Bioinspired Gradient Structure Enabling High Toughness, Shape Memory, and Adaptive Electromagnetic Absorbing Composites

ABSTRACT Electromagnetic (EM) absorbers face growing demands for adaptive performance in dynamically varying environments, yet most existing materials exhibit static attenuation, limited mechanical compliance, and an inability to achieve programmable broadband absorption. Here, inspired by the graded cortical‐trabecular structure of deer antlers, we develop a biomimetic epoxy‐based Fe 3 O 4 /CNT composite (EFC) featuring a continuous gradient structure formed through a one‐step gravity‐induced phase‐separation strategy. The spontaneously generated porous upper layer and Fe 3 O 4 /CNT‐enriched lower layer, together with a reversible hydrogen‐bond network at filler‐matrix interfaces. By controlling the filler content, the elongation at break of EFC can reach 22.17%, while the highly programmable shape memory behavior with shape‐fixity and shape‐recovery ratios of 98.55% and 99.05%, respectively. The hierarchical structure enables synergistic EM dissipation via optimized impedance matching achieving a minimum reflection loss of −67.87 dB and the maximum effective absorption bandwidth of 5.02 GHz. Critically, shape memory‐driven thickness modulation allows reversible reconfiguration of the absorber, enabling intelligent, broadband adaptivity across 2–18 GHz, performance rarely achieved in epoxy‐based composites. This work establishes a multiscale design strategy linking molecular interactions, microstructural gradients, and macroscopic reconfigurability, offering a promising platform for next‐generation adaptive stealth, soft robotics, and multifunctional structural electronics.