Effective electromagnetic interference shields based on cellulose nanofibers-carbon nanotubes layered composites

Abstract

The rapid development of electronic devices and communication technologies has inadvertently led to the production of significant amounts of Electromagnetic Interference (EMI) and radiation, necessitating the development of sustainable, low-density, affordable, and high-performance EMI shielding materials. The present study involves fabricating a layered composite material comprising alternating substrate and conducting layer made primarily of TEMPO-mediated oxidized cellulose nanofibers (TCNF) and carbon nanotubes (CNT). For the substrate layer, TCNF is modified with optimized polydopamine and Fe3+ concentrations to produce mechanically strong film with a tensile modulus of 12.3 GPa. Furthermore, two CNT/TCNF ratios are used in the conducting film: 60% and 80%. In addition to absorption and reflection, the presence of TCNF in the conducting layer creates an impedance mismatch, resulting in a zigzag reflection mechanism for EMI losses. For a thickness of 212 μm, the 5-layered composite exhibited a notable tensile strength of 58 MPa and an efficient EMI shielding effectiveness (EMI SE) of 39 dB in X-band. The prepared composites meet the requirements for a commercial EMI shielding material, namely >20 dB, and outperform the mechanical strength of many other EMI shielding materials.