"Brick-Mortar-Binder" Design toward Highly Elastic, Hydrophobic, and Flame-Retardant Thermal Insulator.

Abstract

Advanced aerogels hold immense potential in thermal insulation. However, achieving high environmental adaptability aerogel insulators with elasticity, hydrophobicity, flame-retardancy, and low temperature tolerance remains a significant challenge. Inspired by a "brick-mortar-binder" biomimetic texture, a layered double hydroxide/carboxylated cellulose nanofibers/Si-O-Si (LCS) hybrid aerogel is developed by bottom-up freeze-drying. Owing to the distinct building blocks and organized structure, as-prepared LCS hybrid aerogel exhibits impressive mechanical elasticity, cycling stability at an extremely low temperature (-196 °C), hydrophobicity, and flame-retardancy (LOI = 44.6%, UL-94: V-0). Additionally, the incorporation of layered double hydroxide effectively improves the thermal insulation property (thermal conductivity = 0.0296 W·m^-1·K^-1). These distinctive features make the LCS hybrid aerogel highly promising for thermal management applications in extreme conditions, such as in pipelines for transporting liquid nitrogen and liquefied natural gas.