High-efficiency electromagnetic wave absorption of lightweight Nb₂O₅/ CNTs/polyimide with excellent thermal insulation and compression resistance integration

With the widespread application of electronic devices, multifunctional electromagnetic wave (EMW) absorbing materials suitable for complex high-temperature and high-pressure environments, have attracted tremendous research attention. Herein, multifunctional polyimide (PI) composites doped with fluffy Nb2O5/CNTs microspheres (NBCP) were prepared by combining the ultrasonic spraying process and freeze-drying technique. Introduction of fillers results in the formation of diverse conduction paths and heterogeneous interfaces, which enhance the dielectric loss. Furthermore, the multi-porous structure of the PI matrix induces multiple reflection scattering events and improves the impedance matching. Such a multi-loss mechanism endows NBCP with an excellent EMW absorption performance. At 15 vol% filling, the minimum reflection loss is -41.66 dB, the effective absorption bandwidth is 2.63 GHz, and the radar cross-section is reduced by 85%. Furthermore, NBCP exhibits outstanding mechanical properties and a thermal insulation of over 100 degrees C in thermal environment at 150 degrees C. The proposed multifunctional NBCP is thus an efficient EMW absorber that offers significant potential for applications in harsh environments.