Synergistic Coupling of MXene Nanosheets and CMC-Na for Integrated Electromagnetic Interference Shielding and Infrared Stealth.

Materials integrating electromagnetic interference (EMI) shielding and infrared (IR) stealth possess great application potential but face obstacles in large-scale production. Herein, MXene/sodium carboxymethyl cellulose (CMC-Na) composite ink is synthesized via facile, scalable vacuum ball milling. CMC-Na chains adhere to MXene through intermolecular hydrogen bonds; electrostatic repulsion restrains nanosheet stacking, while the coating hinders MXene oxidation. The ink exhibits outstanding machinability and can form uniform films on various substrates via screen printing or coating. At a MXene/CMC-Na mass ratio of 4:1, the film achieves balanced performance: a tensile strength of 82.84 MPa, an elongation at break of 2.67%, a toughness of 1.58 MJ·m-3, an EMI shielding effectiveness of 33 dB, and a specific shielding effectiveness of 37,260 dB·cm2·g-1. Low IR emissivities of 19.56% (3-5 μm) and 13.65% (8-14 μm) reduce the surface radiant temperature to 69 °C under 150 °C heating. Its layered structure combines surface and internal multiple reflections to reconcile EMI shielding and IR stealth. This low-cost scalable strategy supports the development of integrated shielding-stealth wearable electronic devices.