Flexible and ultrathin dopamine modified MXene and cellulose nanofiber composite films with alternating multilayer structure for superior electromagnetic interference shielding performance

With the development of modern electronics, especially the next generation of wearable electromagnetic interference (EMI) shielding materials requires flexibility, ultrathin, lightweight and robustness to protect electronic devices from radiation pollution. In this work, the flexible and ultrathin dopamine modified MXene@cellulose nanofiber (DM@CNF) composite films with alternate multilayer structure have been developed by a facile vacuum filtration induced self-assembly approach. The multilayered DM@CNF composite films exhibit improved mechanical properties compared with the homogeneous DM/CNF film. By adjusting the layer number, the multilayered DM3@CNF2 composite film exhibits a tensile strength of 48.14 MPa and a toughness of 5.28 MJ·m^?3 with a thickness about 19 μm. Interestingly that, the DM@CNF film with annealing treatment achieves significant improvement in conductivity (up to 17264 S·m^?1) and EMI properties (SE of 41.90 dB and SSE/t of 10169 dB·cm²·g^?1), which still maintains relatively high mechanical properties. It is highlighted that the ultrathin multilayered DM@CNF film exhibits superior EMI shielding performance compared with most of the metal-based, carbon-based and MXene-based shielding materials reported in the literature. These results will offer an appealing strategy to develop the ultrathin and flexible MXene-based materials with excellent EMI shielding performance for the next generation intelligent protection devices.