Prepartion of Metal Nanoparticles and Core-Shell Composite Nanoparticles
| Autor: | Szu-Han Wu, 吳思翰 |
|---|---|
| Rok vydání: | 2004 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 92 This dissertation concerns the preparation of metal nanoparticles and core-shell composite nanoparticles. In the former, nickel and copper nanoparticles have been prepared in ethylene glycol and aqueous surfactant systems. The preparation conditions and product properties were investigated. In the latter, Ni@Au core-shell composites nanoparticles were prepared in ethylene glycol system and covalently bound with methotrexate (MTX). In ethylene glycol system containing trace bases, Ni nanoparticles could be prepared by hydrazine reduction without the input of extra inert gases and the addition of protective agent. FTIR analysis revealed the formation of a protective layer from ethylene glycol and the Ni-catalyzed decomposition products, which prevented from the agglomeration of particles. The TEM, high-resolution TEM, XRD, electron diffraction pattern, magnetic analyses indicated the resultant particles were pure Ni nanoparticles with the mean diameter of 6-9 nm, fcc structure, and superparamagnetic property. With increasing N2H5OH concentration, The mean diameter decreased and approached a constant when [N2H5OH]/[NiCl2]>20. In addition, hydrazine was catalytically decomposed to hydrogen and nitrogen gases by the resultant Ni nanoparticles. The decomposition rate was 3.1 nmol/h mg Ni at 1 atm and 25℃. In a pure aqueous CTAB solution containing trace bases, Ni nanoparticles could be prepared by hydrazine reduction without the input of extra inert gases. the synthesis of nickel nanoparticles without inert gases was studied. TGA study suggested the formation of a bi-layer structure on particle surface, which prevented from the agglomeration of particles. The TEM, high-resolution TEM, XRD, electron diffraction pattern, magnetic analyses indicated the resultant particles were pure Ni nanoparticles with mean diameters of 10-14 nm, fcc structure, and a superparamagnetic property. With increasing N2H5OH concentration, the mean diameter decreased and approached a constant when [N2H5OH]/[NiCl2]>20. In a pure aqueous CTAB solution, Cu nanoparticles could be prepared by hydrazine reduction without the input of extra inert gases. The key point was the use of ammonia solution to adjust the solution pH up to 10. The concentration of Cu2+ ions allowable was as high as 0.2 M. TGA study suggested the formation of a bi-layer structure on particle surface, which prevented from the agglomeration of particles. The TEM, XRD, electron diffraction pattern, UV-VIS spectrum, and XPS analyses indicated the resultant particles were pure Cu nanoparticles with mean diameter of 5-15 nm and fcc structure. With increasing N2H5OH concentration, the mean diameter decreased and approached a constant when [N2H5OH]/[NiCl2]>40. In ethylene glycol, Ni@Au core-shell composites nanoparticles were prepared. In the absence of protective agent, particle agglomeration was observed. In the presence of polyethyleneimine (PEI) as a protective agent, monodisperse Ni@Au composite nanoparticles with a mean diameter of 14.6 nm were obtained. After surface modification, Ni@Au composite nanoparticles were covalently bound with methotrexate (MTX). Averagely 3.63×104 MTX molecules could be bound on each Ni@Au composite nanoparticle. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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