Preparation and a solid polymer electrolyte fuel cell membrane-electrode assembly for solid polymer electrolyte fuel cell electrolyte material

Having an aliphatic ring structure in good backbone gas diffusibility and by fluorinating was contacted with fluorine gas a fluorine-containing polymer having a sulfonic acid group increases the water repellency, and by stabilizing the molecular end, the polymer is a solid polymer fuel cell electrolyte material, a water-repellent and gas diffusivity is good to obtain a solid polymer fuel cell membrane electrode assembly with high power density. As the fluorine-containing polymer, the repeating units based on a repeating unit Monomer B based on the following monomer A (however, Y is a fluorine atom or a trifluoromethyl group, m is an integer of 0 to 3, p is 0 or is 1, n is an integer from 1 to 12.) copolymer containing is preferably employed. Monomer A: by radical polymerization, perfluoro monomer providing a polymer having a repeating unit containing a main chain in the ring structure. Monomer