Lightweight, flexible, heat resistant and thermal insulating aramid nanofiber/magnetic carbon nanotube interpenetrating network aerogel for microwave absorption in complex environments

Microwave absorbing (MA) materials used in complex environments not only need efficient MA performance, but also should have comprehensive properties of being lightweight, flexible, heat-resistant and insulating. Here, we grew CoFe2O4 nanoparticles (CFO NPs) in situ on oxidized carbon nanotubes (CNTs) by a wet chemical method. Oxidized CNTs limit the aggregation of CFO NPs and form rich heterogeneous interfaces. Then CNT@CFO was mixed with aramid nanofibers (ANFs) dispersions and prepared lightweight and flexible ANF/CNT@CFO interpenetrating network aerogels through a freeze-drying process. Under the action of multiple loss mechanisms, the ANF/CNT@CFO aerogel shows -53.2 dB of minimum reflection loss, and 4.76 GHz of effective absorption bandwidth (1.59 mm). Meanwhile, the composite aerogel inherits the high heat resistance of each component, with the quality and shape remaining stable below 400°C, and TG5% occurs at 460°C. In addition, effective MA properties can be maintained from room temperature to 300°C. ANF/CNT@CFO is expected to become a MA material that can be used in complex environments.