Synthesis and characterization of novel hyperbranched polybenzimidazoles based on an AB₂ monomer containing four amino groups and one carboxylic group

Abstract

A new kind of AB2 monomer, 4‐[2,6‐bis(3,4‐diaminophenyl)pyridin‐4‐yl]benzoic acid, was synthesized, and several hyperbranched polybenzimidazoles (HPBIs) were prepared through self‐polymerization followed by modification reactions with end‐capping reagents such as 4‐methyl benzoic acid and 3‐[3,5‐bis(trifluoromethyl)phenoxy] benzoic acid. The HPBIs had good solubility in strongly aprotic solvents, such as N‐methyl‐2‐pyrrolidone, N,N′‐dimethylformamide, N,N′‐dimethylacetamide, and dimethyl sulfoxide. They also exhibited excellent thermal properties, with glass‐transition temperatures of 318–381 °C and 10% weight loss in the range of 338–674 °C in nitrogen and 329–509 °C in air. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5729–5739, 2006

Synthesis of novel polybenzimidazoles with pendant amino groups and the formation of their crosslinked membranes for medium temperature fuel cell applications

“…The same group has also reported that the commercial PBI could be crosslinked with another kind of crosslinker, dichloromethylphosphonic acid, and the relevant crosslinked membranes displayed significantly higher tensile strength than the linear PBI at similar doping levels 19. We have previously reported that crosslinked hyperbranched PBI membranes could maintain reasonably high‐mechanical strength at high PA‐doping levels, which is superior to the commercial PBI membranes 20, 21, 35…”

How the monomer concentration of polymerization influences various properties of polybenzimidazole: A case study with poly(4,4′‐diphenylether‐5,5′‐bibenzimidazole)

“…PBI is used for various purposes, especially high‐temperature applications, fiber spinning, reverse osmosis membranes, and fluorescence sensors for halide ions 16, 31. A variety of PBI polymers have been synthesized and reported in the literature, such as poly[2,2′‐( m ‐phenylene)‐5,5′‐benzimidazole] (m‐PBI), poly(2,5‐benzimidazole),32 pyridine‐based PBI,11 sulfonated PBI,22 hyperbranched PBI,33 fluorinated PBI,18 and naphthalene‐based PBI 34…”

Synthesis of soluble and thermally stable poly[arylene ether amide (N‐arylenebenzimidazole)]s

“…However, the poor solubility of PBIs, a result of their highly rigid backbones, is a major barrier to their practical use. Many efforts have been made to improve the solubility and processability of these materials by modifying their polymer structures while preserving their desirable properties . The introduction of amide groups along the polymer backbone has been found to improve solubility by disrupting the rigid structure of the polymer without sacrificing its thermal or mechanical properties to any great extent , .…”