TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The persulfate is ammonium sulfate or potassium sulfate.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The initiator is difluorodiazine, perfluoroalkyl peroxide or persulfate.The perfluoro alkyl peroxide is peroxidating perfluoroalkylacyl compounds, perfluorinated alkoxy acyl compounds, peroxidating partial fluoroalkylacyl or peroxidating partial fluoroalkoxyacyl compounds.The perfluoroalkyl peroxide comprises perfluoro-propionyl peroxide, 3-chlorofluoropropionylperfluoromethoxyacetyl peroxide, omega-H-perfluorobutyryl peroxide, omega-fluorosulfonylperfluoro-2,5,8-trimethyl-3,6,9-trioxoundecyl peroxide, 2,2,3,3,4,4,4-heptafluorobutanoic peroxyanhydride, 2,3,3,3-tetrafluoro-2-(perfluoro propoxy)propanoic peroxyanhydride, 3,3,4,4,4-pentafluorobutanoic peroxyanhydride or 2,2,3,3-tetrafluoro-3-(trifluoromethoxy)propanoic peroxyanhydride.    TECHNOLOGY FOCUS - POLYMERS - Preparation (Claimed): The preparation of the fluorinated polymer comprises copolymerizing the tetrafluoroethylene and two sulfonate side group alkene ether monomer having different structures at 10-60 degrees C in presence of an initiator, where the reaction time is 1-8 hours and reaction pressure is 2-10 MPa.Preferred Components: The mole fraction of tetrafluoroethylene is 75-85% and the mole fraction of the sulfonate side group alkene ether monomer is 15-25%.Preferred Method: The copolymerization reaction comprises:(i) adding water and sulfonate side group alkene ether, which is the reaction monomer as well as the emulsifier or dispersant, in the reaction kettle, where the quality % concentration is 5-50%;(ii) adding tetrafluoroethylene monomer in the kettle via the gas gauge tank until the pressure is 2-10 MPa;(iii) adding initiator into the reaction system by a metering pump to initiate the reaction and when the temperature of the kettle reaches 10-60 degrees C, adding the tetrafluoroethylene monomer and initiator continuously into the kettle, to maintain the pressure at 2-10 MPa and the total reaction time is 1-8 hours. The ratio of the total volume of the tetrafluoroethylene monomer and the sulfonate side group alkene ether is 50-99.9:0.1-50; and(iv) removing the unreacted tetrafluoroethylene monomer by the emptying pipeline of the kettle and recycling it, obtaining the milky-white polymer by high speed cutting and drying in the oven at 100 degrees C for obtaining the fluorinated polymer with sulfonate side group. The sulfonate side group alkene ether monomer in the reaction liquid is recycled by recycling system.