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以正硅酸乙酯、乙醇、去离子水、盐酸和氨水为原料制备出SiO2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SiO2气凝胶,研究了表面改性及溶剂置换工艺对SiO2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SiO2气凝胶具有疏水性,与水的接触角约为118°,密度为0.124g/cm3,孔隙率94.3%,平均孔径为23.3nm,比表面积712m2/g。
The silica gel was prepared by using TEOS, ethanol, deionized water, hydrochloric acid and ammonia as raw materials, and then the SiO2 aerogels were prepared by aging, surface modification and solvent replacement, and then dried by atmospheric pressure. Effect of Surface Modification and Solvent Replacement on Properties of SiO2 Aerogels. The results showed that with the increase of surface modification times and modifier concentration, the density and specific surface area of aerogels decreased. Solvent substitution had little effect on the density and specific surface area of aerogels. The SiO2 airgel prepared by the optimized process has hydrophobicity, the contact angle with water is about 118 °, the density is 0.124g / cm3, the porosity is 94.3%, the average pore diameter is 23.3nm and the specific surface area is 712m2 / g.