Poly(vinylidene fluoride-co-trifluoroethylene-co-chlorotrifluoroethylene) (P(VDF-co-TrFE-co-CTFE)) with internal double bond has been reported with high dielectric constant and energy density at room temperature, which is expected to serve as a promising dielectric film in high pulse discharge capacitors. An environmentally friendly one-pot route, including the controllable hydrogenation via Cu(0) mediated single electron transfer radical chain transfer reaction (SET-CTR) and dehydrochlorination catalyzed with N-containing reagent, is successfully developed to synthesize P(VDF-co-TrFE-co-CTFE) containing unsaturation. The resultant polymer was carefully characterized with H-1 NMR, F-19 NMR, and FTIR. The composition of the resultant copolymer is strongly influenced by reaction conditions, including the reaction temperature, catalyst concentration, the types of ligands and solvents. The kinetics data of the chain transfer and elimination reaction demonstrate their well-controlled feature of the strategy. By shifting the equilibrium between the CTR and elimination reactions dominated by N-compounds serving as ligands in SET-CTR and catalyst in the dehydrochlorination of P(VDF-co-CTFE), P(VDF-co-TrFE-co-CTFE) with tunable TrFE and double-bond content could be synthesized in this one-pot route. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3429-3440