TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: Vinyl ether monomers (B) are chosen from 1,1,2,2-tetrafluoro-2-((1,2,2-trifluoroethenyl)oxy)ethane-1-sulfonyl fluoride and 1,1,2,2,3,3,4,4-octafluoro-4-((1,2,2-trifluoroethenyl)oxy)butane-1-sulfonyl fluoride. The vinyl ether monomer (C) is of formula: F2C=CF-O-(CF2-C(-F)(-CF3-O))n-(CF2)m-Br (III). The content of tetrafluoroethylene unit, vinyl ether monomer unit having two sulfonyl fluoride-containing short pendant groups with different structures, and vinyl ether monomer unit having bromine-containing pendant group is 70-80 mol%, 15-29 mol% and 1-5 mol%, respectively. The molar ratio of two kinds of vinyl ether monomers having sulfonyl-fluoride-containing short pendant groups is 0.2-0.8:0.8-0.2, preferably 0.4-0.6:0.6-0.4. The reactive initiator is difluorodiazine, perfluoroalkyl peroxide and/or persulfate. The persulfate is ammonium persulfate, alkali metal persulfide or alkaline-earth metal persulfide. The perfluorinated alkyl peroxide is perfluorinated propionyl peroxide, 3-chlorofluorocarbon propionyl peroxide, perfluorinated methoxy acetyl peroxide, omega -H-perfluorinated butyryl peroxide, omega -S2F-perfluorinated -2,5,8-trimethyl-3,6,9-trioxaundecyl peroxide, fluorine-containing peroxide (CF3CF2CF2CO-OO-COCF2CF2CF3), fluorine-containing peroxide (CF3CF2CF2OCFCF3CO-OO-COCFCF3OCF2CF2CF3), fluorine-containing peroxide (CF3CF2CH2CO-OO-COCH2CF2CF3) or fluorine-containing peroxide (CF3OCF2CF2CO-OO-COCF2CF2OCF3). The persulfate is ammonium persulfate and/or potassium persulfate. Latex emulsion polymerization reaction is also included in water phase. In latex emulsion polymerization, the emulsifier is anionic emulsifier, such as sodium aliphatate, sodium lauryl sulfate, sodium alkyl sulfonate, and sodium alkylarylsulfonate, or nonionic emulsifier such as alkylphenol polyether alcohol, nonylphenol polyoxyethylene ether, polyoxyethylene fatty acid and polyoxyethylene fatty acid ether. In latex emulsion polymerization reaction, the concentration of emulsifier in water is 0.1-20 %mass, the concentration of vinyl ether monomer (B) in water is 5-30 %mass, and concentration of vinyl ether monomer (C) in water is 1-12 %mass.