Properties of SPAES/phosphotungsticacid/sulfonated silica composite membranes prepared by the In situ and sol-gel process

Abstract

An in situ sol-gel method was used to synthesize organic-inorganic composite membranes based on poly(arylene ether sulfone) (SPAES), phosphotungstic acid (PWA), and sulfonated silica (silica-SO3H). The PWA particles were functionalized with an organic silane compound to enhance proton conductivity. This study compares the performance of polymer electrolyte membrane fuel cells with different preparation methods for the membrane and composite of PWA-silica-SO3H particles. The optimum composition of PWA-silica-SO3H is determined on the basis of the mechanical properties, the behavior of water in the membrane, and the level of proton conductivity. The mechanical properties of the sol-gel composite membranes were improved with the introduction of PWA-silica-SO3H particles. The sol-gel composite membrane has higher levels of proton conductivity than the in situ composite membrane and pure SPAES membrane. An increase in the silica content of the PWA-silica sol-gel particles increases the proton conductivity because the inorganic component and the incorporation of PWA lead to a high concentration of hydroxyl groups. These properties make composite membranes potential candidates for direct methanol fuel cell applications.