NOVELTY - Graft polymeric membranes, comprise one or more alpha,beta,beta-trifluorovinyl aromatic monomers of specified formulae, radiation graft polymerized to a polymeric base film.    USE - As an ion-exchange membrane (claimed) for use in an electrode apparatus, a membrane electrode assembly and an electrochemical fuel cell (all claimed). The membrane may also be used in: filtration and ultrafiltration; proton exchange membranes in water electrolysis; membranes in chloralkali electrolysis; electrode separators in conventional batteries; ion-selective electrodes; sensor materials for humidity sensors; ion exchange chromatography; analytical pre-concentration techniques (e.g. Donnan Dialysis); electrodialysis; hemodialysis; removal of alcohol from beer; gas separation and pervaporation techniques; and bipolar membranes in water splitting and the subsequent recovery of acids and bases.    ADVANTAGE - The activated, substituted monomers have increased reactivity (i.e. % graft yield or rate of the polymerization reaction is increased). The substituent are activating to the polymerization reaction, and can be converted to be deactivating to subsequent reaction, so introducing ion-exchange functionality to the grafted chains. The ion-exchange groups are more stable under certain conditions than prior art membranes. More than one ion-exchange group per grafted monomer unit can be introduced, enabling the higher ion-exchange capacities at lower percentage grafts. Cation and anion-exchange groups may be incorporated. The chains may be crosslinked to provide greater dimensional stability.    DETAILED DESCRIPTION - A membrane (M) comprising a polymeric base film, onto which either monomer(s) of formulae (I) and (II) have been graft polymerized, or chains comprising (I) and (II) as monomer units have been grafted.    A1, A2, B1, B2 = H, lower alkyl, lower fluoroalkyl, cyclic alkyl, aryl (other than Ph), CH(X)Ph, PRR', and P(OR)(OR'), (provided that at least one the substituents does not equal H, to enable graft polymerization);    X = F, lower alkyl, lower fluoro alkyl or Ph; and    R, R' = lower alkyl, cyclic alkyl or Ph.    INDEPENDENT CLAIMS are also included for:    (1) the preparation of the membrane (M), comprising graft polymerizing compounds (I) or (II) onto a polymeric base film;    (2) the preparation of a membrane (M1) comprising subjecting membrane (M) to halomethylation, sulfonation, phosponation, amination, carboxylation, hydroxylation or nitration; and    (3) the preparation of a membrane (M2), comprising graft polymerizing compounds of formula (I) or (II) onto a polymeric base film where A1 and B1 = SR (S = sulfur), where a portion of the SR groups are converted (oxidized) to sulfonate or sulfonic acid groups.    DESCRIPTION OF DRAWING(S) - The drawing shows the polarization plots of voltage as a function of current density of a fuel cell utilizing a sulfonated para-methyl-alpha,beta,beta-trifluorostyrene-grafted ion-exchange membrane.