Aug. 2, 2007  10  US 2007/0179263 A  [0101]  The introduction of the Rx is preferred because the  aromatic compound (1) can have a low viscosity and can be  liquefied and also because oxidation resistance can be  imparted to the aromatic compound.  [0102]  The fluorine-containing alkyl group Rx has pref› erably 1 to 10 carbon atoms, more preferably 1 to 5 carbon  atoms, which is preferred from the viewpoint of decrease in  a viscosity, liquefaction and oxidation resistance.  [0103]  Further the fluorine-containing alkyl group Rx hav› ing a higher fluorine content is preferred from the viewpoint  of oxidation resistance. The fluorine content is not less than  40% by mass, more preferably not less than 50% by mass,  particularly preferably not less than 60% by mass, and most  preferably Rx is a perfluoro alkyl group.  [0104]  Concretely examples thereof are:  C$_{3}$F$_{7}$ -, CF 3 -, C $_{2}$F$_{5}$ -, CH $_{3}$CF$_{2}$CF$_{2}$ -, HCF $_{2}$CF$_{2}$CH$_{2}$ -,  CF$_{3}$CH$_{2}$-, HCF$_{2}$CF$_{2}$CF$_{2}$CF$_{2}$CH$_{2}$-, H (CF$_{2}$CF$_{2}$ ) $_{4}$CH$_{2}$ -,  CF$_{3}$CF$_{2}$CH$_{2}$-,  (CF$_{3}$ ) $_{2}$CH-,  (CF$_{3}$ ) $_{2}$CF-,  C$_{8}$F $_{1 7}$CH$_{2}$CH$_{2}$-,  C$_{3}$F$_{7}$0-,  CF$_{3}$0-,  C$_{2}$F$_{5}$0-,  HCF $_{2}$CF $_{2}$CH$_{2}$0-,  HCF$_{2}$CF$_{2}$CF$_{2}$CF$_{2}$CH$_{2}$0-,  C$_{2}$F$_{5}$CH$_{2}$-,  (CF$_{3}$ ) $_{2}$CHO-,  C$_{8}$F $_{1 7}$CH$_{2}$CH$_{2}$-,  CH$_{3}$CF $_{2}$CF $_{2}$0-,  CF$_{3}$CH$_{2}$0-,  H(CF$_{2}$CF$_{2}$ ) $_{4}$CH$_{2}$ 0-,  (CF$_{3}$ ) $_{2}$CFO-,  CH$_{2}$=CF----CF$_{2}$ 0-, CH$_{2}$=CH-CF$_{2}$0-, CF$_{2}$=CF› CF $_{2}$0-,  CF $_{2}$=CF----CF $_{2}$CF $_{2}$0-,  CF $_{2}$=CF---O-,  CH$_{2}$=CH---O-,  CF$_{2}$=CF----CH$_{2}$0-,  CF$_{2}$=CF› CF $_{2}$CF $_{2}$CH$_{2}$-0-,  [0109]  Examples thereof are:  -continued  and the like, and particularly preferred are C$_{3}$F$_{7}$-, CF 3 -,  C$_{2}$F$_{5}$-, CF $_{3}$CH$_{2}$ -, HCF $_{2}$CF$_{2}$CH$_{2}$ -, CF $_{3}$CF$_{2}$CH$_{2}$ -,  (CF$_{3}$ ) $_{2}$CH-, C$_{3}$F$_{7}$ 0-, CF$_{3}$0-, C$_{2}$F$_{5}$0-, CF$_{3}$CH$_{2}$0-,  HCF$_{2}$CF$_{2}$CH$_{2}$-, CF$_{3}$CF$_{2}$CH$_{2}$-, (CF 3 ) $_{2}$CHO- and the  like.  [0105]  Also other examples of Ra are (v) monovalent  organic groups Rx’ having 2 to 20 carbon atoms which have  an ethylenic double bond at an end thereof.  [0106]  Such organic groups are preferred since in addition  to the same effects as mentioned above by the moieties of  -D- and Ry in the ionic liquid type functional material, it is  possible to obtain the fluorine-containing polymer having  the fluorine-containing ether unit -D-, functional group Y  and aromatic ring structure in its side chain by polymeriza› tion using the ethylenic double bond, thereby making it  possible to obtain the ionic liquid type polymer from this  fluorine-containing polymer.  [0107]  If the number of carbon atoms of the organic group  constituting Rx’ is too high, a viscosity is increased and  lowering of polymerizability is recognized. Therefore the  number of carbon atoms is preferably from 1 to 10, more  preferably from 1 to 5.  [0108]  Concretely Rx’ is a moiety represented by the  following formula:  wherein X  1 , X 2 , X $^{4 }$and X$^{5 }$are the same or different and each  is hydrogen atom or fluorine atom; X 3  is selected from  hydrogen atom, fluorine atom, CH$_{3 }$ and CF$_{3}$ ;  n3, n4 and n6  are the same or different and each is  O  or 1, and more  concretely there are radically polymerizable moieties such  as vinyl group, vinyl ether group, ally! ether group, acryloyl  group, methacryloyl group and a-fluoroacryloyl group.  CX$^{1}$X$^{2}$~CX 3 -(CX$^{4}$X$^{5}$)"3(C~O)".(O)"~  h___L.  y  lF3  CH2=CH-C-O-CH2CF2-•  II  0  CH2=CF-C-O-CH2CF2-•  CH2=CF-c-o-,  II  II  0  0  Cp-fF3  3  CF3 