US 9,063,416 B2  73  74  -continued  -continued  (a2-0-12b)  In the formulas, R andA’ are the same as defined above; and  each of c to e independently represents an integer of  1  to 3.  -Structural Unit (a2L):  Examples of the structural unit (a2L) include structural  units represented by the aforementioned general formula ( a2- 0) in which the R$^{28 }$group has been substituted with a lactone- containing cyclic group. Specific examples include structural  units represented by general formulas ( a2-1) to ( a2-5) shown  below.  [Chemical Formula 32]  (a2-1)  (a2-2)  R  ~o  $^{0 }$\  R’-.:...Tir  -1- R’  A"  0  0  (a2-3)  (a2-4)  R  (a2-5)  ~o  0  \  0  (D1Do  In the formulas, R represents a hydrogen atom, an alkyl  group of  1  to 5 carbon atoms or a halogenated alkyl group of  1  to 5 carbon atoms; each R’ independently represents a  hydrogen atom, an alkyl group, an alkoxy group, a haloge- nated alkyl group, a hydroxy group, -COOR", -OC(=O)  R", a hydroxyalkyl group, or a cyano group, wherein R"  represents a hydrogen atom or an alkyl group; R$^{29 }$represents  a single bond or a divalent linking group; s" represents an  integer of0 to 2;A" represents an oxygen atom, a sulfur atom  or an alkylene group of  1  to 5 carbon atoms which may  contain an oxygen atom or a sulfur atom; and m represents  0  or  1.  In general formulas (a2-1) to (a2-5), R is the same as  defined above.  As the alkyl group, alkoxy group, halogenated alkyl group,  ----COOR",---OC(=O)R" andhydroxyalkylgroup forR’, the  same alkyl groups, alkoxy groups, halogenated alkyl groups,  --COOR", ---OC(=O)R" and hydroxyalkyl groups as those  described above as the substituent which a -SO$_{2}$ - contain- ing cyclic group may have, can be mentioned.  In terms of industrial availability, R’ is preferably a hydro› gen atom.  The alkyl group for R" may be any of linear, branched or  cyclic.  When R" is a linear or branched alkyl group, it preferably  has  1  to  10  carbon atoms, more preferably  1  to 5 carbon  atoms. 