Polybenzimidazoles (PBIs) Derived from Non‐Coplanar Dibenzoic Acid Containing Imidazole (IDBA): Synthesis, Characterization and Properties

Abstract

A novel non‐coplanar imidazole dibenzoic acid (IDBA) was successfully prepared, and its structure was carefully characterized by FT‐IR, NMR, MS and elemental analysis. Polybenzimidazoles (PBIs) derived from IDBA were synthesized by a conventional one‐step method in polyphosphoric acid (PPA). The obtained PBIs exhibited good organic solubility, excellent thermo‐stability and interesting optical properties. The initiation decomposition temperature for these PBIs ranged from 560–600 °C, and the 5% weight loss temperature (T5) for all these PBIs was above 600 °C in N2. No obvious glass transition for these PBIs was observed below 350 °C. These PBIs shows UV‐vis absorption maximum around 360–380 nm and strong photoluminescence emission (blue light) around 430–440 nm in solution, which is red‐shifted to 490–510 nm in the solid state.

Amino‐Functional Polybenzimidazole Blends with Enhanced Phosphoric Acid Mediated Proton Conductivity as Fuel Cell Electrolytes

“…Improved membrane preparation processes have been developed during the last two decades and numerous new polybenzimidazole derivatives have been designed, synthesized and evaluated as potential base materials for the phosphoric acid doped membrane. These include e.g., polybenzimidazole sequence isomers, grafted polymers and structures containing ether, sulfone, phenylindane, naphtyl, triazole, imidazole, hexafluoroisopropylidene, perfluorocyclobutyl, or other aliphatic perfluorinated linkages in the main chain. The proton conductivity of such electrolyte systems increases with increasing phosphoric acid content, but the acid also exerts a strong plasticizing effect resulting in dramatic softening and deterioration of the mechanical strength.…”

Investigation of sequence isomer effects in AB-polybenzimidazole polymers

“…PBIs are known for their low solubility and are generally only soluble in aprotic or strong acid solvents . Several attempts to increase the solubility of PBI‐type polymers have been made by incorporation of soluble linkages, functionalities, and copolymerizations . In this work, the effects of randomization of the benzimidazole sequence on solubility were examined.…”