Synthesis of novel poly(N-arylenebenzimidazole)s containing biphenyl groups via N-C coupling reaction

A new bis(benzimidazolyl) monomer containing biphenyl group, 4,4′-bis(2-benzimidazolyl) diphenyl, was successfully synthesized from 4,4′-biphenyldicarboxylic acid and 1,2-phenylenddiamine. The corresponding biphenyl-containing poly(N-arylenebenzimidazole)s were prepared using C-N coupling reaction that removed the N-H sites from the novel bis(benzimidazolyl) derivative with activated aromatic difluorides in sulfolane. The reaction was carried out at 210°C in the presence of anhydrous potassium carbonate. All resulting polymers showed essentially amorphous patterns. This was consistent with the calculated results. Differential scanning calorimetry and thermogravimetric measurements showed that the polymers had high glass transition temperatures (>253°C) and good thermal stability with high decomposition temperatures (>457°C). These novel polymers also showed easy solubility.