In this study, we prepared a multicolor structural-fluorescent CdS-PEGDA photonic crystal hydrogel (SFC-CPH) with a dual display mode, which has two different optical states: structural color mode and fluorescent color mode. SFC-CPH displays structural color mode under visible light and fluorescent color mode under ultraviolet light. Initially, monodisperse CdS colloidal particles were synthesized via a hydrothermal method, leading to the self-assembly of a photonic crystal template. The high refractive index of CdS contributes to the photonic crystals' low-angle dependence and vivid structural colors. Then, a variety of fluorescent molecules were doped into poly(ethylene glycol) diacrylate (PEGDA) hydrogel and combined with photonic crystals with distinct structural colors to prepare three distinct colors of SFC-CPH. We also investigated the optical characteristics and surface properties of these photonic crystal hydrogels. Based on these dual-mode display characteristics, we designed several dual-mode display patterns and a method for information encoding. The unique property of this photonic crystal hydrogel material suggests its substantial potential for applications in information storage, security, and encoding, offering innovative avenues in the realm of information display.

In this study, a multi-monomer organohydrogel network is fabricated based on radical polymerization. Acrylic acid (AA) and dimethylaminoethyl methacrylate (DMAEMA) are used as hydrophilic monomers, and methoxyethyl acrylate (MEA) serves as a hydrophobic monomer. To endow the organohydrogel with a photo-responsive property, a fluorescent monomer, 1 '-acryloyl chloride-3 ',3 '-dimethyl-6-nitrospiropyran (SPMA) is added. Under ultraviolet (UV) and visible light irradiation, SPMA undergoes ring-opening and ring-closing isomerization reactions, respectively. This leads to enhanced and reduced fluorescence. This fluorescence tunability allows for the local regulation of fluorescence in the organohydrogel using a photomask. By employing UV and visible light, complex information can be repeatedly written and erased on the organohydrogel. Additionally, based on the interactions between dimethyl sulfoxide (DMSO) and water within the system, the organohydrogel exhibits excellent anti-freezing and water-holding properties, allowing its use in low-temperature environments and extended preservation time. The organohydrogel has precise information writing capabilities and is more difficult to falsify as an information encryption platform. This study provides guidance for future researchers to develop information writing capabilities with higher precision and broader applications in various environments using smart materials. Organohydrogel with tunable fluorescence can enable information-writing through photo-mask and UV light, erase information with sustained UV irradiation, and erase fluorescence with visible light. Additionally, this organohydrogel possesses excellent anti-freezing and water-holding properties, allowing for low-temperature use and extended preservation time. Therefore, in this study, it is used for information-encryption and anti-counterfeiting. image

In the realms of information storage and display, achieving heightened levels of complexity and security has always been paramount. This study presents a multi-responsive material based on CdS photonic crystals, harnessing the properties of CdS photonic crystals and responsive organohydrogels. We incorporated temperature-responsive monomer N-isopropyl acrylamide (NIPAM), AIE monomer (2-(4-vinylphenyl)ethene-1,1,2-triyl)tribenzene (TPEE), and photochromic unit 2,2-diphenyl-2H-naphtho [1,2-b] pyran-6-carbaldehyde (naphthopyran, Np) into the organohydrogel to prepare the responsive gel material. It was then combined with CdS photonic crystals to fabricate the multistage responsive CdS photonic crystal organohydrogel. This material is not only capable of tuning the structure color of the photonic crystals through temperature but also triggers the AIE effect of the gel upon reaching the phase transition temperature. Additionally, it can initiate the photochromic effect of the material upon exposure to ultraviolet (UV) light. These responsive behaviors underpin the multistage response nature of the material. Capitalizing on these multi-responsive traits, we designed an array of multistage responsive anti-counterfeiting patterns and multistage security codes. This approach not only elevates the density of multi-layered information storage but also fortifies the tamper-resistance of traditional coding systems. The multistage responsive material has a wide spectrum of potential applications, particularly in anti-counterfeiting, information display, and encrypted data transmission, offering fresh perspectives in the domain of information security.

In this study, we proposed a self-healing conductive hydrogel based on polysaccharides and Li + to serve as flexible sensors. At first, the oxidized sodium alginate(OSA) was obtained through the oxidation reaction of sodium alginate(SA). Then OSA, carboxymethyl chitosan(CMC), and agarose(AGO) were dissolved in Li Cl solution, respectively. Finally, the hydrogel was obtained through heating, mixing, and cooling processes. Because of the Schiff base structure and hydrogen bonding, the hydrogel demonstrates good mechanical and self-healing properties. The presence of Li+provides good conductivity for the hydrogel. In addition, we demonstrated the application of the hydrogel as the flexible sensors. It can perceive the process of pressing Morse code with the index finger as a pressure sensor and monitor sliding movement of the thumb as the strain sensor to browse the web with the mobile phone. Thus, the selfhealing conductive hydrogel may have potential applications in flexible wearable sensors.

In this study, we combined CdS photonic crystals with polydimethylsiloxane (PDMS) to develop a photoresponsive CdS/PDMS photonic crystal (CdS/PDMS PC) composite, which formed the photonic crystals of two different structural colors by controlling the size of the nanometer-sized CdS colloidal microsphere and realized the photoresponsive characteristics of the photonic crystals by the addition of photochromic substances. In addition, we studied the effects of the photosensitive material in the photonic crystals on their optical properties and surface features. We used a self-assembly method to periodically arrange CdS nanospheres into photonic crystal templates. The materials with high refractive index such as CdS made photonic crystals less angle-dependent and brightly colored. PDMS combined with spirooxazine is then filled in the photonic crystal matrix, and CdS/PDMS photonic crystal composites of structural red and green colors were obtained by thermal curing. Because of the photochromic effect of spirooxazine, under ultraviolet light irradiation, the photonic crystals had the original structural color and the reversible photochromic chemical color overlaid, exhibiting a mixed color. According to this principle, when irradiated with ultraviolet light, the PDMS substrate changed from colorless to blue and the photonic crystals changed from structural color mode to photochromism mode, and this change was reversible and can be repeated. The structural color of the red photonic crystals fused with the blue PDMS to become purple, and the structural color of the green photonic crystals fused with the blue PDMS to become cyan. When irradiated with visible light, photonic crystals can return to their original structure color. In this approach, we have designed a series of ultraviolet anticounterfeiting labels to expand the application of information anticounterfeiting.

In this study, we proposed a method to prepare multi-color fluorescent hydrogels with polyvinyl alcohol (PVA) as the cross-linking network and 7-(6-carboxylpentoxy)-4-methylcoumarin (CPMC), N-ethoxyhexanoate-3,3dimethyl-6-nitro-indolinspiropyran (SPCOOH) and 2 & PRIME;,7 & PRIME;-dichlorofluorescein (DCF) were introduced to the system. Due to the hydroxyl group in PVA can form a reversible borate bond with borax, the hydrogel could be combined with each other through this chemical bond, thus hydrogels possess reversible cross-linking property and programmable property. The introduction of CPMC, SPCOOH and DCF into the hydrogel could give the hydrogel different photo-response properties. Under UV light irradiation, PVA-CPMC, PVA-CPMC/DCF, PVASPCOOH and PVA/DCF hydrogels could emit blue, cyan, pink purple and green fluorescence respectively. In addition, PVA/DCF and PVA-CPMC/DCF hydrogels could emit green fluorescence under 505 nm light irradiation. Based on the various properties of hydrogels, we respectively demonstrated the application of hydrogels in the fields of two-dimensional information encryption, three-dimensional information encryption, threedimensional information coding and anti-counterfeiting, which can achieve the expected results. Therefore, multi-color fluorescent hydrogels may have potential applications in information encryption, information coding, flexible display and other fields.

In this study, we fabricate magnetic Janus photonic crystal microbeads with multiple fluorescence colors based on photonic crystals, Fe3O4 nanoparticles, and fluorescent dyes by a microfluidic device. We mix the poly(styrene-methyl methacrylate-acrylic acid) (p(St-MMA-AA)) nanoparticles, the Fe3O4 nanoparticles, and the fluorescent dyes. We use the mixture as the dispersed phase and the silicone oil as the continuous phase. We get the Janus photonic crystal microbeads after the self-assembly of the photonic crystals. Due to the greater density, the Fe3O4 nanoparticles sink to the bottom of the Janus microbeads, which are made up of photonic crystals combined with p(St-MMA-AA) nanoparticles. The fluorescent dyes are distributed in the gaps of photonic crystals. The Janus photonic crystal microbeads could rotate upside down under the action of magnets because of the magnetism of the Fe3O4 nanoparticles. Moreover, they can fluoresce under UV light due to the fluorescent dyes. We combine Janus photonic crystal microbeads into arrays of numbers, letters, symbols, and patterns for information coding and anti-counterfeiting. The Janus microbeads have enormous potential for use in array displays, information coding, and anti-counterfeiting.

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.

In this study, we report a kind of fluorescence-structural color photonic crystals (FSC-PCs) based on ultraviolet (UV)-responsive core-interlayer-shell (CIS) colloidal particles. The preparation process includes the synthesis of UV-responsive CIS colloidal particles and quick fabrication of FSC-PCs patterns. Here, fluorescent precursor spiropyran was added to the semi-continuous emulsion polymerization system and grafted onto polymer chains to form the colloidal particles, which were quickly assembled by spray coating method into FSC-PCs within a few minutes. The FSC-PCs have long-range disorder arrangement and angle-independent structural colors, which show structural colors in visible light and red fluorescent color in 365 nm UV light. Therefore, we designed and fabricated a two-side security card, both sides of which show different information under different light conditions. During the light switching progress, completely different information can be demonstrated reversibly, allowing data encryption and reading. The FSC-PCs with a simple quick assembly process and unique optical properties have profound potential in anti-counterfeiting and data display.

In this study, we fabricate magnetic-fluorescent responsive Janus photonic crystal beads (JPCBs) based on poly(styrene-methyl methacrylate-acrylic acid) (p(St-MMA-AA)) colloidal nanoparticles, Fe3O4, and photobase generators used for self-destructive anti-counterfeiting. We synthesize two kinds of photobase generators that can react with fluorescamine to produce various fluorescence colors. A microfluidic method is used to obtain the Janus photonic crystal beads. The upper portions of the JPCBs are photonic crystals assembled with colloidal spheres, whereas the Fe3O4 settles down to the bottom of the JPCBs due to its higher density. Photobase generators are distributed in photonic crystal gaps. Because of the magnetism of the Fe3O4, the JPCBs could be flipped from one side to the other in the presence of a magnet. After being exposed to UVC light and fluorescamine, the JPCBs can fluoresce under UVA light. Then, we create Janus microbeads arrays with various types of beads and apply them to the visitor card, bracelet, and box label to provide irreversible and self-destructive anti-counterfeiting. The JPCBs are capable of being encoded and angle-independently displayed, which are crucial to their applications in anti-counterfeiting, information coding, and array display.

We report a new kind of ultraviolet (UV)-magnetic response Janus colloidal photonic crystal (CPC) beads for information coding. The Janus beads made up of fluorescent CPCs and Fe3O4 nanoparticles show different colors under visible light, UV light and magnetic stimulation. In the concrete scheme, monodisperse colloidal particles with and without fluorescent molecule SPMA were prepared by semi-continuous emulsion polymerization. Then colloidal particles and Fe3O4 nanoparticles were paired as precursors to prepare Janus beads by the droplet template method. During the slow self-assembly process, Fe3O4 nanoparticles were deposited on the bottom and colloidal particles filled the other parts of the beads so that a Janus structure formed. Therefore, the upper surface of Janus beads appears structural color and the lower surface appears black. The variation of Fe content in different hemispheres allows the controllable magnetic response to reverse the beads. The presence of fluorescent molecule SPMA makes fluorescent Janus beads (FJBs) emit fluorescence under UV light. According to design, an array in a particular arrangement of Janus beads can realize reversible changes between three different optical information. Furthermore, the binary cipher was combined with Janus beads to design and fabricate an optical encoding array, revealing an important application in information coding.

Manipulating fluorescence color to achieve patterned function may access to many applications and remains some challenges. In this work, we provide an effective way to manipulate upconversion fluorescence through the photonic crystals. The structure of the photonic crystals (PCs) has a regulatory effect on upconversion fluorescence. We assembled NaYF4:Yb3+/Er3+ upconversion nanoparticles (UCNPs) with SiO2 and CdS photonic crystals respectively to obtain the photonic crystals/upconversion nanoparticles (PCs/UCNPs) composites. We studied the manipulating mechanism of two kinds of photonic crystals on upconversion fluorescence, and realized patterning application. This study provides a new way to realize information coding, patterned display of fluorescence manipulating.

In this study, we proposed programmable photo-responsive self-healing hydrogels containing polyacrylamide (PAM), polyacrylic acid (PAA), poly[2-(dimethylamino) ethyl methacrylate] (PDMAEMA), ammonium molybdate (Mo7), and 7-2(acryloyl hydroxypropyl)-4-methyl-coumarin (AHPMC). Because of the electrostatic interaction of PAA and PDMAEMA, the hydrogel demonstrates good self-healing properties. Moreover, we introduced Mo7 and coumarin derivative in the hydrogel, respectively, which endows the hydrogel photo-responsive properties. Under the control of UV light, PAM-AD/Mo7 hydrogel with photochromic behavior could turn atrovirens, and PAM-AD/AC hydrogel with photoluminescent properties could emit blue fluorescence. In contrast, PAM-AD hydrogel possesses no photo-responsive behavior. Based on the self-healing and photoresponsive properties of the hydrogels, the three hydrogel blocks could be programmed and healed as a whole combination. In addition, we demonstrated the application of the hydrogel in optical information coding and encryption, which possesses good information coding and encryption effect. Therefore, the photo-responsive selfhealing hydrogel may have potential applications in flexible information display and encryption fields.

This paper proposes a patterned material composed of two types of photonic crystals based on CdS and SiO2 nanoparticles. We combined the photonic crystals with poly-(ethylene glycol) diacrylate (PEGDA) by nanoparticle self-assembly and UV curing and successfully formed a material containing the different photonic crystals. The material prepared contains two kinds of photonic crystals with different refractive indices, CdS and SiO2 nanoparticles, and due to the large difference in refractive indices of the two materials, the reflection wavelengths of the photonic crystals composed of the two materials also have disparities when the incident angle changes. Macroscopically, the structural colors of the two photonic crystals change with the change in incident angle. In response to this phenomenon, we designed a variety of applications based on a multiangle patterned photonic crystal film to achieve a variety of information storage functions by changing the incident angle and, through the angle change, to achieve lipstick logo, mobile phone bar code, and antipeeping keyboard applications.

Manipulating fluorescence color may enable multifunctionality access to many applications and remains a huge challenge. In this paper, an efficient approach for achieving obvious fluorescence with tunable color via spiropyran-modified upconversion nanoparticles is reported. In this way, the nanoparticles can generate yellow emission color by the superposition of fluorescence under UV and near-infrared light. The nanoparticles are configured into inks that can be printed or sprayed into diverse coded patterns which emitted various fluorescence under different lights. These patterns reveal the great potential of spiropyran-modified upconversion nanoparticles in multilevel anticounterfeiting and pattern display.

In this work, a hierarchical PVDF-HFP gel polymer electrolyte (GPE) membrane is prepared intentionally and placed between the solid electrolyte and the electrodes. The fabricated LiFePO4/GPE/LAGP/GPE/Li hybrid solid-state cell displays superior rate performance and capacity retention. After 300 cycles at 0.5 C, negligible degradation can be observed, and the specific capacity remains as high as 145.6 mA h/g at room temperature. The excellent battery performance is ascribed to the significantly improved interfacial stability of the sandwich-like hybrid electrolyte and the remarkably enhanced charge transfer kinetics across the interface due to the flexibility of GPE.