Crosslinked terpolymers of vinylidene fluoride, perfluoro-3,6-dioxa-4-methyl-7-octene sulfonyl fluoride, and cure site monomers for membranes in PEMFC applications

摘要: Radical terpolymerisations of perfluoro(8-cyano-5-methyl-3,6-dioxaoct-1-ene) (CNVE) or 2,2,3,3,4,4,5,5,6,6-decafluoro-6-[(1,2,2-trifluoroethenyl) oxy] hexanenitrile (MV5CN), vinylidene fluoride (VDF) and perfluoro(4-methyl-3,6-dioxaoct-7-ene) sulfonyl (PFSVE) are presented. Changing the monomer feed compositions these enabled synthesis different statistical-type poly(VDF-ter-PFSVE-ter-CNVE) terpolymers containing nitrile side groups. Yields higher than 11% were reached in all cases. The hydrolysis groups into sulfonic acid functions, using potassium hydroxide (or lithium carbonate) under mild conditions, was achieved quantitatively without affecting content VDF, assuming that no dehydrofluorination VDF units occurred. These original then thermally crosslinked cyclisation pendant functions to produce films insoluble organic solvents such as acetone dimethylformamide (that completely dissolved uncured terpolymers). thermal stabilities materials those terpolymers. Depending on terpolymers, ion-exchange capacities ranged from 0.95 1.32 meq H+ per g. proton conductivity at 80 °C 100% relative humidity 58 mS cm−1 for a membrane 240 having hydration number 33 H2O/SO3H, while excessive swelling observed membranes lower temperatures.