Synthesis of imide-aryl ether benzoxazole block copolymers

Abstract

Imide-aryl ether benzoxazole multiblock copolymers were investigated. A key feature of these copolymers was the preparation of bis(amino) terminated aryl ether benzoxazole oligomers (PBO) via a novel nucleophilic aromatic displacement polymerization. Oligomers with number average molecular weights of 10,500 and 26,000 g/mol were prepared, which displayed Tg's of 210 and 227°C, respectively. The oligomers were co-reacted with 4,4′-oxydianaline (ODA) and pyromellitic dianhydride (PMDA) diethyl ester diacyl chloride in a NMP/ cyclohexanone solvent mixture in the presence of N-methylmorpholine. The resulting amic ester-aryl ether benzoxazole copolymers were isolated and washed to remove homopolymer contamination. Copolymer compositions were analyzed by 13C NMR. Solutions of the copolymers were cast and cured to effect the imidization, affording tough films with high elongations. Multiphase morphologies were obtained for both of the PBO block lengths used in the copolymerization. © 1989 Springer-Verlag.