Radical Terpolymerization of 1,1,2-Trifluoro-2-pentafluorosulfanylethylene and Pentafluorosulfanylethylene in the Presence of Vinylidene Fluoride and Hexafluoropropylene by Iodine Transfer Polymerizat

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• 作者：Cyrille Boyer ; Bruno Ameduri ; Bernard Boutevin ; William R. Dolbier ; Rolf Winter ; Gary Gard
• 刊名：Macromolecules
• 出版年：2008
• 出版时间：February 26, 2008
• 年：2008
• 卷：41
• 期：4
• 页码：1254 - 1263
• 全文大小：491K
• 年卷期：v.41,no.4(February 26, 2008)
• ISSN：1520-5835

文摘

Iodine transfer terpolymerization of two monomers bearing an SF₅ group, i.e., 1,1,2-trifluoro-2-pentafluorosulfanylethylene (F₂C=CFSF₅) and pentafluorosulfanylethylene (H₂C=CHSF₅), with 1,1-difluoroethylene (or vinylidene fluoride, VDF) and hexafluoropropylene (HFP) is presented. These pentafluorosulfanylmonomers present a peculiar reactivity. They do not homopolymerize by conventional radical polymerization,but they co- and terpolymerize with the above fluorinated olefins. The resulting fluorinated terpolymers werecharacterized by ¹⁹F and ¹H NMR spectroscopies which enabled the assessment of the molar percentages of thethree comonomers. Size exclusion chromatography and NMR characterizations were also used to assess themolecular weights, M_n, ranging between 260 and 8400 g/mol. Interestingly, both these pentafluorosulfanylmonomers exhibit different behaviors in that radical terpolymerization in the presence of C₆F₁₃I as a degenerativechain transfer agent. Thus, CF₂CFSF₅ can be terpolymerized with VDF and HFP with a good control of molecularweight leading fluoropolymers bearing SF₅ groups with low polydispersity index (PDI). Unexpectedly, only twoiodide functionalities of the terpolymers namely two end groups (-CH₂CF₂I and -CF₂CH₂I) were observed andtheir proportions were influenced by the number of VDF units. Indeed, -CH₂CF₂I functionality decreased whenthe number of VDFs per chain increased. In contrast to 1,1,2-trifluoro-2-pentafluorosulfanyl ethylene, H₂C=CHSF₅ could not be terpolymerized by ITP but led to C₆F₁₃[(CH₂CF₂)(CH₂CH(SF₅)]_nI alternating cooligomersof low molecular weight in poor yields (5-20%). The formation of byproduct (C₆F₁₃CH=CHSF₅ monoadductobtained by dehydrofluorination) was also observed, which corresponds to the elimination of HI from the 1:1adduct. In the last part, the thermal properties are discussed. The presence of SF₅ group decreases the T_g offluoropolymers whereas the thermal stabilities depended on the molecular weights.