常压制备疏水性二氧化硅气凝胶

Preparation of hydrophobic silica aerogels at ambient pressure

以正硅酸乙酯(TEOS)为硅源,氢氟酸作催化剂,采用溶胶-凝胶法常压下制备二氧化硅气凝胶,并研究催化剂、乙醇、水等因素对凝胶过程的影响。采用傅里叶变换红外分析(FT-IR)、电子扫描探针(SPM)等对二氧化硅气凝胶的结构和性能进行研究。结果表明,经三甲基氯硅烷(TMCS)表面改性处理后的气凝胶表现出了很好的疏水性能。该气凝胶密度为200～400 kg/m3,与水的接触角大于120°。当n(TEOS)∶n(乙醇)∶n(H2O)∶n(HF)=1∶6∶4∶0.25时,得到的气凝胶各方面的综合性能最好。凝胶时间随着水和氢氟酸用量增加而缩短,随乙醇用量的增加而增加。

Silica aerogels were prepared by sol-gel technique at ambient pressure using tetraethyl orthosilicate（TEOS） as silica source,and HF as catalyst.Influences of some factors,such as water,catalyst,and enthanol（EtOH） on,the gelation process were investigated.Structure and properties of silica aerogels were studied by the means of FT-IR,SPM and so on.Results showed：aerogels showed good hydrophobicity after surface modification by trimethylchlorosilane（TMCS）.Density of as-prepared aerogels was in range of 200～400 kg/m3 and the contact angle with water was larger than 120°.When n（TEOS）：n（EtOH）：n（H2O）：n（HF）=1：6：4：0.25,the comprehensive performance of aerogels was the best.Gelation time would shorten with the increase of water and hydrofluoric acid dosage and would increase with the increase of ethanol.