Synthesis and thermomechanical properties of alternating copolymers containing bisphenol-A

Alternating copolymers containing 4,4-isopropylidene-bisphenol (BPA) and comonomers with various degrees of polarity have been evaluated to find comonomer structures which provide low melt viscosity and good thermal stability. The materials were prepared by pyridine-catalyzed nucleophilic displacement reactions similar to that for the preparation of BPA polycarbonate. The molecular weights of the polycarbonates depend on the concentration and nucleophilicity of the attacking diol and the concentration and stability of a colored pyridine-chloroformate adduct formed during polymerization. The greatest thermal stability occurs for BPA–DMS and BPA–DEG. Thermomechanical flow measurements and T_g measurements were used to evaluate melt viscosity. The shapes and magnitudes of the T_g vs. T^f curves are sensitive to the copolymer chemical structure.