TECHNOLOGY FOCUS - POLYMERS - Preparation (disclosed): Polymeric reaction of a hetero aromatic ring group containing compound which is converted to structural unit (M) and a polymer containing functional group containing structural unit which reacts with hetero aromatic ring group containing compound is carried out, and fluorine-containing polymer is obtained. Preferred Polymer: An ionic group containing fluorine-containing polymer has structural unit of formula: -(M1)-(N)-.M1=structural unit derived from fluorine-containing ethylenic monomer of formula (XI), preferably at least one structural unit derived from fluorine-containing ethylenic monomer of formulae (XV-XIX);andN=same as defined above.X1-X5,a-c=same as defined above;d=1-20;e=0-1;Rfx=1-40C fluorine-containing alkyl or organic group (-Ya) bonded with 2-100C fluorine-containing alkyl having ether bond;Ya=at least one group of formulae (XII,XIII), and is region which forms hetero aromatic ring with nitrogen atom, preferably at least one group of formulae (XIV), and is bonded with terminal of principal chain and/or side chain of Rfx;Rd=H or monovalent organic group;X-=counter anion;andRa=same as defined above.Preferred Composition: A polymer composition comprises the hetero aromatic ring containing fluorine-containing polymer and/or ionic group containing fluorine-containing polymer, and nano filler. Preferred Compound: The nano filler is a nano carbon material. Preferred Definitions:    Y'=group of formula (IV), and is bonded with terminal of principal chain and/or side chain of Rf;and    M=at least one structural unit derived from fluorine-containing ethylenic monomer of formula (V-IX).    Ra=halogen atom, functional group or organic group, however a portion or hole of hydrogen atom of hetero aromatic ring is substituted;and    X1-X5,Rf,a,c-e=same as defined above.    EXAMPLE - Trifluoro methane sulfonic acid-1-methyl-3-(2H,9H,9H-perfluoro-3,6-dioxa-5-methyl-8-nonenyl)imidazolium of formula: CH2=CFCF2OCF(CF3)CF2OCHFCF2-Im+-Me.CF3SO3- (in g) (27.9) and di(7H-perfluoro heptanoyl)peroxide (8.5) of perfluoro hexane solution were reacted in nitrogen atmosphere at 30degreesC for 5 hours, and high viscosity solid was produced. Hexane was poured, and solid separator was dried and dissolved in acetone to obtain colorless and transparent homopolymer (23) of trifluoro methane sulfonic acid-1-methyl-3-(2H,9H,9H-perfluoro-3,6-dioxa-5-methyl-8-nonenyl)imidazolium of formula: CH2=CFCF2OCF(CF3)CF2OCHFCF2-Im+-Me.CF3SO3-. The polymer had number average molecular weight of 13000 and weight average molecular weight of 17000.