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A Flexible, Mechanically Strong, and Anti‐Corrosion Electromagnetic Wave Absorption Composite Film with Periodic Electroconductive Patterns

Demand for high‐efficiency electromagnetic wave (EMW) absorption composite films continues to increase with technical advances in 5G telecommunications, wearable electronics, portable devices, and deployable military applications. However, realizing flexible ultra‐thin single‐layer EMW absorption composite films with multifunctionality, rather than using traditional particle absorbents, is a known challenge. In this study, the authors propose a series of polyimide (PI) reinforced composite films with periodic copper‐based electroconductive units that possess tunable electrical properties for specific applications. These periodic units optimize the electric field distribution of the films in an alternating electromagnetic field, resulting in stronger power loss. Furthermore, the hierarchical structure and abundant heterogeneous interfaces of each unit contribute to multiple scattering and polarization loss. The obtained copper mesh@Cu2−xS@PI (CCP) film shows excellent EM shielding performance (63.7 dB), while the Air@Cu2−xS@PI (ACP) film delivers a superior specific absorbency value of 391.43% mm–1 in the X‐band. Furthermore, owing to their mechanical properties, thermal conduction/dissipation performance, and excellent environmental stability characteristics, these films offer significant potential as high‐performance EMW response materials with resistance to harsh conditions.