Kimura Tatsuo, Tamura Hiroaki, Tezuka Masato, Mochizuki Dai, Shigeno Tetsuro, Ohsuna Tetsu, Kuroda Kazuyuki
Advanced Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan.
J Am Chem Soc. 2008 Jan 9;130(1):201-9. doi: 10.1021/ja0744145. Epub 2007 Dec 12.
Mesoporous silica with squared one-dimensional channels (KSW-2-type mesoporous silica), possessing a molecularly ordered framework arising from a starting layered polysilicate kanemite, was obtained through silylation of a surfactant (hexadecyltrimethylammonium, C16TMA)-containing mesostructured precursor with octoxytrichlorosilane (C8H17OSiCl3) and octylmethyldichlorosilane (C8H17(CH3)SiCl2). The presence of the molecular ordering in the silicate framework was confirmed by XRD and TEM. Octoxy groups grafted on KSW-2 can be eliminated by subsequent hydrolysis under very mild condition, and pure mesoporous silica was obtained with the retention of the kanemite-based framework. The framework is structurally stabilized by the attachment of additional SiO4 units to the framework, and the mesostructural ordering hardly changed under the presence of water vapor. A large number of silanol groups remained at the mesopore surfaces because C16TMA ions and octoxy groups can be removed without calcination. Octylmethylsilyl groups are regularly arranged at the mesopore surface due to the molecular ordering in the silicate framework. The molecularly ordered structural periodicity originating from kanemite is retained even after calcination at 550 degrees C, while that in the precursor without silylation disappeared. The synthetic strategy is quite useful for the design of the silicate framework of mesostructured and mesoporous materials with and without surface functional organic groups.
具有方形一维孔道的介孔二氧化硅（KSW - 2型介孔二氧化硅）由起始层状聚硅酸盐片硅铝石形成分子有序骨架，通过用辛氧基三氯硅烷（C8H17OSiCl3）和辛基甲基二氯硅烷（C8H17(CH3)SiCl2）对含表面活性剂（十六烷基三甲基铵，C16TMA）的介观结构前驱体进行硅烷化反应制得。通过XRD和TEM证实了硅酸盐骨架中分子有序性的存在。接枝在KSW - 2上的辛氧基可在非常温和的条件下通过后续水解去除，从而在保留片硅铝石基骨架的情况下获得纯介孔二氧化硅。通过向骨架附着额外的SiO4单元使骨架在结构上得以稳定，并且在水蒸气存在下介观结构有序性几乎不变。由于无需煅烧即可去除C16TMA离子和辛氧基，大量硅醇基团保留在介孔表面。由于硅酸盐骨架中的分子有序性，辛基甲基硅烷基团在介孔表面规则排列。即使在550℃煅烧后，源自片硅铝石的分子有序结构周期性依然保留，而未进行硅烷化的前驱体中的结构周期性则消失了。该合成策略对于设计具有和不具有表面官能有机基团的介观结构和介孔材料的硅酸盐骨架非常有用。
