Patent ID: 7482415

Claim:
A process for producing a fluorinated ionomer block copolymer, comprising the steps of: copolymerizing, in the presence of a polymerization initiator and an iodine compound, (i) a compound represented by Formula (I) (M) 1/L OSO 2 CFY(CF 2 ) m O(CFXCF 2 O) n CF═CF 2 (I) wherein M is H or a metal with a valence of L wherein L is 1, 2 or 3, X is F, Cl or CF 3 , Y is a halogen atom, m is 1 to 5, and n is 0 to 5, (ii) tetrafluoroethylene and (iii) at least one third monomer selected from the group consisting of hexafluoropropylene and perfluoroalkyl vinyl ether of structure CF 2 ═CFORf wherein Rf is C 1 to C 5 perfluoroalkyl, to form a fluorine-containing polymer chain segment B containing sulfonic acid groups; and reacting, in the presence of a polymerization initiator, the fluorine-containing polymer chain segment B, tetrafluoroethylene and at least one third monomer selected from the group consisting of hexafluoropropylene, and perfluoroalkyl vinyl ether of structure CF 2 ═CFORf wherein Rf is C 1 to C 5 perfluoroalkyl, to form a fluorine-containing polymer chain segment A which is different from the fluorine-containing polymer chain segment B; wherein the fluorine-containing polymer chain segment B comprises: (i) 5 to 49 mole % of repeating units derived from the compound represented by Formula (I), (ii) 50 to 94 mole % of repeating units derived from tetrafluoroethylene, and (iii) 0.5 to 20 mole % of repeating units derived from the third monomer(s).