Xu Minxing, Li Xiaolan, Zhou Dong, Chen Yuzhou, Zhang Lingli, Yao Lishuang, Liu Yongjun
Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, China.
School of Physics, Harbin Institute of Technology, Harbin 150001, China.
ACS Appl Mater Interfaces. 2023 Dec 20;15(50):58955-58966. doi: 10.1021/acsami.3c16079. Epub 2023 Dec 5.
There is still significant room for improvement when combining structural color with fluorescence patterns in dual anti-counterfeiting and dynamic anti-counterfeiting labels. In this study, we achieved significant breakthroughs under dual anti-counterfeiting conditions by using the structural color properties of the hydrogen-bonded cholesteric liquid crystal (HBCLC) and combining them with the fluorescence dye spiropyran (SP) to create anti-counterfeiting patterns. The anti-counterfeiting label can only display storage information after meeting the conditions of humidity and ultraviolet light (UV) and has the functions of dynamic encryption and repeated reading. We adjusted the center of the reflection band of the HBCLC film to transition from red to infrared under 40-90% relative humidity (RH) conditions and used it as a background film to draw anti-counterfeiting patterns with SP. Since these fluorescence dyes can switch between merocyanine (MC) (red) and SP (colorless) under UV and visible light conditions, when combined with the HBCLC, orthogonal dynamic encryption was achieved. Additionally, with the adsorption of SP, the reflection band of HBCLC films under the same humidity range increased from around 160 nm to around 260 nm, greatly improving the sensitivity to humidity changes. Furthermore, under UV conditions, it can still emit red fluorescence, demonstrating a polymorphic encryption feature, which greatly increased the complexity of the anti-counterfeiting pattern with significant significance to dynamic anti-counterfeiting and information storage.
在双防伪和动态防伪标签中，将结构色与荧光图案相结合仍有很大的改进空间。在本研究中，我们利用氢键胆甾相液晶（HBCLC）的结构色特性，并将其与荧光染料螺吡喃（SP）相结合，创造防伪图案，在双防伪条件下取得了重大突破。该防伪标签只有在满足湿度和紫外线（UV）条件后才能显示存储信息，并具有动态加密和重复读取的功能。我们将HBCLC薄膜的反射带中心在40-90%相对湿度（RH）条件下从红色调整为红外，并将其用作背景薄膜，用SP绘制防伪图案。由于这些荧光染料在紫外线和可见光条件下可以在部花青（MC）（红色）和SP（无色）之间切换，与HBCLC结合时，实现了正交动态加密。此外，随着SP的吸附，HBCLC薄膜在相同湿度范围内的反射带从约160nm增加到约260nm，大大提高了对湿度变化的敏感度。此外，在紫外线条件下，它仍能发出红色荧光，展现出多态加密特性，极大地增加了防伪图案的复杂性，对动态防伪和信息存储具有重要意义。
