物理化学学报 >> 2009, Vol. 25 >> Issue (09): 1811-1815.doi: 10.3866/PKU.WHXB20090902

研究论文 上一篇    下一篇

原位法常压干燥制备疏水SiO2气凝胶及其热稳定性

李贵安, 朱庭良, 叶录元, 邓仲勋, 张亚娟, 焦飞, 郑海荣   

  1. 陕西师范大学物理学与信息技术学院, 西安 710062
  • 收稿日期:2009-02-12 修回日期:2009-06-07 发布日期:2009-09-03
  • 通讯作者: 李贵安 E-mail:liguian66@163.com

Hydrophobic Silica Aerogel Prepared In-situ by Ambient Pressure Drying and Its Thermal Stability

LI Gui-An, ZHU Ting-Liang, YE Lu-Yuan, DENG Zhong-Xun, ZHANG Ya-Juan, JIAO Fei, ZHENG Hai-Rong   

  1. College of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, P. R. China
  • Received:2009-02-12 Revised:2009-06-07 Published:2009-09-03
  • Contact: LI Gui-An E-mail:liguian66@163.com

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摘要：

在正硅酸乙酯(TEOS)酸碱两步催化的溶胶-凝胶过程中, 加入干燥控制化学添加剂(DCCA)N,N-二甲基甲酰胺(DMF)和三甲基氯硅烷(TMCS)的混合溶液, 进行原位疏水改性处理, 并结合常压干燥工艺制备了高比表面积的疏水SiO2气凝胶. 利用N2物理吸附, 全自动X射线衍射仪(XRD), 傅立叶变换红外光谱仪(FTIR), 扫描电子显微镜(SEM)等对样品的形貌结构进行了表征. 实验结果表明, 原位疏水改性比非原位疏水改性制备的SiO2气凝胶具有更大的比表面积, 可达979 m2·g-1, 气凝胶表面存在憎水性基团—CH3, 有良好的疏水性. 500 ℃热处理后, 气凝胶因失去大量的—CH3基团, 由憎水性转为亲水性; 800 ℃高温热处理后, 疏水SiO2气凝胶仍处于非晶态, 具有良好的热稳定性能.

关键词: 热稳定性, 原位疏水改性, 常压干燥, SiO2气凝胶

Abstract:

Using an acid-base two-step catalysis for the hydrolysis of tetraethyl orthosilicate (TEOS), hydrophobic silica aerogel with a high specific surface area was prepared by an in-situ sol-gel process and ambient pressure drying utilizing the introduction of drying control chemical additives (DCCA) N,N-dimethylformamide (DMF) and trimethylchlorosilane (TMCS) to allowfor the hydrophobic modification of the sol system. The structure and morphology
of these samples were characterized by N2 physical adsorption, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrometry, and scanning electron microscopy (SEM). Results showed that the specific surface area of the hydrophobic silica aerogel modified by this in-situ method was larger than that of an aerogel modified by the ex-situ method. The specific surface area of the former aerogel was up to 979 m2·g-1. The aerogel had a good hydrophobic property because of the hydrophobic group (—CH3) that was linked to the aerogel's surface. After heat treatment at 500 ℃, the aerogel became hydrophilic because it lost most of its hydrophobic groups (—CH3). After heat treatment at high temperature 800 ℃ the hydrophobic silica was still in an amorphous state, which indicated good thermal stability for the hydrophobic silica aerogel.

Key words: Thermal stability, In-situ hydrophobic modification, Ambient drying, Silica aerogel