Synthesis and investigation of polybenzimidazoles containing alkyl substituents in aromatic nuclei

Abstract

Abstract Polybenzimidazoles have been synthesized from 3,3′‐diamino‐5,5′‐dimethylbenzidine, 3,3′,4,4′‐tetraamino‐5,5′‐dimethyldiphenylmethane, bis(3‐amino‐4‐methylamino)phenylmethane, bis(3‐amino‐4‐methylamino‐5‐methyl)phenylmethane, and diphenyl esters of adipic, sebacic, isophthalic, and terephthalic acids and 4,4′‐dicarboxydiphenyl oxide by solid‐phase polyheterocyclization. Properties of the polybenzimidazoles have been studied. The polymers have high thermal stability. They are soluble in a number of organic solvents and give strong, elastic films. Solubility and thermal stability of polybenzimidazoles is determined by the methyl group position in the polymeric chain. The influence of other alkyl substituents on properties of polybenzimidazoles have been investigated. The polymer structure has been studied by infrared and PMR spectroscopy and elemental analysis.