Particle Size Controlled Chiral Structural Color of Monodisperse Cholesteric Liquid Crystals Particles

Cholesteric liquid crystals (CLCs) are becoming increasingly popular due to their unique chiral structural color. Unlike ordinary CLCs materials, CLCs particles exhibit angle-independence, making them particularly noteworthy. However, currently, there are limited effective methods for controlling the structural color of CLCs particles, other than adjusting the concentration of chiral dopants or introducing stimuli-responsive groups. Here, a scalable and cost-effective process for preparing monodisperse CLCs particles via dispersion polymerization is reported. By making CLCs into micrometer-sized monodisperse spheres, the helical pitch of CLCs can be varied according to its particle size, and the resulting structural color hue due to Bragg reflection can also be changed. Covering the CLCs particles with polydimethylsiloxane results in the formation of a polymer dispersed liquid crystals-like structure, which enhances the structural color appearance and thermal stability of the CLCs particles. Additionally, a simple strategy to produce chiral anti-counterfeiting QR codes is developed. By combining CLCs particles with commercially available pigments, an anti-counterfeiting QR code that can only be displayed under a specific circular polarizer is created. This approach and resulting CLCs particles expand the modulation of CLCs structural color and enrich the application of structural color in the field of chiral optical anti-counterfeiting.