A PSCLC Pattern Prepared Based on Handedness Inversion for Anti‐counterfeiting

Abstract

Handedness inversion has been widely studied in supramolecular chemistry and material sciences. Herein, a photoisomerizable chiral dopant was synthesized, which could induce the formation of a cholesteric phase with right‐handedness. The Bragg reflection band of the cholesteric liquid crystal (CLC) mixture shifted to the long wavelength with extending 365 nm UV light irradiation time. Based on this photochromic property, a colourful polymer‐stabilized CLC (PSCLC) film was prepared using a grayscale mask. A handedness reversible CLC mixture was prepared using a mixture of this chiral dopant and S5011. With extending the UV light irradiation time, the handedness of the CLC mixture changed from right‐ to left‐handedness. A patterned PSCLC film was prepared using this CLC mixture. Complementary images were observed under right‐ and left‐handedness circularly polarized lights. The results shown here not only give us a better understanding the competition between photopolymerization and photoisomerization, but also lay the foundations for decoration and anti‐counterfeiting.

Circularly Polarized Luminescence of Cholesteric Liquid Crystal Polymer Networks with a Europium(III) Complex as an Emitter

“…The distinct images of structurally colored CLCN films under different handedness CPs could be ascribed to the selective reflection of circularly polarized light. These results were similar to those reported by our group. , Under UV light, the red emission of the patterns through LH-CP was brighter than that through RH-CP (Figure e–g). As shown in Figure S17b, the S -CLCN-Eu III film exhibited an opposite result to R -CLCN-Eu III .…”

“…These results were similar to those reported by our group. 59,60 Under UV light, the red emission of the patterns through LH-CP was brighter than that through RH-CP (Figure 7e−g). As shown in Figure S17b, the S-CLCN-Eu III film exhibited an opposite result to R-CLCN-Eu III .…”

Structural coloured epoxy resin patterns prepared using thermochromic epoxy liquid crystal mixtures

“…16 Polyacrylate CLCN films have been extensively studied since 1980s and 1990s, [17][18][19] and much attention has been paid to functionalities on them. [20][21][22][23][24][25][26][27][28][29] They are potentially applied in decoration, displays, and anti-counterfeiting. However, since oxygen can react with the initiator, primary and polymer radicals, the polymerization of acrylate monomers is usually inhibited by the formation of peroxyl radicals.…”

“…33,34 Moreover, for reducing oxygen inhibition, initiators with a tertiary amino group were usually selected. [26][27][28][29] For the cationic polymerization of epoxy monomers, the photoinitiator induces the formation of carbocation. Then, the as-formed carbocation directly initiates the cationic polymerization of the epoxy monomer, and this process does not suffer from oxygen inhibition.…”

Photorewriting, Time-Resolved Encryption, and Unclonable Anticounterfeiting with Artificial Intelligence Authentication via a Reversible Photoswitchable System

“…In the digital age, information can be disseminated through a wide variety of means, including printed material, radio, television, and the Internet. − However, easy access to information through multiple channels has also led to the common occurrence of confidential and secure information, such as passports, bank checks, and ID cards, being forged or leaked, posing significant property and security risks to individuals, companies, and even governments. − From the recognition of the necessity for diverse anticounterfeiting labels, it is noted that the majority of these labels are static and susceptible to replication. With inspiration from the color-changing mechanisms observed in nature, the development of anticounterfeiting labels with dynamic color-changing capabilities proves effective in mitigating issues related to replication. − Consequently, researchers have created a range of anticounterfeiting materials with various stimulus-responsive properties, all of which are inspired by these distinctive qualities. − Among them, optical materials are advantageous because to their simple processing, high yield, and exact design. ,− However, because most optical materials rely on static characteristics or signals and particular security features are easily replicated, they offer minimal security. − Considering this, organic multistimulus-responsive luminescence materials would be promising candidates. − As a result of the fact that they exhibit color and fluorescence change behavior in response to stimuli as well as a controllable structure and function, responsive materials have important applications in the field of anticounterfeiting and information encryption. In recent years, a variety of stimuli-sensitive materials have been developed for mixed combinations of light, − temperature, pH, electricity, ions, mechanical forces, and other stimuli …”