Novel Source of Trifluoromethyl Radical As Efficient Initiator for the Polymerization of Vinylidene Fluoride

Abstract

A persistent perfluoroalkyl radical (PPFR), perfluoro-3-ethyl-2,4-dimethyl-3-pentyl, is shown to be a good source of •CF(3) radicals and a useful radical capable of initiating the polymerization of vinylidene fluoride (VDF). NMR characterizations of the resulting PVDF homopolymers showed that polymerization of VDF was exclusively initiated by •CF(3) radicals. The addition of •CF(3) radical onto VDF was regioselective leading to CF(3) -CH(2) -CF(2) -PVDF and the CF(3) end-group acted as an efficient label to assess the molecular weights by (19) F NMR spectroscopy. Various [PPFR](0) /[VDF](0) initial molar ratios lead to CF(3) -PVDF-CF(3) of different molecular weights. When that ratio decreased, both the molecular weights and the thermostability of these PVDFs increased, showing less defects of chaining and higher crystallinity.

Radical copolymerisation of chlorotrifluoroethylene with isobutyl vinyl ether initiated by the persistent perfluoro-3-ethyl-2,4-dimethyl-3-pentyl radical

“…The small signals in the polymer spectra are ascribed to cumulative intensities of the small signals seen in the iBuVE spectrum. These signals are due to 1 H- 13 C coupling.…”

“…The literature 10,13 indicates that, if the polymerisation occurs in a regioselective way via path 1a, there should be only one 19 F NMR signal for CF 3 , centered at -63 ppm.…”

Waterproof and Breathable Electrospun Nanofibrous Membranes

“…Due to the stable CF bond (high bond energy 540 kJ mol −1 ) and the shielding effect that the highly electronegative fluorine atoms can have on the carbon chain, fluorinated compounds possess a lot of interesting properties, including low surface free energy, and good water and oil resistance, making them as promising dopants for constructing W&B membranes. Based on carbon chain length of perfluoroalkyl chain (C n F 2 n +1 ), fluorinated compounds can be divided into the long‐chain ones (perfluorocarboxylic acids, n ≥ 7; perfluoroalkane sulfonic acids, n ≥ 6) and the short‐chain ones . Recently, Ge et al .…”

“…Based on carbon chain length of perfluoroalkyl chain (C n F 2n+1 ), fluorinated compounds can be divided into the long-chain ones (perfluorocarboxylic acids, n ≥ 7; perfluoroalkane sulfonic acids, n ≥ 6) and the short-chain ones. [71,72] Recently, Ge et al [73] synthetized novel C8FPU containing long terminal perfluoroalkane segment (C 8 F 17 ) via solution polymerization and incorporated the C8FPU into PU spinning solution to fabricate C8FPU/PU W&B fibrous membranes. The incorporation of FPU not only endowed the nanofibers with low surface energy, but also introduced hierarchically rough structures on fiber surface (Figure 5a).…”

Spectroscopic observation of charge transfer complex formation of persistent perfluoroalkyl radical with aromatics, olefin, and ether

“…The study on these persistent perfluoroalkyl radicals has been hampered with difficult availability due to the need of manipulation of fluorine gas or an electrochemical fluorination cell for the preparation and has accordingly appeared sporadically in the literatures [3][4][5][6][7][8][9][10]. The most recent ones are on the use of PFR-1 as the convenient trifluoromethyl radical source for initiating the polymerization of fluoro monomers [11][12][13]. Here we unveil some new cryptic nature of the persistent perfluoroalkyl radicals on the unexpected intermolecular interactions with the electrons of some chemicals such as p-electrons of the benzene derivatives or 1-decene and also with the unshared electron pairs of ether through chargetransfer (CT) complexation.…”