Recent Advances in Block Copolymer Self‐Assembly for the Fabrication of Photonic Films and Pigments

The self‐assembly of block copolymers (BCPs) into photonic materials has drawn significant attention due to the flexibility and diversity of the building blocks that can be synthesized. This review provides a brief overview of the development of this research area and then discusses in detail recent advances in the use of BCPs as photonic pigments. In particular, the role of confinement upon the self‐assembly process to form well‐ordered lamellae is described and compared to correlated disordered structures derived from densely packed micelles. These systems respectively act as 1D (multilayered) photonic crystals and photonic glasses and are here critically compared in terms of their structural characteristics and optical performance. Finally, based on this understanding, the current challenges in this field are discussed and the potential for future developments is explored. Block copolymer self‐assembly is an effective route to fabricate photonic materials. This review summarizes the advances in this research field and highlights current strategies to develop functional photonic films. Additionally, the role of confinement upon the self‐assembly process and its application towards the production of hierarchical photonic pigments is described, with the optical appearance explained using an Ewald's sphere construction.