Facile Synthesis of Dual Modal Pore Structure Aerogel with Enhanced Thermal Stability

Abstract

Regarding the preparation of aerogels by the co-precursor method, the skeleton collapse caused by its low strength is one of the key problems that needs to be solved urgently. In this study, vinyl-functionalized silica aerogel was prepared under atmospheric drying conditions (APD) with vinyltriethoxysilane (V) and water glass (W) as co-precursors. The performance of aerogels varied with the components of co-precursors. When the V:W ratio was 0.8, the aerogel had excellent properties of low thermal conductivity (0.0254 W/(m·K)), super hydrophobicity (hydrophobic angle of 160°), high specific surface area (890.76 m2/g), high porosity (96.82%), and low density (0.087 g/cm3). Test results of SEM and BET showed that the V:W ratio affected the pore structure. When the V:W ratio was around 0.8, the aerogel had a dual modal pore structure composed of both small (6–8 nm) and large (20–30 nm) mesopores, which could contribute to enhance the skeleton strength of the aerogel. On the other hand, the addition of vinyltriethoxysilane promoted the skeleton stability by reducing the capillary force. The vinyltriethoxysilane and water glass as novel co-precursor combinations can provide guidance for the preparation of aerogels under APD conditions.