A porous or non-porous polymeric substrate having its surface modified with an immobilized fluorocarbon such as perfluorocarbon, polymeric composition is provided. The immobilized fluorocarbon is formed from a monomer having formula: [T--SO.sub.2Y--SO.sub.2T'].sup.-M.sup.+ in which --T and T' are identical or different and comprise an organic radical bearing at least one active polymerization function such as an unsaturation or a ring that can be opened; --M.sup.+ comprises an inorganic cation. --Y comprises N or CQ in which Q comprises H, CN, F, SO.sub.2R.sup.3, substituted or unsubstituted C.sub.1-20 alkyl, substituted or unsubstituted C.sub.1-20 aryl, substituted or un-substituted C.sub.1-20 alkylene, in which the substituent comprises one or more halogens, and in which the chain comprises one or more F, SO.sub.2R, aza, oxa, thia or dioxathia substituents; and --R.sup.3 comprises F, substituted or unsubstituted C.sub.1-20 alkyl, in which the substituted or unsubstituted C.sub.1-20 aryl, substituted or unsubstituted C.sub.1-20 alkylene, in which the substituent comprises one or more halogens.