The Collaborative Innovation Center for Eco-Friendly and Fire-Safety Polymeric Materials (MoE), National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), College of Chemistry, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610064, China.
Shenzhen Institute of Advanced Electronic Materials, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
ACS Appl Mater Interfaces. 2023 May 3;15(17):21425-21434. doi: 10.1021/acsami.3c00931. Epub 2023 Apr 20.
Numerous biological systems in nature provide much inspiration for humanity to master diverse coloration strategies for creating stimuli-responsive materials and display devices, such as to access gorgeous structural colors from well-defined photonic structures. Cholesteric liquid crystals (CLCs) are a fascinating genre of photonic materials displaying iridescent colors responsive to circumstance changes; however, it is still a big challenge to design materials with broadband color variation as well as good flexibility and freestanding capacity. Herein, we report a feasible and flexible strategy to fabricate cholesteric liquid-crystal networks (CLCNs) with precise colors across the entire visible spectrum through molecular structure tailoring and topology engineering and demonstrate their application as smart displays and rewritable photonic paper. Influences of chiral and achiral LC monomers on the thermochromic behaviors of CLC precursors as well as on the topology of the polymerized CLCNs are systematically investigated, demonstrating that the monoacrylate achiral LC facilitated the formation of a smectic phase-chiral phase (Sm-Ch) pretransitional phase in the CLC mixture and improved the flexibility of the photopolymerized CLCNs. High-resolution multicolor patterns in one CLCN film are generated through photomask polymerization. In addition, the freestanding CLCN films show perceivable mechanochromic behaviors and repeated erasing-rewriting performances. This work opens avenues toward the realization of pixelated colorful patterns and rewritable CLCN films promising in technology fields ranging from information storage and smart camouflage to anti-counterfeiting and smart display.
自然界中许多生物系统为人类提供了很多灵感，以掌握多样化的变色策略，用于创造对刺激有响应的材料和显示设备，例如从明确的光子结构中获取绚丽的结构色。胆甾相液晶（CLC）是一类迷人的光子材料，它们对环境变化呈现出彩虹色响应；然而，设计具有宽带颜色变化、良好的柔韧性和自支撑能力的材料仍然是一个巨大的挑战。在此，我们通过分子结构剪裁和拓扑工程报告了一种可行且灵活的策略，可制造具有精确颜色的胆甾相液晶网络（CLCN），涵盖整个可见光谱，并展示了它们在智能显示器和可重写光子纸中的应用。研究了手性和非手性 LC 单体对 CLC 前体的热致变色行为以及聚合的 CLCN 拓扑结构的影响，证明了单丙烯酸酯非手性 LC 有利于 CLC 混合物中形成近晶相-胆甾相（Sm-Ch）预过渡相，并提高了光聚合 CLCN 的柔韧性。通过光掩模聚合在一个 CLCN 薄膜中生成高分辨率的多色图案。此外，自支撑 CLCN 薄膜表现出可感知的机械变色行为和可重复的擦除-重写性能。这项工作为实现彩色图案的像素化和可重写 CLCN 薄膜开辟了道路，有望在信息存储、智能伪装、防伪和智能显示等技术领域得到应用。
