Synthesis of fluorinated polymer electrolyte membranes by radiation-induced grafting and atom transfer radical polymerization techniques

Zhai, M.; Hasegawa, Shin; Chen, J.; Maekawa, Yasunari

To develop a highly chemicallly stable polymer electrolyte membrane for appilcation in a direct methanol fuel cell, a fluorinated monomer, Bromotetrafluoroethyl trifluorovinyl ether (BrTFF), was grafted firstly into poly(ethylene-co-tetrafluoroethylene) (ETFE) membrane by irradiation. Further, a new-type polymer electrolyte membrane was synthesized by atom transfer radical polymerization of styrene into ETFE-graft-polyBrTFF membrane followed by sulfonation. The bromine groups in ETFE-graft-polyBrTFF membrane functioned as initiators, and a Cu-based catalytic system of Cu(I)Br and bipyridyl (bpy) was empolyed for the ATRP. It was found that styrene was grafted homogeneously into ETFE-graft-polyBrTFF membrane and the prepared polymer electrolyte membrane have higher ion exchange capacity (IEC) and proton conductivity than that of normal ETFE-g-PSSA membrane.