From waste to wealth: recycled PBO nanofiber/CNT/CoFe2O4/MXene aerogels with multiscale architecture for radar stealth and thermal insulation

The application of recycled high-performance fibers is expanding across various fields, driven by their potential for high value utilization and the sustainable management of waste resources. The improper disposal of substantial poly (p-phenylene benzobisoxazole) (PBO) waste generated from manufacturing or end-of-life product squanders valuable resources and may pose potential environmental concerns. In line with cost-reduction and resource-saving objectives, we present a feasible paradigm centered on the top-down transformation of PBO waste pulp into a high-value, multifunctional PNF/CNT/CoFe 2 O 4 /MXene aerogel (PCMA) with favorable radar stealth and thermal insulation capacities. Driven by a multiscale porous architecture engineered through the integration of CNT/CoFe₂O₄ and MXene, the PCMA achieved well-balanced dissipation capacity and matching impedance with an optimal figure of merit (FOM) of 41.83 dB·GHz·mm −1 . Furthermore, its slender skeleton and abundant pores effectively suppress heat transfer, achieving a thermal conductivity of 0.065 W·m −1 ·K −1 and maintaining a temperature difference of 73.2 °C on a 150 °C hot plate for 30 min. Moreover, PCMA-100 demonstrates desirable thermal stability with a decomposition peak temperature of 737.4 °C. At a treatment temperature of 400 °C in air, the sample achieves an effective absorption bandwidth of 5.56 GHz at 2.1 mm. Therefore, this work provides a feasible strategy for valorizing waste PBO fibers into multifunctional stealth composites that are applicable to harsh environments.