Pickering Emulsion Based On Covalent Organic Frameworks Catalytic Material And Its Properties

The Pickering emulsion catalytic system is a kind of important green chemical synthesis.The huge phase interface provided by the particle film can greatly improve the reaction efficiency,solve the problems of low efficiency of multi-phase catalysis and the dependence of surfactant and endow the heterogeneous catalytic system with new properties and functions.However,the efficient construction and functional integration of emulsion catalysts is still not perfect.The development of multifunctional interfacial catalytic systems has become a current research hotspot and difficulty,in which the key is to design new and efficient interfacial active particles.As a new class of crystalline porous materials,covalent organic frameworks（COFs）have a highly ordered pore structure,as well as many advantages such as structure,function,and morphology replaceable,consequently,it has important application prospects.With the above understanding,we intend to construct a multifunctional emulsion interface catalytic system by using nano-scale COFs-based catalytic materials as the stabilizers and to realize its efficient application in the fields of enzyme catalysis,including the following two parts of research content:Ⅰ:COFs-based magnetic core-shell nanospheres（abbreviation:Fe₃O₄@Dha Tph-lipase）loaded with enzyme were synthesized by using Fe₃O₄nanoparticles as a template.The composite nanoscale spheres can effectively stabilize the Pickering emulsion system composed of water/n-hexane,and the magetic responsive Pickering emulsion can realize the rapid demulsification behavior upon magnetic stimulation.Meanwhile,due to the presence of photosensitive porphyrin moieties in the COFs-based composite nanospheres,the above-mentioned emulsion system exhibited excellent photothermal conversion performance.Upon visible light irradiation(56 m W cm^-2,40 min),the temperature can rise from 28 to 55 ^oC.On this basis,the above-mentioned emulsion system can be efficience of catalyse for photothermal-assisted enzyme-catalyzed esterification reaction of caproic acid and 1-hexanol,and the facile separation and recovery of the catalyst can be in-situ realized by magnet for recyclability.Ⅱ:Six kinds of imine COFs nanocrystals with different hydrophilic and hydrophobic properties were synthesized,and which can be applied to stabilize the styrene-in-water（O/W）and water-in-styrene（W/O）Pickering high internal phase emulsions.COFs-based composite microspheres and porous monoliths were fabricated respectively by using the as-synalysized（W/O）and（O/W）HIPE as the template,through the in-situ free radial polymerization of styrene phase respectively.Among them,COFs/styrene composite microspheres constructed from gold nanoparticle-loaded COFs nanocrystals（Au NPs@Ta Pa-1）can be used as fillers and catalysts for fixed-bed reactors for the continuous flow-through catalytic reduction of 4-nitrophenol,which possessed a good applied prospect in the filed of water treatment and green catalysis.