Fabrication Of Robust MOFs/Aerogel Composite Via Covalent Post-Assembly Method

Metal-organic frameworks(MOFs)represent an emerging class of microporous coordination polymers,which are self-assembled in a highly modular manner from metal ions and organic linkers.Due to their molecular-level tunable framework structure and tailored pore environment,MOFs architectures have been applied in catalysis,storage/separation,energy conversion,drug delivery and so on.In recent years,MOFs have been mixed with other materials to prepare MOFs composites to maximize its potential.Polyimide(PI)has been widely used in aerospace,microelectronics,separation membrane and other fields due to its non-toxic and environmental protection property.A covalent post-assembly strategy is developed to prepare composite of dispersive MOFs particles in aerogel matrix.Briefly,UiO-66-NH2 is modified with pyromellitic dianhydride(PMDA)to produce UiO-66-NH-PMDA,which was used with Monomers(4,4’-diaminodiphenyl ether and pyromellitic dianhydride)of synthesizing polyimide through a simple one-pot method for amidation to achieve covalent connection among them.Subsequently,UiO-66-PI aerogel composite was obtained through the process of gel-sol,freeze-drying and thermal imidization.UiO-66-PI has better adsorption capacity of cationic dye(methylene blue)than UiO-66-NH2 powder.The removal rate is as high as 98.2%,and the equilibrium adsorption capacity is 3.70 mg/g.In addition,the material recovery loss is small and the reuse rate is high.Moreover,the efficiency can still be more than 90%of the initial after multiple cycles.For the[2+3]cycloaddition reaction of catalyzing carbon dioxide and styrene oxide,compared to UiO-66-NH2 powder,the yield was increased by 12%.In the fourth cycle,the catalytic efficiency still maintains more than 91%of the initial.