SynopsisThe entropic gradient contributions to the free energy of nonuniform polymer-solvent systems and polymer-polymer-solvent systems have been obtained using a mean field approach. The results for a polymer-polymer-solvent system reduce to those of de Gennes for a polymer-polymer system a t the appropriate limit. The binary results for a polymer-solvent system predict interfacial tensions that are systematically high but closer to experiment than those predicted by the earlier model of Balsara and Nauman. The ternary results have been applied to spinodal decomposition in polymerpolymer-solvent systems. The linear theory predicts a decrease in the domain size with increasing quench depth. Also, it predicts an increasing domain size with an increase in compatibility between the two polymers for any given quench depth.Hence the free energy of a nonuniform system consisting of M components may be written in a more general form as',

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SynopsisThe free energy of an inhomogeneous polymer-polymer-solvent system has been obtained by extending Debye's approach for a polymer-solvent system. Our ternary result reduces to Debye's result for a binary polymer-solvent system and to McMaster's result for a binary polymer-polymer system at the appropriate limits. Like Debye's work, we neglect the entropic gradient contribution to free energy. Based on the ternary result we suggest a generalized expression for the free energy of multiple polymers dissolved in a common solvent. This expression is used to find the free energy of an inhomogeneous polydispersed polymer-solvent system. (2)Ks(polymer-polymer) = -__ 6 NlGl NzG2

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