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

Abstract

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.

Cholesteric liquid crystal doped with spiropyran and zinc ions for multi-state anti-counterfeiting

“…The CLC microspheres arrange their helical axes radially and perpendicular to the surface, ensuring consistent structural color from any viewing angle. 29 Moreover, compared to CLC, the size of CLC microspheres can be controlled through technological means, significantly enhancing security for encryption and anti-counterfeiting purposes. Consequently, we have further processed anti-counterfeiting ink to produce CLC anti-counterfeiting microspheres.…”

Bioinspired reflective display based on photonic crystals

“…CLCs are becoming increasingly popular due to their unique chiral structural colors. He et al [ 132 ] prepared monodisperse CLC particles by dispersion polymerization (Figure 10C). By producing CLCs into micrometer‐sized monodisperse spheres, the pitch of the CLCs can be altered according to their particle size, allowing control over the structural color of CLC particles by influencing the spacing of Bragg reflection and photonic bandgap.…”

“…Reproduced with permission. [ 132 ] Copyright 2023, John Wiley and Sons. (D) Polarization angle‐responsive LC structural color display.…”

“…CLCs are becoming increasingly popular due to their unique chiral structural colors. He et al [132] prepared monodisperse CLC particles by dispersion polymerization F I G U R E 9 Display based on responsive liquid crystal (LC) structural color. (A) Humidity-responsive cellulose-liquid crystal structural color display.…”

Efficient Multi-stimulus-Responsive Luminescent Eu(III)-Modified HOFs Materials: Detecting Thiram and Caffeic Acid and Constructing a Flexible Substrate Anti-counterfeiting Platform

“…With the rapid development of the social economy, counterfeit and shoddy products in food, medicine, electronic products, and other fields are still recurring, which has a serious impact on the development of famous products and is not conducive to the effective maintenance of a stable social and economic order. − Currently, various anti-counterfeiting strategies have been developed, including the use of holograms, watermarks, barcodes, Quick Response (QR) codes, and luminescence . Luminescent materials possess exceptional optical properties and diverse luminescence modes, making them challenging to decipher and clone.…”