Synthesis and properties of novel copolymers of poly(ether ketone ketone) and poly(ether sulfone ether ketone ketone) containing 1,4-naphthylene moieties

A new monomer containing naphthalene and sulfone groups, 4,4′-bis(1-naphthoxy)diphenylsulfone (BNODPS), was easily prepared by the condensation reaction of 4,4′-dichlorodiphenylsulfone with 1-naphthol in the presence of base in dimethyl sulfoxide. Novel copolymers of poly(ether ketone ketone) and poly(ether sulfone ether ketone ketone) containing 1,4-naphthylene moieties were synthesized by the electrophilic Friedel–Crafts acylation copolycondensation of terephthaloyl chloride with a mixture of diphenyl ether (DPE) and BNODPS, over a wide range of DPE/BNODPS molar ratios, in the presence of anhydrous AlCl₃ and N-methylpyrrolidone (NMP) in 1,2-dichloroethane. The polymers obtained were characterized by different physicochemical techniques. The copolymers with 5–25 mol% BNODPS are semicrystalline and had remarkably increased T_gs and decreased T_ms over the wholly para-linked poly(ether ketone ketone) due to the incorporation of bulky and rigid 1,4-naphthylene moieties and flexible sulfone linkages in the main chains. The copolymer VI with 25 mol% BNODPS had not only high T_g of 185°C but also moderate T_m of 335°C, having good potential for melt processing. The copolymer VI had tensile strength of 102.2 MPa, Young’s modulus of 2.78 GPa, and elongation at break of 15.9% and exhibited high thermal stability and good resistance to organic solvents.