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.

中文翻译：

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受 Janus 启发的交替结构 CNF/MXene/ZnFe2O4@PANI 复合薄膜，具有出色的电磁干扰屏蔽和焦耳热


随着电子设备的不断进步，兼具热管理功能和优异电磁干扰 （EMI） 屏蔽性能的柔性薄膜受到了广泛关注。因此，受 Janus 的启发，通过使用真空辅助过滤方法调节导电层和磁性层的填料含量，成功制备了具有不对称梯度交替结构的 CNF/MXene/ZnFe₂O₄@PANI 复合薄膜。得益于 ZnFe₂O₄@PANI 的磁共振和磁滞损耗、MXene 的导电损耗和偶极极化，以及交替多层薄膜中独有的“吸收-反射-再吸收”屏蔽特性，CM&CZFP-4G 薄膜具有优异的 EMI 屏蔽性能，EMI SE 高达 45.75 dB，屏蔽效能为 99.99%。令人惊讶的是，即使在高温/低温、高湿度、酸碱等恶劣环境中长时间侵蚀后，复合膜也能保持可靠的 EMI 屏蔽性能。此外，CM&CZFP-4G 在约 50 s 内响应迅速，在 9.0 V 外加电压下达到最高稳态温度 235.8 °C，表明所得薄膜获得了出色且可控的焦耳热性能。这一结果归因于 MXene 的均匀分散，以建立导电网络并赋予 CNF/MXene 高导电性。同时，CM&CZFP-4G 的耐火性能与纯 CNF 相比显著提高，保证了其应用过程中的防火安全。 此外，得益于 CNF 的长纤维纠缠、广泛的氢键相互作用和多层结构设计，CM&CZFP-4G 薄膜表现出优异的力学特性，拉伸强度和断裂应变分别为 27.74 MPa 和 6.21%。这项工作为制备具有电磁屏蔽和焦耳热的多功能复合薄膜提供了一种创造性的途径，适用于各种应用环境。