Synthesis of poly(benzothiazole) by direct polycondensation of dicarboxylic acids with 2, 5-diamino-1, 4-benzenedithiol dihydrochloride using phosphorus pentoxide/methanesulfonic acid as condensing agent and solvent

Abstract

A convenient method for the synthesis of poly(benzothiazole) of high molecular weights has been developed. These polymers were prepared readily by direct polycondensation of aliphatic, alicyclic, and aromatic dicarboxylic acids containing phenyl ether structures with 2, 5-diamino-1, 4-benzenedithiol dihydrochloride using phosphorus pentoxide/methanesulfonic acid (PPMA) as both a condensing agent and solvent. Polycondensations proceeded smoothly and were completed within several hours at 140°C to produce poly(benzothiazole)s with inherent viscosities up to 2.9 dl g−1. The thermogravimetry of the aromatic poly(benzothiazole)s showed 10% weight loss in air and nitrogen at 405—490°C and 450—595°C, respectively. © 1986 The Society of Polymer Science, Japan.