Alkoxysilylated-derivatives of double-four-ring silicate as novel building blocks of silica-based materials
Alkoxysilylated-derivatives of double-four-ring silicate as novel building blocks of silica-based materials
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DOI：
10.1021/cm0716194
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发表时间：
2008-02-12
影响因子：
8.6
通讯作者：
Kuroda, Kazuyuki
中科院分区：
文献类型：
--
作者：
Hagiwara, Yoshiaki;Shimojima, Atsushi;Kuroda, Kazuyuki
新型低聚烷氧基硅烷组成的双四环（D4 R）单元功能化的单，二，和三烷氧基甲硅烷基（指定为1，2，和3，分别）被设计为用于合成二氧化硅基纳米材料的纳米结构单元。这些低聚物的水解和缩聚在酸性条件下进行。凝胶化比单体、二聚体和立方八聚体烷氧基硅烷发生得快得多，这应取决于分子大小和硅氧烷结构。衍生自1-3的干凝胶的结构分析强烈表明D4 R单元至少部分保留在其骨架中。烷氧基的数量对其孔隙率有很大的影响：衍生自2的干凝胶是一种微孔固体，BET表面积为600 m2/g，而衍生自1和3的干凝胶具有非常低的BET表面积。在此基础上，以两亲性三嵌段共聚物表面活性剂为结构导向剂，成功地合成了介孔结构的SiO2薄膜。这种方法将导致分子设计的硅氧烷网络的建设。
Novel oligomeric alkoxysilanes consisting of double-four-ring (D4R) units functionalized with mono-, di-, and trialkoxysilyl groups (designated as 1, 2, and 3, respectively) were designed as nanobuilding blocks for synthesizing silica-based nanomaterials. Hydrolysis and polycondensation of these oligomers were performed under acidic conditions. The gelation occurred much faster than monomeric, dimeric, and cubic octameric alkoxysilanes, which should depend on both molecular size and siloxane structures. Structural analyses of the xerogels derived from 1-3 strongly suggested that the D4R units are at least partly retained in their frameworks. The number of alkoxy groups had a large effect on their porosities: the xerogel derived from 2 was a microporous solid with the BET surface area of 600 m(2) g(-1), whereas 1- and 3-derived xerogels had very low BET surface areas. Furthermore, mesostructured silica films were successfully synthesized froth 2 and 3 by using amphiphilic triblock copolymer surfactant as a structure-directing agent. Such an approach will lead to the construction of molecularly designed siloxane networks.