Hydrophobic Interaction-Directed Solvent-Free Ambient-Pressure-Dried MXene Aerogels

Scalable solvent-free ambient-pressure drying (APD) of robust multifunctional MXene aerogels remains significantly challenging. We present a hydrophobic interaction-directed assembly strategy among MXene, chitosan (CS), and glutaraldehyde (GA) to engineer aerogels with programmable hydrophobicity-mechanics. Selective reduction of CS amine groups suppresses capillary forces upon solvent-free APD, yielding 4,477% compressive strength enhancement over conventional MXene aerogels. Composition tuning delivers switchable electromagnetic functionality: 25.6 wt.% CS generates a 76 dB microwave shielding effectiveness, while 67.4 wt.% yields a 6.4 GHz broadband microwave absorption, which is comparable to the best MXene aerogels. The APD MXene aerogels further exhibit exceptional thermal protection, characterized by a record-high limiting oxygen index of 60%, outstanding thermal insulation, reliable structural integrity at elevated temperatures, and a high-efficiency early fire-warning capability, outperforming previously reported nanostructured monoliths. This work offers a general, scalable, and solvent-free route for assembling MXene and other nonstructured aerogels with integrated mechanics and functionalities, advancing their application in aerospace and energy systems.