Gradient‐Structured PVDF Composite Foams With an Optimized “Capture‐Loss‐Intercept” Multilayer Design for High Absorption‐Dominant Electromagnetic Interference Shielding

ABSTRACT

The increasing density of wireless electronic devices has intensified electromagnetic interference (EMI), highlighting the limitations of conventional reflection‐dominant shielding materials, in which a substantial fraction of incident electromagnetic energy is reflected back into the surrounding environment, potentially causing secondary electromagnetic interference. In this study, we propose a structurally optimized absorption‐dominant gradient composite foam based on a “capture‐loss‐intercept” multilayer design. Multilayer PVDF‐based foams were fabricated through a combined vacuum‐assisted hot‐pressing and supercritical CO ₂ (scCO ₂ ) foaming strategy, enabling precise control over pore morphology and filler distribution at low filler loadings (2.07 vol%). The resulting hierarchical structure promotes graded impedance matching, multiple internal reflections, dielectric and magnetic losses, and conduction pathways, yielding a synergistic attenuation effect. The optimized trilayer foam achieves an EMI shielding effectiveness of 55.73 dB, a high absorption coefficient (A = 0.9316), and a green shielding index (g _s  = 13.63), outperforming most previously reported polymer‐based foams while maintaining a lightweight configuration. Approximately 99.99% of incident electromagnetic waves are effectively attenuated, demonstrating the structure's superior suppression of secondary reflection. This work provides an efficient and scalable design route for eco‐friendly, absorption‐dominant EMI shielding materials and offers strong potential for next‐generation 5G/6G electronics, aerospace equipment, and lightweight electromagnetic management applications.