A simple model for baroplastic behavior in block copolymer melts

A simple model for the free energy of mixing of compressible polymer blends is derived, based on the regular solution model. Its ability to predict ph ase behavior for weakly interacting polymer pairs using only the pure compo nent properties of mass density, solubility parameter, and thermal expansio n coefficient is illustrated for mixtures of polystyrene and poly(n-alkyl m ethacrylates) with n less than or equal to 12. The model yields a clear exp lanation for the strong pressure effects observed in some of these systems, including the first reported baroplastic elastomer. (C) 2001 American Inst itute of Physics.