Three-Dimensional Low Symmetry Mesoporous Silica Structures Templated from Tetra-Headgroup Rigid Bolaform Quaternary Ammonium Surfactant
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- 作者：Shaodian Shen ; Alfonso E. Garcia-Bennett ; Zheng Liu ; Qingyi Lu ; Yifeng Shi ; Yan Yan ; Chengzhong Yu ; Weichang Liu ; Ya Cai ; Osamu Terasaki ; and Dongyuan Zhao
- 刊名：Journal of the American Chemical Society
- 出版年：2005
- 出版时间：May 11, 2005
- 年：2005
- 卷：127
- 期：18
- 页码：6780 - 6787
- 全文大小：535K
- 年卷期：v.127,no.18(May 11, 2005)
- ISSN：1520-5126
文摘
Two kinds of highly ordered mesoporous silica materials (FDU-11, FDU-13) with novel three-dimensional (3-D) tetragonal and orthorhombic structures were synthesized by using tetra-headgroup rigidbolaform quaternary ammonium surfactant [(CH3)3NCH2CH2CH2N(CH3)2CH2(CH2)11OC6H4C6H4O(CH2)11CH2N(CH3)2CH2CH2CH2N(CH3)3·4Br] (C3-12-12-3) as a template under alkaline conditions. High-resolutiontransmission electron microscopy (HRTEM), small-angle X-ray scattering (SAXS), and X-ray diffraction(XRD) show that mesoporous silica FDU-11 has primitive tetragonal P4/mmm structure with cell parametersa = b = 8.46 nm, c = 5.22 nm, and c/a ratio = 0.617. N2 sorption isotherms show that calcined FDU-11has a high BET surface area of ~1490 m2/g, a uniform pore size of ~2.72 nm, and a pore volume of ~1.88cm3/g. Mesoporous silica FDU-13 has primitive orthorhombic Pmmm structure. The cell parameters are a= 9.81, b = 5.67, and c = 3.66 nm. N2 sorption isotherms show that calcined FDU-13 has a high BETsurface area of 1210 m2/g, a uniform mesopore size of ~1.76 nm, and a large pore volume of ~1.83cm3/g. Such low symmetries for 3-D mesostructures (tetragonal and orthorhombic system) have not beenobserved before even in amphiphilic liquid crystals, which maybe resulted from an oblate aggregation ofthe bolaform surfactant and its strong electrostatic interaction with inorganic precursor. A probablemechanism has been proposed for the formation of such a 3-D low symmetrical mesostructure. Theseresults will further extend the synthesis of mesoporous materials and may open up new opportunities fortheir new applications in catalysis, separation, and nanoscience.