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

A new kind of AB(2) 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 degrees C and 10% weight loss in the range of 338-674 degrees C in nitrogen and 329-509 degrees C in air. (c) 2006 Wiley Periodicals, Inc.