Incorporation of<i>N</i>-phenyl in poly(benzimidazole imide)s and improvement in H₂O-absorbtion and transparency

Abstract

5-Amine-2-(4-amino-benzene)-1-phenyl-benzimidazole (<i>N</i>-PhPABZ) was successfully synthesized and polymerized with 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA) to obtain a novel <i>N</i>-phenyl-poly(benzimidazole imide) (<i>N</i>-Ph-PBII). The successful incorporation of <i>N</i>-phenyl addressed the issue of high H₂O-absorption of traditional PBIIs while retained the superheat resistance property. The resulting <i>N</i>-Ph-PBII possessed a high glass-transition temperature (<i>T</i> _g) up to 425 °C and a low affinity for water of 1.4%. Furthermore, the loose molecular packing and noncoplanar structures led to an increase in optical transparency for the modified PBII.