Gemini Surfactant Micelle Template Synthesis Of Mesoporous And Advanced Micro Devices, Mesoporous Silica Materials

According to the classification made by IUPAC, porous materials can be arranged in three main categories, depending on their pore size (diameter, d), micro- (d < 2 nm), meso- (2 nm < d < 50 nm), and macroporous materials (d > 50 nm). Super-microporous possess uniform-sized pore in the 1.0-2.0nm range .Mesoporous materials are usually synthesized templated by self-assembly of surfactants through sol-gel chemistry process. Compared with the classical porous materials, mesoporous materials have the characters as follows: (1)regular and well-defined channel systems; (2)narrow pore size distribution with pore size in the range of 1.3 30.0nm; (3) high BET specific surface areas; (4) excellent thermal and hydrothermal stability; (5) particals with different shapes. Mesoporous materials are promising catalysts, catalyst supports, chromatographic packing materials, adsorbent, and the host or template for the synthesis of advanced nanostructures.In this thesis, high-quality mesoporous silica materials are synthesized templated by a new family of Gemini surfactant [C_nH_2n+1N⁺(CH₃)₂-(CH₂)_s-N⁺(CH₃)₂C_n -H_2n+1]· 2Br^-, abbreviated as Cn-s-n. The resulting samples were characterized by small angle X-ray diffraction (SXRD), scanning electron microscopy (SEM) and Nitrogen adsorption- desorption analyses. We have studied the effects of the ratio of surfactant to sodium silicate on the structures and properties of mesoporous materials.Hexagonal phase mesoporous silica was prepared using C_16-2-16 as template. When when the ratio of C16-2-16 to sodium silicate is in the range: 0.08:1-0.16:1, highly ordered silica was synthesized. The results of N₂ sorption showed type IV isotherm, indicating that pore size of sample is in the range of mesopore.Using sodium silicate as precursor, hexagonal phase mesoporous silica was synthesized templated by Gemini surfactant C_8-2-8. The resulting samples were characterized by small angle X-ray diffraction (SXRD) , SEM and nitrogen adsorption-desorption technique. The results showed that the pore diameter was between 1.3-1.5nm,which is in the range of super-micropores. Ordering of pore...