Nov.  22, 2018  4  US 2018/0335696 Al  polymerizable unsaturated bond and a fluorosulfonic acid  and specifically, a polymer comprising recurring units hav› ing the formula (al) or (a2).  It is noted that recurring units  having the formula (al) or (a2) are simply referred to as  recurring units (al) or (a2), hereinafter.  [0042]  Preferably, the recurring units (al) and (a2) are  represented by the formulae (al-1) and (a2-l), respectively.  [0041]  Herein  RA  is hydrogen or methyl. X 1  is a single  bond or ester group. X 2  is a C$_{1 }$-C$_{12 }$ straight, branched or  cyclic alkylene group or CcC$_{10 }$ arylene group, any meth› ylene moiety in the alkylene group may be substituted by an  ether moiety, ester moiety or lactone ring-containing moiety,  and at least one hydrogen in the group X $^{2 }$is substituted by  iodine. X 3  is a single bond, ether group, ester group or  C$_{1 }$-C$_{12 }$ straight, branched or cyclic alkylene group, any  methylene moiety in the alkylene group may be substituted  by an ether or ester moiety. Rf$^{1 }$to Rf$^{1 }$are each independently  hydrogen, fluorine or trifluoromethyl at least one of Rf 1  to  R:t4 is fluorine or trifluoromethyl, and Rf $^{1 }$and Rf may bond  together to form a carbonyl group. R 1  to Rs are each  independently a C$_{1 }$-C$_{12 }$ straight, branched or cyclic alkyl  group, C$_{2}$ -C$_{12 }$ straight, branched or cyclic alkenyl group,  C$_{2}$-C$_{12 }$ straight, branched or cyclic alkynyl group,  CcC$_{20 }$ aryl group, C$_{7}$ -C$_{12 }$ aralkyl group, or C$_{7}$ -C$_{12 }$ aryloxyalkyl  group, in which at least one hydrogen ( one or more or even  all hydrogen atoms) may be substituted by hydroxyl, car› boxyl, halogen, oxo, cyano, amide, nitro, sultone, sulfone or  sulfonium salt-containing moiety, and in which any meth› ylene moiety may be substituted by an ether, ester, carbonyl,  carbonate or sulfonate moiety. Also, R 1  and R 2  may bond  together to form a ring with the sulfur atom to which they are  attached.  (al)  (a2)  ~  A  R\-~~  lm~Rfl  Rf$_{2 }$ A  S03- 0  0  Rf 3  Rf4  (al-1)  ~  A  R$^{6}$n-~~  1 m~Rf1  RF  A  S03- 0  0  Rf 3  Rf4  (a2-1)  [0043]  Herein  RA,  R 1  to Rs, Rf 1  to Rf\ and X 1  are as  defined above. R  6  is a C$_{1 }$-C$_{4 }$ straight, branched or cyclic  alkyl group, halogen atom exclusive of iodine, hydroxyl  group, C$_{1 }$-C$_{4 }$ straight, branched or cyclic alkoxy group, or  C$_{2}$-Cs straight, branched or cyclic alkoxycarbonyl group, m  is an integer of 1 to 4, and n is an integer of Oto 3.  [0044]  Examples of the anion moiety in the monomer  from which recurring units (al) or (a2) are derived are given  below, but not limited thereto. 