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−CH 3 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 CO 2 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 CO 2 capture. The self-catalyzed gelling strategy provides an alternative routine for the simple preparation of silica-based aerogels.

Use of Ball Drop Casting and Surface Modification for the Development of Amine-Functionalized Silica Aerogel Globules for Dynamic and Efficient Direct Air Capture

“…Their surface chemistry can be easily tailored by surface grafting and in situ copolymerization. Moreover, silica aerogels have a high specific surface area and porosity, interconnective pore structure, and large pore size compared with other mesoporous solids, which favors the CO 2 diffusion and interaction with surface functional groups. − Besides, the silica aerogels with a simple and cost-effective manufacturing technique have been industrialized and commercialized, which are competitive candidates for DAC. Amine-functionalized silica aerogels showed high CO 2 capture performances including high capacity, low regeneration temperature, fast adsorption kinetics, high amine efficiency, and excellent cyclic stability. − However, silica aerogels, as well as most other adsorbents, available for CO 2 capture are powdery, which can lead to a high pressure drop or blockage of the fixed bed. ,, Pelletizing of powdery adsorbents leads to an obvious decrease in the CO 2 adsorption capacity, and the use of monolithic adsorbents can limit gas diffusion.…”

Flexible Aerogel Materials: A Review on Revolutionary Flexibility Strategies and the Multifunctional Applications

“…Besides, by adjusting the chemical component, organic aerogels are prepared by the cross-linking of molecular chains and have higher mechanical flexibility than inorganic aerogels. For example, silica aerogels using organosilane as monomers have high flexibility and compressive resilience compared to inorganic silica aerogels. ,− Currently developed organic aerogels such as silane aerogels, , polyurea aerogels, and polyimide aerogels ,,− exhibit high flexibility and can be used as functional materials in many fields.…”

Effect of Silicone Modifier on the Physical Properties of Flexible Silica Aerogels

“…It has a particle size that is smaller than the wavelength of visible light [12]. Moreover, to be classified as aerogel, it has to be of ultra-low density (porosity of >99%), making it a favorable material in thermal insulation [13], catalyst [14], chemical adsorption and absorption [15], chemical sensors [16], dielectric material [17], and medical applications (i.e., Drug delivery) [18].…”