Density Functional Theory Study on Polybenzimidazole with Sulfonic Acid Functional Group for PEMFC Applications

Abstract

In this study, we performed density functional theory (DFT) calculations to elucidate the effect of sulfonic acid functional group on the hydrophilicity of polybenzimidazole (PBI). We investigated the adsorption of $H_2O$ molecules on sulfonated PBI (SPBI) and on disulfonated PBI (DSPBI) with cis- or trans-conformation. We analyzed electronic properties such as charge re-distribution and electronic band gap in terms of the optimized structure of PBI systems. We found that PBI with higher degree of sulfonation shows greater hydrophilicity and that trans-DSPBI shows greater hydrophilicity than cis-DSPBI.