Nacre-Inspired Tunable Electromagnetic Interference Shielding Sandwich Films with Superior Mechanical and Fire-Resistant Protective Performance.

With the rapidly increasing development of portable device hardware and flexible electronics, ultrathin electromagnetic interference (EMI) shielding films with a combination of high flexibility and excellent mechanical properties are noticeably required. In addition to minimizing the electromagnetic wave pollution problem, the fire hazards caused by accidental electrical leakage or aging are also a cause of extensive concern. Inspired by nacre and sandwich structure, herein, we fabricated for the first time an electrical insulating sandwich-structured film based on Ca ion cross-linked sodium alginate (SA)-montmorillonite (MMT) and Ti3C2Tx MXene through a step-by-step vacuum-assisted filtration process. This novel design strategy not only maintains the inner EMI shielding network but also can act as an excellent fire-resistant barrier to protect the electronic device in case of accidental fire. Compared with the pure Ti3C2Tx layer, such kind of sandwich film can effectively maintain the EMI shielding performance (50.01 dB), dramatically enhance the mechanical properties (84.4 MPa), and exhibit excellent fire-resistant performance. Especially, compared with the film composed of mixture, the EMI shielding effectiveness value is only 55% that of sandwich films. Besides, it functions well under long-term heat aging test at 80 °C. Therefore, this unique design provides a novel EMI material strategy to facilitate its future applications in flexible electronics.