Metal-Level Robust, Folding Endurance, and Highly Temperature-Stable MXene-Based Film with Engineered Aramid Nanofiber for Extreme-Condition Electromagnetic Interference Shielding Applications.

Polymer-based electromagnetic interference (EMI) shielding materials possess many irreplaceable advantages than metals, such as superior flexibility, easy processing, and low density. However, impeded by their limited mechanical properties, inferior temperature resistance and unsatisfactory electrical conductivity, it is still challenging to extend their shielding applications under some extreme conditions, i.e., <-50 or >200 °C. Herein, we report an ultrathin, highly robust, superflexible, and temperature-stable film via engineering a worm-like aramid nanofiber (ANF) into the rod-like microscopic configuration, followed with self-assembly with Ti3C2Tx (MXene) into a hierarchical brick-and-mortar architecture. With stiff and symmetric aromatic rings fully straightened and well packed into a crystalline form in the backbone, this rod-like ANF enables an augmented network with effective energy dissipation, resulting in the metal-like mechanical properties, i.e., unprecedented tensile strength (300.5 MPa), high Young's modulus (13.6 GPa), and excellent folding endurance (>10 000 times). More significantly, this MXene/ANF composite film with outstanding specific EMI shielding effectiveness (8814.5 dB cm2 g-1) and flame retardancy performs a broad range of operations in the temperature range from -100 °C (355 MPa) to 300 °C (136 MPa), in which >99% electromagnetic waves could be eliminated; this promises its potential EMI shielding applications even in some extreme conditions.