Dynamically tunable and broadband electromagnetic wave absorption cellulose nanofiber-based aerogel metamaterial via...

Dynamic materials with broadband absorption and deflecting reflective beam properties are crucial for electromagnetic defense in complex environments. This work presented a cellulose nanofiber-based aerogel (MBAA) with superb elastic properties, featuring a reticulated pore wall structure via one-dimensional interface engineering. The reticulated pore walls of MBAA ensured excellent stress transfer, while the incorporation of silver nanowires introduced significant conductive losses. These features enabled the strain-driven tunable electromagnetic property of MBAA, yielding the lowest RL value of -65.56 dB and EAB of 4.0 GHz at 20% strain amplitude. Furthermore, a hollow aerogel metamaterial (MBAM) inspired by the natural structure of pine was proposed. Simulation results confirmed that the structural advantages of hexagonal cavity in MBAM activated EMW transmission paths, achieved broadband EMW absorption across a wide frequency range (1-18 GHz) optimizing through eight structural parameters. Moreover, MBAM demonstrated surprisingly deflection reflected beam properties varying from effective attenuation to anomalous reflection/scattering at different strain amplitudes. This was due to the abundant structure resonance and edge scattering effects, with a reduction in radar cross-section (RCS) reaching up to 43.33 dB·m². This study pioneers the realization of dynamically tunable broadband absorption and deflection-reflected beam properties, offering valuable insights for metamaterial design in electromagnetic defense.