TECHNOLOGY FOCUS - POLYMERS - Preferred Polymer: The polymer is polyethylene, polytetrafluoroethylene, polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-propylene copolymer, tetrafluoroethylene-ethylene copolymer, hexafluoropropylene-propylene copolymer, hexafluoropropylene-ethylene copolymer, polyvinylidine fluoride, vinylidine fluoride tetrafluoroethylene copolymer, vinylidine fluoride tetrafluoropropylene copolymer, polyvinyl fluoride, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyvinylidine-hexafluoropropylene copolymer, chlorotrifluoroethylene-ethylene copolymer, chlorotrifluoroethylene-propylene copolymer, perfluoroalkyl vinyl ether copolymer or perfluoroalkoxy copolymer.Preferred Process: The total radiation dose for activating the cross-linked polymer is 1-10 Mrad (preferably 6-9 Mrad) and that for activating the polymer is 10-80 Mrad. The contacting step is conducted at 15-70degreesC (preferably 45-55degreesC) for 0.5-6 h (preferably 2-3 h). The step of quenching the activated polymer includes (i) heating in an oxygen free atmosphere and (ii) adding one or more cross-linking agents. The process also includes (aa) bubbling nitrogen through the reaction mixture and (bb) sulfonating the monomer-grafted cross-linked polymer by contacting it with a mixture of methylene chloride and chlorosulfonic acid. Preferred Structure: The polymer is an expanded microporous polymer structure. It is in a form of threads, non-woven fabrics, tubes, powders, pellets, sheets or films.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: The unsaturated monomer is styrene, trifluorostyrene, alpha-methylstyrene, alpha,beta-dimethylstyrene, alpha,beta,beta-trimethylstyrene, orthomethylstyrene, meta-methylstyrene, para-methylstyrene, divinylbenzene, triallylcyanurate, acrylic acid, methacrylic acid, vinylpyrrolidone, vinylpyridine, vinylacetate, trifluorovinylacetate, methyvinyltoluene or their mixture.Preferred Composition: The emulsion contains 25-70 wt.% (preferably 45-55 wt.%) monomer and 1-15 wt.% (preferably 5-10 wt.%) emulsifier.Preferred Emulsifier: The emulsifier is alkyl sulfates, alkyl aromatic sulfonates, ethoxylated fatty alcohols, fatty acid esters or their mixture.Preferred Preparation: The emulsion is prepared by:(a) heating the emulsifier until it melts and(b) adding the monomer and the water with stirring.Preferred Agent: The cross-linking agents are divinylbenzene or triallyl cyanurate. Preferred Component: The emulsion also comprises isopropyl alcohol.    TECHNOLOGY FOCUS - IMAGING AND COMMUNICATION - Preferred Method: The radiation is provided by gamma rays, X rays, ultraviolet (UV) radiation, plasma irradiation or beta particles. EXAMPLE - A piece of tetrafluoroethylene-ethylene copolymer film having a thickness of 5.1 mum and a full size of 13x10 cm was irradiated to 30 Mrad to activate the polymer and again at 6 Mrad to activate the cross-linked polymer. It was contacted with an emulsion at 55degreesC for 2 h. The emulsion was prepared using 47.25 wt.% styrene, 5.5 wt.% Atlas 3969 and 47.25 wt.% water. The percentage graft obtained was 150 at much shorter reaction time and lower reaction temperature.