Research On Design,Preparation And Properties Of Superhydrophobic MOF And Their Composites

Metal Organic Frameworks?MOFs?belong to a new class of crystalline materials that consist of coordination bonds between metal clusters,metal atoms,or rod-shaped clusters and multidentate organic linkers.One of the foremost challenges that plague the translation of MOFs into materials suited for commercialization is their water-influenced degradation,largely accountable to hydrolytic instability and the ubiquity of water.Hydrophobic MOFs offer one of the most promising solutions.Based on the research background of energy and environmental problems,under the current social development,in this paper,several super-hydrophobic MOF composites are designed and prepared,and their properties and mechanism of action are studied.The main results of this thesis are as follows:1.A universal strategy is developed to construct MOFs-based superhydrophobic/superoleophobic materials by the reaction of activated MOFs and octadecylamine.The porosity and crystallinity of the as-synthesized MOFs materials were nearly unchanged by this strategy and the S-MOF exhibited surface superhydrophobicity.They all demonstrated high adsorption capacities toward organic solvents and exhibited excellent oil-water separation performancewithout external pressure.After 10 cycle experiments,the oil-water separation performance was maintained.2.The terrible moisture or water stability of MOFs has become a daunting challenge for their practical applications in industry fields.In this study,an original porous polymer-confined strategy is developed to prepare superhydrophobic MOF composite?noted as PDVB-vim/ZIF-8 composite?.The obtained PDVB-vim/ZIF-8 composite features a unique superhydrophobic composite which confined MOF in porous polymer and can act as efficient heterogeneous catalyst for the Friedel-Crafts alkylation reaction of indoles with trans-?-nitrostyrene.The results revealed that the superhydrophobic catalyst promotes reactions via restraining the water molecules from the solvent or humid environment to influence the catalytic activity of ZIF-8 with a mechanism for synergistic activation by Lewis acid site and H-bond interaction.3.The conversion of CO₂ into chemical feedstock has attracted attention in recent years as it is an abundant C1 resource and the conversion of CO₂ into value-added fine chemicals is of environmental and practical importance.In this study,we developed a novel post-synthetic modification strategy?PSM?to prepare superhydrophobic MOF composites?noted as MOF-CF₃?.Under relatively mild conditions,we used these composites as catalysts to catalyze the cycloaddition reaction between CO₂ and epoxides,and TBABr was used as a co-catalyst and the catalytic efficiency was excellent compared to bare MOFs as catalysts.This phenomenon was attributed to that superhydrophobic MOF-CF₃ could enrich the substrate and the Lewis acidity of the metal sites in MOF-CF₃ was stronger than that of the original MOF.This maight be ascribed to the strong electron-drawing property of the trifluoromethyl group and delocalizing the charge of the metal site in the MOF,which thus enhanced the catalytic activity of the composites.