Radical copolymerization of vinylidene fluoride with perfluoroalkylvinyl ethers

The radical copolymerization of perfluoromethylvinyl ether (PMVE) and perfluoropropylvinyl ether (PPVE) with vinylidene fluoride (VDF), initiated by tertiobutyl peroxypivalate (TBPPI) and ditertiobutyl peroxide (DTBP), respectively, are presented. The kinetics of copolymerization were investigated for each monomer from series of at least eight reactions for which the initial [VDF]0/[fluorinated vinyl ether]0 molar ratios ranged between 20/80 and 80/20. The copolymer compositions of these random-type copolymers were calculated by means of 19F NMR spectroscopy and allowed one to quantify the respective amounts of each monomeric unit in the copolymer. According to the Tidwell and Mortimer method, the reactivity ratios (ri) of both comonomers for each type of copolymerization were obtained : rVDF = 3.40 ± 0.40 and rPMVE = 0 at 74 °C; and rVDF = 1.15 ± 0.36 and rPPVE = 0 at 120 °C. Moreover, the glass transition temperatures (Tg's) of poly(VDF-co-PMVE) and poly(VDF-co-PPVE) copolymers containing different amounts of VDF and PMVE or PPVE, were determined and the theoretical glass transition temperatures of poly(PMVE) and poly(PPVE) homopolymer were deduced.