Abstract: Excellent mechanical flexibility, thermal insulation, microwave absorption and stress-strain sensing characteristics are essential properties for multifunctional materials applied in next-generation wearable electronics. These properties, however, are challenging to improve due to their incompatibility. Herein, N-doped C foams@Ni@C (NCFs@Ni@C) elastomers are synthesized via a simple freeze-drying and annealing route. Their composition, heterointerface, texture, and defects are co-regulated by changing m and T_a to achieve boosted electrical, magnetic, thermal, and hydrophobic properties. Results show that the selective incorporation of Ni@C core-shell nanoparticles into N-doped C can improve magnetic properties, electrical conductivity, and hydrophobic properties (133°-138°). Besides, the elastomers encapsulated by AB silicone exhibit strong ultra-wideband absorption (-52.25 dB, 10.16 GHz) and large Radar cross-section reduction (-47.41 dB m²) thanks to their 3D porous skeleton, multiple heterointerfaces, abundant defects, N-doping, and magnetic/dielectric components. Also, they exhibit excellent thermal insulation (0.104-0.179 W/(m K)), strain sensitivity, stability, and durability. These features endow them with fascinating functions of Radar-infrared compatible stealth and motion monitoring. Furthermore, their mechanisms of thermal transfer and dielectric loss are analyzed by experimental data combined with theoretical calculations, including density functional theory, CST, and COMSOL simulations. This study sheds new light on the development of multifunctional materials applied in Radar-infrared compatible stealth and motion monitoring.

Key words: N-doped C foams@Ni@AB silicone elastomer, Radar infrared-compatible stealth, Motion monitoring, Theoretical calculation