disco elastic liquid the drag
force are due to the disco elastically what is even more complicated than the direct costs of the water and there is no particular reason to suppose that the start of stocks Stokes Einstein's equations remains there OK so what do you fight well during diffusion notification that Paul and the solution and so was then invited the diffusion coefficient he has installed progress you go fishing the depends on polymer concentrate on finding the bodies of the 2 you find a stretched exponential concentration said you measure diffusion and a series of concentrations may we lost the against the you see Aluminium plot something that looks like that and that is actually this war fortunately have found the period which we found this was also the period which microcomputers were available for Benecol microcomputers personal computers were available I happened to find book that discussed nonlinear least squares using the simplex algorithm and I was able to to write software the extracted these parameters in a nonlinear way you really have to treat this as a home problem and nonlinear least squares minor side there are 2 completely separate groups all over function fitting using the simplex algorithm ordered 1 of them you're doing linear fits so you have a very large matrices for example in trying to stretch of the means and the other doing functional status and you try and find parameters that were inside among linear equations and you have to realize the 2 of them because if you just look up the wrong 1 will be totally baffled about how you feeling across so there's nonlinear least squares using the simplex algorithm well a sound so we actually were able to do that and we now advance to the next we advanced to the discussion of looking at a lot of problems what was my word for all the people tailored pro-life Indiana size of all whining from 100 ventilators we kept looking for smaller probes that reusable resistance and as I recall he never got much below about 15 minutes meters in a satisfactory way some people look at the system and the 1st thing you actually used to measure the White scary Spec and so we plot I did the dynamics of the spectrum itself more detail on the structure of their feared as follows later on it's all lost several of the 171 of policies on that on a lot of plot to see something that looks like this and with available technology when I started doing this that is about all you can see with modern technology covering much wider spectrum ranges you discover there are often but not always multiple relaxations I we will eventually get systems show 2 or 3 very distinct relaxations Sabra and time by 1 meant where separated from her and even then talk about the whole however was that also used say we can see the initial relaxation and the initial relaxation early time relaxation which you can extract from human and offices of lights the earliest part of the relaxation gives us In the future nullification it well respected him into the minus the EU's we're the word of warning if you try feeding the spectrum was single exponential pure exponential you will get out nonsense with Captain Moussa said we have a relaxation spectra weekend visit to Finland expansion and in that case the 1st human element of relaxation gives us if you don't have a single fitting to pure exponential extremely disappointing were extremely dangerous because the fitting process is on stage if you fit to Cumulus instead which are intrinsically convergence this is discussed in modest detailed objectives for you however get reasonable results but now have sent this the people of fusion of and you should realize that there is a feeling of approach which will sometimes years later but approach is to play that she belonged is given by Of the confidence needed minus and there is a huge square there is no mean square displacement has evolved time this equation is correct for
defusing particles in a system that satisfies a lot on where there is a system in which there is no memory function that no viscoelasticity well if the equation is only correct get wife only correct systems that are not fiscally lasting it does not imply polymer solutions and quite wrong there How can you tell of this equation is you can tell the questions because he is the major news correct the these of constant and relaxation spectrum is a single exponential time this is buildings their which shows that if you want him to we're displacement here you must have a relaxation process that is of Markoff process process with no memory and the process is a mark of process you must know that the case the relaxation is linear in the simplest case cases beyond modest 1st spheres in pure water to win by dispersing fears in pure water if you follow this correct and what means we're displacement versus time for by 1st mixtures spheres while straight line and while the specter of the virus 1st on the same scale as Baltimore small here you got something that is probably wrong by his management of longtime because the spectrum does not measure the mean square displacement except the 1 trivial special case OK let us pushing and let us pushing ahead to turn around house and what kind and how it is say we have marched and we have to have a best friend who is a very nice falls far outweigh the neutral doesn't 10 states spheres at all and therefore we can do measurements and we can measure the future versus ears eyes for his Paul concentration burst other things did Paula molecular weight what the find 1st of all if we several different size fears we see the same behavior of course different-sized fears in different diffusion coefficients impure water could invite them out and once you divided that out the diffusion coefficient of the fears and dextrose is independent of the size of the CIA on the other hand the diffusion of television he says "quotation mark markedly on the Paul molecular weight it should take a specific sentence fears they fixed polymer concentration and you start increasing the polymer molecular weight increased the molecular weight of matrix of concentration and radius being takes the view that the television large followers are more effective at returning the motions steers that are small off further that would give
functional forms enabling the this functional was the reminded some constant a concentration in the 1st that is they saw a simple concept a simple concept exponential concentration the 1st of pure exponential concentration them and they did this fall for a variety of polymer molecular weights saw these results they also measured by indirect means her all data by indirect means the all this and also any of the system and what they found was viscosity they measure success with the macroscopic it was the same as the viscosity they inferred from the home diffusion coefficient well if literature stops here if this resulted in generally true you would have had a light scattering spectrometer a laser probes purification and he would have had a an incredibly expensive replacement a replacement that would cost almost a thousand times as much for example can advance the removal of misconduct if the 2 Saturday's were simply equal or light scattering spectroscopy optical problem fusion would have been a very expensive way to do something that you couldn't job just as well .period for much less money OK so what happened Wells the answer is we can shrug ahead to the next few paper I think from the beginning but my friend Alastair Jamison and entered paper by Jamison and collaborators on standby and if you look carefully at this instead solutions they measured the diffusion coefficient probes they measure the viscosity Baker a fairly interesting set of results on the other hand you control your head and you can say let's look carefully at this fall appearing very slightly later but In the papers on the final day there was no national chains .period University in Harlem I want and what we did was to observe diffusion coefficient in politics across the absence of polycrystalline tacitly as we look there may be a short of looking at the mountains relies Polly acrylic acid we didn't have to do that we could neutralized it looked all electrolyte effects and in retrospect it was probably lucky that we did what we did because you can go Polly electrolyte affects you have many more variables it's March Kurdish unsought what's going on it turns out and in addition of the experimental methodology of the time particularly the available digital correlated with white skin expected by modern standards at the limit nonetheless we looking for a series of 300 fellow all qualities :colon yesterday and the fire and terrified and I have great effect was for his variable as a function of polymer concentration what we filed for several sizes years was the RH 100 radius tended to fall with increasing all concentrate no the fact that the current hydrodynamic radius tended fall that is the fact that the light from viscosity was less than America's of the Stasi we got 2 very large 1 medical quality :colon gasses my from discussing much less than that stuff starts that was a very fortunate turn of events the reason I was fortunate is that you can think of several artifacts that would appear to cause the stock's Einstein equations fail for example in the upstairs and put them in the polymer solution they stick to each other and the big object romance fears or even bundling the ball a solution policy states that years that 1 has him now have a furry sphere the success the 2 big under most conditions you would expect them to move to slowly and if they moved too slowly the apparent viscosity and my discussing what appeared to be too large In fact the observed viscosity was too small therefore we were able as a best guess at the time to rule out the notion that there is aggregation of there were forming furry spheres Syria aggregation has since been studied somewhat interestingly it systematically by Paul all Russo collaborators but we were very the other thing we found was that this behavior is dependent on polymer molecular weights and for 300 will evolve always provided there was much promised Garcetti was a bit small the effects were incredibly more and you might argue Well maybe trace factories for 1 man and all that follows Holly acrylic acid were approached the city the of nonstops Einstein in behavior could be enormous at the orders of magnitude and there was absolutely no doubt that you at least with our instruments are interpretations were seen dramatic announced outside behavior on the other hand if you went in and said let's look at all of the features of all polygraph yesterday and we're looking at 50 killed all policies relating to what we found some reasonable approximation was the viscosity was equal partner stopped stuff so we actually did the experiments and haven't done the experiments what we found was that there was not so excited Stiliyan behavior it was could be quite dramatic and in addition to being quite dramatic it was molecular weight handed him a somewhat plausible way now for better or worse we also were able to make point that some of the solutions were extremely investors the and therefore by Orthodox standards if you believe in the future all or ideas solutions were an hour if you believe the usual diGenova arguments all it seemed tho once you get
called intelligent solutions what was supposed to matter With the size of 2 people .period with the policy change not the length of the polymer chains and is there and all the various laws and if you changed policy alot of molecular weight means Boeing in certain cases random always you change the polymer molecular weight by some fare about the whole here don't care about this because you haven't done anything wrong well that interpretation was so was seemingly rejected by experiment I'm always put up objections as to why you should believe the experiment that was seen in case we did however advanced clinical trial and I think the title intraday credit for this did advance the possible interpretation of of this namely that what we
seeing this year now the advanced the interpretations and at least 1 referee immediately raised the basically reasonable objection superficially that the system was not under share so why should it be the Fed and the answer is yeah they said the answer is clear in this sphere is moving this way and right United Services some distance out there is a hydrodynamic flow field of also worked at the height of the dynamics of the of weakens as you go further and further from the sphere and therefore because the diffuse spheres it's surrounded by a nonlinear non-uniform hydrodynamic flow field and there is sharing their frequent sense Seashera fending all limit extended this major experiments in by itself abreast of most time staying this year's and looked Taipei in years Paul that following belt was not very high molecular weight but it really wasn't melt that was polyethylene oxide and what he did was to to measure the diffusion of this year's In Vermont overstaffed and I realize its polymer solutions it's sheer thing so I thought viscosity of the measured viscosity versus the sharing of our instrument that is we have work there plates and moved 1 played faster and faster with respect to the other forcefully the apparent viscosity of the system falls on the appropriate jails like that and people took this and extrapolated that you could infer the shear rate corresponded to the diffusion coefficient and the microbe Garcetti also all the staff of the probes which were hiding his fears and an effective share rate that is the ZEC light of the staff and there is some share range which thing would give us there at all sort of thing of polymer solution we had what the sharing and universities came up with was about something more than the workers that wants a number to about 10 . 4 per cent and then since we also ask no diffusion coefficient this gives us a number of times to know what the future of the and the infirmity and diffusion coefficient Texas where he to please we can infer he for the displacement a length scale that corresponds to the sheer and analysts scale was extremely small and their forces we got molecular regions the all share :colon the distance sales of rough approximations but it was something like the thickness of polymer chain that manages the
observed the you go efficient users timescale for the Sheraton corresponds to the time needed for solving problems to move something like the thickness of a polymer chain and there were 1 polishing here who had steered the side of 1st hearing that they're out of the way so this year the song a certain sense this was Michael reality experiment but it was not being done exactly the same sense that has been done by cents for a coveted OK so I'll simply well I don't you these stress did give you however if you look back a bit figures Sunday after the following day for heart disease also called Polish acrylic acid into water and growth in Europe and we will now advance ball In the elements of book if you 90 s fights and these are large problems in the next which turned out be a very well-behaved material although we did experiments rattled detergent seriously the ideas is here you get a little tried next 100 resolve surfactant mysterious surfactants closest and prevents Palmer fusion has turned out not to be a big deal with this that it was a much bigger detail deal when we studied polyethylene oxide solutions and we looked at the radius fears on other meters and we looked at very next France's various electoral rights and what we found 1st of all was the diffusion coefficient followed the universal scale for the latest Elvis the other thing we could do and you can find this figure 9 Act is plot out of order against all molecular weight we have a whole series of values elsewhere and a full series molecular weights and what we saw I was actually a fairly clean straight lines and we in this and also showed a fairly clean behavior as a function of this lack I have had people
tell me that this history these results were much more convincing than those before and we have a Terranova of molecular weights the scanner Alpha was quite small you really did see a straight line and therefore you say proportional and solve our which we were able to OK there are a lot of other experiments on the same system the same sorts of were still talking about Laura 4 of which are really about probes the bigger the bigger the whole ball of some cases and so let's struggle ahead and we have for example studies follows and where so therefore call where and 1 can then measure the microscopic viscosity and she was able to do do this as a function of probe size so here is my here this varsity and was labeled bring my 1st start 3rd factor was on a measurement of the Orthodox macroscopic viscosity and then there were several sources probes willing to molecular weights all and overseas which is God these experiments were done with France was the elastic quite scary and what was found was that is being used to make the froze small didn't you also felt there are experiments however that finally opposite results of what seems to be a little more complicated today so as to push ahead and 1 the experiments talk about the rights of their own they get an notion this we will do 2 sets of men you will find from Bloomberg to probe diffusion coefficient to Haiti over the rental of and we will measure the sedimentation coefficient which is also part or all that this is a sedimentation coefficient for parole in some whole-grain matrix and we asked how are these 2 relays and the answer is that the diffusion coefficients itself patient coefficient to reasonable precision and use the same brandy goldfish throughout so that instead of and comparison of this comparison has an interesting features Warsaw trip if you're doing light scattering spectroscopy your manager the motion of particles over a distance scale that is moderately smaller than 1 wavelength battering diffusion over distances the fraction of a lightly .period What if you go to a very low angle scattering you can make that distance scales all work for sedimentation you're measuring objects
dropping through a significant part of the wave centrifuge analytical ultra centrifuge self you're looking at macroscopic distance so this is a direct test as described in the text that the microscopic diffusion coefficient and the of sedimentation coefficient very long wavelength sedimentation of they are using the same sort of thing if you want to see deviations of the sensible process preceding deviations on this scale is to go to a very short distances and nephew the of the diffusion coefficient of scattering angle because conventional very short distances using skin however what was demonstrated that is very important positive is that you can use less scary to what is basically a long wavelength delivered a large distance measurement diffusion of all right the probably talked about so far I have mostly been polystyrene latex spheres blobs of polystyrene .period staring doesn't dissolve in water so should make polystyrene blocks you they're not in water got a code that was trifecta surface modified so that charge states solutions but they have no tendency to dissolve their very stable polystyrene stand so what an alternative profitable alternative that the main problem is the character process and process us Louis-Philippe this year still at this year's turnout to be extremely Connell dispersed there are some very well-behaved uniformed service modified and invited them to alter their usual ball and silicon spheres unlike not of cross-linked polystyrene spheres are stable inorganic salts very passed and we come to compensate here Sunday after a Sunday by a user of the future some of these old fears In solutions following the the amendment there is our polymer and we can plot the diffusion coefficient is a function of the state and there is a function of the classic way where once again has increased the molecular weight of it becomes more effective rhetorical motion spheres In of additional measurements of this sort the lines that figure With respect to the continent news of collaborators and the jury gas measurements of diffusion of spheres he's been cross-linked because we're looking at series of polystyrene and ended up the fulfillment Polisario and that will form in which increased concentration of the polymer until the future of the falls on the history sensibly also the strategies we were and what they found the bottom of the In the group it is 0 that is the is reduces the viscosity is increased all by fractional increase viscosity strongside behavior is back and that's not what they found it comes off like a mile of the use of core issue here is that we're looking at all probes into Orthodox followers polystyrene in a fairly standard organic solvents and so any suggestion that the nonstop excited society and behavior was so complicated issue that you were water-soluble polymers you were doing charged probes you were in a previous system With all sorts of possible complications well although the issues were removed by this experiment on so this year's variability the opposite direction is to work with Cowell and collaborators from bonds sold there will still be is they also benefit from 1 of the best of Best of all the people more the service is also the main material discharged water molecules are charged 1 in neutral on the other it's surfactant but the other features that it will form for example is limited by the way I wanted to options so you have this while it really is all insiders water they also did multimillion-dollar vesicles and all the other half of the things that have not signed life on and what they found was that the polymer solution they looked at was more effective in return motion of a rigid body then returned to the motion would not sphere that is they found in the fact that could be correlated with fair systems flexible OK and that is it for simple measurements of March the reason I say that set for simple measurements is that with more modern technology using posse elastic .period scary you can readily measured the detailed shape of like scary stuff and if you do that you cannot use it methods are likely to give a reason why answers they actually break light-scattering spectrum into different modes OK so we're going to break the specter different moments and we're going to ask what sorts of things happen well there are nice experiments .period now next ball and we're looking at small growers and we find interesting results which some small probes Oregon always talked about what precisely for that all of the lottery or are you even talking about proteins a lot of articles all difficulty with studying proteins is they don't scare vastly more likely than the polymer dollars and therefore was elastic light-scattering turns out not to be an ideal weight measurements of message about all you can also talk about we were in the materials the most farmers that what is the start of the continent starting point we have something short comes out with a skating the details if and then there is branch .period consensus is branch .period is such that you have Paris Colorado right wing controlled chemistry so that each set within the coming out of the branches all the same light and if you may have discovered that off the number of links standards they asked square radius and he actually start running indications are however the core issue here is the based very nice very small spheres OK so you do these measurements and then I ask what you find well I won't give 1 example of the conviction that time I thought about groups we cannot and will not stand by and all I don't want to look very carefully at our very carefully very briefly and measurements by torture and collaborators and they measured the diffusion of something known as Green progressive prompting and material diffusing variously through the call center and also through the NRA and what I have plotted 1st is the the house so we have a short DNA very clearly controlled molecular weight linear hold all the calls are along the way and what happens when we do the experiment will what we find is not so scientists studying behavior of the small materials and David agrees nonstops Einstein immediately and matrix on different protein measurement is work that I did myself war-affected myself we will the fluidity the in the 1st viscosity and we're looking at polyethylene oxide solutions in addition to looking at polyethylene oxide solutions we're going for the ball I assume that dealt with using ball serial human approach and what we found but all the was a fusion there was the fluidity of the material there was the ability of the on pros who had the polyethylene oxide was more effective at reducing the fluidity is more effective than increasing staff that that was reducing the diffusion coefficient so we tried the experiments and actually work OK last set of experiments in Poland radical and several others in the world and the experiments were programs and policies gasoline cost and what we did in this case we were able to demonstrate that under some conditions the Palmer would stick to the problem but but and at 1st we didn't really work we sort of water into the sideways says we didn't realize it was going to to be an issue but the dependence of the diffusion coefficient on all concentration was a bit odd and so what we did today all of this is due to the cold and we put into the solution surfactant and surfactant and found work all right all right next 100 and this is a neutral material and avert what the surfactant does is that it sticks to the surface of the probe and it sticks to the surface of the probe sufficiently firmly Paula can get into no way demonstrate this is if you look at the future cooperation as a function of track ball surfactant concentration and what but once you put in last effective diffusion coefficient saturates some value it's saturated you go through all the numbers those fears are a bit larger than they were before throwing their lot and if you have more if you change the fall of concentration there you think that you will require policy of creating you can still demonstrate that out here someplace the diffusion coefficient is independent of of the surfactant concentration and this leads directly to the conclusion that you successfully surface coating spheres with detergent and the all this fall and only then but the fact of the 1st set of amendments that'd be or equivalently the life of viscosity Asian news promptly Lowery as a function of polymer concentration for several different sizes of years and got out curves that show that is where fall the diffusion coefficient went down the migrant viscosity went all I want to renounce now as compared with measurements we already have Of the diffusion coefficient of the series in which there is no tried next 100 these fears a changing size the changing size because this policy however at the same time changing size the microbes Garcetti's the growth of the sphere can be described by adsorption laissez-faire and and it has a fairly nice form the Micro viscosity can be described by the just measures and so we used fears of known size to be determined how microbicides that he has tall ones you have to be a little careful because the Micro viscosity cares about the Sphere size so we get measurement for a series of spheres of different radius finding that might be because Michael viscosity and concentration does change slowly this year's size but if we use this fear about the right size to measure we knew we should get out the right answer for the life of the Stasi and therefore from the and Michael viscosity you terminal binding Eisele said alternatively you say we have a binding items there and we can determine the thickness of the bomb material on how goes down example and we can calculate the diffusion coefficient based on statements by 1 of the findings of the number to get a nonstop outside society in the years you get some fairly complicated curves and the fairly complicated 1st described entirely accurately by the small that is we could show yes you can seize the Olva adhering to the spirit and when you do you were clever in our experiments you can actually determine the fate of the effective hydrodynamic thickness binding where and when emphasizing this idea dining effective guided them because you don't know the fakes sold all fortunately atmosphere of few change just enough tails sticking out of their distance so this year most Laura and can actually distinguish between these 2 the experiments with OK what I've done today is to introduce optical probe effusions of experimental technique we talked about the diffusion of large programs is always we've talked about the diffusion small roles polymer solutions the major points when they were world number 1 the falls off with increasing concentrations number 2 it often but not always this was not always does not depend strongly on the radius of probe on number 3 if you say we're measuring b we can infer micro discussed city the microbe Scott City in the case discussed here is always less than the macroscopic viscosity the probes are advancing faster than you would have thought from the viscosity of late while we can also look at such things as the flexibility of the probe flexible programs based on limited data and further weaken looking very small trials that's been done so we have not had the introduction of the probe that's it class dismissed


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