Synthesis and properties of poly(arylene ether benzimidazole)s

Abstract

Poly(arylene ether benzimidazole)s were prepared by the aromatic nucleophilic displacement reaction of three new bis[(4-hydroxyphenyl)benzimidazole] compounds with activated aromatic difluoro compounds in N, N-dimethylacetamide at 155°C in the presence of anhydrous potassium carbonate. The polymers exhibited glass transition temperatures ranging from 264 to 352°C and inherent viscosities from 0.79 to 1.99 dl g −1. Unoriented thin films exhibited tensile strengths, moduli and elongations at break at 23°C of 121–157 MPa, 3.7–4.5 GPa and 6–18%, respectively. In most cases the films exhibited 50–60% retention of 23°C tensile properties when tested at 232°C. Based on preliminary evaluation, one polymer was prepared at several different controlled molecular weights and end-capped with a monofunctional benzimidazole compound. The polymer with a calculated number-average molecular weight of ∼9700 g mol −1 exhibited improved processability without significantly reducing thin-film properties. Composite specimens fabricated at 360°C under 1.4 MPa for 1 h exhibited good flexural and compressive propeties at 23°C and excellent retention of flexural strength and modulus at 232°C.