Process for producing polymeric films for use as fuel cells

Abstract

A method for producing polymeric, e.g., polybenzimidazole (PBI) films, is provided by forming a porous membrane by coagulating a polymeric dope solution in a liquid coagulation bath containing a non-solvent alone or a mixture of a non-solvent and solvent; submerging the resulting membrane into a non-solvent bath to remove any residual solvent; placing the membrane into an acid solution, whereby the pores become filled with the acid solution; and drying the membrane to remove residual non-solvent which collapses the porous structure entrapping the acid and forming a dense film. An alternative method involves coagulating said polymer solution directly into an acid/solvent/non-solvent mixture to produce a porous membrane which imbibes the acid solution, followed by drying.

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