Cholesteric Hydroxypropyl Cellulose Acrylate Microspheres as Noniridescent Photonic Pigments

Structural color has emerged as a compelling alternative to conventional organic dyes and inorganic pigments, offering advantages including fade-resistant brilliance, eco-friendliness, and versatile functionality across numerous technological domains. In this study, we demonstrate the fabrication of cellulosic photonic pigments via shear-induced self-assembly of cholesteric liquid crystalline hydroxypropyl cellulose acrylate (HPCA) microspheres. The as-prepared photonic pigments exhibit vivid noniridescent structural colors with remarkable thermal stability across a broad temperature range of 25-70 °C. We comprehensively studied the internal structure of HPCA microspheres, elucidating the origin of their noniridescent optical properties and revealing the interactions between surfactants and the liquid crystalline HPCA phase during shearing. Moreover, a mask-assisted assembly process was employed to organize HPCA microspheres into region-specific color patterns of diverse shapes, which can act as photonic inks for information encryption and decoding. We envision that the synthesized cholesteric-organized photonic pigments can serve as a sustainable, high-performance alternative to conventional chemical dyes, exhibiting excellent market prospects in sensing, anticounterfeiting, and decorative applications.