Modeling of the phase behavior of binary and ternary blends involving copolymers of styrene, methyl methacrylate and cyclohexyl methacrylate

Modeling of the lower critical solution temperature, LCST, phase boundary of binary blends of poly(styrene) (PS) and random poly(cyclohexyl methacrylate-co-methyl methacrylate) copolymers was carried out incorporating temperature-dependent segmental interaction parameters, χ ij (T), into the classical mean field binary interaction model. By using literature data of the temperature dependence of the PS/poly(methyl methacrylate) (PMMA) interaction parameter, the temperature variation of the interaction energy of both PS/poly(cyclohexyl methacrylate) (PCHMA) and PMMA/PCHMA blends was obtained. The magnitude of the interaction energy between PS and PCHMA from the model was in good agreement with those estimated from experimental heat of demixing data of PS/PCHMA blends and from heats of mixing of low molecular weight model compounds. The segmental interaction parameters obtained were further employed to predict the phase behavior of binary and ternary blends involving copolymers of S, MMA and CHMA. The agreement between prediction and experiment was satisfactory.