Temperature-driven pore size engineering in multilayer graphene/polyimide aerogels for ultra-broadband electromagnetic wave absorption

While the pore architecture of aerogels significantly impacts electromagnetic wave (EMW) absorption, current designs predominantly focus on pore orientation, leaving the quantitative relationship between pore size and electromagnetic performance largely unexplored. To bridge this gap, we develop cross-scale graphene/polyimide aerogels, integrating temperature-driven microscale pore size engineering with macroscopic multilayer configurations. At the microscale, tuning the freezing temperature enables systematic regulation of pore sizes from 4.4 to 33.5 μm, thereby elucidating a complementary loss mechanism wherein large pores mitigate excessive permittivity to optimize impedance matching, while ultrafine pores compensate for insufficient intrinsic attenuation. Consequently, the optimal single-layer aerogel achieves an effective absorption bandwidth (EAB) of 7.05 GHz, alongside a minimum reflection loss (RLmin) of −54.58 dB. At the macroscale, a genetic algorithm is employed to systematically explore the parameter space—encompassing pore size, thickness, and filler loading—to construct optimized multilayer architectures. The resulting multilayer aerogels (MAs) exhibit a remarkable RLmin of −68.85 dB alongside an EAB of 8.83 GHz at 3.5 mm, while achieving an ultra-wide EAB of 14.05 GHz coupled with a strong RLmin of −54.63 dB at 10 mm. Furthermore, the optimized MAs demonstrate an exceptional radar cross-section reduction capability of up to 45.91 dB, establishing a robust design paradigm for next-generation EMW absorbers.