Polymeric Photonic Pigments: Confined Self-Assembly, Optical Properties, and Emerging Applications

In nature, structural color is of paramount importance because it provides a vibrant, durable, and often dynamic visual language that is essential for survival and reproduction. Unlike traditional pigment-based colors, which can fade, structural colored pigments are generated by intricate microscopic structures that manipulate light, resulting in intense iridescence and metallic sheens. The development of structural colored pigments presents a critical opportunity to replace traditional toxic colorants with safe, sustainable alternatives. Inspired from the nature, self-assembly of different polymeric building blocks including colloidal nanoparticles, cellulose nanocrystals, and block copolymers, have been reported to fabricate photonic pigment. This review focuses on the summary of various polymeric building blocks, preparation strategies, and optical properties. Meanwhile, the state-of-the-art applications are discussed, including macroscopic photonic materials, colorimetric sensors, painting and drug delivery. Finally, we conclude by outlining the current challenges and future prospects in the field, positioning this review not only as a summary of design principles for artificial photonic pigment but also as a roadmap for guiding the exploration of next-generation photonic pigments for real applications.