Wu Suli, Nan Jinjian, Wu Yue, Meng Zhipeng, Zhang Shufen
State Key Laboratory of Fine Chemicals, Dalian University of Technology, 2# Linggong Road, Dalian 116024, P. R. China.
ACS Appl Mater Interfaces. 2022 Jun 6. doi: 10.1021/acsami.2c04901.
The application of photonic crystals (PCs) as anticounterfeiting materials has been widely investigated because of their tunable photonic stop band and corresponding changeable structural colors. In this work, we designed a composite PC structure including an information CdS PC layer at the bottom and a polymer-based layer composed of an inverse opal PC (IOPC) layer and a disordered porous layer on the top, which can be decoded by an alcohol tissue. The high refractive index of the bottom patterned CdS PC layer provides the structure with a vivid low-angle-dependent structural color in the decoded mode, which ensures the stability of the information conveyed by this label. When the incident angle changed from 5 to 45°, the structural color of the patterned CdS layer changed slightly. In the hidden mode, the low transmittance shields the structural color of the CdS layer. When the structure was wiped with the alcohol tissue, the transmittance of the upper IOPC layer could be increased quickly due to the similar refractive indexes of the used polymer and alcohol, and the pattern of the CdS layer was decoded. Thus, the designed composite PC can act as an anticounterfeiting label, in which the encrypted pattern can be decoded by alcohol tissue wiping and shows a vivid low-angle-dependent structural color. To enhance the anticounterfeiting ability of the designed structure, a double-sided label with different encryption patterns on both sides was designed. Based on the simple reversible encryption and decryption process as well as the color stability, the label shows great application potential in the daily anticounterfeiting field.
由于光子晶体(PCs)具有可调谐的光子禁带和相应的可变结构颜色,其作为防伪材料的应用已得到广泛研究。在这项工作中,我们设计了一种复合PC结构,底部是信息CdS PC层,顶部是由反蛋白石PC(IOPC)层和无序多孔层组成的聚合物基层,该结构可以用酒精擦拭布进行解码。底部图案化的CdS PC层的高折射率使该结构在解码模式下具有鲜明的低角度依赖性结构颜色,这确保了该标签所传达信息的稳定性。当入射角从5°变为45°时,图案化CdS层的结构颜色略有变化。在隐藏模式下,低透射率屏蔽了CdS层的结构颜色。当用酒精擦拭布擦拭该结构时,由于所用聚合物和酒精的折射率相似,上层IOPC层的透射率会迅速增加,CdS层的图案被解码。因此,所设计的复合PC可以用作防伪标签,其中加密图案可以通过酒精擦拭布擦拭进行解码,并呈现出鲜明的低角度依赖性结构颜色。为了增强所设计结构的防伪能力,设计了一种双面标签,两面具有不同的加密图案。基于简单的可逆加密和解密过程以及颜色稳定性,该标签在日常防伪领域显示出巨大的应用潜力。