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A TEMPERATURE AND pH DOUBLE SENSITIVE CHOLESTERIC POLYMER FILM FROM A PHOTOPOLYMERIZABLE CHIRAL HYDROGEN-BONDED ASSEMBLY

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Chinese Journal of Polymer Science 2013年第4期31卷 630-640页

作者： Feng-jin Chen 郭金宝 Ou-yu Jin 魏杰 College of Materials Science and Engineering Beijing University of Chemical Technology

In this study, a novel H-bonded cholesteric polymer film responding to temperature and pH by changing the reflection color was fabricated. The H-bonded cholesteric polymer film was achieved by UV-photopolymerizing a cholesteric liquid crystal （Ch-LC） monomers mixture containing a photopolymerizable chiral H-bonded assembly （PCHA）. The cholesteric polymer film based on PCHA can be thermally switched to reflect red color from the initial green/yellow color as temperature is increased, which is due to a change in helical pitch induced by the weakening of H-bonded interaction in the polymer film. Additionally, the selective reflection band （SRB） of the cholesteric polymer film in solution with pH 〉 7 showed an obvious red shift with increasing pH values. While the SRB of the cholesteric polymer film in solutions with pH = 7 and pH 〈 7 hardly changed. This pH sensitivity in solutions with pH 〉 7 could be explained by the breakage of H-bonds in the cholesteric polymer film and the structure changes induced by --OH- and --K＋ ions in the alkaline solution. In contrast, it couldn＇t happen in the neutral and acidic solutions. The cholesteric polymer film in this study can be used as optical/photonic papers, optical sensors and LCs displays, etc.

关键词： Cholesteric polymer film Reflection band stimulus responsive Chiral hydrogen-bonded assembly.

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Excitation-wavelength-dependent fluorescent organohydrogel for dynamic information anti-counterfeiting

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Chinese Chemical Letters 2023年第11期34卷 180-183页

作者： Dong Guo Xiaoxia Le Hui Shang Fuqing Shan Danyang Li Chunfa Ouyang Tao Chen School of Materials Science and Engineering Shanghai Institute of TechnologyShanghai 201499China Key Laboratory of Marine Materials and Related Technologies Zhejiang Key Laboratory of Marine Materials and Protective TechnologiesNingbo Institute of Material Technology and EngineeringChinese Academy of SciencesNingbo 315201China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China

Anti-counterfeiting labels with various fluorescent colors are of great importance in information encryption-decryption,but are still limited to static information ***,it is urgent to develop new materials and encryption-decryption logic for improving the security level of secret *** this study,an organohydrogel made up of poly(N,N-dimethylacrylamide)(pDMA)hydrogel network and polyoctadecyl methacrylate(pSMA)organogel network that copolymerized with two fluorophores,6-acrylamidopicolinic acid moieties(6APA,fluorescent ligand)and spiropyran units(SPMA,photochromic monomer),was prepared by a two-step interpenetrating *** UV light of 365nm and 254nm can both cleave C_(spiro)-O bonds of SPMA,and the green fluorescence of 6APA-Tb^(3+) can only be excited by 254nm light,the organohydrogel displays yellow and red under the irradiation of 254nm and 365 nm,*** addition to wavelength selectivity,these two fluorophores are thermal-responsive,leading to the fluorescence variation of the organohydrogel during heating *** a result,secret information loaded on the organohydrogel can be decrypted by the irradiation of UV light,and the authenticity of the information can be further identified by thermal *** fluorescent organohydrogel can act as an effective anti-counterfeiting label to improve the information security and protect the information from being cracked.

关键词： Fluorescent organohydrogel Anti-counterfeiting stimulus responsive Encryption-decryption Dynamic fluorescence

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