Fabricating Of Highly Catalytieally Active Metal Nanoparticle/Polymer Composites At The Liquid/Liquid Interface

Nanoparticles exhibit particularly optical,electric,and magnetic properties than bulk solids due to their small-size effect,surface effect and macroscopic quantum tunneling effect.In general,the catalytic activities of the particles increase with decreasing size.Metal nanoparticles provide highly active site but are very small and unstable due to high surface energy and the large surface.There are a number of methods to prevent them from aggregation,such as addition of stabilizing agents and depositing nanopartices onto the substrates.Though small size nanoparticles capped with protective agents are stable,the process that reactant diffuse into the surface of catalyst is long which is disadvantageous for improving the rate of the catalytic reaction.Therefore,it is crucial to find a new way to prevent nanoparticles from aggregation and improve the rate of the catalytic reaction at the same time.We developed a facile method to fabricate PS-b-PAA/nanoparticle composite film at the planar liquid/liquid interface between the solution of metal salt and a chloroform/DMF mixed solution of PS-b-PAA.The composite film was immersed into into a KBH4 aqueous solution in order to reduce the Cu(?)species to Cu(0).The treated films exhibit good catalytic activity and good recyclability.We also explored the influence of different metal ion to the assembly of PS-b-PAA.1.Fabricating Highly Catalytically Active Block Copolymer/Metal Nanoparticle Microstructures at the Liquid/Liquid InterfaceIn this work,the experiment is mixed DMF/CHCl3 solution of block copolymer PS-b-PAA and an aqueous solution of Cu(CH3COO)2 formed a liquid/Iiquid interface,Water droplets containing Cu2+ ions migrate to the organic phase due to the ouzo effect that arise from the miscibility of water with DMF,leading to the formation of a W/O emulsion.PS-b-PAA molecules penetrate into the droplets,interact with Cu2+ions,and self-assemble into spherical miceilles.At the same time,free PS-b-PAA molecules self-assemble into nanofibers that connect up the micelles.The spherical micelles and the nanofibers adsorb at the planar liquid/liquid interface and accumulate to form a porous microstructure.Tiny and well-dispersed Cu nanoparticles are generated in the microstructure after treatment.This composite structure exhibits high catalytic activity and good recyclability both for the reduction of the substrates,such as nitroarenes,methylene blue and methyl orange,and for the oxidation of the substrates,such as o-phenylenediamine in aqueous solutions due to the large porous structure,homogeneous dispersion of tiny nanoparticles,the hydrophilicity and good water wettability of the matrices.The rate constant for the reduction of p-nitroaniline reaches to 1965 s-1g-1.2.Effect of metal ions on the self-assembly behavior of amphiphilic block copolymerThe experiment is mixed DMF/CHCl3 solution of block copolymer PS-b-PAA as lower phase and an aqueous solution of Co(CH3COO)2(Ni(CH3COO)2)as upper phase,then formed a liquid/liquid interface.The morphology of PS-b-PAA/Co and PS-b-PAA/Ni is similar,which is composite spherical aggregation.The structure of the interior of the composite spherical aggregation is micro-phase structure.The reason of the similar morphology of PS-b-PAA/Co and PS-b-PAA/Ni may be the same coordination number when PS-b-PAA coordinated with Co2+ and Ni2+.We also researched influence of Zn2+ and Cd2+ to the assembly of PS-b-PAA.This composite film of PS-b-PAA/Co and PS-b-PAA/Ni exhibit high catalytic activity.