High-strength and superamphiphobic chitosan-based aerogels for thermal insulation and flame retardant applications

In recent years, aerogel has been reported as a good thermal insulation material. However, it has remained a great challenge to realize high mechanical property and excellent anti-fouling performance concurrently of aerogel in practical applications. Here, a composite aerogel was developed via directional freezing and chemical vapor deposition (CVD) modification using chitosan (CS) and montmorillonite (MMT) as heat-resistant raw materials and cellulose nanofibrillated fiber (CNF) as reinforcing filler. The intercalation between the CS molecular chain and MMT endows the aerogel with excellent mechanical properties. Due to the anisotropic structure, the axial Young's modulus is high up to 630 KPa, and the radial thermal conductivity is as low as 31 mW m(-1) K-1. Meanwhile, the aerogel shows a high limiting oxygen index (LOI) value of 43%. Furthermore, CVD treatment increases the contact angles to water and various oils higher than 150 degrees, which portects the aerogle from being contaminated by common liquids. Compared to conventional insulation materials, this aerogel can maintain excellent insulation performance in extreme environments such as heavy rain or oil leakage. The composite aerogel is expected to play an important role in the fields of house warmth, vehicle interior, aviation, and etc.