Hydrocarbon proton-conductive membranes prepared by radiation-grafting of styrenesulfonate onto aromatic polyamide films

Li, D.*; Chen, J.; Zhai, M.; Asano, Masaharu; Maekawa, Yasunari; Oku, Hiroyuki*; Yoshida, Masaru

Novel method for preparing aromatic hydrocarbon proton-conductive membranes without sulfonation and membrane casting process is achieved by radiation grafting of sodium styrenesulfonate to an aromatic polyamide, poly(m-xylylene adipamide) (Nylon-MXD6) films and subsequent ion-exchange. The styrenesulfonate was easily grafted into the Nylon-MXD6 films from an oxygen-free dimethyl sulfoxide (DMSO) solution. As a result, the resulted styrenesulfonic acid-grafted Nylon-MXD6 films, namely proton-conductive membrane, with high ion exchange capacity up to 1.63 mmol/g, can be obtained. The membrane was transparent and highly hydrophilic. Furthermore, the methanol permeability was significantly lower than that of the Nafion membrane. Therefore, the Nylon-MXD6-based proton-conductive membrane is a more promising material for the direct methanol fuel cells (DMFCs).