常压干燥制备疏水SiO_2气凝胶

Preparation of Hydrophobic SiO_2 Aerogels at Ambient Pre ssure

以聚二乙氧基硅氧烷(PDEOS)为原料,用甲基三乙氧基硅烷(MTES)对制得的醇凝胶进行表面改性,经乙醇和正己烷洗涤,在常压条件下干燥后得到疏水二氧化硅气凝胶。研究表明:溶胶—凝胶体系中各组分的最佳配比为C2H5OH∶PDEOS∶HF∶H2O=20∶10∶3∶0.5(重量比);当MTES/PDEOS(重量比)大于1.2时,经表面改性的疏水二氧化硅气凝胶与水的接触角大于110°,其密度和比表面积分别在125～160kg/m3和560～900m2/g范围。

The alcogel prepared by sol-gel process of polydiethoxysiloxane (PDEOS) according to the mass ratio of PDEOS:HF:H2O = 20:10:3:0.5, was modified by methyltriethoxysilane (MTES) and washed with alcohol and n-hexane. The obtained gel was then dried under ambient pressure to prepare hydrophobic SiO2 aerogel. It is shown that hydrophobic SiO2 aerogels can be obtained when the mass ratio of MTES/PDEOS is higher than 1.2. The contact angle between hydrophobic SiO2 aerogels and water is larger than 110°, the densities and specific surface areas of hydrophobic SiO2 aerogels are in the range of 125-160 kg/m3 and 560-900 m2/g respectively.