SYNTHESIS AND CHARACTERIZATION OF POLYBENZIMIDAZOLES CARRYING ADDITIONAL PYRIDINE AND IMIDAZOLE GROUPS IN THE MAIN CHAIN

Six polybenzimidazoles have been prepared by a dispersion polycondensation process using polyphosphoric acid as a dehydrating reagent. Two of these contained an additional pyridine residue in the mainchain, and three of them additional imidazole groups. The molecular structures have been characterized by u.v., i.r. and H-1 n.m.r. spectra. Physical characterization has involved solubility measurements, solution viscosity evaluation and thermal stability assessment via thermogravimetric analysis. The latter has confirmed that the inherently high thermo-oxidative stability of polybenzimidazoles is retained in the case of polymers and copolymers with additional nitrogen heterocycles in the mainchain.