Magnetically driven hierarchically ordered carbonyl iron@SiO2/Ni@Ag/silicone rubber composite film for enhanced electromagnetic interference shielding with ultralow reflection

Flexible electromagnetic interference (EMI) shielding materials are highly desired for wearable electronic devices and military equipment. Meanwhile, to reduce the secondary electromagnetic pollution caused by the reflected electromagnetic waves (EMWs), these materials are required to possess strong EMW absorption capacities. However, it still remains a big challenge for flexible shielding materials to achieve absorption-dominated EMI shielding and maintain effective performances under large tensile strain. Herein, we propose a novel strategy for ultralow-reflection EMI shielding composite films made by magnetically driven hierarchically ordered alignment of carbonyl iron@SiO2 (CS) and Ni@Ag (NA) in silicone rubber. Flaky carbonyl iron was coated with SiO2 to prepare CS microparticles, and magnetic alignment was applied within silicon rubber to obtain a highly ordered absorption layer. Then, NA microparticles were magnetically aligned to integrate with the CS layer to construct the CSNA composite film. In this case, the EMI shielding performances of the CSNA film under various strains (0-100%) were investigated in detail. Based on the unique absorption-reflection-reabsorption mechanism, an EMI shielding effectiveness (SE) of 64.5 dB with an ultralow reflected power coefficient (R = 0.044) could be achieved in the unstretched state and reached similar to 38.6 dB even at 100% strain. This work provides a new strategy to fabricate highly efficient adsorption-dominated flexible EMI shielding materials, indicating great potential for EMI shielding applications under large strain.