超临界干燥法制备疏水性二氧化硅气凝胶

Preparation of hydrophobic silicon aerogel by supercritical drying

以正硅酸乙酯为硅源,用超临界乙醇干燥制备了疏水性二氧化硅气凝胶。主要考察了溶胶-凝胶法制备二氧化硅气凝胶过程中水、乙醇、催化剂(氢氟酸)的用量以及加热工艺对疏水性二氧化硅气凝胶性质的影响,从而确定最佳制备工艺条件及应用环境。最佳制备工艺条件:正硅酸乙酯、乙醇、水、氢氟酸物质的量比为1∶6∶4∶0.25,反应温度为60℃。工业应用疏水性二氧化硅气凝胶时,应尽量保证温度不超过300℃。

Silica aerogel was prepared by supercritical ethanol drying with TEOS（ethyl orthosilicate） as silica source.The influences of amounts of water,ethanol and catalyst（hydrofluoric acid）,as well as heating process on performances of hydrophobic silicon aerogel were investigated.The optimum preparation conditions and application environment of hydrophobic silicon aerogel were obtained as follows： the amount-of-substance ratio of TEOS：ethanol∶water∶HF=1∶6∶4∶0.25 and the reaction temperature was 60 ℃.When the hydrophobic silicon aerogel was applied industrially,try to make the temperature not exceed 300 ℃.