Janus-inspired alternating architecture CNF/MXene/ZnFe2O4@PANI composite films with outstanding electromagnetic interference shielding and Joule heating

Abstract

With the continuous advancement of electronic devices, flexible thin films with both thermal management functions and excellent electromagnetic interference (EMI) shielding properties have received much attention. Hence, inspired by Janus, a CNF/MXene/ZnFe₂O₄@PANI composite film with an asymmetric gradient alternating structure was successfully prepared by adjusting the filler content of the conductive and magnetic layers using a vacuum-assisted filtration method. Benefiting from the magnetic resonance and hysteresis loss of ZnFe₂O₄@PANI, conductive loss and dipole polarization of MXene, as well as the exclusive “absorption-reflection-reabsorption” shielding feature in the alternating multilayered films, CM&CZFP-4G film has superior EMI shielding performance, with an EMI SE of up to 45.75 dB and shielding effectiveness of 99.99%. Surprisingly, the composite film maintains reliable EMI shielding properties even after prolonged erosion in harsh environments such as high/low temperatures, high humidity, acids and alkalis. Furthermore, the CM&CZFP-4G responded quickly within about 50 s and reached a maximum steady-state temperature of 235.8 °C at an applied voltage of 9.0 V, indicating the obtained film acquired outstanding and controllable Joule heating performance. This result was attributed to the homogeneous dispersion of MXene to build up a conductive network and endow the CNF/MXene with high conductivity. Meanwhile, the fire resistance of CM&CZFP-4G was significantly improved compared to pure CNF, which guaranteed fire safety during its application. Additionally, contributed by long fiber entanglement of CNF, extensive hydrogen-bonding interactions and multilayer structural design, the CM&CZFP-4G film exhibits excellent mechanical characteristics, with the tensile strength and fracture strain of 27.74 MPa and 6.21%, separately. This work offers a creative avenue to prepare multifunctional composite films with electromagnetic shielding and Joule heating for various application environments.