Kinetics of radical copolymerization of vinylidene fluoride with tert-butyl 2-trifluoromethyl acrylate: a suitable pair for the synthesis of alternating fluorinated copolymers

Abstract

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 r_VDF = 0.0399 and r_MAF-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.