Effect of molecular structure of polyarylates on the compatibility in polyarylate/poly(vinyl chloride) blends

A homologous series of polyarylates were prepared by condensation polymerization of three different bisphenols, isophthaloyl, and terephthaloyl chlorides (their molar ratio = 2:1:1). The resulting polyarylates were tetramethyl bisphenol S– (TMBPS–), bisphenol S– (BPS–), and tetramethyl bisphenol A– (TMBPA–) polyarylates, and each have structural variants; (1) methyl or no substitution on the biphenyl rings of bisphenol, and/or (2) central group connecting the biphenyl rings with or without polarity. Only the polyarylate having both methyl substitution and polar connector, i.e., TMBPS–polyarylate, was found to be compatible with PVC. The sulfone groups of TMBPS–polyarylate and chlorides of PVC exerted a dipole–dipole interaction only when the tetramethyl substitution on the bisphenol rings was present. In the absence of tetramethyl groups (BPS–polyarylate), incompatibility with PVC was observed. The strength of polar interactions appeared to be influenced by the methyl substitution causing electronic rearrangement in bisphenol rings. However, due to the lack of polar connector groups, the inclusion of methyl substitution in TMBPA–polyarylate was found to have no effect on the specific interactions, and hence, the compatibility with PVC. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2173–2180, 1998