Substituted aliphatic polybenzimidazoles as membrane separator materials

When initially evaluated as potential membrance separators for a heat-sterilizable silver-zinc battery, aliphatic polybenzimidazoles (PBI) proved to be unsatisfactory because of their excessively high resistivity. Later, various polymer modifications such as sulfonation, N-hydroxyethylation, N-cyanoethylation, and N-carboxyethylation were made in an attempt to increase the hydrophilicity of the PBI's. As a result of these efforts, an N-carboxyethylated, suberic acid-based PBI shows promise as a sterilizable battery separator material.