Keywords: Polybenzimidazole; ferrocene carboxylic acid; ferrocene; amide; proton conductivity

Abstract

Polymer electrolyte membranes with high proton conductivity continue to pose a challenge especially in the fields of biomaterial, semiconductor, membrane separation, and ion conductive membrane. Here, an alternative of a new class of highly conductive ferrocene-modified polybenzimidazole (PBI/Fc) membranes was prepared by the solvent casting method after the amidation reaction of ferrocene carboxylic acid (FCA) with imidazole groups in PBI solution. The properties of the as-prepared membranes were characterized by varied spectroscopic measurements. For instance, in the attenuated total reflectance-Fourier transform infrared (ATR-FTIR) measurements the characteristic vibrational bands of ferrocenyl moieties, and amide bond formation were identified. Interestingly, in the electrochemical studies, membrane PBI/Fc-5 was found to exhibit low absolute impedance and high proton conductivity of 537 × 10³ Ω and 0.0249 × 10^-8 S/cm, respectively.