Bio-inspired non-iridescent structural coloration enabled by self-assembled cellulose nanocrystal composite films with balanced ordered/disordered arrays

Cellulose nanocrystal (CNC) is an interesting polysaccharide nanomaterial that can self-assemble into a chiral nematic liquid crystalline structure in aqueous solution, producing brightly structural color upon selectively reflection of visible light. However, till now, only iridescent structural colors can be created by such colloidal array, making it impossible to be used as colorimetric sensors. Here, inspired by longhorn beetle having short-range ordered but long-range disordered microstructures, it is demonstrated to develop low-/non-angle-dependent structural-color CNC composite films through interference against the long-range orders as a result of introducing positively charged poly (dimethyl diallyl ammonium chloride) (PDDA). By exploring balanced ordered/disordered structures, vivid angle-independent structural colors are realized, enabling accurate cognition for environmental signals, which is crucial to promising applications in sensing, anti-counterfeit, and decoration technology. [Display omitted] •Low-/non-angle-dependent structural-color CNC composite films are fabricated.•Balanced ordered/disordered arrays are manipulated by co-assembly with PDDA.•The composite films can be used as colorimetric sensor.