Patent ID: 8754140

Claim:
A multi-segmented fluoropolymer that comprises at least one of a block copolymer or a graft copolymer having at least two types of fluoropolymer chain segments C 1 and D 1 containing sulfonic acid functional groups, wherein: the fluoropolymer chain segment C 1 is a copolymer having a molecular weight of 5000 to 750000 and comprising: (g) 13 to 50 mol % of at least one type of ethylenic fluoromonomer structural unit containing sulfonic acid functional groups and represented by Formula (1) CX 2 ═CX 1 —(O) n —Rf—SO 2 Y (1), and (h) 87 to 50 mol % of at least one type of ethylenic monomer structural unit containing no sulfonic acid functional groups; and The fluoropolymer chain segment D 1 is a fluoropolymer chain having a molecular weight of 3000 to 120000 and comprising: (i) not less than 0.1 mol % but less than 13 mol % of at least one type of ethylenic fluoromonomer unit containing sulfonic acid functional groups and represented by formula (1) CX 2 ═CX 1 —(O) n —Rf—SO 2 Y (1), and (j) more than 87 mol % but not more than 99.9 mol % of at least one type of ethylenic monomer unit containing no sulfonic acid functional groups, wherein X and X 1 may be the same or different and are each hydrogen or fluorine; Y is F, Cl or OY 1 , wherein Y 1 is hydrogen, alkali metal or C 1 to C 5 alkyl; Rf is C 1 to C 40 divalent fluoroalkylene or C 1 to C 40 divalent fluoroalkylene having ether bond(s); and n is 0 or 1, and wherein the ratio of segment C 1 : segment D 1 in the segmented fluoropolymer is 30:70 to 90:10 wt. %.