Development of preparation of core-shell particles and their ordering

点击翻译按钮获取中文摘要

For preventing aggregation and damage of particles, silica-coating has been proposed. Ag nanoparticles with a size of 10 nm, Au nanoparticles with a size of 15 nm and Co nanoprticles with a size of 20 nm were successfully coated with silica with a modified Stober method. Silica shell thickness was varied with varying concentration conditions. Photo-properties for the silica-coated Ag and Au nanoparticles could be explained with a Mie theory. The silica-coated Co nanoparticles showed magnetic properties different from bulk materials. The proposed method could be also extended to silica -coating AgI nanopartides and fluorescent microspheres.Mono-layering of sub-micron-sized polystyrene and silica spheres on glass substrates by a dip-coating technique has been demonstrated. For the mono-layering the spheres in a hexagonal close-packed structure on the substrates, it was necessary to reduce ionic strength of dispersion of the colloidal suspension. Multi-layering of the spheres was achieved by repeating the dip-coating process. For the case of large spheres layered on small ones, the large spheres were mono-layered on the mono-layer of the small spheres just as spheres were mono-layered on a flat surface. For the case of small spheres layered on large ones, the small spheres were located in void along periphery of the large spheres.