A robust silicone aerogel via copolymerization of a difunctional organoalkoxysilane and polymethylmethoxysiloxane for high-temperature thermal insulation

Abstract

Aerogels are porous materials that show immense potential in thermal insulation, but achieving low-cost preparation of aerogels with both high strength and high thermal stability remains a challenge. Herein we report robust silicone aerogels for high-temperature thermal insulation, which are prepared by a facile sol–gel process followed by low-cost ambient pressure drying. The key to the preparation lies in the utilization of long-chain polymethylmethoxysiloxane as the framework and a difunctional organoalkoxysilane as the crosslinker, leading to the formation of a 3D crosslinked Si–O–Si network. Long-chain polymethylmethoxysiloxane can promote the formation of a robust gel skeleton by enhancing the binding between gel particles, while the difunctional organoalkoxysilane can adjust the microstructure and mechanical properties of the gel by modulating the crosslinking degree. The resultant aerogels exhibit low densities of ca. 0.3 g cm⁻³, low room-temperature thermal conductivities of ca. 0.03 W m⁻¹ K⁻¹, and superior compressive strength up to 3.7 MPa. Furthermore, they demonstrate exceptional thermal stability with over 70% residual mass in both air and nitrogen atmospheres at 800 °C. Remarkably, these silicone aerogels show great potential as high-temperature thermal insulation materials, in which a 20 mm-thick aerogel plate can withstand a 1000 °C flame for 500 s with a backside temperature of only 60 °C.