Innovative Trifluoromethyl Radical from Persistent Radical as Efficient Initiator for the Radical Copolymerization of Vinylidene Fluoride with <i>tert</i>-Butyl α-Trifluoromethacrylate

Abstract

A persistent perfluoroalkyl branched radical (PPFR), perfluoro-3-ethyl-2,4-dimethyl-3-pentyl, was shown to be a good source of • CF 3 radicals able to initiate the radical copolymerization of vinylidene fluoride (VDF) with tert -butyl α-trifluoromethacrylate (MAF-TBE). NMR characterizations of the resulting poly(VDF- co -MAF-TBE) copolymers showed that copolymerization was exclusively initiated by • CF 3 radicals, as evidenced by the thermal decomposition of PPFR above 80 °C. The addition of • CF 3 radical onto VDF/MAF-TBE system was regioselective leading to CF 3 -CH 2 -CF 2 • radical that further cross propagated onto MAF-TBE unit and the α,ω-trifluoromethyl group acted as an efficient label to assess the molecular weights of the resulting copolymers by 19 F NMR spectroscopy. Three [PPFR] 0 /([VDF] 0 + [MAF-TBE] 0 ) initial molar ratios (2.0, 1.0, and 0.5%) led to various molecular weights ranging from 21300 to about 105000 g·mol –1 . When that ratio decreased, both the molecular weights and the thermostability of these original poly(VDF- co -MAF-TBE) copolymers increased.