Robust flexible Janus composites for absorption-dominated EMI shielding

Abstract

Developing electromagnetic interference (EMI) shielding materials with high absorption capability is an effective strategy to mitigate electromagnetic radiation and the associated secondary electromagnetic pollution. Herein, a Janus asymmetric EMI shielding composite based on an ethylene propylene diene monomer (EPDM)/polyolefin elastomer (POE) matrix is constructed, and electromagnetic functional partitioning is realized via a facile lamination–vulcanization process. The composite integrates EPDM/POE/Fe₃O₄@thermally expandable microsphere (TEMs) foam as the absorbing layer and a highly conductive EPDM/POE/carbon nanotubes (CNTs)/carbon black (CB) layer as the reflective backing, thereby establishing a gradient impedance-matching interface and a multistage “absorb–reflect–reabsorb” attenuation pathway. Under absorbing-side incidence, the composite exhibits absorption-dominant “green” shielding, delivering an average total EMI shielding efficiency (SE_T) of ∼40.00 dB in the X-band with a high absorptivity (A ≈ 0.82). Benefiting from a robust crosslinked elastomer network, the composite maintains a stable mechanical response and shielding durability after 500 compression cycles at 60% strain, with SE_T decreasing only slightly from ∼40.00 dB to 37.42 dB. Moreover, rapid and reversible Joule heating with a spatially uniform temperature distribution is achieved at low voltages (3 V). Overall, we offer a feasible strategy for fabricating flexible, compressible, low-reflection, and durable EMI shielding materials in this study.