通过控制醇凝胶强度常压制备低密度疏水SiO2气凝胶

常压干燥制备低密度气凝胶是促进高性能气凝胶发展应用的重要途径。以正硅酸乙酯为硅源,采用溶胶-凝胶和常压干燥工艺制备出低密度(<100 kg·m^-3)的疏水SiO₂气凝胶,通过工艺参数的控制制备出不同压缩模量的醇凝胶,探讨了反应物配比对醇凝胶压缩模量和气凝胶密度间的影响关系,获得了通过控制醇凝胶压缩模量制备低密度疏水SiO₂气凝胶的方法;发现将醇凝胶压缩模量控制在0.25~2.5 kPa范围内,可制备出密度小于100 kg·m^-3的疏水SiO₂气凝胶,该研究可以为低密度疏水SiO₂气凝胶的低成本常压制备及其控制方法提供指导。

Preparation of low density hydrophobic silica aerogels by controlling strength of alcogels

Preparation of aerogels via ambient pressure drying has well been acknowledged as an extremely important way to the development and application of high performance silica aerogels. Low density (<100 kg·m^-3) and hydrophobic silica aerogels were successfully prepared via sol-gel process and ambient pressure drying by using tetraethyl ortho silicate as silica precursor. Various silica alcogels with different compression modulus were prepared by varying preparing parameters. Effects of preparing parameters on the compression modulus of silica alcogels and the density of as-prepared silica aerogels were studied. The preparing method of low density and hydrophobic aerogels by controlling the compression modulus of alcogels was accordingly explored. The results indicated that the low-density and hydrophobic silica aerogel (<100 kg·m^-3) could be prepared by controlling the compression modulus of the Alcogels within the range of 0.25~2.5 kPa. This finding provided valuable guidance for the preparation and control of low-density and hydrophobic silica aerogels via low-cost ambient pressure drying.