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

作者：Li Gui An^*; Zhu Ting Liang; Ye Lu Yuan; Deng Zhong Xun; Zhang Ya Juan; Jiao Fei; Zheng Hai Rong

来源：Acta Physico - Chimica Sinica, 2009, 25(9): 1811-1815.

• Thermal stability
• In-situ hydrophobic modification
• Ambient drying
• Silica aerogel

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 allow for the hydrophobic modification of the sol system. The structure and morphology of these samples were characterized by N(2) 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 m(2).g(-1). The aerogel had a good hydrophobic property because of the hydrophobic group (-CH(3)) that was linked to the aerogel's surface. After heat treatment at 500 degrees C, the aerogel became hydrophilic because it lost most of its hydrophobic groups (-CH(3)). After heat treatment at high temperature 800 degrees C the hydrophobic silica was still in an amorphous state, which indicated good thermal stability for the hydrophobic silica aerogel.

• 出版日期2009-9
• 单位陕西师范大学