二氧化硅气凝胶常压干燥工艺的研究进展

二氧化硅气凝胶因具有低密度、高比表面积、稳定的物理化学性质等特性在吸附分离、隔热保温等领域表现出巨大的应用潜力。但长耗时、高成本的制备工艺限制了它的发展，尤其是湿凝胶向气凝胶转变的干燥工艺。本文介绍了二氧化硅气凝胶在常压干燥的过程中面临的主要难点及解决方法，虽然常压干燥方法工艺简单、过程安全、对设备要求低且可连续制备，成为近年来的研究热点，但也存在制备周期长、体积收缩大、需要消耗大量有机溶剂和改性剂等不足。文中从凝胶基体增强与优化、降低毛细管力与减少不可逆收缩两种角度，介绍了二氧化硅气凝胶常压干燥的改进方法及其发展现状，分析归纳了不同改进方法的优缺点，总结了二氧化硅气凝胶常压干燥目前面临的技术挑战。并且，立足于目前二氧化硅气凝胶基体增强和表面改性技术发展的趋势，对今后二氧化硅气凝胶常压干燥过程中结构可控、成本降低以及产品多功能化的发展路线进行了展望。

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.