Acta Phys. -Chim. Sin. ›› 2009, Vol. 25 ›› Issue (09): 1811-1815.doi: 10.3866/PKU.WHXB20090902

• ARTICLE • Previous Articles     Next Articles

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

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

MSC2000: 

  • O647