Polymer opals as novel photonic materials

Synthetic opals, based on self‐assembled arrays of core–shell (bead–matrix) polymer microparticles, are a promising platform for next‐generation bulk‐scale photonic structures, coatings, fibres and sensors. This perspective article highlights recent work in this area, ranging from characterization and application, to advances in more fundamental understanding of structural colour effects. These advances include viscoelastically tuned symmetry breaking, the observation of anisotropic optical scattering and the study of polymer opals as an analogue to the intrinsically disordered, low‐refractive‐index contrast systems associated with opals seen in nature.