Innovative reactor design for the preparation of polymer electrolyte membranes for vanadium flow batteries from preirradiation induced graft copolymerization of acrylic acid and AMPS on PVDF

An innovative reactor concept is reported that allows for efficient mass transfer from the liquid phase to the base material and compensates for the growth of the material throughout the synthesis of polymer electrolyte membranes (PEM). The novel reactor allows for the synthesis of PEMs with high reproducibility of their dimensions and properties. PEMs are synthesized via graft copolymerization of the monomers acrylic acid and 2-acrylamido-2-methylpropane sulfonic acid on poly(vinylidene fluoride) films serving as base material, which was activated by electron beam treatment. Both monomers are already containing protogenic groups; thus, follow-up functionalization reactions are avoided. The PEMs were characterized with respect to their electrochemical properties (area specific resistance, recharge current, and ion exchange capacity) relevant for application in vanadium flow batteries and compared to commercially available PEMs.