the research of the silica porous nano-composite material
Date Issued
2004
Date
2004
Author(s)
Pan, Han-Chung
DOI
zh-TW
Abstract
The main purpose of this research was to study the processing, structure and physical properties of cetyltrimethylammonium bromide (CTABr) templated nano-porous silicate material. We altered the ratios of cetyltrimethylammonium bromide, tetramethoxysilane, water and pH value in the formulations to investigate the suitable condition for the the formation of micelles and their templated mesostructural silicate film.
There are three factors for the formation of surfactant-templated nano-porous structure needed to be considered. First, the concentration effect of the surfactant: when the concentration of the surfactant exceeds CMC, surfactant molecules can aggregate to form micelles. Second, the effect of the pH value: when the amount of HCl is increased, micelles interact wih silicate stronger, resulting in severe aggragation between micelles and silicate. Third, the concentration effect of the silicate: silicate is regarded as an anionic polyelectorolyte which can interact with micelles through the cationic amine groups of CTABr. The concentration of silicate should be high enough to cover the surface of micelles and further divide the aggregate of micelles into an array of nanotubes. After freeze-drying the solution into powders, we calcinated the powders and used small angle x-ray scattering, TEM, XRD, BET, AFM to investigate their meso-porous structures and estimate their pore size distribution.
Besides, we attempted to employ pyrene as a fluorescence sensor to investigate the micelle formation and their aggregation condition after the incorporation of silicate. Because the fluorescence properties of pyrene show strong solvation effects, we could use it to determine the critical micelle concentration of the surfactant as well as to study the initial formation of mesoporous structure in solutions.
Subjects
矽酸鹽
tetramethoxysilane
silica
cetyltrimethylammonium bromide
Type
thesis
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