| Summary: | 博士 === 國立中興大學 === 材料科學與工程學系所 === 97 === The topic of this study consists of two parts. First, furfuryl alcohol (FA) is used as a precursor for synthesis of glassy carbon. During the polymerization reaction, hydrochloric acid, phosphoric acid and acetic acid are respectively used as a catalyst to examine the degree of FA polymerization and the ensuing carbonized structure when catalyst chemistry and pyrolysis temperature are varied. Experiments revealed that the presence of acids does indeed promote polymerization of FA, leading to a reduced defect population. On the other hand, by increasing the pyrolysis temperature, one can achieve ordered glassy carbon with well-defined structure. This is particularly pronounced when the hydrochloric acid was used as a catalyzer, forming “nonstick” polyfurfuryl alcohol (PFA) particles with a diameter ca. 0.5-1 μm. The polymeric particles were then converted into microporous carbon spheres with a specific surface area of 297 m2/g when subjected to calcination at 600oC in argon atmosphere. On the contrary, FA in the rest of the catalyst systems showed aggregated form with a pronouncedly reduced specific surface areas ranging from 0.3 to 5.2 m2/g.
The second part of this study is to synthesize monodispersed silica microspheres with mean particle sizes of 280, 450, and 680nm, respectively using Stöber method. Centrifugal self-assembly is then conducted to investigate the effect of experimental variables such as particle size and rotational speed of the centrifuge on the packing periodicity of the colloidal crystal structures. As shown by the UV-visible spectroscopy measurements, a strong reflection peak at a wavelength of 632nm is observed for the periodic colloidal crystal structure orderly formed by the silica microspheres with particle size of 280 nm at 2000 rpm of centrifugal speed. Moreover, it is also confirmed by scanning electron microscope (SEM) that high-quality colloidal crystal can indeed be obtained via the centrifugal self-assembly of silica microspheres with particle sizes of 280, 450, and 680nm. Furfuryl alcohol is subsequently infiltrated into the interstitial spacings of the silica colloidal crystal, which is serving as a template, followed by processes of polymerization and carbonization. The silica colloidal crystal template is then removed by hydrofluoric acid (HF) to acquire a well-ordered porous structure consisting of hexagonal close-packed arrays, with the glassy carbon as the backbone and each spherical pore surrounded by six adjacent similar pores. An inverse opal structure of glassy carbon has been prepared.
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