以正硅酸乙酯、乙醇、去离子水、盐酸和氨水为原料制备出SiO_2凝胶后,经老化、表面改性、溶剂置换工艺,再通过常压干燥制备出SiO_2气凝胶,研究了表面改性及溶剂置换工艺对SiO_2气凝胶性能的影响.结果表明,随着表面改性次数和改性剂浓度的增加,气凝胶的密度和比表面积降低;溶剂置换对气凝胶的密度和比表面积影响不大.通过优化的工艺制备出的SiO_2气凝胶具有疏水性,与水的接触角约为118°,密度为0.124 g/cm~3,孔隙率94.3%,平均孔径为23.3 nm,比表面积712 m~2/g.
SiO_2 aerogel with low density and high specific surface area was prepared at ambient pressure. The aerogels were made from tetraethoxysilane, water, ethanol, hydrochloric acid and ammonia with a definite molar ratio. The effects of surface modification and solvent exchange on the silica aerogel were investigated. The density and specific surface area of aerogel decreased with the modification times increasing; however there was almost no change with the increasing of solvent exchange times. A light-weight mesoporous solid, with a contact angle to water of 118° a density of 0.124 g/cm~3, pore diameter of 23.3 nm, and specific surface area of 712 m~2/g was prepared.
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