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Theory of competitive solvation of polymers by two solvents and enthalpy-entropy compensation



Jack F. Douglas, Jacek Dudowicz, Karl Freed


A Flory-Huggins (FH) type theory is derived to describe the competitive equilibrium sol- vation of long chain polymers B by a pair of relatively low molar mass, mutually miscible, mutually unassociated solvents A and C. The derivation applies basic concepts of the FH mean field approximation to the equilibrium mixture of solvated polymer clusters and free molecules A, B, and C. This new theoretical development is used then to generate expressions for the boundaries for phase stability (spinodals) and for the system's internal energy U, entropy S, specific heat CV , extent of solvation, average degree of solvation , and second osmotic virial coeffcient B2 as functions of temperature and the com- position of the mixture. The large potential predictive ability of the theory is illustrated by discussing examples of the enthalpy-entropy compensation phenomenon that is predicted to occur upon the dilution of a binary A=B polymer solvent mixture by the addition of a diluent solvent C. This composition phenomenon has many applications in liquid chromotography.
Journal of Chemical Physics


mixed solvents, chromatography, entropy-enthalpy compensation, extra-thermodynamic relationship


Douglas, J. , Dudowicz, J. and Freed, K. (2015), Theory of competitive solvation of polymers by two solvents and enthalpy-entropy compensation, Journal of Chemical Physics (Accessed June 14, 2024)


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Created June 7, 2015, Updated January 27, 2020