DTAB表面活性剂在硅气凝胶干燥中的应用

Application of DTAB surfactant in drying of silica aerogel

使用十二烷基三甲基溴化铵(DTAB)阳离子表面活性剂溶液对湿凝胶进行处理,可降低凝胶中液体表面张力,从而得到保持较完整孔隙结构的硅气凝胶。结果表明,采用DTAB水溶液浸泡湿凝胶的方法要优于在凝胶形成前加入DTAB的方式。使用浓度为1.48×10-2mol/L的DTAB水溶液浸泡湿凝胶可得到孔隙率为81.8%、平均孔径为15.749 nm、总孔体积为2.836 cm3/g、比表面积为923 m2/g的二氧化硅气凝胶;其吸脱附曲线明显高于其他添加浓度的吸脱附曲线,表明具有较高的吸附能力;在TEM图中可明显看出其具有孔隙结构。DTAB处理过的气凝胶明显优于未经处理的二氧化硅气凝胶。

The wet gel has been treated by cationic surfactant of dodecyltrimethylammonium bromide（DTAB） aqueous solution,so that the liquid surface tension can be reduced in the wet gel and the silica aerogel with intact pore structure can be obtained.Results showed that the method of using DTAB solution to soak wet gel is better than the method of adding DTAB before the forming of wet gel.The test parameters of silica aerogel were as follows： porosity of 81.8%,average pore size of 15.749 nm,total pore volume of 2.836 cm3/g,and specific surface area of 923 m2/g,when the wet gel was soaked in 1.48 × 10-2mol/L DTAB aqueous solution;the adsorption and desorption curve was obviously higher than that of other concentrations of DTAB,exhibiting strong adsorptivity;the pore structure can be observed clearly from the TEM photogaphy;and the silica aerogel after being treated by DTAB was significantly better than those without treatment.