| abstract |
A functional membrane is provided, which has high functionality combined with the gas barrier performance and mechanical strength inherent in a polymer film substrate. In particular, a polymer electrolyte membrane is provided, which is excellent in terms of high proton conductivity and gas barrier performance and is most appropriate to serve as a polymer electrolyte membrane for fuel cells. A method for producing a functional membrane is provided, which comprises: a step of ion irradiation, in which active species are generated in a polymer film substrate containing nonconductive inorganic particles by irradiating the polymer film substrate with high-energy heavy ions to the extent of 104/cm2 to 1014/cm2; and a step of graft polymerization subsequent to the step of ion irradiation, in which one or more monomers selected from group A consisting of monomers containing useful functional groups are added such that the monomers are graft polymerized with the polymer film substrate. |