The radical copolymerization in solution of vinylidene fluoride (VDF; or 1,1-difluoroethylene) with methyl 1,1-dihydro-4,7-dioxaperfluoro-5,8-dimethyl non-1-enoate (MDP) initiated by di-tert-butyl peroxide is presented. Six copolymerization reactions were investigated with initial [VDF](0)/[MDP](0) molar ratios of 35/65 to 80/20. Both of these comonomers copolymerized in this range of copolymerization. Moreover, these comonomers homopolymerized separately under these conditions. The copolymer compositions of these random copolymers were calculated by means of F-19 NMR spectroscopy, which allowed the quantification of the respective amounts of each monomeric unit in the copolymers. The Tidwell-Mortimer method was used for the assessment of the reactivity ratios (r(i)) of both comonomers, which showed a higher incorporation of MDP in the copolymers (r(MDP) = 2.41 +/- 2.28 and r(VDF) = 0.38 +/- 0.21 at 120 degreesC). The Alfrey-Price Q and e values of the trifluoroallyl monomer MDP were calculated to be 0.024 (from Q(VDF) = 0.008) or 0.046 (from Q(VDF) = 0.015) and 0.70 (vs e(VDF) = 0.40) or 0.80 (vs e(VDF) = 0.50), respectively, indicating that MDP was an electron-accepting monomer. The thermal properties of these fluorinated copolymers were also determined. Except for those containing a high amount of VDF, the copolymers were amorphous. Each showed one glass-transition temperature (T-g) only, and with known laws of T-g's, T-g of the MDP homopolymer was assessed. It was compared to that obtained from the direct radical homopolymerization of MDP and discussed. Indeed, these two values were close (T-g = -3 degreesC). Thermogravimetric analyses were performed, and they showed that the copolymers were rather thermostable because the thermal degradation occurred at 280 degreesC. (C) 2003 Wiley Periodicals, Inc.