基于双硅氧烷先驱体制备的氧化硅基气凝胶研究进展

气凝胶材料具有高比表面积、高孔隙率、低密度、低热导率和高透过率等特性, 在隔热、隔声和光学等领域具有广泛的应用前景。但该类材料纤细骨架构成的多孔结构所呈现的高脆性是限制其应用的主要因素。本文依据硅氧烷先驱体含有不可水解基团数量的特征, 综述了采用全水解双先驱体、全/部分水解双先驱体和部分水解双先驱体等三类采用双硅氧烷先驱体制备气凝胶材料的研究现状, 分析了这三类气凝胶所呈现出的组织结构特征及其在力学、热学、光学和疏水性等方面的性能特点。通过对硅氧烷先驱体类型的选择和组合, 可以设计气凝胶材料的组织结构与性能, 为改善气凝胶材料的力学行为提出了新思路。

An Overview on Silica Aerogels Synthesized by Siloxane Co-precursors

Due to their unique features, such as high specific surface area, high porosity, low density, low thermal conductivity, and high transmittance, aerogels can be widely applied in the fields of thermal insulation, sound insulation and optics. However, aerogels usually tend to be destructive collapse, due to their porous structures constituted by slightly brittle skeletons, which is a negative factor to restrict their applications. According to the number and variety of non-hydrolytic groups in siloxane precursors, an overview of the literatures is presented on silica aerogels synthesized by three kinds of siloxane co-precursors, i.e. integral hydrolytic co-precursors, integral/partial and partial hydrolytic co-precursors. The characteristics of porous structures and properties in mechanics, thermal insulation, optics, and hydrophobicity are analyzed. It is an effective method by choosing appropriate precursors to realize the designs and improve mechanical behaviors of aerogels in respect of structures and properties.