Revisiting the Radical copolymerization of Vinylidene Fluoride with Perfluoro(4-methyl-3,6-dioxaoct-7-ene) sulfonyl fluoride
Résumé
The preparation of new membranes made of fluorofunctional copolymers based on vinylidene fluoride (VDF) and perfluoro(4-methyl-3,6-dioxaoct-7-ene) sulfonyl fluoride (PFSVE) comonomer is presented. Prior to process the membranes, the copolymers were synthesized by radical copolymerization of VDF with PFSVE, as in Scheme 1.
Scheme 1. Free radical copolymerization of trifluoroethylene (TrFE) with perfluoro(4-methyl-3,6-dioxaoct-7-ene) sulfonyl fluoride (PFSVE).
The radical copolymerization of VDF with PFSVE has been disclosed in patents1,2 or article3.and it was worth revisiting that reactions that was optimized by varying the natures of initiators (peroxypivalate or persulfate) and media (solvent or water). The results regarding the microstructures (determined by 1H and 19F NMR spectroscopy), molar mases, and thermostability of the resulting copolymers, evidenced the success of such a copolymerization.
Emulsion process was also studied and enabled to reach higher molar masses.
Monitoring the radical reaction versus time evidenced a formation of statistic copolymers (Figures 1 and 2). The SO2F containing copolymers were further hydrolyzed in slightly basic medium to lead to copolymers bearing -SO3H functions.
Hydrolysis of PFSVE monomer was also attempted and the resulting monomer was also copolymerized with VDF.
Processing these different copolymers into membranes by casting led to a wide range of materials of different characteristics that are discussed.
References:
1. Feiring, A. E.; Bekiarian, P. G.; Doyle, C. M.; Farnham, W. B.; Morken, P. A.; Roelofs, M. G. (to E. I. DuPont de Nemours & Co.). U.S. Patent 6,667,377, 2003.
2. B. Ameduri, M. Armand, M. Boucher, A. Manseri, WO 2001/49757; US2007185293 (assigned to Hydro-Québec).
3. L. Sauguet, B. Ameduri, and B. Boutevin, J. Polym. Sci. Part A: Polym. Chem., 45, 2007, 1814-1834.