Telomerization of vinylidene fluoride with alkyl (or aryl) trifluoromethanethiosulfonates

The photochemical-induced telomerization of vinylidene fluoride (VDF) with cyclohexyl (or phenyl) trifluoromethanethiosulfonate (CF3SO2SR), leading to CF3(VDF)(n)SR telomers, where R stands for cyclohexyl or phenyl, is presented. These sulfurated transfer agents were synthesized by the reaction between sodium triflinate (CF3SO2Na) and disulfide in the presence of bromine. F-19 NMR spectroscopy enabled an assessment of the average degrees of telomerization (DPn) of these telomers with a neat CF3 end group as the label. These DPn values increased for higher [VDF](0)/[CF3SO2SR](0) initial molar ratios. Interestingly, the normal/reversed ratio of VDF units in these telomers was low. Finally, the cotelomerization of VDF and hexafluoropropylene with these transfer agents was successfully achieved, leading to original omega-CF3 fluoroelastomers, the thermal properties of which were investigated. (C) 2002 Wiley Periodicals, Inc.