| Summary: | 碩士 === 國立清華大學 === 原子科學系 === 92 === Porous materials have recently received much attention due to its application in a wide variety of fields such as biosensors, catalysis, and photonic crystal. Several methods have been successfully developed for the preparation of porous materials. The physical method using template is the most often used technique to attain the macroscopic features (> 130 nm) of the highly ordered porous materials. Whereas the chemical methods have made significant contributions to the nanoscopic length scales (< 70 nm). However, the fabrication of highly ordered porous structures in a controlled process leading to the fabrication of tunable structures for different applications has received less attention.
The purpose of this study was to fabricate the highly ordered porous materials with tunable morphologies for different applications. Physical template method using polystyrene (PS) as the template at diameters of 90 – 1000 nm was used. Sol-gel materials using tetramethylorthosiliane (TMOS) as the precursor was employed to fill the voids between the microspheres. After hydrolysis, condensation and gelation process, TMOS became SiO2. The number of layers (mono- or multi- layer) and the size of pore were obtained by simply changing the concentration of suspension solution and the size of polystyrene template. Thermogravimetric analysis (TGA) revealed that the polystyrene microspheres can be completely removed at 280 – 320 �aC, and thus calcination at 500�aC is sufficient to fabricate the highly ordered porous structure. SEM images clearly showed the highly ordered porous structures arranged mainly in hexagonal closed-pack plane lattices. Addition suitable concentration of polystyrene suspension solution can fabricate ordered 2D porous structure (monolayer), while addition of high volume of polystyrene microspheres resulted in the formation of highly ordered 3D porous structures. Moreover, AFM results showed the topography of the mono- and multi-layer ordered porous structures. The distance between two spherical cavities was about 70 nm, clearly depicting the nanocrystalline property of SiO2 in the porous structure. Results obtained in this study demonstrate the feasibility of the developed nanotechnology fin fabricating the highly ordered 2D and 3D porous materials with tunable pore sizes. This technology can be used to fabricate the 2D porous structure for biosensor or to prepare the highly ordered 3D porous structure for the application of catalysis and photonic crystal.
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