The Preparation And Characterization Of Differents Types Of Core-shell Silica

In recent years, a series of innovative achievements about the research andapplication of nanometer materials have been obtained[1].The semiconductornanomaterial is attracting more attention from people! Si what is the first generationof semiconductor materials had an important position[2-3]. With the core-shellmesoporous silica come out, Various ordered mesoporous silica core-shell structurewith different morphologies have appeared(such as globular、rodlike、schistose etc)[4-9].Sang Hoon Joo[10]who come from University of California hydrolyzed TEOS andadded TTAB what was template by the sol-gel method. So he prepared the Pt/SiO2which enabled the precise control of the size and shape[11-15]. Zhang[16]alsohydrolyzed TEOS, He syntheticed the magnetic core-shell silica that not only enabledthe precise control of the size and shape but also low density, high specific surfacearea and large diameter. Dong-yuan Zhao[17]syntheticed the core-shell mesoporoussilica that diameter of400nm, uniform size of aperture of3nm by Stober method.Hyeon[18-22]reported a new method of Fe3O4/SiO2. The magnetic core-shell SiO2which used the new method has super paramagnetism, but it magnetic field intensitywas low and it mesopore shell was disordered structure. So we can’t use it inbioseparation.Here, it describes the preparation and characterization of two kinds of SiO2core-shell:The mesoporous silica core-shell can be prepared by hydrolysis process (Thefirst step) and Sol-gel method (The second step). Preparation of PS/SiO2core-shellspheres and hollow silica spheres can be described as follows: By using the specialsurfactant, PS microspheres are coated by silica shell. And then, to remove PS spheres,PS/SiO2core-shell spheres were Calcined at high temperatures due to the volatile ofPS microspheres. Then core-shell silica hollow microspheres can be obtained. Thecore-shell mesoporous silica was prepared successfully via the sol-gel method.Moreover, it was observed the morphology and ultrastructure by the TEM, Raman spectrum. The results indicated that the core-shell mesoporous silica was consisted ofsilica shell which was about7nm diameter of outside surface and the silica shell ofthickness was about30nm. It also contained silica microspheres which diameter wasabout200nm. The core-shell mesoporous silica had a larger surface area and perfectspectral characteristic.