Multifunctional T3C2Tx-(Fe3O4/polyimide composite films with Janus structure for outstanding electromagnetic interference shielding and superior visual thermal management

Flexible multifunctional polymer-based electromagnetic interference (EMI) shielding composite films have important application values in the fields of 5G communication technology, wearable electronic devices and artificial intelligence. In this work, Fe3O4/polyamic acid (PAA) nanofiber films are prepared by in-situ polymerization and electrospinning technology, and Ti3C2Tx-nanosheets are deposited on the surface of the Fe3O4/PAA nanofiber films via vacuum-assisted filtration. Then, Janus Ti3C2Tx-(Fe3O4/polyimide (PI)) composite films are obtained by thermal imidization. The two sides of the Janus films exhibit completely different properties. The Fe3O4/PI side has excellent hydrophobicity and insulation property, and the Ti3C2Tx side has hydrophilicity and terrific conductivity. When the mass fraction of Ti3C2Tx is 80 wt.%, the Janus Ti3C2Tx-(Fe3O4/PI) composite film has excellent EMI shielding performances and mechanical properties, with EMI shielding effectiveness, tensile strength and Young's modulus reaching 66 dB, 114.5 MPa and 5.8 GPa, respectively. At the same time, electromagnetic waves show different absorption shielding effectiveness (SEA) when incident from two sides of the Janus films. When the electromagnetic waves are incident from the Fe3O4/PI side, the SE A of the Janus film is 58 dB, much higher than that when the electromagnetic waves are incident from the Ti3C2Tx side (39 dB). In addition, the Ti3C2Tx side of the Janus Ti3C2Tx-(Fe3O4/PI) composite films also has excellent electrothermal and photothermal conversion performances. When the applied voltage is 4 V, the stable surface temperature reaches 108 degrees C; when it is irradiated by simulated sunlight with power density of 200 mW/cm(2), the stable surface temperature reaches 95 degrees C.

Automated summary

In this study, flexible multifunctional polymer-based electromagnetic interference (EMI) shielding composite films with Janus properties were prepared. The composite films exhibited excellent EMI shielding performance, mechanical properties, and electrothermal and photothermal conversion capabilities.