All‐Cellulose‐Based Photonic Glitters

Abstract Glitters, traditionally made from petroleum‐derived polymers, pose significant environmental concerns due to their persistence in soil and oceans. Naturally sourced cellulose nanocrystals (CNCs) can self‐assemble into cholesteric structures, and form structurally colored films upon drying. However, producing CNC glitters with uniform shape and colors remains a challenge. In this study, a method to fabricate uniform is developed, disc‐like CNC photonic glitters with various structural colors using electrospray deposition. The CNC microdroplets are generated by electrostatic force and dried on hydrophilic ethyl cellulose (EC) films covered with silicone oil, then separated by dissolving the EC films in ethanol. Both the silicone oil and EC‐ethanol mixtures can be recycled. The diameters of the glitters are controlled by modifying the flow rate and electrostatic voltage, ranging from 288 ± 34 to 978 ± 62 µm. Vibrant red, green, and blue CNC glitters can be achieved by simply adjusting the ultrasonication energy input in the initial CNC suspension. These all‐cellulose‐based CNC photonic glitters are suitable for food and pharmaceutical colorants and environment friendly pigments. Additionally, patterned CNC arrays are created by depositing microdroplets onto EC films with designed hydrophilic treated regions, demonstrating their potential applications in inkjet printing and anti‐counterfeiting.