Synthesis and Properties of Hexafluoroisopropylidenecontaining Polyarylates and Copolyarylates

Abstract

A homologous series of four aromatic polyesters and two series of copolyarylates were synthesized under phase-transfer conditions from monomers containing the isopropylidene (IP) and/or the hexafluoroisopropylidene (HFIP) moiety. The homopolymers were obtained in good yields, were soluble in common organic solvents, and would readily form clear, colorless films from solution. Thermal stabilities in air (dynamic-10% weight losses at 440°C-490°C; isothermal-100 h at 350°C, 7%-86% weight loss) revealed that resistance to thermo-oxidation was highest when the HFIP group replaced the IP moiety in the bisphenol rather than in the diacid. Other properties of the homopolymers which were measured were water absorption of 0.07%-0.35% (by weight), and the dielectric constant of 2.32 for the fully fluorinated polymer. Copolymers were prepared from mixtures of bisphenols A and AF, and each of the two diacids. The thermal stability and water absorption of both series were measured as functions of BPAF content. No significant change in properties was observed for copolymers with less than 70 mol.% BPAF comonomer.