Synthesis and properties of novel copolymers of poly(ether ketone ketone) and poly(ether ether ketone ketone) containing amide and sulfone linkages

Abstract

N, N′-Bis(4-phenoxybenzoyl)-4,4′-diaminodiphenyl sulfone (BPBDAS) was prepared by the condensation of 4,4′-diaminodiphenyl sulfone with 4-phenoxybenzoyl chloride in N, N-dimethylacetamide. Novel copolymers of poly(ether ketone ketone) (PEKK) and poly(ether ether ketone ketone) containing amide and sulfone linkages (PEASAEKK) were synthesized by electrophilic Friedel–Crafts copolycondensation of terephthaloyl chloride with a mixture of diphenyl ether (DPE) and BPBDAS over a wide range of DPE/BPBDAS molar ratios, in the presence of anhydrous AlCl3 and N-methylpyrrolidone in 1,2-dichloroethane. The influences of the reaction conditions on the preparation of copolymers were examined. The copolymers obtained were characterized by different physicochemical techniques. The copolymers containing 10–25 mol% BPBDAS are semicrystalline and had remarkably increased Tgs compared to the commercially available poly(ether ether ketone) and PEKK due to the incorporation of amide and sulfone linkages in the main chains. The copolymer V with 25 mol% BPBDAS had not only high Tg of 187°C but also moderate Tm of 343°C, with good potential for melt processing. The copolymer V had a tensile strength of 102.7 MPa, Young’s modulus of 2.19 GPa, and elongation at break of 14.1%, and it also exhibited high thermal stability and good resistance to organic solvents.