Investigating the Role of Aniline Structure in Improving Proton Exchange Membranes for High Conductivity

Polybenzothiazole exhibits high proton conductivity; however, its rigid backbone limits its applicability, necessitating processes such as modification or doping. The aniline structure can participate in various reactions, including nucleophilic or electrophilic substitution reactions, salt formation, and acylation reactions. In this experiment, an aniline structure is integrated into the main chain of sulfonated polybenzothiazole to investigate the potential of aniline for enhancing proton exchange membranes. The incorporation of the aniline structure is confirmed through infrared and nuclear magnetic resonance analyses. A comparison of different proportions of aniline revealed that 12.5% aniline increased the tensile modulus to 274.40 MPa and the elongation at break to 6.26%. Furthermore, the water absorption rate reached 65.73%, while the expansion rate remained at 25%. The aniline structure exhibits inherent basicity and utilizes phosphoric acid adsorption to enhance proton conductivity. After aniline adsorbs phosphoric acid, the proton conductivity peaks at 0.157 S cm^-1. Additionally, the introduction of amino groups provides further modification potential to the main chain of polybenzothiazole.