常压干燥法制备SiO2气凝胶及表征

Fabrication and characterization of SiO2 aerogel by ambient pressure drying

以水玻璃为硅源,采用常压干燥法制备了SiO2气凝胶.探究了凝胶反应pH值、改性剂中三甲基氯硅烷(TMCS)用量对SiO2气凝胶性能的影响.当凝胶反应pH值为6、TMCS与凝胶的体积百分比为60%时,SiO2气凝胶综合性能最佳,表观密度为0.0178 g/cm^3,孔隙率为91.9%.该气凝胶是一种非晶态无定形结构,孔径小于50 nm,具有较强的疏水性和优异的热稳定性.

SiO2 aerogel is prepared by ambient pressure drying with sodium silicate as silicon source.The effects of pH value of gel reaction and the amount of trimethylchlorosilane(TMCS)in modifier on the properties of SiO2 aerogel are investigated.When pH value is 6,volume percentage of TMCS to hydrogel is 60%,SiO2 aerogel has the best comprehensive performance,the apparent density is 0.0178 g/cm^3,and the porosity is 91.9%.The as-prepared SiO2 aerogel has amorphous structure,and the aperture is less than 50 nm.In addition,it has strong hydrophobicity and excellent thermal stability.