A convenient synthesis of silylated silica xerogels
A convenient synthesis of silylated silica xerogels
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DOI：
10.1021/cm981037
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发表时间：
1999-05-01
影响因子：
8.6
通讯作者：
Lentz, CW
中科院分区：
文献类型：
--
作者：
Burns, GT;Deng, Q;Lentz, CW
通过在异丙醇存在下用六甲基二硅氧烷或烷基氯硅烷原位处理水凝胶，制备了具有可控孔隙率和表面积的处理过的二氧化硅干凝胶。所得水凝胶是疏水性的，并且在接触时容易转移到非极性有机溶剂中。干凝胶的表面积和孔隙率通过改变在处理之前用于水凝胶干燥的pH、时间和温度来控制。在一般情况下，随着老化时间或温度的增加，比表面积下降，而总孔体积和孔径增加。水凝胶在水相中的甲硅烷基化保留了水凝胶的结构，并允许以最小的结构塌陷进行分离。通过使用该技术，获得了比表面积为200至>700 m2/g，孔体积为1.5至3.8 cm 3/g的硅烷化干凝胶。
Treated silica xerogels with controlled porosity and surface area were prepared by the in situ treatment of hydrogels with hexamethyldisiloxane or alkylchlorosilanes in the presence of isopropyl alcohol. The resulting hydrogels were hydrophobic and readily transferred to nonpolar organic solvents upon contact. The surface area and porosity of the xerogel were controlled by varying the pH, time, and temperature used to polymerize the hydrogel prior to treatment. In general, the surface area decreased with increases in aging time or temperature, whereas the total pore volume and pore size increased. Silylation of the hydrogel in the aqueous phase retains the structure of the hydrogel and permits isolation with minimum structure collapse. By using this technique, silylated xerogels with surface areas ranging from 200 to >700 m(2)/g and pore volumes of 1.5 to 3.8 cm(3)/g were obtained.