In this work, we developed inverse opal photonic crystals (IOPCs) for real-time identifiable labels by tuning the structure color and chemical color under ultraviolet (UV) light and near-infrared (NIR) light. We prepared IOPCs by etching a silica photonic crystal template in thermosensitive hydrogel added to 2,2-diphenyl-2H-naphtho [1,2-b] pyran-6-carbaldehyde (NP). In this way, the transparent hydrogel turned red under UV light due to the photochromic naphthopyran. Meanwhile, the green structure color of IOPCs was superimposed with the red chemical color of the hydrogel, so that IOPCs with naphthopyran (IOPCs/NP) appeared yellow. When irradiated by NIR light, the structure color of IOPCs turned blue from green due to the volume contraction of the thermosensitive hydrogel. When irradiated by UV and NIR light simultaneously, the blue structure color of IOPCs was superimposed with the red chemical color of the hydrogel, and the IOPCs/NP would finally appear purple. Thus, we realized the real-time controllable IOPCs by two light sources. Based on this, we designed a series of identifiable labels with multiple colors under UV and NIR light, which expanded the application of information anticounterfeiting and identification.
Youming Zhu,Xudong Zheng,Guomeng Li,Xi Zhang,Lin Guo,Jinfeng Mei,Zhongyu Li
The development of smart responsive materials is crucial for not only achieving high-performance adsorption of rare earth elements but also enabling green regeneration. Herein, we report the fabrication of ultraviolet (UV)-light responsive imprinted chitosan-based aerogel (UV-IA) and near-infrared (NIR)-light responsive imprinted chitosan-based aerogel (NIR-IA) for the selective adsorption and eco-friendly desorption of Dy(III). Both light-responsive imprinted chitosan-based aerogels were prepared by low-temperature thermally induced phase separation (LT-TIPs), and NIR-IA was prepared by adding the photo-thermal conversion material croconaine. The chitosan aerogels with nanofiber network pore structure were prepared by LT-TIPs. The adsorption capacities of 10 mg of UV-IA and NIR-IA were 76.32 mg g -1 and 76.11 mg g -1 under the condition of pH 5.0 and room temperature, respectively. The selective adsorption effect of UV-IA and NIR-IA on dysprosium ions was obviously better than other competitive ions, and their adsorption separation constants can reach 2408.45 mL g -1 and 2623.29 mL g -1 , respectively. The results showed that cinnamic acid in UV-IA changed to cis structure under UV irradiation, while croconaine in NIR-IA decomposed the chitosan/cinnamic acid conjugate by applying heat to it under NIR irradiation. These changes caused the imprint sizes of UV-IA and NIR-IA to be changed, realizing the green desorption of Dy(III). The best desorption rate of 88.64% was achieved by UV-IA. These materials provide a promising approach for the green and economical separation and recovery of Dy(III) from secondary resources.
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