US 2016/0334706 Al  34  Nov. 17,  2016  -continued  f:  0  0  I  Rl22  ’Rf  Herein R  114  is each independently hydrogen, fluorine,  methyl or trifluoromethyl. R $^{118 }$is each independently hydro› gen or a straight, branched or cyclic C$_{1 }$-C$_{20 }$ alkyl or fluo› roalkyl group, or two R $^{115 }$in a common monomer may bond  together to form a ring with the carbon atom to which they  are attached, and in this event, they together represent a  straight, branched or cyclic C$_{2}$ -C$_{20 }$ alkylene or fluoroalky› lene group. R$^{116 }$is fluorine or hydrogen, or R$^{116 }$may bond  with R$^{117 }$to form a non-aromatic ring of 3 to 10 carbon  atoms in total with the carbon atom to which they are  attached. R$^{117 }$is a straight, branched or cyclic C$_{1}$-C$_{5 }$ alky› lene group in which at least one hydrogen atom may be  substituted by a fluorine atom. R $^{118 }$is a straight or branched  C$_{1 }$-C$_{10 }$alkyl group in which at least one hydrogen atom is  substituted by a fluorine atom. Alternatively, R  11 7  and R  118  may bond together to form a non-aromatic ring with the  carbon atoms to which they are attached. In this event, R 117 ,  R 118  and the carbon atoms to which they are attached  together represent a trivalent organic group of2 to 12 carbon  atoms in total. R $^{119 }$is a single bond or a C$_{1 }$-C$_{4 }$ alkylene. R  120  is  each  independently  a  single  bond,  ---0-,  or  -CR$^{114}$R 114 -. R $^{121 }$is a straight or branched C$_{1}$-C$_{4 }$ alky› lene group, or may bond with R 115  within a common  monomer to form a C$_{3}$ -C$_{6 }$ non-aromatic ring with the carbon  atom to which they are attached. R 122  is 1,2-ethylene,  1,3-propylene, or 1,4-butylene. Rf is a linear perfluoroalkyl  group of3 to 6 carbon atoms, typically 3H-perfluoropropyl,  4H-perfluorobutyl, 5H-perfluoropentyl, or 6H-perfluoro› hexyl. X $^{2 }$is each independently----C(=O)-O-, -0-, or  -C(=O)-R$^{123}$----C(=O)---0-.  R 123  is  a  straight,  branched or cyclic C$_{1 }$-C$_{10 }$alkylene group. The subscripts are  in the range:  0s(a’-1)<1, 0s(a’-2)<1, 0s(a’-3)<1,  0<(a’-l)+(a’-2)+(a’-3)<1, 0sb’<l, 0sc’<l, and  0<(a’-1 )+(a’-2)+(a’-3)+b’+c’sl.  [0120]  Examples of these units are shown below. 