Resilient silica-based aerogels with organic and inorganic molecular hybrid structure prepared by a novel self-catalyzed gelling strategy for efficient heat insulation and CO2 adsorption

Abstract

Silica aerogels have been attractive candidates for thermal insulation in many scenes, but they still suffer from high costs and especially brittle nature. In this work, a novel self-catalyzed gelling strategy was proposed to prepare resilient hybrid aerogels (HAs) with an organic–inorganic in-situ hybrid structure at the molecular level. Bis(trimethoxysilylpropy)amine is chosen as the single silicon source because it has alkalinity from the amine groups, high six functionality and molecular organic–inorganic hybrid nature, which help to achieve self-catalyzed gelling, high strength, and great resilience, respectively. For the as-prepared HAs, a 20 % fully recoverable strain, high Young’s modulus up to 10.40 MPa, high ultimate stress as high as 2.41 MPa and large ultimate deformation of 52 % are achieved together. Interestingly, HAs exhibit an improved modulus and strength after multiple compression, and this can increase the servicing safety in practical application. Benefiting from the synthetic effects of low density, high specific surface area and small pore size, the thermal conductivity of our aerogels is down to 18.8 mW·m−1·K−1 at ambient condition. Furthermore, the hydrophobic aerogels prepared through chlorotrimethylsilane modification also display a low thermal conductivity of 18.9 mW·m−1·K−1 at −50 °C and desirable mechanical properties at low temperatures. Unexpectedly, the rich amine groups and large specific surface area endow the fabricated aerogels with a remarkably high CO2 adsorption capacity up to 5.21 mmol/g at 273 K and excellent cyclic reusability. Considering these excellent functionalities, HAs have great prospects to serve as ideal thermal insulators, cold insulators and CO2 sorbents. The self-catalyzed gelling strategy provides an alternative route for the simple preparation of silica-based aerogels.