MISCIBLE BLENDS FORMED FROM INTRAPOLYMER REPULSIVE INTERACTIONS - 2 -PHASE-BEHAVIOR OF BLENDS OF BISPHENOL A POLYCARBONATE AND ZINC-SULFONATED POLYSTYRENE IONOMERS

The phase behavior of mixtures of bisphenol A polycarbonate and the zi nc salts of lightly sulfonated polystyrene ionomers (Zn-SPS) was studi ed as a function of the sulfonation level and the molecular weight of the ionomer. This system exhibits upper critical solution temperature (UCST) phase behavior and miscibility is attributed to intramolecular repulsion between the ionic and non-ionic groups of the ionomer. The c loud point temperature decreased with increasing sulfonation level of the ionomer over the range of 8.7-13.7 mol.%, and it increased with in creasing molecular weight of Zn-SPS for a fixed sulfonation level. Fou rier transform infrared spectroscopy revealed that no specific interac tions involving either the carbonate carbonyl group or the metal sulfo nate group occurred in the blends. The composition dependence of the g lass transition of the miscible Zn-SPS/PC blends also gave no indicati on that specific interactions occurred in this system. (C) 1998 Elsevi er Science Ltd. All rights reserved.