Synthesis Of Light-responsive Materials And Their Applications In Anti-counterfeiting Field

Stimuli-responsive materials have attracted great interest in a diverse range of applications due to their sensitive response to the surrounding environmental variation,including physical,chemical or biochemical stimuli.As a ubiquitous stimulus,light can be localized in time and space,and can also be triggered from outside the system,causing widespread concern.Photostimuli-responsive materials generally refers to a material with specific functions generated by chemical or physical reactions that lead to a series of structural and morphological changes under the action of light.Triarylethylene derivatives are excellent light-responsive materials,which have wide applications in data encryption,information storage,biological imaging,optical sensing,military camouflage and other fields.In this paper,three new kinds of triarylethylene molecules with good photoluminescence and color change properties were synthesized by introducing different substituents into triarylethylene for molecular design and structural modification on the basis of previous research in the laboratory.The relationship between the structure and photoluminescence and photochromic properties was discussed by studying the structure and optical properties,The photoluminescence and photochromic behavior of triarylethylene in powder state and solution state were compared and analyzed.The results provide a theoretical basis for the design and synthesis of photoresponsive compounds with excellent properties.Finally,the prepared triarylethylene compounds were dispersed in polymethyl methacrylate(PMMA)by physical blending method,respectively,to prepare the photostimuli-responsive polymer films,and their properties were studied in depth,came to the following conclusions:(1)First of all,we through introducing ethyl good compatibility in the polymer base three aryl photochromic units,successfully developed a new type of rapid response photochromic materials triarylethylene ethyl ester(EF-TrPEF₂)this chemical structure simple new photochromic molecules in the solid solution state showed a rapid photochromic behavior.Under UV irradiation(365 nm),the solution and the solid produced a strong absorption peak at 460 nm and 500 nm,and the compound exhibited excellent reversibility and fatigue resistance by repeat rate tests.(2)To rationally control the photoluminescent and photochromic properties,triarylethylene derivatives combining ethynyl and ethynyltrimethylsilane groups,namely TrPEF₂?H and TrPEF₂?TMS,were designed and synthesized in this work.Their molecular structures can be mutual converted,which gives an easy access to manipulate their photochromic properties and fluorescence emission intensity.Detailed photophysical and photochromic investigations reveal that these two novel molecules exhibit distinct emissive and photochromic behaviors in crystalline state.Crystalline TrPEF₂?TMS features a high photoluminescence quantum yield(PLQY)of 14.2%but invisible photochromism.This is mainly due to the addition of the bulky trimethylsilane moiety,which effectively suppresses the molecular vibrations and photocyclization reactions.On the contrary,TrPEF₂?H shows a pronounced photochromic property while a low PLQY of 1.5%.Single crystal analyses and TD-DFT calculations were further carried out to interpret the photophysical and photochromic properties of these compounds.(3)Finally,the photochromic polymer films were prepared by solution casting method using polymethyl methacrylate(PMMA)as matrix,triarylvinyl as photochromic molecule and tetrahydrofuran as solvent.The results of UV-Vis absorption spectra and scanning electron microscopy show that the introduction of different groups has a certain effect on the photochromic properties and the fading rate of the films.In particular,EF-TrPEF₂ has the best compatibility with PMMA,and can be uniformly dispersed in PMMA films.