Structural color is a phenomenon where colors are produced through the interaction of light with nanostructured materials, resulting in the reflection and interference of light waves, distinct from dyes and pigments which induce coloration through absorption. Structural color is advantageous over dyes and pigments given their environmental stability, biocompatibility, brilliance and adaptability.

This coloration strategy is widespread in nature, arising from a diverse range of structures and producing a wide spectrum of colors determined by the scattering mechanism. Bottlebrush block copolymers (BBCPs) have emerged as promising materials for structural color applications.

Their unique architecture prevents entanglement and facilitates rapid assembly kinetics, enabling the formation of various photonic crystals with high tunability of structural color from the visible to the infrared range. In this paper, large modulation of a microphase separated morphology of the polystyrene-b-polylactide (PS-b-PLA) BBCP is reported using a single material by exploiting selective solubility of the two blocks in a series of structurally similar solvents. Correspondingly, the peak reflected wavelength can be modulated from 693 to sub-350 nm, which corresponds to orange to deep-blue color.