Preparation of Monodisperse Hollow Microsphere
| Autor: | Teng-Kuei Hu, 胡登貴 |
|---|---|
| Rok vydání: | 2001 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 89 Micro-sized monodisperse hollow or porous copolymer particles of poly(2-hydroxyethylmethacrylate-co-Ethylene glycol dimethacrylate) with its size about, will be prepared by using seeded emulsion polymerization. The effects on the properties of the particles, such as : surface and interior structure, shell thickness, specific surface area,……etc., were studied by changing the recipes and polymerization conditions, such as : kind and amount of diluents, the ratio of the monomer to crosslinking agent, and polymerization time,……etc. By using the electron microscope to observe the surface and interior structure of obtained polymer particles during polymerization courses, the major effect on the surface and interior morphology on the polymer particles was investigated, and the mechanism of hollow particles formation was also proposed and testified. From the experimental results, it can be found that: (1) By using good solvent, toluene, to the obtained polymer as diluent, when the ratio of toluene to the monomer and crosslinking agent mixture is higher than 5/7, the monodisperse hollow particles can be prepared. (2) By using poor solvent, n-octanol, as diluent, only porous copolymer particles can be obtained. From the experiment of the drying of the toluene from highly swollen and saturated hollow particles, the rate of toluene released is conformed and has relationship with their shell thickness, shell and surface structure, and the inside void volume in the hollow particles. If the thickness of shell increases or the surface and shell structure is more dense, the rate of toluene released decrease. For the case of porous copolymer particles prepared by using nonsolvent as diluent, the the surface and interior is formed by aggregated the globules and is loose, so the released rate is faster than that of hollow particles. As the amount of corsslinking agent increases, the number of the crosslinking node and the specific surface area of copolymer particles also increases. When the amount of HEMA increases, the copolymer particles become irregular shape like raisin due to the low Tg of HEMA. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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