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 terrific hydrophilicity and 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 SEA 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 have excellent electrothermal and photothermal conversion performances. When the applied voltage is 4 V, the stable surface temperature reaches 108oC; when it is irradiated by simulated sunlight with power density of 200 mW/cm2, the stable surface temperature reaches 95oC.

柔性多功能聚合物基电磁干扰（EMI）屏蔽复合膜在5G通信技术、可穿戴电子设备和人工智能等领域具有重要的应用价值。本文通过“原位聚合-静电纺丝”法制备四氧化三铁/聚酰胺酸（Fe3O4/PAA）纳米纤维膜，借助真空辅助抽滤在Fe3O4/PAA纳米纤维膜表面沉积Ti3C2Tx纳米片，再经热亚胺化制备具有Janus结构的Ti3C2Tx-（Fe3O4/聚酰亚胺（PI））复合膜。该复合膜两侧表现出截然不同的性质，Fe3O4/PI侧具有优异的疏水性和绝缘性，而Ti3C2Tx侧具有出色的亲水性和导电性。当Ti3C2Tx质量分数为80 wt%时，Ti3C2Tx-（Fe3O4/PI）复合膜兼具优异的屏蔽性能和力学性能，EMI屏蔽效能达到66 dB、拉伸强度和杨氏模量分别达到114.5 MPa和5.8 GPa。同时，电磁波从Janus结构复合膜两侧入射时表现出不同的EMI吸收屏蔽效能（SEA）。当电磁波从Fe3O4/PI侧入射时，复合膜的SEA为58 dB，远高于从Ti3C2Tx侧入射时的SEA（39 dB）。此外，Ti3C2Tx-（Fe3O4/PI）复合膜的Ti3C2Tx侧还具有优异的电热和光热转化性能。当施加4 V电压时，其表面稳定温度达到108oC；当受到功率密度为200 mW/cm2模拟太阳光照射时，表面稳定温度达到95oC。