Kinetics of radical copolymerization of vinylidene fluoride with tert-butyl 2-trifluoromethyl acrylate: a suitable pair for the synthesis of alternating fluorinated copolymers
The kinetics of the radical copolymerization of vinylidene fluoride (VDF) with tert-butyl 2-trifluoromethacrylate (MAF-TBE) initiated by tert-butyl peroxypivalate in solution is presented. The evolution of the microstructure and molecular weights of such resulting poly(VDF-co-MAF-TBE) copolymer was monitored using 19F nuclear magnetic resonance spectroscopy and gel permeation chromatography over the whole conversion range. In the early stage of the polymerization, an equimolar composition of VDF and MAF-TBE in the copolymer was observed until the total conversion of the latter. Subsequently, the polymerization of VDF was achieved leading to a mixture of poly(VDF-alt-MAF-TBE) copolymers and PVDF homopolymer chains. Closer investigation of the copolymerization was performed by synthesizing a series of seven copolymerization reactions from initial [VDF]0/[MAF-TBE]0 molar ratios ranging between 25/75 and 90/10. The kinetics of copolymerization led to the assessment of the reactivity ratios of both comonomers according to the Mayo–Lewis method and yielded rVDF = 0.0399 and rMAF-TBE = 0.0356 at 57 °C, evidencing an alternating copolymerization. The Q and e values of MAF-TBE were deduced to be 1.312 and 3.0, respectively.