MODELING OSMOTIC-PRESSURE 2ND VIRIAL AND PREFERENTIAL ADSORPTION COEFFICIENT DATA OF TERNARY SOLVENT POLYMER SOLVENT SYSTEMS USING EQUATION-OF-STATE SOLUTION THEORIES
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Three equation-of-state (EOS) solution theories have been applied to binary and ternary solvent-polymer-solvent data at infinite dilution of the polymer. The data, from light scattering, osmotic pressure, and sedimentation equilibrium experiments, were taken from literature and were in the form of the osmotic pressure second virial coefficient of the solvent and the preferential adsorption coefficient of the polymer. The systems studied were the binary benzene-polystyrene and cyclohexane-polystyrene systems and the resulting ternary system, benzene-polystyrene-cyclohexane. A significant result is that the solution theory interaction parameter values obtained for the binary solvent-polymer system in the infinitely dilute polymer regime using these data are consistent with parameters at the other extreme (polymer-rich) and obtained by different experiments. For the ternary system, the three EOS solution theories were able to model the osmotic pressure second virial coefficient, and, using the same model parameters, they had reasonable success at modeling the preferential adsorption coefficient. For the Flory EOS model, the solvent-solvent binary parameter estimated with the ternary data matched that obtained from binary solvent-solvent VLE data and the solvent/polymer segment-surface ratios estimated with the ternary data matched the average of the geometric and group contribution values. 1987, American Chemical Society. All rights reserved.