of one or more monomers selected from compounds represented by the general formula: Y--(CF2)a --(CFRf)b --(CFRf')c --O--[CF(CF2 X)--CF2 --O]n --CF═CF2(II) where: Y is selected from the group consisting of --SO2 Z, --CN, --COZ, and C(R3 f)(R4 f)OH; Z is --I, --Br, --Cl, --F, --OR, or --NR1 R2 ; R is a branched or linear alkyl radical having from 1 to about 10 carbon atoms or an aryl radical;