Synthesis of aromatic polybenzimidazoles by the reductive polyheterocyclization of poly-(o-nitro)amides

Polymers with Heterocyclic Rings in the Chain

“…In spite of the original evidence to the contrary, some variation in stability due to different substitution patterns in aromatic linking groups has been observed. It has been claimed, for example, that the paraphenylene-linked system is more stable under oxidizing conditions than the corresponding ortho-or metaanalogs, 284 mally or thermo-oxidatively stable than the all-ring systems. Their decomposition temperatures in inert atmospheres or air range between 450 and 550°C.…”