Pre-Oxidized Acrylic Fiber Reinforced Ferric Sulfophenyl Phosphate-Doped Polybenzimidazole-Based High-Temperature Proton Exchange Membrane

Pre-oxidized acrylic fiber (POAF) and ferric sulfophenyl phosphate (FeSPP) are incorporated into polybenzimidazole (PBI) membrane for the first time to prepare high-temperature proton exchange membranes (PEMs). The strong hydrogen bonds formed between PBI/POAF and FeSPP lead to good dispersion of POAF and FeSPP, facilitate the construction of proton channels, and enhance the dimensional and mechanical stability of the membranes. PBI/FeSPP (30 wt%) shows good proton conductivity (5.43 x 10(-2) and 4.13 x 10(-2) S cm(-1) at 180 degrees C at 50% and 0 relative humidity (RH), respectively) and improved dimensional and mechanical stability compared with pristine PBI. By incorporating 5 wt% POAF into PBI/FeSPP (30 wt%), the swelling ratios are halved and the mechanical strength is enhanced by almost 30% while the proton conductivity is slightly affected (3.84 x 10(-2) and 2.97 x 10(-2) S cm(-1) at 180 degrees C at 50% and 0 RH for PBI/FeSPP (30 wt%)/POAF (5 wt%), respectively). This work offers a new route in the preparation of high-temperature PEMs with enhanced properties.