Synthesis and modification of alternating copolymers based on vinyl ethers, chlorotrifluoroethylene, and hexafluoropropylene

International audienceFluorinated copolymers bearing ammonium groups were prepared by radical copolymerization of fluorinated olefins (chlorotrifluoroethylene, hexafluoropropylene) with different vinyl ethers (2-chloroethyl, cyclohexyl, n-butyl, and ethyl vinyl ethers) followed by the cationization of these copolymers with trimethylamine. Copolymers were obtained in high yield (generally >85%), with molecular weights ranging from 8000 to 25 000 g mol-1. From elemental analysis as well as 1H and 19FNMR spectroscopy, the alternating structure of these polymers was confirmed. The chemical modification of these copolymers consisted of a two-step reaction: (i) the replacement of the chlorine atom by an iodine atom followed by (ii) the substitution of the halogen atom by the trimethylamine into a quaternary ammonium. The resulting copolymers were characterized with the usual techniques to assess their compositions and structures. Their thermal analyses, in dynamic mode, under air, showed decomposition temperatures (Td,10%) higher than 200 C. Electrochemical properties of some of these polymers were also studied, showing ionic exchange capacities (IEC) ranging from 0.50 to 0.75 mequiv g-1 (theoretical IEC up to 3.63 mequiv g-1) and water uptake of 13-25%