Multifunctional Chitosan-Based aerogels combining flame Retardancy, thermal insulation and oil adsorption performance

A multifunctional aerogel with ultralow thermal conductivity, high flame retardancy, hydrophobicity, and robust mechanical properties was developed. The aerogel’s support skeleton comprised amidoxime-functionalized polyacrylonitrile and silica nanofibers. Under acidic conditions, chitosan and montmorillonite formed an electrostatically driven network, with positively charged chitosan and negatively charged montmorillonite interweaving into the nanofiber matrix to create a three-dimensional, interpenetrating, multivariate cross-linked structure. The incorporation of montmorillonite nanosheets into the flexible nanofiber network significantly enhanced the aerogel’s mechanical properties, facilitating triple cross-linking with chitosan. The resulting aerogel exhibited a porosity of 98.58%, an ultralow density of 27 mg/cm 3 , and a mechanical strength of 428.89 kPa, comparable to or better than some reported aerogels under similar conditions. Additionally, it demonstrated superior thermal insulation (0.0299 W/(m·K)), exceptional flame retardancy with a limiting oxygen index exceeding 50%, and hydrophobicity with a water contact angle of 146.2°. Notably, the aerogel maintained over 96.95% of its initial adsorption efficiency after 10 cycles, highlighting its excellent reusability. These findings establish a provide a useful reference for the development of multifunctional aerogel materials for building insulation, meeting stringent fire safety standard.