Synthesis of poly(benzoxazinone)s by direct polycondensation of dicarboxylic acids with bis(anthranilic acid)s

Abstract

AbstractA convenient method for the synthesis of poly(benzoxazinone)s of high molecular weights has been developed. These polymers were prepared readily by direct polycondensation of aromatic dicarboxylic acids containing phenyl ether structures with bis(anthranilic acid)s using phosphorus pentoxide/methanesulfonic acid (PPMA) as a condensing agent and solvent. Polycondensations proceeded smoothly and were completed within several hours at 140°C to produce poly(benzoxazinone)s with inherent viscosities up to 2.6 dL/g. The synthesis of 2‐substituted benzoxazinones by the reaction of aromatic carboxylic acids or dicarboxylic acid with anthranilic acid in PPMA was studied in detail to demonstrate the feasibility of the reaction for polymer formation. The thermogravimetry of the aromatic poly(benzoxazinone)s showed 10% weight loss in air and nitrogen around at 440 and 460°C, respectively.