Structurally resilient carbon nanofiber aerogels from aramid nanofibers for thermal insulation under extreme conditions

Lightweight aerogels are recognized as advanced thermal insulators for diverse applications due to their unique microstructure. However, developing highly resilient aerogel insulators that maintain structural integrity under wide temperature fluctuations and mechanical stresses remains a significant challenge. In this work, we report cross-scale, structurally engineered carbon nanofiber aerogels (CNFAs) synthesized through the carbonization of three-dimensionally assembled nanofibrillated aramid nanofibers (ANFs). The nanofibrillated ANFs preserve the high crystallinity characteristic of Kevlar fibers, resulting in carbon nanofibers with enhanced structural regularity and mechanical robustness. The resulting CNFAs, with an ultralow density (<3.8 mg/cm³), exhibit a hierarchical, interconnected nanofibrous cellular architecture that imparts exceptional structural resilience and durability. They demonstrate superior thermal insulation performance, with a thermal conductivity of 19.93 mW/m·K at room temperature. Additionally, they exhibit excellent mechanical stability over a wide temperature range from −196 °C to 1000 °C, maintaining structural integrity under extreme conditions. The combination of outstanding structural resilience and thermal insulation capabilities makes these CNFAs particularly promising for thermal management in extreme environments, such as aerospace applications, industrial furnaces, and cryogenic systems, where both mechanical durability and reliable thermal protection are crucial.