Tailoring electromagnetic interference shielding properties in sandwich architectures made with low-concentration multi-walled CNT–reinforced PDMS†

Abstract

This study presents a strategically designed multilayered polydimethylsiloxane (PDMS) nanocomposite reinforced with functionalized multi-walled carbon nanotubes (MWCNTs), designed for absorption predominant electromagnetic interference (EMI) shielding. The layered configuration achieves a shielding effectiveness (SE_T) of ∼25 dB across the X-band (8.2–12.4 GHz) and Ku-band (12.4–18 GHz) at a minimal thickness of 0.7 mm, significantly outperforming conventional designs. Electromagnetic simulations predict an improved SE_T of ∼35 dB (∼99.99% attenuation) at 3.5 mm thickness, with absorption accounting for ∼80% of the SE_T, indicating its efficiency. The interface-rich architecture enhances interfacial polarization, a key mechanism in achieving high shielding efficiency. A green shielding material with 1 wt% MWCNT achieves ∼15 dB SE_T (>90% shielding), with a reflection component (SE_R) of less than 3 dB and a green shielding index (g_s) ≥ 1, demonstrating excellent EMI shielding performance. The self-assembled MWCNT networks improve interfacial density, leveraging impedance mismatches and energy transfer mechanisms to maximize absorption. This design enables the facile solution processing of high-performance EMI shielding materials at low filler concentrations, with tunable layer orientations and thicknesses to meet electromagnetic application-specific requirements. The approach provides a scalable and efficient pathway to address the increasing demand for advanced EMI shielding solutions. Despite challenges related to scalability and anisotropy, this work represents a significant step toward the development of environmentally conscious, high-performance EMI shielding materials.