Ordered Mesoporous Silica Materials And The Preparation Of The Composite Phase Change Material

Ordered mesoporous materials are pores solids that pore channels with diameter in the range of 2⁵0nm are arrayed orderly in three dimension, which templated by self-assembly system of surfactant. Mesoporous materials are widely used in many fields such as catalysis and cataluzer carrier, adsorption and separation, environment science, host-guest chemistry, biomimic and else functional materials, because of their bigger and uniform pores, high surface areas and comparatively favorable stability.In this thesis ordered mesoporous silica (MCM-41) was templated by ordered system of cetyltrimethyammonium bromide (CTAB) in basic solution. Small angel X-ray diffraction (SXRD), N₂ adsorption-desorption and Scanning electron microscope (SEM) techniques were used to characterize the calcined samples to study the effect of synthesis temperature, P-Cyclodextrin (β-CD), Trimethylben-zene, the concentration of surfactant (CTAB) and tetraethyl-orthosilicate(TEOS) on pore structure, surface areas, pore size distribution and morphologies. The obtained results were as follows:1. With the increase of synthesis temperature, the long-range order in these samples became better, the pore size and the pore wall thickness of the samples increased.2. The pore size and the pore wall thickness of the mesoporous samples increased with the increase of the content of P-CD, respectively. The particle shape changed from ellipse to sphere, and became amorphism finally. The surface areas decreased.3. The concentrations of CTAB and TEOS affected obviously the morphology and the mesostructure of the mesoporous silica.4. Addition of a few TMB decreased the long-range order of samples, and became un-mesoporous materials. When TMB/CTAB = 0.5, the pore size and the surface areas increased obviously. Addition of TMB could change the morphology of the silica samples.The phase change materials (PCMs) can absorb energy from the circumstance or release energy to circumstance during the materials change phases. The technique of using PCMs can settle the contradiction that energies' supply and demand do not match in the same time and space. In this thesis Ci7H35COOH/SiO2 composite phase change material was prepared by Sol-Gel. The properties of the materials including phase change temperature, phase change enthalpy and microstructure were determined by DSC, IR and SEM. The obtained results were as follows:1. The phase change enthalpy of the PCMs increased with the increase of content of the stearic acid. The phase change temperature was a little lower than the pure stearic acid.2. The results of SEM showed that there were many holes on the surface of the PCMs. The holes could improve reversible phase change of the material.3. The stearic acid was embedded in silicon dioxide simply, moreover, no new matter was created.The main innovation of this thesis: Using the self-assembly p-Cyclodextrin (P-CD) and cetyltrimethylammonium bromide (CTAB) as structure-directing agent, high-quality ordered MCM-41 silicas were prepared. The effect of P-CD were studied on pore size distribution, the pore wall thickness, surface areas and morphologies.