Surface Functionalization Of Magnetic Polymer Nanoparticles And Its Application In Heterogeneous Reaction

Surface functionalized polymer nanoparticles have been widely used in heterogeneous catalysis reaction.By adding nanoparticles into the liquid-liquid heterogeneous reaction system,the reaction rate can be improved significantly.In this paper,we synthesized magnetic polymer nanoparticles with different surface properties and combined it with Pickering emulsion,the mechanisum of nanoparticles enhanced heterogeneous reactions were investigated and its application was studied.The main research content of this paper is as follows:?1?A green strategy using magnetic polymer nanoparticles to enhance liquid-liquid heterogeneous reaction was developed.We synthesized magnetic polymer nanoparticles?Fe₃O₄/PS[Im-C_n]Cl?modified by different N-alkyl imidazoles,and systematically discussed the effect of surface properties on the formation of emulsions and the reaction rate in the oxidation of alcohols.It was found that,by loading such particles,droplet size controllable Pickering emulsion can be formed,and the reaction conversion can be improved for nearly 4 times.The mechanisum of nanoparticle enhanced heterogeneous reaction was revealled:nanoparticle stabilized Pickering emulsion can transfer traditional Montanarioxidation system from unstable millimeter scale dispersions into stable micrometer scale emulsions,which tremendously reduced the reactant transfer distance and resulted in a high reaction rate.?2?Magnetic polymer nanoparticles with multipoint load of TEMPO catalyst were designed and prepared.In this method,RAFT agent benzyl 9H-carbazole-9-carbodithioate?BCBD?were first immobilized onto the surface of Fe₃O₄/Chloromethyl PS.Subsequently,RAFT polymerization was conducted by grafting N-vinylimidazale polymer brush on the surface of Fe₃O₄/PS-BCBD.The effect of the BCBD addition quantity on the grafting amount of polymer was investigated,and it was found that grafting amount of polyvinylimidazale was increased with the increased addition quantity of BCBD.At last,the catalyst Fe₃O₄/PS-PVI-?CH₂?₆-TEMPOwaspreparedbyimmobilizing Br-?CH₂?₆-TEMPO onto the N-vinylimidazole polymer brush.The reaction efficiency was evaluated by Montanari oxidation of alcohols and the result show that the Fe₃O₄/PS-PVI-?CH₂?₆-TEMPO nanoparticle has a good catalytic activity.?3?Montanari oxidation reaction system with concentrated sea-water as bromine sources was developped.The study found that,the reaction efficency of TEMPO/NaClO oxidation system can be improved double by using concentrated sea-water as bromine sources.To further improve the reation efficency,surace modified magnetic polymer nanoparticles Fe₃O₄/PS[Im-C₆]Cl were introduced to the reaction,and the reaction conversion improved almost seven times.The reseach found that nanoarticles as Pickering emulsifier can be also applied to high salt concentration?concentrated seawater?reaction conditon,and this Montanari heterogeneous reaction system with concentrated sea-water as bromine sources has a high application value.