Patent ID: 7846982

Claim:
A proton-conducting electrolyte membrane obtained by a process comprising the steps of: a) swelling a polymer film with a liquid comprising a vinyl-containing sulphonic acid and vinyl-containing phosphonic acid, wherein the polymer film comprises after swelling at least 10% by weight vinyl-containing sulphonic acid and vinyl-containing phosphonic acid; and b) polymerizing the vinyl-containing sulphonic acid and vinyl-containing phosphonic acid present in the liquid introduced in step a), wherein the membrane obtained in step (b) comprises at least 10% by weight of polyvinyl-containing phosphonic acid, and wherein the conductivity of the membrane at temperatures of 160° C. is at least 0.001 S/cm wherein this value is achieved without humidification and wherein the polyvinyl containing phosphonic and sulphonic acid formed in step b) forms an inter-penetrating network with the polymer of the polymer film from step a).