Hydrophobic and elastic silica-based aerogels with organic and inorganic in-situ hybrid structure for cryogenic insulation

Abstract

Silica aerogels have potential to be used as alternatives in the cryogenic applications, but are still limited by the complex preparation process and high cost. In this work, a simple self-catalyzed gelling process and ambient drying method were utilized to prepare hydrophobic and low-density silica-based gels (HSAs) with organic and inorganic in-situ hybrid structure using methyltrimethoxysilane and bis[3-(triethoxysilyl)propyl]amine (BTPA) as precursors. The self-catalyzed gelling strategy is ascribed to the amine groups from BTPA. HSAs show a reversible deformation of 14 % and high failure strength up to 1.6 MPa even at the low temperature of −50 °C. Benefiting from the low density and high specific surface area, the thermal conductivity of the silica-based aerogels at −50 °C is as low as 21.8 mW·m−1·K−1. The HSAs are potential as ideal cryogenic insulation materials in a low-temperature and humid environment.