Rheology-Guided Assembly\nof a Highly Aligned MXene/Cellulose\nNanofiber Composite Film for High-Performance Electromagnetic Interference\nShielding and Infrared Stealth

Abstract

Delicately aligned structures of two-dimensional (2D)\nMXene nanosheets\nhave demonstrated positive effects on applications, especially in\nelectromagnetic interference (EMI) shielding and infrared (IR) stealth.\nHowever, precise regulation of structural assembly by theory-guided\nsolution processing is still a great challenge. Herein, one-dimensional\n(1D) cellulose nanofibers (CNFs) with a high aspect ratio are applied\nas a reinforcing agent and a rheological modifier for MXene/CNF colloids\nto fabricate aligned MXene-based materials for EMI shielding and IR\nstealth. Notably, a systematical rheological study of the MXene/CNF\ncolloids is proposed to determine the optimal solution-processing\nconditions for finely oriented component arrangement requirements\nand provides in-depth information on the interactions between the\ncomponents. The delicately regulated orientation structure assembled\nby shear inducement is convincingly demonstrated through micro-CT\nand wide-angle X-ray diffraction/small-angle X-ray scattering (WAXD/SAXS),\nwhich endows the MXene/CNF film with a significantly enhanced electrical\nconductivity of 46 685 S m^–1, a tensile strength\nof 281.7 MPa, and Young’s modulus of 14.8 GPa. Furthermore,\nthe highly aligned structure of the ultrathin film possesses a great\nenhancement in EMI shielding effectiveness (50.2 dB) and IR stealth\n(0.562 emissivity). These findings provide a fruitful understanding\nof the optimized fabrication in solution processing of high-performance\nMXene-based functional composite films and open up a great opportunity\nfor the development of multifunctional stealth materials.