Preparation,Structure And Properties Of Imidazolyl Ionic Liquids Modified Poly(Vinylidene Fluoride) Composite Membrane

In this paper,based on the preparation and property reasearch of semi-permeable me mbrane,which is a core material of membrane separation technology,the"green solvent"?i.e.,the ionic liquid?was applied to modify the polyvinylidene fluoride to obtain the new-type separation membrane with theoretically good application properties.Firstly,three kinds of ionic liquids have been prepared:1-butyl-3-vinylimidazole tetrafluoroborate ionic liquids?[C₄VIm][BF₄]?,1-octyl-3-vinylimidazole tetrafluoroborate ionic liquids?[C₈VIm][BF₄]?and 1,6-hexyl-3'-bis-1-vinylimidazole tetrafluoroborate ionic liquids?[HVIm][BF₄]?.Meanwhile,the properties of composite film,the influence of different types and lengths of alkyl chain in ionic liquids were also explored.The effects of the contents of ionic liquid on the properties including thermal stability,crystallization property,morphology,dielectric property and contact angles,of composite films,have also been researched in this paper.The results indicated that the mono-cationic ionic liquids modified membrane?ILs-PVDF?is a kind of composite membrane with interpenetrating network structure and high thermal stability,good compatibility and uniform morphology.Dication ioinic liquids modified membrane?DILs-PVDF?has a phase-separated structure with high thermal stability and good hydrophilicity.Through the comparison of the both membranes,DILs-PVDF membrane displayed a better hydrophilicity than ILs-PVDF membrane.The dielectric property of ILs-PVDF membrane was also proved more excellent compared with DILs-PVDF membrane.Therefore,mono-cationic ionic liquids play a significant role in improving the dielectric properties of composite membrane.The results show that dication ioinic liquids has a wide prospect in hydrophilic modification of PVDF membrane.