Hierarchical Cellular Engineering toward Exceptional Mechanical and Thermal Insulating Aerogels

Abstract

Aerogels are considered highly promising materials for superior thermal insulation across building, electric vehicle, and textile area. Nevertheless, the inherent deficiency in mechanical compressibility and stability of sole ceramic aerogels poses significant challenges to their further application. The hybrid aerogels with an oriented cellular structure and parallel walls connected by bridges in the orthogonal direction are presented through a physical process. The fibrous frames composed of bacterial cellulose are constructed and enhanced by montmorillonite nanosheets and silica sols through the self-assembly process to achieve high compressibility (>99% strain) and mechanical robustness (1.015 MPa), retaining 97.8% height retention under a considerable compressive strain of 50% for 500 cycles. Moreover, the aerogels demonstrate a remarkable set of properties, such as being superlight (8.85 mg·cm^–3 and 99.39% porosity), excellent thermal insulating performance (λ = 0.0131 W·m^–1·K^–1), wide working temperature range (−196 to 200 °C), self-extinguishing, and self-cleaning/hydrophobic performance (126.4° WCA). The successful synthesis of hybrid aerogels provides more opportunities to design high compressive and mechanical robust aerogels for thermal management.