Abstract
Recent advance of study of phase equilibria of polymer solutions is reviewed. Thermodynamical conditions of phase equilibria at constant temperature and pressure, originally given by Gibbs, are very rigorously applied to the solutions of polymer, consisting of super-multicomponents having the same chemical structure and the different molecular weight. The theories, in which the concentration and the molecular weight-dependences of the polymer-solvent interaction parameter χ were reasonably taking into account, were established. The systematic computer experiments were carried out to investigate the effects of the starting polymer molecular characteristics and the phase separation conditions on the characteristics of the phase equilibria, the critical solution points, cloud point curves, the binodal and spinodal curves of the multicomponent polymer-single solvent system (quasi-binary solution) and of the multicomponent polymer-binary solvents mixture system (quasi-ternary solution). The reliability of the experiments was confirmed by comparing with actual experiments. It was shown that the entropy parameter φ can be evaluated, by considering the concentration dependence of χ parameter, from the critical point data and φ values thus obtained were in good agreement with those from the temperature dependence of the second virial coefficient A2 in vicinity of the Flory temperature. Occurrence of co-solvency was theoretically predicted by the theory of quasi-ternary solutions.
