Cellulose Nanocrystal-Based Chiral Photonic Pigments with Iridescent Structural Color and Fluorescence for Anticounterfeiting

Structurally colored photonic pigments are widely used in decorating, paints, and security packaging due to their unique iridescent colors and nontoxicity. However, the poor solvent stability and single optical property of the photonic pigments hinder their applications in the fields of multilevel anticounterfeiting and information encryption. Herein, by integration of cellulose nanocrystals (CNCs) with fluorescent carbon dots, solid CNC films with both fluorescent and structural colors are successfully fabricated via a self-assembly strategy. Ultrasonic treatment is employed to modulate the structural color of CNC films across the visible spectrum. After that, CNC-based photonic pigments are produced by heat and pulverization treatment, displaying excellent solvent stability and good color responsiveness. Importantly, the CNC-based photonic pigments display structural color and fluorescence stability under a wide range of temperatures (−65–70 °C) and photoirradiation. In addition, polymers are used to encapsulate CNC-based chiral photonic pigments to produce photonic plastics and coatings with fluorescent and structural colors, which can be applied in multidimensional anticounterfeiting and photonic coatings. This strategy provides a pathway for the functionalization of biomass photonic pigments.