Humidity-Driven Dynamic Structural Color and Infrared Emissivity of MXene-Integrated Supramolecular Cholesteric...

Multispectral materials that adaptively regulate structural color and infrared (IR) emissivity in response to environmental changes are highly desirable for adaptive camouflage and wearable thermoregulation. However, the development of humidity-responsive multispectral materials capable of dynamic visible structural-color tuning and reversible IR-emissivity regulation remains challenging. Here, we report a humidity-responsive MXene-integrated supramolecular cholesteric liquid-crystal material (Hygro-MXene-CLC) that combines an evaporation-induced self-assembled supramolecular CLC layer with a semitransparent cellulose nanofiber (CNF)-intercalated MXene layer through covalent interfacial bonding. Upon humidity variation, Hygro-MXene-CLC exhibits vivid structural-color modulation, with a reflection peak shift from 467 to 625 nm, together with IR-emissivity modulation from 35% to 82% over 3-14 µm. Mechanistic analyses reveal that water uptake simultaneously expands the cholesteric pitch and hydrates the CNF/MXene interlayers, producing a Bragg-reflection red shift and progressive IR-emissivity increase. Stepwise photopolymerization enables programmable visible-IR patterns, while reversible emissivity switching supports passive thermal regulation by enhancing heat dissipation at high humidity and reducing outward thermal radiation at low humidity. This work provides a promising strategy for humidity-responsive multispectral materials for smart camouflage and dynamic thermal management.