POLYBENZIMIDAZOLE, PRECURSOR POLYAMIDE THEREOF, AND METHOD FOR PRODUCING SAME

A method for producing a polybenzimidazole precursor polyamide including a repeating unit represented by the following formula (2): wherein Ris —SO—, —O—, —CO—, an alkylene group optionally containing a substituent, or a group represented by the following formula: two Xs are each individually a monovalent organic group; and Ris a divalent organic group, the method including: a step (1-1) of polymerizing a tetramine compound (3) and a dicarboxylic acid derivative compound (4) as defined herein to provide the polybenzimidazole precursor polyamide.