Xinkai Li, Bo Zhou, Xiaoyan Qiu, Jin Lv, Yuyan Wang, Lingmi Hou, Xinxing Zhang
Endowing wood with a tunable wide range of colors for sustainable optical functionality is attractive but challenging. The existing wood coloring approaches based on heterogeneous additives and petroleum-based monomers are limited by dye diffusion, reduced eco-friendliness, and non-adjustable optical properties. Here, modulable chromatic wood materials (CW) are developed based on native wood microchannel-confined assembly of cellulosic liquid crystal (CLC). The CLC assemblies with nanoscale cholesteric helical pitch are constrained and integrated through microchannel boundary conditions provided by delignified wood skeletons, effectively realizing precise ordered structural regulation and stability improvement. The nanostructure of the pixel-like discrete iridescent units in CW can be actively regulated due to the reversible temperature-related hydration degree, forming adjustable photonic arrays for reliable on-demand patterning and covering a substantial gamut in the visible spectrum (419-695 nm). Besides, the utilization of a high proportion of bio-based derivatives (≈93.1 wt.%) dramatically reduces potential ecotoxicity and improves biodegradability. We foresee CW will serve as sustainable alternatives for the next generation of intelligent full-color optical devices, covering the fields of digital displaying, anti-counterfeiting, biomedical imaging, etc.