Host-guest engineered polyimide aerogels with integrated Fe3O4@CoNi@PDA and CNT for broadband microwave absorption and multifunctional electromagnetic protection

Developing lightweight and multifunctional electromagnetic absorption (EMA) materials remains important for advanced electromagnetic protection applications. Herein, we report a multifunctional composite aerogel constructed through a host–guest engineering strategy. The polyimide (PI) framework serves as the host matrix, while magnetic hollow Fe 3 O 4 @CoNi@PDA microspheres and conductive carbon nanotubes (CNT) act as functional guests. Molecular dynamics simulations indicate hydrogen-bond-assisted interactions between acidified CNT and PAA chains during precursor assembly. These interactions help support the formation of a stable porous framework. The optimized PCH-3 aerogel achieves a minimum reflection loss (RL min ) of − 33.1 dB at 2.8 mm and a wide effective absorption bandwidth (EAB) of 7.9 GHz at 3.6 mm. Beyond EMA performance, PCH-3 shows low density, thermal insulation capability, and mechanical resilience. Its density and thermal conductivity are 24.0 mg cm⁻ 3 and 0.043W m −1 K −1 , respectively. It also retains 97% of its stress after 50 compression cycles. Furthermore, radar cross-section (RCS) simulations indicate a maximum reduction of 30.2 dB  2 under the given simulated conditions. This study provides a feasible strategy for designing lightweight multifunctional aerogels for electromagnetic protection and thermal management.