Self-catalyzed Gelling Synthesis of Aerogels with Inorganic and Organic Nanocomponents for Thermal Insulation and CO2 Capture

Abstract

Silica aerogels have already been recognized as potential candidates in the fields of thermal insulation, sorption, and separation, but the intrinsic brittleness and cumbersome preparation process limit their broad applications. In this work, a simple self-catalyzed gelling strategy was applied to prepare organic–inorganic in situ hybrid aerogels (OIHAs) derived from bis[3-(triethoxysilyl)propyl]amine (BTPA) and methyltrimethoxysilane (MTES). The Si–CH3 groups from MTES make it possible for OIHAs to be prepared through ambient drying and exhibit good hydrophobicity. Owing to the alkalinity of the amine groups from BTPA, self-catalyed hydrolyzation and condensation reactions occur between two silicon precursors to build a uniform pearl-chain nanoporous structure. The high specific surface area and amine groups existing on the nanoskeleton surface of the obtained OIHAs endow them with fascinating CO2 capture ability up to 5.89 mmol/g at 298 K and 100 kPa, which are significantly higher than the values of other aerogels reported under the similar conditions. Furthermore, ultralow thermal conductivity (as low as 20.1 mW/(m·K) at 25 °C), high strength (up to 2.38 MPa), and great elasticity (fully recoverable elastic strain of 14%) are achieved together for the OIHAs due to the organic–inorganic in situ cross-linked architecture. The as-prepared OIHAs with versatile properties have great application prospects in the fields of building thermal insulation and CO2 capture. The self-catalyzed gelling strategy provides an alternative routine for the simple preparation of silica-based aerogels.