Tetrafluoroethylene ( TFE ) and hexafluoropropylene ( HFP ) were subjected to reactions with freshly distilled sulfur trioxide to obtain 1-fluorosulfonyldifluoro-acetylfluoride (FSDFAF, yield 65-70% ) and pentafluoro-2-propenylfluorosulfate (PPFS, yield up to 50% ) .A subsequent reaction of FSDFAF with PPFS under anhydrous conditions led to a preparation of 2-( 1-pentafluoro-2-propenyloxy ) tetrafluoroethanesulfonyl fluoride ( PPOTESF, yield 40-41% ) whose structure was proved by both infrared (IR) spectroscopy and nuclear magnetic resonance ("F NMR) . TFE was copolymerized with PPOTESF in bulk by using a free radical initiator of the hydrocarbon type at a temperature of 50°C. Various TFE/ PPOTESF mole ratios were employed and the presence of sulfonyl fluoride (-SOZF) functional groups in the copolymers was proven by IR spectroscopy. The copolymers were subjected to alkaline hydrolysis and the -SOzF content was found not to exceed 0.70-0.80 mEq/g with polymer yields in the range of 11-31%. The reactivity ratios rl and rz related to TFE and PPOTESF, respectively, were determined by using the Fineman-Ross method. A random distribution of PPOTESF units along the polymeric chain, consisting mainly of TFE fragments, was found to exist. The copolymers had melting temperatures 40-45OC lower than polytetrafluoroethylene and were thermally stable to 305-315°C.
INTRODUCTIONCopolymers of tetrafluoroethylene (TFE) and perfluorinated functional monomers containing sulfonyl fluoride (-S02F) groups are valuable materials. The application of these copolymers as cation-exchange membranes in chlor-alkali electrolytic cells, 's2 as well as utility as heterogeneous polymeric catalysts in the organic synthesis, is due to their high thermal and chemical stability combined with facile alkaline hydrolysis. Thus, the perfluorinated functional copolymers are known to acquire hydrophilic and ion-exchange properties, extending the area of their utilization.Synthesis of perfluorovinyl functional monomers with general formula * To whom correspondence should be addressed. Journal of Applied Polymer Science, Vol. 47,735-741 (1993) is a multistage and time-consuming procedure. A comparatively easy method of synthesizing such monomers has been suggested in the literature? According to some publications, TFE and hexafluoropropylene (HFP ) can be subjected to reactions with sulfur trioxide 5-8 followed by condensation of the products obtained to 2-( l-pentafluoro-2-propenyloxy ) -tetrafluoroethanesulfonyl fluoride (PPOTESF) CF2 = CFCF20CF2CF2S02FS. Some of the synthetic steps for PPOTESF preparation need, however, a further rationalization.Copolymers of TFE and PPOTESF have also been prepared in both solution and emulsion by using pentafluoropropionyl peroxide as a free radical initiator? However, no data concerning the influenceof the initial monomer composition on the content of perfluorovinyl functional monomer in the copolymers have been reported so far. The corresponding reactivity ratios remain unknown under the conditions studied.The ai...
IR spectroscopy method has been designed in order to determine the average molecular weight of polysulfide polymers of the general formula:where: the symbol End denotes the fragment H3C -CH(C,H,) or SH functionality;x = 1 -4 , m = 1 -4 0 a n d n = 1 -4 0 .The average molecular weight was determined, according to the formula: L I . M I + L I . X . M Z + L J . M J + L~. M J + Ls.Ms Ll+L5 M = 2 where L, represented the number of H3C -CH(C,H,) fragments; L2corresponded to the number of polysulfide bonds; the parameter x was the number of sulfur atoms per one polysulfide bond; L, was the number of CH2 -CH(C,H,) fragments bound along the polymer chain; L4 represented the number of the ethylene fragments involved; L5 denoted the number of -SH end groups and Mi, M2, MS, M4, M, corresponded to the molecular masses of the various structural fragments indicated above.
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