Anisotropic Iridescence and Polarization Patterns in a Direct Ink Written Chiral Photonic Polymer.

The iridescence of structural color and its polarization characteristics originate from the nanoscale organization of materials. A major challenge in materials science is generating the bright, lustrous hues seen in nature through nanoscale engineering, while simultaneously controlling interaction of the material with different light polarizations. In this work, a suitable chiral nematic liquid crystal elastomer ink is synthesized for direct ink writing, which self-assembles into a chiral photonic structure. Tuning the writing direction and speed leads to the programmed formation of a slanted photonic axis, which exhibits atypical iridescence and polarization selectivity. After crosslinking, a freely programmable, chiroptical photonic polymer material is obtained. The strongly perspective-dependent appearance of the material can function as specialized anticounterfeit markers, as optical elements in decorative iridescent coatings, or, as demonstrated here, in optically based signaling features.