| Summary: | 碩士 === 逢甲大學 === 化學工程學所 === 95 === The colloidal spheres may take the form of a solid, a core-shell, or a hollow structure, and the chemical compositions could be either metallic like Au, Ag, Ni, Se, Bi, Pb, Pt; inorganic like CdSe, SiO2 or TiO2; or organic such as polystyrene (PS) or poly(methyl methacrylate) (PMMA). In the past decade, there have been immense efforts to fabricate hollow colloidal particles with tailored structural, optical and surface properties. Hollow particles often exhibit improved physical and chemical properties, and hence are potentially useful in a broader range of applications.
In this thesis, monodisperse, micro/nano-meter sized hollow particles prepared by the sol-gel method using oil- and bio-templates are reported. In experimental part A, we prepared silica hollow capsules using rod-like clostridium and its spherical spores as template. These two shapes of silica shell were formed via the sol-gel method. In experimental part B, we report the syntheses of hollow silica particles based on a convenient one-step process in a mini/micro-emulsion using an oil template. An ultrasonicator was utilized to create a surfactant stabilized mini-emulsion of very small droplets. It was found possible to make silica particles having voids with facile control of particle diameter by changing the working temperatures.
At surfactant concentrations below the 25˚C critical micelle concentration (CMC) of cetyl trimethyl ammonium bromide (CTAB), morphologies of the silica particles are flaky, broken, or anomalous. At 4 CMC of CTAB and 30˚C, hollow silica nanoparticles could be obtained with a diameter of 20 nm. Hollow spheres of a few hundred nanometers in size were also obtained by vaporization and expansion of the oil template at elevated temperatures. Monodispersed hollow silica nanoparticles of 500 nm in diameter were obtained at 60˚C. Finally, hollow PMMA spheres of about 500 nm in size were obtained using similar procedures and reported.
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