| dc.description.abstract | This study focuses on monodisperse submicron-scale and micron-scale polymer spheres prepared and their application. The four topics were discussed in this study. The first topic is preparation and characterization of monodisperse poly(n-butyl methacrylate-co-methyl methacrylate) submicron spheres via soap-free emulsion. The composition, particle size, glass transition temperature, molecular weight, and Mark–Houwink constant were proposed on the copolymer submicron spheres with various copolymer compositions and various monomer feed concentrations (M0).
In second topic, bromo-initiators for atom transfer radical polymerization (ATRP) were successfully immobilized on the surfaces of cross-linked poly(methyl methacrylate) (PMMA) spheres by soap-free emulsion polymerization using CBr4 as the chain transfer agent. Subsequent surface-initiated ATRP (SI-ATRP) afforded a layer of PMMA brushes covalently attached to the sphere surfaces. Colloidal crystal films of these monodisperse spheres were then studied to identify the relationship between variation in particle diameter and the optical properties.
In third topic, the monodisperse micron-scale polymer spheres were prepared by dispersion polymerization and packed column for aqueous chromatography. The different kind of polymer spheres and different particle size were discussed for separation of steroids.
In fourth topic, luminescence of hollow silica spheres was prepared by using micron-scale polymer spheres as template. The micron polymer spheres were mixed with tetraethyl orthosilicate (TEOS) and 3-Aminopropyltriethoxysilane (APTES) to obtain polymer core and silica shell composite via Stöber process. After rinsed with THF and calcination, the luminescence of hollow silica spheres can be obtained. The hollow silica layer was discussed by variation of particle diameter. In addition, the effect of various APTES concentrations and calcination temperatures were estimated for obtaining luminescence of material.
In results of the thesis, the monodisperse submicron-scale polymer spheres with different Tg values, branched structure, different cross-linking degrees, and different particle diameter were successfully prepared by soap-free emulsion polymerization. Subsequent facile preparation of surface-immobilized bromo-initiators was obtained using CBr4 as a chain transfer agent. These modified spheres could be employed for grafting polymer brushes through SI-ATRP, and will therefore find application in colloid crystals covering all of the visible regions could be controlled through the various particle diameters. On the other hand, monodisperse micron-scale polymer spheres were successfully prepared by dispersion polymerization. It was observed that the separation efficiency of micron-scale PMMA spheres were grater than PS spheres for steroids. In addition, Stöber process afforded a multilayer of ca. 30 nm silica nanoparticles attached to micron-scale polymer of templating. After calcination, the micron-scale hollow silica spheres were obtained. Furthermore, a combining photoluminescence property with entrapping APTES in the hollow silica sphere was carried out via Stöber process. The luminescence was appeared when APTES increase to 1 mol% and calcination temperature between 300 °C and 500 °C. The APTES-containing hollow silica spheres appeared luminescence because of the NH-related defect led to a broad emission of wavelength covering the visible regions.
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