Stimuli-responsive noniridescent structural color of a thin-film coating based on multilayered nanosheets preserving the interlayer space

Two-dimensional (2D) anisotropic structures have numerous advantages for designing functional materials. Layered materials accommodate guests in their interlayer space, and exfoliated nanosheets are used as units to obtain organized architectures. If exfoliated nanosheets preserving their multilayered structures are prepared, both the intercalation and building-block capabilities can be used for functionalization. In the present work, a stimuli-responsive thin-film coating with noniridescent structural color was prepared using exfoliated nanosheets with multilayered structures. The precursor layered composite of a host transition-metal oxide and a guest organic molecule was exfoliated into surface-modified nanosheets. The resultant nanosheet was not a monolayer but comprised multilayers with an interlayer space. Coating the exfoliated nanosheets provided a thin film with uneven thickness and noniridescent structural color. As additional guest molecules were introduced into the interlayer space of the multilayers in the nanosheet, an increase in the film thickness induced changes in the structural color. Harmful biogenic amines and their mixtures were colorimetrically quantified using the prepared thin-film sensor. The thin-film coating of the multilayered nanosheets has potential for a variety of sensing applications.