Aug.  27,  2020  148  US 2020/0272048 Al  carbonyl, ether bond, ester bond, sulfonic acid ester bond,  carbonate moiety, lactone ring, sultone ring, carboxylic  anhydride or haloalkyl moiety.  [0137]  The divalent hydrocarbon groups may be straight,  branched or cyclic. Examples thereof include straight or  branched alkanediyl groups such as methylene, ethylene,  propane-1,3-diy  1,  butane-1,4-diy  1,  pentane-1, 5-diy  1,  hexane- 1,6-diy  l,  heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl,  decane-1, 10-diy  1,  mundecane-1, 11-diy  1,  dodecane-1, 12- diy  l,  tridecane-1,13-diyl, tetradecane-1,14-diyl, pentade› cane-1, 15-diyl, hexadecane-1, 16-diyl, and heptadecane-1,  17-diyl; divalent saturated cyclic hydrocarbon groups such  as cyclopentanediyl, cyclohexanediyl, norbomanediyl and  adamantanediyl; and divalent unsaturated cyclic hydrocar› bon groups such as phenylene and naphthylene. In these  groups, some hydrogen may be substituted by an alkyl  moiety such as methyl, ethyl, propyl, n-butyl or t-butyl:  some hydrogen may be substituted by a moiety containing a  heteroatom such as oxygen, sulfur, nitrogen or halogen; or  some carbon may be replaced by a moiety containing a  heteroatom such as oxygen, sulfur or nitrogen, so that the  group may contain a hydroxyl, cyano, carbonyl, ether bond,  ester bond, sulfonic acid ester bond, carbonate, lactone ring,  sultone ring, carboxylic anhydride or haloalkyl moiety. Of  the heteroatoms, oxygen is preferred.  [0138]  Of the PAGs having formula (2), those having  formula (2’) are preferred.  [0139]  In formula (2’), LA is as defined above.  RHF  is  hydrogen or trifluoromethyl, preferably trifluoromethyl.  R 301 , R $^{302 }$and R$^{303 }$are each independently hydrogen or a  C$_{1 }$-C$_{20 }$ monovalent hydrocarbon group which may contain a  heteroatom. The monovalent hydrocarbon groups may be  straight, branched or cyclic, and examples thereof are as  exemplified above for  R  107 . The subscripts x and y are each  independently an integer of  O  to 5, and z is an integer of 0  to  4.  [0140]  Examples of the PAG having formula (2) are  shown below, but not limited thereto. Notably,  RHF  is as  defined above.  (2’)  -continued 