常压制备疏水性二氧化硅气凝胶

摘要

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.