Effect of Anion on the Formation of Mesoporous Silica and Synthesis of Metal Modified Hollow Silica Sphere
Date Issued
2010
Date
2010
Author(s)
Liou, Jia-Shin
Abstract
Using amphiphilic triblock copolymers [poly (methyl acrylate)-b- (ethylene oxide)-b- (methyl acrylate)] as templates, we have investigated the anion effect toward the porosity of mesoporous silicas. Under high concentration of potassium salts, pore diameters of the obtained silicas increases in the following order: no salt added < KNO3 < KBr < KCl. However, different hysteresis loops of the nitrogen adsorption diagrams were observed when adopting the low concentration of these salts.
Different morphology of mesoporous silica with high loading of transition metal ions can be achieved by the co-condensation method. A simple co-condensation of iron(III) acetylacetone, 3-aminopropyltrimethoxysilane, and TEOS in the presence of triblock copolymers provided the mesoporous silicas in hollow spheres (MSHs) with the diameters in the range of 100-400nm, possessing uniform shell with the thickness of 35-40nm. After removal of the surfactants, iron oxide nano-particles (< 5 nm) were well-dispersed on the surface of meso-channels. Even for the higher concentration of metal ions used, the pore channels remain unblocked. The BET surface area was about 378 m2/g and the pore volume was 0.450 cm3/g.
Subjects
salt effect
mesoporous silica
triblock copolymer
hollow sphere
Fe2O3
Type
thesis
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