Crosslinking and grafting of polyetheretherketone film by radiation techniques for fuel cells

Chen, J.; Asano, Masaharu; Maekawa, Yasunari

An aromatic polymer electrolyte membrane (PEM) was prepared by direct modification of polyetheretherketone (PEEK) film using the radiation-induced crosslinking and grafting techniques. The crosslinked PEEK (cPEEK) film retained high mechanical strength, and was not dissolved either in the grafting solution or in the sulfonation solution. Divinylbenzene (DVB) was thermally grafted into the cPEEK film, by which the following radiation induced grafting of styrene from 1-propanol solution was largely enhanced. The PEM was obtained by sulfonation of the styrene-grafted film. The water uptake, proton conductivity and methanol permeability of the PEM increased with increasing ion exchange capacity, which was a function of the grafting yield of styrene. The PEM exhibited better mechanical property compared to Nafion, and especially, a higher cell performance of direct methanol fuel cell at the high temperature, reaching a high maximum power density.