Synthesis and characterization of novel poly(aryl ether ketone)s containing biphenylene moieties and pendant cyano groups

Two monomers, 4,4′-bis(4-phenoxybenzoyl)diphenyl (BPOBDP) and 2,6-diphenoxybenzonitrile (DPOBN), were conveniently prepared via simple synthetic procedures from commercially readily available materials. A series of novel poly(aryl ether ketone)s containing biphenylene moieties and pendant cyano groups were synthesized by the Friedel-Crafts acylation copolycondensation of isophthaloyl chloride (IPC) with a mixture of BPOBDP and DPOBN, over a wide range of BPOBDP/DPOBN molar ratios, in the presence of anhydrous AlCl₃ and N-methylpyrrolidone (NMP) in 1,2-dichloroethane (DCE). The copolymers with 10–50 mol% DPOBN are semicrystalline and had higher T _gs than those of the conventional PEEK and PEKK due to the incorporation of biphenylene moieties and pendant cyano groups. The copolymer VI with 50 mol% DPOBN had not only high T _g of 168 °C, but also moderate T _m of 333 °C, having good potential for melt processing. The copolymer VI had tensile strength of 103.4 MPa, Young’s modulus of 2.62 GPa, and elongation at break of 20.7 % and exhibited high thermal stability and excellent resistance to organic solvents.