Fluorinated copolymers and terpolymers based on vinylidene fluoride and bearing sulfonic acid side‐group

Abstract

The radical co‐ and terpolymerization of perfluoro(4‐methyl‐3,6‐dioxaoct‐7‐ene) sulfonyl fluoride (PFSVE) with 1,1‐difluoroethylene (or vinylidene fluoride, VDF or VF2), hexafluoropropene (HFP), chlorotrifluoroethylene (CTFE), and bromotrifluoroethylene (BrTFE) is presented. Although PFSVE could not homopolymerize under radical initiation, it could be copolymerized in solution under a radical initiator with VDF, while its copolymerizations with HFP or CTFE led to oligomers in low yields. The terpolymerizations of PFSVE with VDF and HFP, with VDF and CTFE, or with VDF and BrTFE also led to original fluorinated terpolymers bearing sulfonyl fluoride side‐groups. The conditions of co‐ and terpolymerization were optimized in terms of the nature and the amount of the radical initiators, of the nature of solvents (fluorinated or nonhalogenated), and of the initial amounts of fluorinated comonomers. The different mol % contents of comonomers in the co‐ and terpolymers were assessed by 19F NMR spectroscopy. A wide range of co‐ and terpolymers containing mol % of PFSVE functional monomer ranging from 10 to 70% was produced. The kinetics of copolymerization of VDF with PFSVE enabled to assess the reactivity ratios of both comonomers: rVDF = 0.57 ± 0.15 and rPFSVE = 0.07 ± 0.04 at 120 °C. The thermal and physicochemical properties were also studied. Moreover, the glass transition temperatures (Tgs) of poly(VDF‐co‐PFSVE) copolymers containing different amounts of VDF and PFSVE were determined and the theoretical Tg of poly(PFSVE) homopolymer was deduced. Then, the hydrolysis of the SO2F into SO3H function was investigated and enabled the synthesis of fluorinated copolymers bearing sulfonic acid functions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1814–1834, 2007

Radical copolymerization of vinylidene fluoride with 1‐bromo‐2,2‐difluoroethylene

“…We have found that r VDF = 1.20 ± 0.50 and r BDFE = 0.40 ± 0.15 at 75 °C showing that VDF is more reactive than BDFE and showing also that they are statistic copolymers as most of the copolymers of VDF 7. (a), 8 (c), 35–57 Compared with the reactivity ratios of other fluoromonomers able to copolymerize with VDF (Table 4), the value of the reactivity ratio of BDFE was found to be between that of HCFCF 2 (0.50) and that of F 2 CCF(CH 2 ) 3 SAc (0.41) (Table 4) but r VDF is much lower ( r VDF = 0.70 or 0.60, respectively vs. 1.20 in that present study). These values can be compared with the reactivity of other fluoromonomers able to copolymerize with VDF (Table 4),7 (a), 8 (c), 35–57 and with the values arising from the radical copolymerization of TFE with BDFE ( r TFE = 0.82; r BDFE = 0.24) 20…”

Original Fuel‐Cell Membranes from Crosslinked Terpolymers via a “Sol–gel” Strategy

“…In fact, starting from a VTEOS-feed molar percentage of 9.4 ( The hydrolysis of the sulfonyl fluoride group of these poly(VDFter-PFSVE-ter-VTEOS) terpolymers in a basic medium was studied to generate the sulfonic acid functions necessary for the proton conductivity. As the VDF groups are very sensitive to basic conditions, [34][35][36][37][38][39] the conversion of the -SO 2 F groups in the PFSVE units into -SO 3 Li in the terpolymer was achieved using Li 2 CO 3 (2 mol equivalents for 1 mol of SO 2 F group) at room temperature (Scheme 1).…”

“…In this way, the vinyltriethoxysilane (VTEOS) units of the terpolymer help to bind and assemble the inorganic network into a continuous medium and the perfluoro(4-methyl-3,6-dioxaoct-7-ene) sulfonyl fluoride (PFSVE) chains are able to bridge the conduction paths in the hybrid membrane by way of their -SO 3 H-functionalized chain ends. The synthesis of such terpolymers was investigated through the radical terpolymerization of vinylidene fluoride (VDF), [30][31][32][33][34][35] PFSVE [36] and VTEOS (Scheme 1). To the best of our knowledge, no reports have been published as to the synthesis of such a type of copolymer or terpolymer, containing both Si(OR) 3 and SO 2 R 0 (R ¼ CH 3 , C 2 H 5 , etc.…”

Perfluorosulfonated ionomers membranes: Melt‐processing and characterization for ion exchange applications

“…Recently, Dongyue Research Institute in China has developed a series of PFSI precursors, structurally similar to the ionomers reported by Sauguet et al In Scheme , the radical copolymerization of tetrafluoroethylene and perfluoro[2‐(2‐fluorosulfonylethoxy) propyl vinyl ether] the copolymerization was initiated using perfluoroacyl peroxide in fluorocarbon solvent. After conversion of –SO 2 F groups into –SO 3 Na or –SO 3 H, the PFSI membranes are proved to be a good alternative to Nafion ® in most applications.…”