Scalable and robust silica aerogel materials from ambient pressure drying

Abstract

Aerogels constitute one of the most effective superinsulation materials, typically featuring remarkably low values of thermal conductivity due to their extremely high porosity comprised mostly of mesopores with an average size of approximately 10 nm, as well as considerably high values of specific surface area, all properties that give rise to an outstanding thermal insulator for applications related to energy-saving purposes. However, two of their main disadvantages are (i) a relatively high cost, and (ii) a pearl-necklace structure that result in inherent mechanical brittleness. Here, by leveraging the benefits of ion-exchange sodium silicate solution as a silica source, as well as the use of surfactants, the resulting silica aerogel precursor obtained using the ambient pressure drying (APD) technique is combined with the cellulose-based fiber to produce a composite material that yields an extraordinary combination of significantly low thermal conductivity (28.6 mW m⁻¹ K⁻¹) and high mechanical properties (∼11 MPa maximum compressive stress and Young's modulus of 13.5 MPa in compression at 50% strain). Such a combination of aqueous-based material components and the ambient pressure drying process provides an exceptional low-cost alternative for the production of aerogel-based, eco-friendly solutions that are suitable for energy efficient applications at an industrial scale.