| Summary: | 碩士 === 國立成功大學 === 化學系碩博士班 === 95 === In this thesis, miscible polymer blends of homo- or triblock-polymer surfactants and phenol formaldehyde resin (PF) were used as novel templates to synthesize the mesoporous silicas and carbons. The F127-PF-silica nano-composite in well-ordered hexagonal mesostructure was efficiently synthesized by mixing an ethanol/water solution of F127-PF polymer blend and a acidified sodium silicate aqueous solution. This nano-composite can be converted into mesoporous carbons via consequent processes of drying at 100oC, pyrolysis under N2 atmosphere at 1000 oC and HF-etching. Alternatively, the mesoporous silica can be obtained form calcination in air.
To explore the effects of various reaction factors on the morphology and mesostructures of the mesoporous carbons and silicas, we changed pH value of the silicate solution, H2O/EtOH ratio, and temperature, and used PF resins with different molecular weights. At EtOH/H2O ratio = 0, a well-order mesoporous carbon in a particle morphology was synthesized. As increasing the H2O/EtOH ratio, the morphology was transformed from vesicle-like particles to short nanorods. The resulted mesoporous carbons possess high surface area of 1000–1500 m2g-1 and
large porosity of 0.75–2.0 cm3g-1.
In addition, we also proposed another method to synthesize the mesoporous carbons from different PF resin and polymer surfactants by dissolving the organic compositions in a highly alkaline sodium silicate solution (pH > 11). After acidifying that gel solution to pH value around 6.0, the PF-F127-silica composite can be rapidly synthesized. Typically, this composite can also be converted into mesoporous carbons or silica as will. This method can avoid using the organic ethanolic solvent. To
extending the method, we performed PF resins in different molecular weights and various surfactants to synthesize different mesoporous carbons with high surface area (1000-2000 m2g-1), large porosity, and novel-morphology.
To avoid using the hazardous HF for silica removal, we tried to use ZnO nanoparticles as solid spacer, which could be removed by other inorganic acids, to prepare the mesoporous carbons. After solvent evaporation, a PF-P127-ZnO homogeneous composite was obtained. With a well-control on the synthetic compositions, the mesoporous
carbon of high surface are and large pore size has been conveniently synthesized after pyrolysis at 1000 oC and HCl-etching.
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