Cholesteric liquid crystal paints: in situ photopolymerization of helicoidally stacked multilayer nanostructures for flexible broadband mirrors

Utilizing sequential layer-by-layer (LBL) coating and subsequent photopolymerization, we developed circular-polarizing and free-standing mirrors with a broad reflection bandwidth. Photopolymerizable cholesteric liquid crystal (CLC) paints were first prepared by considering the intrinsic chirality and the coating viscoelasticity. The polymer-stabilized nanostructures had finely tuned helical pitches that selectively reflected light over the entire visible wavelength range. The CLC films exhibited excellent thermomechanical properties and chemical stabilities, which enabled the preparation of patterned optical objects at macroscopic dimensions. The LBL coating and photopolymerization of the CLC paints demonstrated here can provide a simple solution for manufacturing flexible photonic devices with large areas at low cost. Helicoidally stacked polymer networks constructed by coating and curing the chirophotonic crystal paints has great potential to fabricate flexible mirrors with macroscopic dimensions and broad bandwidth. An innovative paint containing polymer-stabilized liquid crystals can be turned into bendable and highly reflective mirrors. The brilliant hues found on peacock feathers arise from structural coloration, a phenomenon where tiny microstructures deflect and modify light waves. Kwang-Un Jeong at Chonbuk National University in Jeonbuk, South Korea, and colleagues now report a technique to generate structural colors inside acrylic-based paints. By adding precise amounts of helical liquid crystals to the paint and curing it with ultraviolet light, ordered nanoscale regions appeared that generated either red, green, or blue colors. The paint could be lithographically fabricated into free-standing objects that have exceptional chemical and mechanical stability. Vertically stacking paint coatings with different colors onto a single substrate yielded silvery flexible mirrors that were able to reflect the entire visible light spectrum.