Synthesis and copolymerization of vinylidene fluoride (VDF) with Trifluorovinyl Monomers, 11

Abstract

The radical telomerization of vinylidene fluoride with 1-chloro-1,2-dibromotrifluoroethane is presented. This dibrominated transfer agent was produced readily from the addition of bromine to chlorotrifluoroethylene in high yields. Four different ways of initiation (thermal, photochemical, or in the presence of redox catalysts or radical initiators) were used in order to obtain optimized yields and degrees of telomerization. Interestingly, the thermal process carried out at 210°C led to fair to good yields in contrast to photochemically induced reaction or that catalyzed by redox systems (this latter reaction produced the monoadduct only). When radical initiators were used, tert-butyl peroxypivalate was the most efficient one, despite the lower reaction temperature. 1 H and 19 F NMR spectra enabled the microstructure of VDF telomers to be described and to determine the cumulative average degrees of telomerization (DP n ). Similarly, gas chromatography, able to detect even the ninth-order adduct, was also useful to assess the DP n . The kinetics of telomerization of this reaction allowed the determination of the first three order transfer constants (C T i ) and led to C T ∞ = 1.3 at 75 °C.