疏水二氧化硅气凝胶的常压制备及性能研究

Synthesis and characterization of hydrophobic silica aerogels via ambient pressure drying

以正硅酸乙酯(TEOS)为硅源,采用酸、碱两步催化法,经正硅酸乙酯乙醇溶液老化、三甲基氯硅烷(TMCS)疏水改性后,结合常压干燥工艺制备出了具有良好疏水性能的二氧化硅气凝胶。探讨了改性剂浓度对所得气凝胶疏水性能的影响,并对其化学组成及疏水性能进行分析。结果表明:经TMCS改性后,样品表面—CH3含量显著增加,样品由亲水性向疏水性转变,当TMCS质量分数为20%时,样品疏水角可达138.4°。

The silica aerogels with excellent hydrophobic performance were prepared with tetraethyl orthosilicate （TEOS） as silica source and aging agent, trimethylchlorosilane （TMCS） as hydrophobic modifier, via a two-step acid-alkali catalysis pro- cess followed by an ambient pressure drying.The effects of TMCS concentration on the hydrophobic properties of silica aero- els were investigated and the chemical composition and hydrophobic performance of the prepared product were also analyzed. It was found after modified by TMCS, the -CH3 contents showed a great increase in absorbance peak, and the silica aerogels transfered from hydrophilic to hydrophobic, the contact angle was 138.4° when the mass fraction of TMCS kept at 20%.