New Proton Exchange Membrane Blends based on Polybenzimidazole and Poly(1,4- Phenylene Ether Ether Sulfone) for Fuel Cells Application

To develop proton exchange membrane blends based on polybenzimidazole (PBI), a novel polymer blend membrane consisting of PBI and sulfonated poly 1,4-phenylene ether ether sulphone (SPEES) was prepared by solution casting method. The goal of the work was to study the performance of the acid-base composition on its properties, such as mechanical stability, thermal stability, and proton conductivity of PBI-SPEES blend membranes. The N−H···O interactions between the PBI and SPEES in the blend membranes indicated that the two polymers form a miscible blend. The acid uptake (12 moles) and proton conductivity (101 mS/cm in 160 °C) of the blend membranes were significantly ameliorated as compared to pure phosphoric acid-doped PBI (APBI) membranes. A single glass transition value of PBI-SPEES blend membranes which were between the glass transition value of the PBI and SPEES membranes confirmed the miscible properties of PBI-SPEES blend membranes. The presence of SPEES in the blend membranes decreases the friability and hardness and increases the flexibility and proton conductivity of APBI membranes. According to the PEM fuel cell results, with a high-power density of 0.65 W/cm2 at 180 ºC, the PBI-SPEES blend membranes have a high potential for use as an appropriate membrane in the fuel cells.