Nov. 17,  2016  20  US 2016/0334706 Al  (4)  -continued  Herein R $^{1 }$to R$^{4 }$are as defined above, Rs is a straight C$_{1 }$-C$_{40}$,  branched or cyclic C$_{3}$ -C$_{40 }$ monovalent hydrocarbon group  which may be substituted with or separated by a heteroatom,  Wis each independently hydrogen, fluorine or fluoroalkyl, L  is a single bond or linking group, xl is an integer ofO to 10,  and x2 is an integer of 1 to 5.  [0082]  Examples of the group Rs are as exemplified above  for R$^{1 }$to R 4 . Exemplary of the linking group Lare an ether  bond, ester bond, thioether bond, sulfinic acid ester bond,  sulfonic acid ester bond, carbonate bond, and carbamate  bond.  [0083]  More preferably, the ammonium salt (B) has a  structure represented by the general formula (5).  (5)  Herein R $^{1 }$to R$^{4 }$are as defined above, R $^{6 }$is a straight C$_{1 }$-C$_{40}$,  branched or cyclic C$_{3}$-C$_{4}$ ,  monovalent hydrocarbon group  which may be substituted with or separated by a heteroatom,  and  R11  is each independently hydrogen or trifluoromethyl.  [0084]  Examples of the group R  $^{6 }$are as exemplified above  for R 1  to R 4 .  [0085]  Preferred structures of the anion moiety in the  ammonium salt (B) are shown below, but not limited thereto.  [0079]  In formulae (3a), (3b) and (3c), the groups  ofWa,  WZ,  1 ,  WZ, 2 ,  We  1 ,  Wc $^{2 }$and  Wc3  are as exemplified for R $^{1 }$to R  4 .  Specifically, examples of the sulfonate having formula (3a)  include  trifluoromethanesulfonate,  pentafluoroethanesul› fonate, nonafluoro butanesulfonate, dodecafluorohexanesul- fonate,  2-benzoy loxy-1, 1,3 ,3 ,3-pentafluoropropanesul- fonate,  1, 1,3,3,3-pentafluoro-2-( 4-phenylbenzoyloxy)  propanesulfonate,  1, 1,3 ,3 ,3-pentafluoro-2- pivaloyloxypropanesulfonate,  2-cyclohexanecarbonyloxy- 1, 1,3 ,3 ,3-pentafluoropropanesulfonate,  2-naphthoyloxy-l,  1,3 ,3 ,3-pentafluoropropanesulfonate, 2-( 4-tert-butylbenzoy› loxy )-1, 1,3,3,3-pentafluoropropanesulfonate, 2-adamantan› ecarbonyloxy-l, 1,3 ,3 ,3-pentafluoropropanesulfonate,  2-acetyloxy-l, 1,3 ,3 ,3-pentafluoroprop anesulfonate, 1, 1,3 ,3,  3-pentafluoro-2-hydroxypro panesulfonate, 1,1,3,3,3-penta› fluoro-2-tosyloxypropanesulfonate, 1, l-difluoro-2-naphthy› lethanesulfonate, and 1,1,2,2-tetrafluoro-2-(norboman-2-yl)  ethanesulfonate.  [0080]  Examples of the anion having formula (3b) include  bistrifluoromethanesulfonylimide, bispentafluoroethanesul› fonylimide, bisheptafluoropropanesulfonylimide, and 1,3- perfluoropropylenebissulfonylimide.  Typical of the anion having formula (3c) is tristrifluorometh› anesulfonylmethide.  [0081]  The ammonium salt (B) preferably has a structure  represented by the general formula (4). 