NOVELTY - Novel monomer units of VF2 are used in the ionic polymer (ionomer).    USE - The ionomers are used in electrochemical applications such as batteries, fuel cells, electrolysis cells, ion exchange membranes, sensors, electrochromic windows, electrochemical capacitors and modified electrodes. They may also be used as strong acid catalysts.    DETAILED DESCRIPTION - An ionic polymer (ionomer) comprises monomer units of VF2 and further comprises 2-50 mol. % of monomer units having pendant groups comprising a radical of formula (I): -(OCF2CFR)a-OCF2-(CFR')b-SO2X-(M+)(Y)(Z)c (I), where    R, R' = F, Cl or 1-10C perfluoroalkyl group optionally substituted by one or more ether oxygens;    a = 0, 1 or 2;    b = 0-6;    M+ = H+ or a univalent metal cation;    X = C or N provided that c = 1 when X is C and c = 0 when X is N;    when c = 1, Y and Z are electron-withdrawing groups selected from CN, SO2(Rf), SO2R3, P(O)(OR3)2, CO2R3, P(O)(R3)2, C(O)RfC(O)R3, and cycloalkenyl groups formed with them; or    when c = 0, Y may be an electron-withdrawing group of formula -SO2(Rf') optionally substituted with one or more ether oxygens;    Rf = a 1-10C perfluoroalkyl group optionally substituted with one or more ether oxygens;    R3 = 1-6C alkyl group optionally substituted with one or more ether oxygens or an aryl group optionally further substituted;    Rf' = a radical of formula: -(RfSO2N-(M+)SO2)m-Rf';    m = 0 or 1;    Rf = -CnF(subscript 2n);    Rf' = -CnF(subscript 2n+1); and    n = 1-10.    INDEPENDENT CLAIMS are also included for:    (a) an ethylenically unsaturated composition of formula (II): CF2=CF-(OCF2CFR)a-OCF2-(CFR')b-SO2C-(M+)YZ (II), where all the variable substituents are as above and Y and Z are as when c = 1;    (b) a process for making a methide ionomer comprising: (i) combining in an inert organic liquid at a temperature of 0-150 degrees C: a copolymer comprising monomer units of VF2 and 2-50 mol. % of monomer units of formula (III): CF2=CF(OCF2CFR)a-OCF2-(CFR')b-SO2F (III) with a carbanion derived from a methylene compound of formula CH2YZ, where all the variable substituents are as above and Y and Z are as when c = 1, to form a reaction mixture; (ii) reacting the reaction mixture until the desired degree of conversion has been achieved; and (iii) removing the bulk of the organic liquid;    (c) a process for making a methide composition as above for (b) except the monomer units of (III) are replaced with a composition of formula (IV): CF2A-CFA(OCF2CFR)a-OCF2(CFR')b-SO2F (IV), where A = Br or Cl; and R, R', a and b = as above, and step (i) is performed at 0-100 degrees C;    (d) a process for forming an ionomer comprising: (i) combining in an aqueous reaction medium VF2 with an ionic monomer of formula (V): CF2=CF-(OCF2CFR)a-OCF2(CFR')b-SO2X-(M+)(Y)(Z)c (V), where all the variable substituents are as above, to form a reaction mixture; (ii) introducing a free radical initiator; and (iii) reacting the reaction mixture to form an ionomer having a m.pt. of at least 150 degrees C;    (e) a conductive composition comprising the above claimed ionomer and a liquid imbibed with it;    (f) an electrode comprising at least one electrode active material and the above conductive composition; and    (g) an electrochemical cell comprising a separator disposed between a positive electrode and a negative electrode, and a means for connecting the cell to an outside load or source where at least one of the group consisting of the separator, the cathode and the anode comprises the above claimed ionic polymer.