Advanced monomer combinations for radiation grafted fuel cell membranes

Proton exchange membranes based on poly(styrene sulfonic acid) obtained through radiation grafting show intrinsic susceptibility towards oxidative degradation in the fuel cell environment. An alternative monomer offering potentially higher chemical stability is α-methylstyrene (AMS). However, the radical polymerization kinetics of pure AMS are poor. Radiation grafting of AMS to obtain membranes with practical ion exchange capacity was achieved using methacrylonitrile (MAN) as co-monomer, which shows high probability to form an alternating copolymer chain with AMS. The obtained membranes display a conductivity of around 100 mS/cm. Durability in the fuel cell is significantly higher compared to styrene based membranes. The advanced radiation grafted membranes prepared and characterized in this study show a high potential and offer the prospect of a cost-effective, functional, and durable membrane for the polymer electrolyte fuel cell.