Preparation Of Metal-metal Oxide Nanoparticles By Using Block Copolymer As Templates

Metal-metal oxide nanoparticles represent an important class of multicomponent heterostructured nanoparticles. Single component material can not meet people's demand compared with multifunctional materials. In order to meet people's needs of materials for versatility, integration of multiple components not only provides new physical properties due to the coupling between the different components but has its own roperties improved. It has potential values in catalysis, biosensors, drug delivery, electronics, optics and other fields. This thesis mainly investigated the preparation methods of metal-metal oxide nanoparticles by using the block copolymer micelles of polystyrene-b-poly(2-vinyl pyridine)(PS-b-P2VP), polystyrene-b-poly(ethylene oxide)(PS-b-PEO) and poly(2-vinylpyridine)-b-poly(ethylene oxide)(P2VP-b-PEO) as the templates. Using the block copolymer micelles as templates which were formed in the selective solvents, Au-Ce O2 and Au-Cu2 O nanoparticles were synthesized by oxidation reduction method and hydrazine reduction method. To remove the block copolymers, the nanoparticles were calcined at high temperature under nitrogen gas and then the catalytic properties of Au-Ce O2 nanoparticles by ultrasonic degradation of methyl orange were tested.(1) The micelles of PS-b-P2 VP block copolymer were used as a template to prepare Au-Ce O2 nanoparticles. Cerium nitrate and chlorine gold acid solutions in ethanol were added in a toluene solution of the PS-b-P2 VP block copolymer to form reverse micelle emulsion. At the same time, Na OH ethanol solution was added in a PS-b-P2 VP toluene solution and formed another reverse micelles. Na OH provided the whole system a alkali environment. Ce3+ in a strong alkaline environment exhibit strong reducing ability, Au3+ was reduced to Au. Finally the "strawberry" shaped Au-Ce O2 nanoparticles were obtained. The samples were calcined in the conditions of N2 atmosphere to remove the block copolymer, and the samples before and after calcined were used as catalyst to degrade methyl orange by ultrasound catalytic, the effects of calcination time on the catalytic performance of nano-particles were studied. The prepared catalytic nano-materials showed good properties in the catalytic degradation of organic dyes and other organic reactions.(2) PS-b-PEO block copolymers micelle were also used as a template to prepare Au-Ce O2 nanoparticles. The ethanol solution of gold chloride acid and cerium nitrate was added to the micelles of PS-b-PEO then the redox reactions between Ce3+and Au Cl4- was triggered by adding a strong base Na OH, and eventually Au@Ce O2 core-shell nanoparticles were generated. The obtained nanoparticles were characterized by UV-vis spectra, X-ray diffraction(XRD) and transmission electron microscopy(TEM). By adjusting the ratio between different metal precursors in the system, Au@Ce O2 core-shell nanoparticles of different morphologies and sizes were obtained.(3) Using the P2VP-b-PEO block copolymers micelles as template, Au NPs were obtained by UV reduction. Then copper nitrate was added to the Au NPs solution, Cu2+ complex with P2 VP block which arounding Au NPs. Using hydrazine as reduction to reduce the Cu2+, yolk-shell Au-Cu2 O nanoparticles were obtained after the Ostwald ripening process. In order to get different degree of hollow nanoparticles, the influence of reaction times was considered. different shapes of Cu2 O nanoparticals were obtained by adjusting the amount of hydrazine which can change the p H value of the system and affect the formation of Cu2 O nanoparticals.