Flory Paul polymer solutions

When the temperature of a polymer solution diminishes, the attractive long-range forces become more efficient than the hard-core repulsive forces. At a temperature Tf recognized by Paul Flory in 1942, attractions and repulsions compensate. In this case, for a temperature slightly smaller than TF, the solution separates into two phases and this phenomenon is called demixtion. 

Theta state n. A term introduced by Dr. Paul Flory to describe the condition in a polymer solution in which there is little interaction between the molecules of the solvent and those of the polymer, and in which the polymer molecules exist as statistically distributed coils. Kamide K, Dobashi T (2000) Physical chemistry of polymer solutions. Elsevier, New York. Flory PJ (1969) Statistical mechanics of chain molecules. Interscience Publishers Inc., New York. Flory PJ (1953) Principles of polymer science. The Cornell University Press, Ithaca, NY. 

Paul Flory and Maurice Huggins presented, independently, the thermodynamics theory for polymer solutions. 

Keywords Paul Flory Herman Mark Carl Marvel Gaussian chain Excluded volume Rubber Polymer solutions Molecular weight distributions Intrinsic viscosity Herman Staudinger... 

In the first section, up to Uhlmann s paper, we arc concerned with polymer melts in equilibrium. In dilute solution, the dominant restriction on randomness, apart from the very fact that the polymer molecule is a chain, is self-exclusion, and Paul Flory taught us how to cope with that many years ago. In the interior (and I emphasize interior) of the pure amorphous phase, mutual exclusion has a large effect on the total entropy, but its effect on molecular conformations is the relatively minor one of virtually cancelling the effects of self-exclusion. That knowledge we also owe to Flory. Hence a limited number of parameters suffice both to describe and explain the conformations in this case. Uhlmann s paper dismisses for us the aberrant nodular structures which have been proposed there only remains to ask how in certain circumstances the appearance of nodular structure can be produced. 

Flory Statistics of the Molecular Weight Distribution. The solution to the complete set (j - I to j = 100,000) of coupled-nonlinear ordinary differential equations needed to calculate the distribution is an enormous undertaking even with the fastest computers. However, we can use probability theory to estimate the distribution. This theory was developed by Nobel laureate Paul Floty. We have shown that for step ipolymeiization and for free radical polymerization in which termination is by disproportionation the mole fraction of polymer -with chain length j is... 

The importance of viscosimetry as an independent area in the field of polymer analytics becomes clear through the Nobel prices awarded for two works in this area. The name of the 1953 honored Prof. Hermann Staudinger for his proof of the existence of polymers is still used in viscosimetry in the intrinsic viscosity (German "Staudingerindex ) (see "Intrinsic viscosimetry in Chap. 4). In 1974, Prof. Paul J. Flory was honored with the Nobel price for his groundbreaking works on the conformation of polymers in solution and his name is conserved for posterity in the Flory constant (see "The Fox-Flory theory in Chap. 8). 

While at Standard Oil, Dr. Flory developed a quantitative statistical mechanical theory of macromolecular solutions (8). It was my pleasure to attend the Gibson Island (MD) conferences in the early 1940 s and to hear Paul discuss his theory with Maurice Huggins who had arrived at comparable theory, independently. Some may be amazed to learn that polymer chemists, such as Flory and Huggins, would discuss these ndamental breakthroughs at these conferences. However, the other attendees were not permitted to publicize such discussions. Hence, there were many other meritorious discussions at these conferences by polymer chemists of comparable statue. 

Paul J. Flory addressed the problem of predicting the shape of a polymer molecule and so provided an understanding of the way in which chemical structure influences conformational changes in polymers. His approach was essentially an extension of that presented above for pentane and the substituted hexanes. He considered that the range of the important interactions was very short. This approximation is surprisingly accurate and has allowed theoretical prediction of the equilibrium structures of many polymers, at least when the molecules are present as separate entities in dilute solution. 

Figure 9.5 Influence of composition on the polymer-solvent interaction parameter. Experimental values of the interaction parameter Xi are plotted against the volume ftaction (j)2 of polymer. Data for polydimethylsiloxane (M = 3850) in benzene (A), polystyrene in methyl ethyl ketone ( ), and polystyrene in toluene (O) are based on vapor-pressure measurements. Those for rubber in benzene (T) were obtained using vapor-pressure measurements at higher concentrations and isothermal distillation equilifaratian with solutions of known activities in the dilute range. (Reprinted fiom Paul J. Flory, Principles of Polymer Chemistry. Copyright 1953 Cornell University and copyright 1981 Paul J. Flory. Used by permission of the Puhhsher, Cornell University Press.)...

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