Gradient-Nested Organic/Inorganic Aerogels Achieve High Mechanical Strength and Feedback-Tunable Microwave Absorption.

The integration of multiband and multimode systems has substantially increased the complexity of electromagnetic interference, revealing critical limitations of existing absorbers in tuning efficiency and structural resilience. Here, we propose a nested microaerogel strategy to simultaneously improve the mechanical strength and microwave absorption (MA) performance of polyimide (PI) aerogel. By incorporating pomelo-peel-derived cellulose micronetworks and helical carbon nanocoil microaerogels to construct a gradient-nested framework, the long-standing issues of filler agglomeration and structural shrinkage in aerogels are effectively resolved. The aerogel combines low density, impact resistance, and thermal insulation with remarkable MA performance. The compressive strength reaches 1.3 MPa, which is about 20 times higher than pristine PI aerogel. Furthermore, it exhibits a minimum reflection loss of -50.16 dB, a broad effective absorption bandwidth of 7.44 GHz, and an ultrawide tunable range of 5.6 to 16.4 GHz. Benefiting from its exceptional mechanical properties and pressure-dependent tunability, the aerogel establishes a clear correlation between compression-induced capacitive response and MA performance. These features highlight its potential as a new generation of intelligent microwave absorbers with integrated sensing and adaptive regulation capabilities.