关键词: 疏水性气凝胶, 二氧化硅, 常压干燥, 表面改性

Abstract: 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.

Key words: hydrophobic aerogels, silica, ambient pressure drying, surface modification