Patent ID: 8168105

Claim:
A process for producing a doped polymer polyazole membrane comprising the steps of: A) casting a film using a solution of polyazole polymers in a polar, aprotic organic solvent; B) partially drying the film formed in step A) with heat or under reduced pressure or both until it is self-supporting and forms a partially dried film, said partially dried film having a residual content of said polar, aprotic organic solvent in a range of 10 to 23%; C) treating the film obtained in step B) with a treatment liquid at a temperature in the range from 20° C. to the boiling point of the treatment liquid; D) removing the treatment liquid from step C) by drying and/or dabbing the film; and E) doping the film treated according to step D) with a concentrated doping agent, said concentrated doping agent has a concentration of at least 85 wt % and is selected from the group consisting of: Lewis acids and BrØnsted acids; and where doping is to a degree from 3 to 15 mol of acid per mol of recurring unit of polymer to obtain a polymer electrolyte membrane.