Reduction of the monomer quantities required for the preparation of radiation-grafted alkaline anion-exchange membranes

Abstract

Alkaline anion-exchange membranes (AAEM) for alkaline polymer electrolyte fuel cells (APEFC) were successfully prepared using electron beam irradiated poly(ethylene-co-tetrafluoroethylene) precursor films grafted with vinylbenzyl chloride (VBC) monomer. The resulting chloromethyl groups were subsequently reacted with trimethylamine to form quaternary ammonium anion-exchange functional head-groups. The concentration of toxic and expensive VBC, that is required to achieve an optimal level of grafting, was reduced from 100%v/v (undiluted) to 20%v/v by dilution with propan-2-ol and the inclusion of a surfactant. Fuel cell tests using hydrogen and oxygen gave the same peak power densities (164±3mWcm−2) for the AAEMs prepared with both 100%v/v VBC and 20%v/v VBC. This highlights the (desirable) lack of any detrimental effect on performance of the resulting APEFC with the reduction in grafting monomer concentration used for the synthesis of the component AAEM.