Title: Dual-Mode Patterns Enabled by Photofluidization of an Azobenzene-Containing Linear Liquid Crystal Copolymer

Author: Feng Pan, Yaoqing Feng, Yuyao Qian, Lang Qin*, Yanlei Yu*

Journal: Langmuir, 2024, 40, 22, 11766–11774

Abstract:

Creating dual-mode patterns in the same area of the material is an advanced method to increase the dimension of information storage, improve the level of encryption security, and promote the development of encoding technology. However, in situ, different patterns may lead to serious mutual interference in the process of manufacturing and usage. New materials and patterning techniques are essential for the advancement of noninterfering dual-mode patterns. Herein, noninterfering dual-mode patterns are demonstrated by combining the structural color and chromatic polarization, which is designed with an azobenzene-containing linear liquid crystal copolymer featuring a photofluidization effect. On the one hand, structural color patterns are imprinted via silicon templates with periodic microstructures after a UV-light-induced local transition of the polymer surface from a glassy to rubbery state. On the other hand, different polarization patterns based on the local photoinduced orientation of mesogens are created within the photofluidized region by the Weigert effect. Especially, the secondary imprinting is used to eliminate the partial damage to the structural color patterns during writing of the polarization patterns, thus obtaining dual-mode patterns without interference. This study provides a blueprint for the creation of advanced materials and sophisticated photopatterning techniques with potential cross-industry applications.

Fulltext Link：https://pubs.acs.org/doi/10.1021/acs.langmuir.4c01297?ref=pdf

Information storage and security is a topic of wide concern worldwide. To address this issue, researchers have developed many optical materials, such as photonic crystals, stimulus-responsive materials, and luminescent materials, which are used to authenticate banknotes, valuable products, and important documents. Patterned polymer materials are widely used for encryption and information storage. Compared with single-patterned patterns, dual-patterned patterns can be stored and read independently, which not only increases the dimensionality of information storage, but also improves the security level of encryption. However, the introduction of two patterns at the same location may lead to strong mutual interference during fabrication and use, and thus storing and reading these dual-patterns independently is a major challenge. In this paper, the photofluidic properties of azobenzene-containing linear liquid crystal copolymers are exploited to construct noninterfering structural color and chromatic polarization dual-patterns, which can be written and recognized independently. The information storage characteristics ingrained in these dual-mode pattern labels manifest outstanding resolution, enduring durability, and rapid recognition via the naked eye, delivering an innovative strategy for the creation of advanced encryption technology.