Sandwich Structural Hollow Glass Microspheres/Organosilicone Composite for High‐Performance Electromagnetic Interference Shielding with Ultra‐Low Conductivity

ABSTRACT Traditionally, high electromagnetic interference (EMI) shielding materials prioritize high conductivity via heavy filler loading, often causing short circuits and overheating problems in highly integrated electronic devices. To address this, conductive hollow glass microspheres@Ag@Polydopamin (HAP) were employed as polar plates, dispersing uniformly in an isolated state within in an insulating organosilicone (OSi) matrix that acts as the dielectric layer to construct a micro‐capacitor model. The resulting induced currents, ingeniously driven by electron oscillation, enhance interface polarization and conductance loss. Consequently, the HAP/OSi composite achieves a remarkable EMI shielding effectiveness (SE) of 45 dB at an ultra‐low conductivity of 0.0435 S/m and 8 wt.% loading. Furthermore, integrating polyimide/CNT‐COOH@Ag (PCA) aerogel onto the upper and lower surfaces of the HAP/OSi composite forms a sandwich structural PCA‐HAP/OSi‐PCA composite, elevating EMI SE to a superior 60 dB at the extremely low 0.0501 S/m conductivity. This is attributed to the synergistic effects of enhanced interlayer polarization and multiple reflections within the micro‐capacitance network. In addition, the PCA‐HGMs@Ag@PDA/OSi‐PCA composites also exhibit excellent thermal conductivity, thermal mechanical stability across an ultra‐wide temperature range, and sound insulation. This multifunctional design effectively addresses EMI, heat accumulation, and acoustic pollution, providing comprehensive protection and broadening its application in extreme environments.