Flexible <scp>TPU</scp> / <scp> CoFe ₂ O </scp> ₄ / <scp>MWCNT</scp>

Abstract

The rapid advancement of flexible electronics, wearable systems, aerospace components, and compact communication devices has intensified the demand for lightweight, mechanically compliant materials capable of absorption‐dominant electromagnetic interference (EMI) shielding. Herein, flexible thermoplastic polyurethane (TPU) nanocomposite films incorporating cobalt ferrite (CoFe 2 O 4 ) nanoparticles and multiwalled carbon nanotubes (MWCNTs) were fabricated via stepwise solution processing followed by compression molding. The CoFe 2 O 4 loading was fixed at 5 wt%, while the MWCNT content was varied up to 5 wt% to regulate conductive network formation within the elastomeric matrix. Homogeneous dispersion of hybrid fillers enabled the development of interconnected conductive pathways and distributed magnetic domains, resulting in enhanced dielectric permittivity (~150 at 100 Hz) and alternating current conductivity (~10 −3  S m −1 ). The synergistic interaction between dielectric loss, conduction loss, interfacial polarization, and magnetic loss mechanisms promoted efficient electromagnetic attenuation. The optimized composite delivered a shielding effectiveness of 43.76 dB in the X‐band (8.2–12.4 GHz) at 5 mm thickness, significantly exceeding the 20 dB industrial benchmark. These findings demonstrate that conductive‐magnetic hybrid networks in TPU provide a viable strategy for designing flexible, high‐performance EMI shielding materials suitable for next‐generation portable and structural electronic applications.