Supramolecular Polymers with Photoswitchable Multistate Fluorescence for Anti-Counterfeiting and Encryption

Abstract

Photoswitchable fluorescent materials are desirable for many applications because their emission signals can be easily modulated on demand. In this study, novel photoswitchable multistate fluorescent supramolecular polymers (PMFSPs) were prepared via host−guest interactions under a facile ultrasonication strategy. In the system, photochromic fluorescent diarylethylene monomer (SDTE, donor) and adamantane-containing monomer (BAC) were covalently combined into the backbone of the guest polymer (P1) via radical copolymerization. Meanwhile, the host moiety (CDSP, acceptor) was synthesized by covalent incorporation of photochromic spiropyran dye (SPCOOH) with β-cyclodextrin. By adjusting the stimulation wavelength and utilizing photoinduced fluorescence resonance energy transfer (FRET), the supramolecular polymers can undergo reversible tristate fluorescence switching among none, red, and green. In addition, due to the high contrast, rapid photoresponsiveness and prominent photoreversibility of the prepared PMFSPs, we demonstrated that they have great potential in advanced anti-counterfeiting and multilevel information encryption.

Photoresponsive Diarylethene‐Containing Polymers: Recent Advances and Future Challenges

“…[ 21–25 ] Among various stimulus‐responsive polymer materials, the modulation of material properties by phototriggered mechanisms offers the advantages of remote and noncontact control, dose dependence, lack of waste, noninvasiveness, and high spatial and temporal resolution [ 26–32 ] compared to other triggering mechanisms such as temperature, [ 33–37 ] pressure, [ 38–42 ] pH, [ 43–47 ] and other chemical methods. [ 48–52 ] Photoresponsive molecules can be classified as azobenzene (AZO), [ 53–64 ] spiropyran (SP), [ 65–76 ] diarylethene (DAE), [ 77–89 ] fulgides, [ 90–97 ] ruthenium‐containing dynamic bonds, [ 98–107 ] etc. Among them, AZO, SP, and DAE are the most commonly used photochromic agents ( Figure ).…”

Quadri-Dimensional Anti-counterfeiting Flexible Label Programmed by a Photoresponsive Liquid Crystal Polymer Film

“…The widespread counterfeiting of banknotes, certificates, brands, pharmaceuticals, and jewelry has become a serious worldwide problem because of its harmful effects on the global economy, security, and health. − Developing anti-counterfeiting materials is highly desirable to increase the level of security. , Over the past few decades, various macroscopic patterns have been developed to prevent counterfeiting and information leakage, including watermarking, holograms, barcodes, and QR codes. − However, these strategies are relatively changeless and easy to copy . Therefore, photoresponsive materials have attracted accumulated attention due to their variable color or fluorescence triggered by light, − providing tremendous potential for information encryption. , Among these photoresponsive systems, liquid crystal (LC) performs excellently in tunability and responsiveness . Especially the photoresponsive cholesteric liquid crystal (CLC) can adopt self-organized helical superstructures and modulate its reflective color via pitch variation under light stimuli, , thus showing great potential in the field of multiple anti-counterfeiting .…”

Dual host–guest interaction-mediated photoswitchable fluorescent supramolecular polymers for anti-counterfeiting and encryption

“…4,7,[14][15][16][17][18] However, nanoparticles with poor processability and films with low flexibility in the regulation of optical performance still hinder their applicability in anticounterfeiting and information encryption. [19][20][21] Therefore, the development of novel PFPs with excellent processability and the flexibility of optical performance regulation are desired for anticounterfeiting and encryption. Supramolecular fluorescence polymers have been developed by introducing supramolecular interactions (such as host-guest interactions, hydrogen bonds, and coordination complex) and fluorescent molecules into polymer networks, which have shown some outstanding properties, including processability, recyclability, flexibility, and adjustable optical properties.…”