Research progress on preparation of silica aerogels at ambient pressure drying

Silica aerogel has shown great application prospects in the fields of adsorption separation and thermal insulation due to their low density, high specific surface area and stable physical and chemical properties. However, the extended application is limited by the time-consuming and high-cost preparation process, especially the drying process of wet gel to aerogel transforms. This paper introduced the main difficulties and solutions of silica aerogels prepared at ambient pressure drying. Although The method of ambient pressure drying had become a research hotspot in recent years because of its simple process, safe process, low equipment requirements and continuous preparation, there were also some disadvantages for ambient pressure drying method such as long preparation time, large volume shrinkage and large consumption of organic solvents and modifiers. From the following two aspects: enhancement and optimization of gel matrix, reduction of capillary force and reduction of irreversible shrinkage, the improvement methods and development status of ambient pressure drying of silica aerogels were introduced. The advantages and disadvantages of different improvement methods were analyzed and the technical challenges of ambient pressure drying of silica aerogel at present were summarized. In addition, based on the current development trend of matrix enhancement and surface modification technology of silica aerogels, the future development route of ambient pressure drying of silica aerogels, such as controllable structure, low cost and multifunctional products, was proposed. © 2022, Chemical Industry Press Co., Ltd. All right reserved.