METHOD OF OBTAINING PERFLUORO-3-OXAPENTENESULFONYL FLUORIDE COPOLYMER AND TETRAFLUOROETHYLENE AS PRECURSOR OF PERFLUORINATED PROTON-CONDUCTING MEMBRANES

摘要

FIELD: chemistry.;SUBSTANCE: invention relates to the field of the chemistry of high-molecular compounds. Method of obtaining a perfluoro-3-oxapentenesulfonyl fluoride copolymer and tetrafluoroethylene as a precursor of perfluorinated proton-conducting membranes by emulsion copolymerization consists in preparing an aqueous microemulsion of the first comonomer – perfluoro-3-oxapentenesulfonyl fluoride with an average particle size of 1,000 nm by the method of ultrasonic dispersion in an atmosphere of inert gas at a temperature of 20 °C with the volume ratio of the phases of comonomer: water 1:6–1:12 (monomer concentration of perfluoro-3-oxapentenesulfonyl fluoride 22.2–12.8 wt.%, 13.5–7.8 % by volume) in the presence of an emulsifier – perfluorinated surfactant in an amount of 2–3 wt. % relative to the comonomer perfluoro-3-oxapentenesulfonyl, component of the water-soluble redox system – potassium or ammonium persulfate in the amount of 0.85–1.2 wt. % relative to perfluoro-3-oxapentenesulfonyl fluoride and pH regulator to pH 7–8, then the microemulsion is loaded into the reactor in an inert gas atmosphere, the reactor is flushed with a second comonomer – tetrafluoroethylene to a pressure of 0.1 MPa, the microemulsion is stirred at 100 rpm and heated to an operating temperature of 40–50 °C, add another component of a water-soluble redox system – sodium metabisulfite in the amount of 0.26–0.30 wt. % relative to perfluoro-3-oxapentenesulfonyl fluoride, a redox system of two components is formed in a microemulsion, the stirring speed is set to 450 rpm and the copolymerization is carried out by feeding tetrafluoroethylene directly into the microemulsion by bubbling at a working pressure of tetrafluoroethylene 0.9–1.1 MPa with constant stirring of the reaction medium for 4.5–6.5 h with the formation of latex, the copolymerization process is completed with the conversion of perfluoro-3-oxapentenesulfonyl fluoride of 90–92 %, the latex is subjected to coagulation by freezing, followed by separation of the target copolymer from the liquid phase by filtration, the copolymer is washed from the starting materials with deionized water at 80–90 °C and dry under vacuum. Proposed technology allows to carry out the process of copolymerization to deep degrees of transformation of the first comonomer (more than 90 %) while maintaining the constancy of the composition of the resulting copolymer, regardless of the degree of conversion of the comonomer.;EFFECT: mechanical properties of the resulting sulfonic acid membranes are not inferior to the mechanical properties of extruded unmodified Aquivion E-87^® membranes of Solvay Solexis brand.;5 cl, 7 ex