METHOD OF MANUFACTURING POLYMER ELECTROLYTE MEMBRANE FOR FUEL CELL, ELECTROLYTE MEMBRANE MANUFACTURED THEREBY AND MEMBRANE ELECTRODE ASSEMBLY FOR FUEL CELL USING THE MEMBRANE

PROBLEM TO BE SOLVED: To provide a polymer electrolyte membrane for a fuel cell, which provides high proton conductivity at a low graft ratio while inhibiting deterioration of characteristics inherent to a polymer film substrate, inhibits dimensional change, mechanical strength change and permeation of methanol fuels, and moreover has favorable heat resistance and oxidation resistance and to provide a method of manufacturing the same. SOLUTION: A method of manufacturing a polymer electrolyte membrane for a fuel cell is used, the method comprising a photografting polymerization step of carrying out irradiation of ultraviolet rays while a polymer film substrate is brought into contact with a monomer solution containing a vinyl monomer to which a sulfonic group is introduced, water and a ketone solvent so as to subject the vinyl monomer to photografting polymerization from the surface of the polymer film substrate in a liquid phase system, thereby extending graft chains on the substrate surface and from the substrate surface toward the inside, and a step of introducing a sulfonic group to a part to which a sulfonic group is introduced in the graft chains formed by the photografting polymerization step. As a result, since radicals are generated only on the substrate surface, the vinyl monomer is graft polymerized from the substrate surface toward the inside, and further, sulfonic groups are introduced to obtain a polymer electrolyte membrane for a fuel cell having favorable properties while keeping properties inherent to the substrate. COPYRIGHT: (C)2009,JPO&INPIT