| Summary: | 碩士 === 臺灣大學 === 化學研究所 === 98 === By using atom transfer radical polymerization (ATRP), triblock copolymers poly(ethylene glycol)-b-(methacrylate)-b-styrene, EO45MAmSTn have been prepared and their PDI values (Mw/Mn) of these copolymers are in the range of 1.21 ~ 1.33. The obtained copolymers are used as templates for the preparation of mesoporous silica materials. By controlling the length of polystyrene, the ratio of co-solvents and the pH value, ordered mesoporous silicas can be obtained.
Hydrolysis of the methacrylate on the triblock copolymers provided the corresponding carboxylic acid (-COOH) material (EO45MAOHmSTn). Due to the highly polar nature of –COOH, the morphology of the obtained silicas is totally different from the non-hydrolyzed copolymers. Furthermore, we have learned that the addition of cobalt ions play an important role for the synthesis of mesoporous silicas. Without cobalt ions, the micelles are not stable after the pre-hydrolysis TEOS added, which leads to the formation of nonporous silicas. On the other hand, foam-like mesoporous silicas were constructed in the presence of the cobalt ions under the pH ranging from 5 to 7. After calcination, the loading of cobalt was found to be in the range of 1% ~ 11%; the cobalt content increases with the increasing pH value. These foam-like materials have high BET surface area (350-500m2/g), large pore volume (1.0-1.2cm3/g) and uniform pore size (~20nm). The cobalt containing materials can be used as heterogeneous acid catalyst and show good catalytic activity on Friedel-Craft alkylation.
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