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.