Abstract: A method for the preparation of a graft polymer membrane comprising an inactive polymer film having TFS as a graft chain. The inactive polymer film is irradiated with ionizing radiation, and the resulting irradiated film is graft-polymerized by contacting said film with TFS.This product may then be sulfonated to provide a cation exchange membrane; or the obtained graft polymer may be haloalkylated, and quarternary aminated to provide an anion exchange membrane; or the graft polymer membrane may be used to prepare a weakly acidic cation exchange membrane by substituting at least part of the benzene rings of the graft polymer by one of the groups among hydroxyl groups, carboxylic acid groups, phosphoric acid groups and phosphorous acid groups.The polymeric membrane products are also disclosed and claimed.