Lightweight Aramid Nanofiber Aerogel with a Hierarchical Cellular Structure for Thermal Insulation

Excellent insulation materials are urgently needed to insulate or reduce thermal transfer. However, the creation of such materials with ultralow thermal conductivity, high temperature tolerance, and mechanical robustness still faces enormous challenges. Here, a lightweight and robust aramid nanofiber (ANF) aerogel with a hierarchical cellular framework is reported by physically isolate ANFs from poly(p-phenylene terephthalamide) fibers, directional freezing of ANFs to cellular structure, and establishing chemical bonding of ANFs. Given the synergistic effect, the resulting aerogel exhibits a low thermal conductivity of 23.7 mW m–1 K–1, a low density of 1.42 mg cm–3, a high porosity of 90%, and a high compressive strain of up to 90%, indicating its excellent overall performance. The successful synthesis of the ANF aerogel may provide insights into the development of lightweight, flexible, and structurally adaptable thermal insulators.