A multi-stimulus responsive photonic thin-film display material, its preparation method and its application

Abstract

This invention discloses a method for preparing a multi-stimulus responsive photonic thin-film display material, comprising the following steps: uniformly dispersing monodisperse nanoparticles, anthracene fluorescent monomers, monomers, and initiators in ethanol to obtain a suspension; evaporating the ethanol in a thermal environment to obtain a precursor solution, wherein the anthracene fluorescent monomers simultaneously contain anthracene groups and carbon-carbon double bond end groups; obtaining a photonic thin film through a photopolymerization reaction of the obtained precursor solution; and subjecting different regions of the photonic thin film to secondary photo-irradiation treatment to obtain a multi-stimulus responsive photonic thin-film display material. This invention utilizes the cycloaddition reaction of anthracene groups to achieve pattern drawing in different regions by varying the duration of secondary photo-irradiation treatment. It can achieve "one input, multiple outputs" display and encryption strategies through multiple stimuli, showing broad application prospects in intelligent display, sensing, information encryption, and anti-counterfeiting fields.

Description

Technical Field

[0001] This invention relates to the field of stimulus-responsive polymer materials technology, specifically to a multi-stimulus responsive photonic thin-film display material, its preparation method, and its applications. Background Technology

[0002] Stimulus-responsive colloidal photonic crystals, as a class of smart materials, exhibit outstanding optical properties and the ability to sense and respond to environmental stimuli due to their unique self-assembled periodic nanoscale structure. Their significant application value in data storage, information encryption, and anti-counterfeiting has attracted widespread attention from scientists.

[0003] The excellent optical stability of stimulus-responsive colloidal photonic crystals ensures their long-term, efficient color response to ambient stimuli, prompting widespread efforts to achieve structural colors in synthetic materials. Generally, the generation of these striking structural colors follows Bragg's law, which can be effectively adjusted by manipulating the types and proportions during material preparation. Furthermore, the structural colors of the prepared stimulus-responsive colloidal photonic crystals exhibit flexible tunability by changing the viewing angle and surrounding environmental conditions, which is related to the stimulus-responsiveness and angle-dependent advantages of the host polymer matrix.

[0004] Various stimuli, including temperature, ions, pH, light, electricity, magnetism, humidity, chemical signals, and mechanical signals, have been explored for regulating the color of process structures, showing great promise for applications in anti-counterfeiting, sensors, information encryption / display, and intelligent actuators.

[0005] Chinese patent document CN118707778A discloses a method for preparing a photosensitive thermochromic thin film with an information pattern: a chiral nematic liquid crystal, a polymer, and a photochromic monomer are mixed in a good solvent to prepare a mixed solution; the mixed solution is coated onto a substrate and dried to form a thin film; a transparent mask with a target pattern is placed on the surface of the thin film, and the film is then irradiated with visible or ultraviolet light, or marked with an ultraviolet laser using the target pattern as the marking pattern, so that the target pattern is marked on the surface of the thermochromic thin film. This invention achieves a response to thermal stimuli by cleverly combining a reversible photochromic monomer with a reversible thermochromic cholesteric liquid crystal and a polymer matrix.

[0006] Chinese patent document CN116813956A discloses a method for preparing a solvent-responsive photonic crystal film. The method involves first mixing monomers to obtain a pre-emulsion, then obtaining monodisperse polymer microspheres through semi-stepwise emulsion polymerization, and finally uniformly coating the microspheres onto a substrate surface to obtain a three-dimensional photonic crystal film. This photonic crystal film can detect numerous solvents and solvent mixtures, identifying specific solvent types based on different color responses, and exhibits bright structural colors and a fast response speed.

[0007] However, the monotonous color conversion mode affects the accuracy of material information reading and its applicability in different application scenarios. Therefore, post-adjustment in a deterministic system with a defined composition to achieve multi-color separation under multiple display modes is highly challenging but of paramount importance.

[0008] It is worth noting that stimulating fluorescent dyes, as a class of functional materials, undergo dynamic changes at the molecular scale, which can be amplified into macroscopic effects, greatly expanding the field of emission displays in non-visible light channels. Currently, a large number of studies have been conducted to obtain luminescence with a wide wavelength range and high quantum efficiency by manipulating molecular morphology, in order to meet important applications such as high-level information security and storage, and multi-mode anti-counterfeiting.

[0009] Despite the great potential of display channels utilizing these non-visible light components to enrich intelligent stimulus-responsive colloidal photonic crystal optical materials, their widespread application is hampered by various challenges, including complex fabrication processes, isolated and cumbersome modulation procedures, and invasive stimuli residues.

[0010] Furthermore, light, as a representative non-contact triggering factor, can induce changes in the properties of photopolymers with high spatiotemporal precision. These non-invasive techniques have attracted widespread attention and are being used as alternatives to invasive modulation triggers. Typically, traditional methods of individually modulating display channels have achieved interference-free multi-optical displays, which requires ensuring unimpeded stimulus transmission. Asynchronous display systems with co-programmable mechanisms remain very attractive and cost-effective.

[0011] Therefore, there is an urgent need to find a photonic thin-film display material that can solve the problems of cumbersome preparation process, difficulty in color separation, and limited display channels of existing stimulus-responsive materials. Summary of the Invention

[0012] To address the aforementioned technical problems, this invention provides a method for preparing a multi-stimulus responsive photonic thin-film display material. This method features mild conditions, a short preparation process, and low cost. The resulting photonic thin-film display material exhibits excellent stimulus-response characteristics and can display information through various exogenous stimuli.

[0013] A method for preparing a multi-stimulus responsive photonic thin-film display material includes the following steps:

[0014] (1) Monodisperse nanoparticles, anthracene fluorescent monomers, monomers and initiators are uniformly dispersed in ethanol to obtain a suspension. The suspension is placed in a hot environment to evaporate the ethanol to obtain a precursor solution. The anthracene fluorescent monomers contain both anthracene groups and carbon-carbon double bond end groups.

[0015] (2) The precursor solution obtained in step (1) is subjected to photopolymerization to obtain a photonic thin film;

[0016] (3) The different regions of the photonic thin film obtained in step (2) are subjected to secondary light irradiation to obtain a multi-stimulus responsive photonic thin film display material.

[0017] This invention uses anthracene fluorescent monomers as functional agents to regulate fluorescence and structural color. These monomers are doped into a precursor solution, and a photonic thin film is prepared via photo-initiated free radical polymerization (i.e., photopolymerization). Subsequently, different regions of the photonic thin film undergo secondary light irradiation, causing dimerization reactions between anthracene units on the polymer chain, i.e., [4+4] addition reactions between anthracene units to form heterogeneous cross-linked structures. This enables spatiotemporal programming of different regions on the photonic thin film, resulting in a multi-stimulus responsive photonic thin film display material. The multi-stimulus responsive photonic thin film display material prepared by this invention can distinguish the heterogeneous cross-linked structures through various stimulus response mechanisms (such as ultraviolet light response, tensile force response, and solvent-assisted response), achieving color separation and pattern display.

[0018] Preferably, the monodisperse nanoparticles are silica, polystyrene, or polymethyl methacrylate, and the particle size of the monodisperse nanoparticles is 200–300 nm.

[0019] Preferably, the amount of monodisperse nanoparticles added is 30% to 74% of the monomer volume.

[0020] In this invention, monodisperse nanoparticles can self-assemble into a non-closely packed periodic structure. This structure has unique advantages such as photonic bandgap, angle-dependent color, slow photon effect, and fluorescence enhancement. When mixed with anthracene fluorescent monomers, it produces a bright structural color.

[0021] The structural color generated in this invention follows Bragg's law. The effective refractive index and lattice distance can be controlled by adjusting the type, particle size, amount added, and observation angle of the monodisperse nanoparticles, thereby achieving the display of full-spectrum structural color.

[0022] Preferably, the anthracene fluorescent monomer is 9-vinylanthracene, anthracene-9-methyl acrylate, or anthracene-9-methyl methacrylate.

[0023] The structures of the above-mentioned anthracene fluorescent monomers are shown below:

[0024]

[0025] The anthracene group of anthracene fluorescent monomers can undergo a [4+4] cycloaddition reaction, i.e. a dimerization reaction, during secondary light treatment. After the dimerization reaction occurs, the fluorescence intensity decreases.

[0026] Preferably, the amount of the anthracene fluorescent monomer added is 1% to 5% of the monomer mass.

[0027] In this invention, high quantum yield fluorescence emission can be achieved by adding only a small amount of anthracene fluorescent monomer to the precursor solution. This invention can regulate the dimerization ratio of the anthracene fluorescent monomer by controlling the amount added, thereby regulating the fluorescence intensity, which in turn regulates the degree of polymer crosslinking and synergistically influences / regulates the structural color.

[0028] Preferably, the monomer is at least one selected from polyethylene glycol methyl ether acrylate (PEGMA), ethylene glycol dimethacrylate (EDA), poly(ethylene glycol) dimethacrylate (MPL), diethylene glycol ethyl ether acrylate (DEGEEA), 1,6-hexanediol diacrylate (HEDA), 2-methyl-2-acrylate-2-(2-methoxyethoxy)ethyl acrylate (MEO2MA), ethylene glycol phenyl ether methacrylate (2-PEMA), polyethylene glycol phenyl ether acrylate (PEGPEA), ethylene glycol phenyl ether acrylate (2-PEA), poly(ethylene glycol) diacrylate (PEGDA), and trimethylolpropane ethoxylate triacrylate (ETPTA).

[0029] The structure of the aforementioned monomer is shown below:

[0030]

[0031] In this invention, the monomers mentioned above all contain carbon-carbon double bonds at their ends, which can undergo photo-initiated free radical polymerization under the action of an initiator.

[0032] Preferably, the initiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone or 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylphenylpropanone.

[0033] In this invention, 2-hydroxy-2-methyl-1-phenyl-1-propanone and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylpropanone are both free radical photoinitiator molecules that can initiate cross-linking reactions of monomers after being irradiated with ultraviolet light.

[0034] Preferably, the amount of initiator added is 1% to 5% of the monomer mass.

[0035] Preferably, the thermal environment temperature is 60–100°C, and the volatilization time is 5–24 hours.

[0036] Preferably, the photonic thin film is prepared by: firstly, the precursor solution is spontaneously permeated into the gap between two glass slides separated by a spacer layer under the action of capillary force, and then a photopolymerization reaction is carried out to obtain the photonic thin film.

[0037] More preferably, the thickness of the spacer layer is 40 μm to 1 mm.

[0038] In this invention, when the thickness of the spacer layer is within the above-mentioned range, it is beneficial to the formation of capillary force.

[0039] Preferably, the wavelength of the photopolymerization reaction is 260–380 nm, and the photopolymerization time is 5–10 min.

[0040] In this invention, when the polymerization time is controlled within the above range, dimerization between anthracene groups can be reduced, thus avoiding failure of secondary light treatment.

[0041] Preferably, the secondary illumination treatment involves illuminating different regions of the photonic thin film for varying durations, wherein the wavelength of the light used in the secondary illumination treatment is >300nm and the illumination time is 20–180min.

[0042] In this invention, the [4+4] cycloaddition efficiency of anthracene groups is lower than that of photopolymerization. Therefore, the time for secondary light treatment is longer than that for photopolymerization. Sufficient secondary light treatment time is required to distinguish between the addition region of anthracene groups and the region of photopolymerization only. Customized color separation and pattern drawing are achieved by distinguishing the regions.

[0043] This invention also provides a multi-stimulus responsive photonic thin-film display material prepared by the above-described method. This multi-stimulus responsive photonic thin-film display material exhibits excellent stimulus responsiveness, high structural color reflectivity, narrow half-maximum width, and high fluorescence intensity, enabling rapid responses to various stimuli (including UV response, uniaxial tensile mechanical response, and solvent-assisted response). Furthermore, based on the dimerization reaction of anthracene groups, direct interaction between fluorescence and structural color can be avoided, achieving asynchronous multi-channel display.

[0044] This invention also provides applications of the aforementioned multi-stimulus responsive photonic thin-film display material in information storage and display, information encryption and anti-counterfeiting, warning and sensing fields. This invention utilizes the regional addition reaction of anthracene groups to synergistically influence the fluorescence and structural color properties of the multi-stimulus responsive photonic thin-film display material, enabling interference-free multi-channel display. By subjecting different regions of the photonic thin film to secondary illumination treatment, the degree of cross-linking of the multi-stimulus responsive photonic thin-film display material is spatially adjusted, achieving customized color separation and patterns. Patterns or encrypted information can be displayed through various stimuli (including UV response, uniaxial tensile mechanical response, and solvent-assisted response).

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] (1) In this invention, the cycloaddition reaction of anthracene groups is used to achieve pattern drawing in different regions by varying the duration of secondary light treatment in different regions. The preparation method is novel and ingenious. Using light as a control means, this non-contact / non-invasive control method has high spatiotemporal resolution and can remotely customize various types of text / patterns. The preparation method is low in cost, simple in process, mild in reaction conditions, low in equipment requirements, and widely applicable.

[0047] (2) The multi-stimulus responsive photonic thin-film display material prepared by this invention has excellent stimulus responsiveness, high structural color reflectivity, narrow half-maximum width, and high fluorescence intensity, and can achieve rapid response to various stimuli (including UV response, uniaxial tensile mechanical response, and solvent-assisted response). At the same time, based on the dimerization reaction of anthracene groups, the direct interaction between fluorescence and structural color can be avoided, enabling customized color separation and pattern drawing in different regions.

[0048] (3) The multi-stimulus responsive photonic thin film display material obtained by the present invention can be processed into any shape using a mold.

[0049] (4) This invention adjusts the degree of crosslinking of multi-stimulus responsive photonic thin film display material in space by performing secondary light irradiation on different regions of the photonic thin film, thereby achieving customized color separation and patterns. It can realize "one input, multiple output" display and encryption strategies through various stimuli (including UV response, uniaxial tensile mechanical response and solvent-assisted response), and has broad application prospects in the fields of intelligent display, sensing, information encryption, and anti-counterfeiting. Attached Figure Description

[0050] Figure 1 Image of the precursor solution prepared in Example 1.

[0051] Figure 2 This is a photograph of the multi-stimulus responsive photonic thin film display material prepared in Example 1 under natural light.

[0052] Figure 3 This is a scanning electron microscope (SEM) image of the cross-section of the multi-stimulus responsive photonic thin-film display material prepared in Example 1.

[0053] Figure 4 Images of regions of the multi-stimulus responsive photonic thin-film display material prepared in Example 1 under natural light at different illumination times.

[0054] Figure 5 The image shows the reflectance spectra of the multi-stimulus responsive photonic thin-film display material prepared in Example 1 at different illumination times.

[0055] Figure 6 The image shows CIE diagrams of the regions of the multi-stimulus responsive photonic thin-film display material prepared in Example 1 under different illumination times.

[0056] Figure 7 The images show fluorescence images of regions of the multi-stimulus responsive photonic thin-film display material prepared in Example 1 under ultraviolet light at different illumination times.

[0057] Figure 8 The image shows the steady-state fluorescence spectra of the multi-stimulus responsive photonic thin-film display material prepared in Example 1 under ultraviolet light at different illumination times.

[0058] Figure 9 These are images of the multi-stimulus responsive photonic thin film display material prepared in Example 1 under different stimuli.

[0059] Figure 10 The infrared spectra of the ordinary photonic thin film material prepared in Comparative Example 1 are shown in the region under different illumination times. Detailed Implementation

[0060] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited to the following embodiments.

[0061] All raw materials used in this invention are commercially available.

[0062] Example 1

[0063] (1) Preparation of precursor solution

[0064] 1.2224 g of SiO2 nanoparticles (197 nm), 15 mg of 9-vinyl anthracene, 1.0 mL of polyethylene glycol phenyl ether acrylate (n ≈ 2), and 15 μL of 2-hydroxy-2-methyl-1-phenyl-1-propanone were uniformly dispersed in 15 mL of ethanol and ultrasonically mixed to obtain a white suspension. The suspension was then placed in a 65°C oven for 24 h to evaporate the ethanol until complete evaporation, resulting in an iridescent precursor solution. The precursor solution is as follows: Figure 1 As shown;

[0065] (2) Fabrication of photonic thin films

[0066] The rainbow-colored precursor solution obtained in step (1) spontaneously permeates into the gap between two clean glass slides (60×60mm) separated by a spacer layer (200μm) under the action of capillary force. After the precursor solution fills the entire mold, it is transferred to a 365nm ultraviolet lamp for photopolymerization reaction for 5min. The mold is carefully removed to obtain a photonic thin film.

[0067] (3) Fabrication of multi-stimulus responsive photonic thin film display materials

[0068] Different regions of the photonic thin film obtained in step (2) are subjected to differentiated secondary photon processing. Specifically, the photonic thin film is irradiated with a 365nm ultraviolet lamp for 30 min, 60 min, 90 min, 120 min, 150 min, and 180 min respectively, with the assistance of a black mask, to obtain a multi-stimulus responsive photonic thin film display material, such as... Figure 2 As shown, a bright red structural color can be observed under natural light.

[0069] Example 2

[0070] (1) Preparation of precursor solution

[0071] 0.713 g of polymethyl methacrylate nanoparticles (207 nm), 15 mg of anthracene-9-acrylate, 1.0 mL of diethylene glycol ethyl ether acrylate, and 15 μ L of 2-hydroxy-2-methyl-1-phenyl-1-propanone were uniformly dispersed in 20 mL of ethanol and ultrasonically mixed to obtain a white suspension. The suspension was then placed in an 85 °C oven for 24 h to evaporate the ethanol until the ethanol was completely evaporated, resulting in an iridescent precursor solution.

[0072] (2) Fabrication of photonic thin films

[0073] The rainbow-colored precursor solution obtained in step (1) spontaneously permeates into the gap between two clean glass slides (60×60mm) separated by a spacer layer (150μm) under the action of capillary force. After the precursor solution fills the entire mold, it is transferred to a 365nm ultraviolet lamp for photopolymerization reaction for 5min. The mold is carefully removed to obtain a photonic thin film.

[0074] (3) Fabrication of multi-stimulus responsive photonic thin film display materials

[0075] Differential secondary photon processing is performed on different regions of the photonic thin film obtained in step (2), that is, the photonic thin film is irradiated with a 365nm ultraviolet lamp with the assistance of a black mask for 30min, 60min, 90min, 120min, 150min and 180min respectively to obtain a multi-stimulus responsive photonic thin film display material.

[0076] Example 3

[0077] (1) Preparation of precursor solution

[0078] 0.635 g of polystyrene nanoparticles (191 nm), 15 mg of anthracene-9-acrylate, 1.0 mL of diethylene glycol ethyl ether acrylate, and 10 μ L of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone were uniformly dispersed in 20 mL of ethanol and ultrasonically mixed to obtain a white suspension. The suspension was then placed in an 85 °C oven for 24 h to evaporate the ethanol until the ethanol was completely evaporated, resulting in an iridescent precursor solution.

[0079] (2) Fabrication of photonic thin films

[0080] The rainbow-colored precursor solution obtained in step (1) spontaneously permeates into the gap between two clean glass slides (60×60mm) separated by a spacer layer (180μm) under the action of capillary force. After the precursor solution fills the entire mold, it is transferred to a 365nm ultraviolet lamp for photopolymerization reaction for 10min. The mold is carefully removed to obtain a photonic thin film.

[0081] (3) Fabrication of multi-stimulus responsive photonic thin film display materials

[0082] Differential secondary photon processing is performed on different regions of the photonic thin film obtained in step (2), that is, the photonic thin film is irradiated with a 365nm ultraviolet lamp with the assistance of a black mask for 30min, 60min, 90min, 120min, 150min and 180min respectively to obtain a multi-stimulus responsive photonic thin film display material.

[0083] Example 4

[0084] (1) Preparation of precursor solution

[0085] 1.23 g SiO2 particles (195 nm), 15 mg anthracene-9-acrylate, 1.0 mL polyethylene glycol phenyl ether acrylate (n≈2), and 15 μL 2-hydroxy-2-methyl-1-phenyl-1-propanone were uniformly dispersed in 13 mL ethanol and ultrasonically mixed to obtain a white suspension. The suspension was then placed in a 100 °C oven for 12 h to evaporate the ethanol until the ethanol was completely evaporated, resulting in an iridescent precursor solution.

[0086] (2) Fabrication of photonic thin films

[0087] The rainbow-colored precursor solution obtained in step (1) spontaneously permeates into the gap between two clean glass slides (60×60mm) separated by a spacer layer (100μm) under the action of capillary force. After the precursor solution fills the entire mold, it is transferred to a 365nm ultraviolet lamp for photopolymerization reaction for 10min. The mold is carefully removed to obtain a photonic thin film.

[0088] (3) Fabrication of multi-stimulus responsive photonic thin film display materials

[0089] Different regions of the photonic thin film obtained in step (2) are subjected to differentiated secondary photon processing, that is, the photonic thin film is irradiated with a 365nm ultraviolet lamp with the assistance of a black mask for 30min, 60min and 120min respectively to obtain a multi-stimulus responsive photonic thin film display material.

[0090] Comparative Example 1

[0091] (1) Preparation of precursor solution

[0092] 1.23 g of SiO2 particles (210 nm), 1.0 mL of polyethylene glycol phenyl ether acrylate (n ≈ 2) and 10 μL of 2-hydroxy-2-methyl-1-phenyl-1-propanone were uniformly dispersed in 20 mL of ethanol and ultrasonically mixed to obtain a white suspension. The suspension was then placed in a 90 °C oven for 12 h to evaporate the ethanol. After the ethanol was completely evaporated, a precursor solution with iridescent colors was obtained.

[0093] (2) Fabrication of photonic thin films

[0094] The precursor solution obtained in step (1) spontaneously permeates into the gap between two clean glass slides (60×60mm) separated by a spacer layer (200μm) under the action of capillary force. After the precursor solution fills the entire mold, it is transferred to a 365nm ultraviolet lamp for photopolymerization reaction for 10min. The mold is carefully removed to obtain a photonic thin film.

[0095] (3) Fabrication of conventional photonic thin-film display materials

[0096] Differentiated secondary photon processing is performed on different regions of the photonic thin film obtained in step (2), that is, the photonic thin film is irradiated with a 365nm ultraviolet lamp with the assistance of a black mask for 30min, 60min, 90min, 120min, 150min and 180min respectively to obtain ordinary photonic thin film display material.

[0097] The obtained ordinary photonic thin film material was tested for its photophysical properties. This material does not exhibit fluorescence; no fluorescence was observed after adding an excitation light source. Figure 10 As shown, for the prepared ordinary photonic thin film material, the changes in the corresponding molecular structure and chemical composition of the material under various ultraviolet treatment times were detected by micro-FTIR. It was found that the peak shape of the corresponding infrared spectrum did not change, the spectrum did not detect the characteristic peak changes of the dimerization behavior of anthracene, and the stimulus response of the ordinary photonic thin film material was limited, possessing only a single structural color characteristic.

[0098] Sample Analysis

[0099] I. Cross-sectional structural analysis

[0100] The cross-section of the multi-stimulus responsive photonic thin film display material obtained in Example 1 was analyzed by scanning electron microscopy.

[0101] Figure 3 Here is a scanning electron microscope (SEM) image of the cross-section of the multi-stimulus responsive photonic thin-film display material prepared in Example 1, as shown. Figure 3 As shown, the silica nanoparticles exhibit a hexagonal close-packed structure, with polymers of 9-vinyl anthracene and polyethylene glycol phenyl ether acrylate filling the gaps (d ~ 210 nm) between the silica particles, laying the foundation for the iridescent structural colors. The polymer network is sufficient to fix the physical color units in place during the initial stage of free radical polymerization, and may be accompanied by a very small amount of dimerization of anthracene groups.

[0102] II. Photophysical performance testing under natural light

[0103] The multi-stimulus responsive photonic thin film display material prepared in Example 1 was placed under natural light. Specifically, digital photos of the corresponding natural light were recorded using a digital camera. The color changes of the region under different illumination times were observed. The reflectance spectra of each region were detected using an ultraviolet-visible-near-infrared spectrophotometer (LAMBDA), and the corresponding reflectance spectra were mapped into the CIE 1931 color space.

[0104] Figure 4 Images of regions of the multi-stimulus responsive photonic thin-film display material prepared in Example 1 under natural light at different illumination times, such as... Figure 4 As shown, the areas treated with secondary illumination for 0–180 min all exhibit a bright red color, with almost no difference visible to the naked eye.

[0105] Figure 5The figure shows the reflectance spectra of the multi-stimulus responsive photonic thin-film display material prepared in Example 1 at different illumination times. As shown, the maximum reflectance wavelengths in the regions treated with secondary illumination from 0 to 180 min are 644.43 nm, 644.43 nm, 644.09 nm, 642.40 nm, 646.11 nm, 644.09 nm, and 643.42 nm, respectively, with an average maximum reflectance wavelength of 644.14 nm and a standard deviation of less than 0.18%.

[0106] Figure 6 This is a CIE diagram of the region of the multi-stimulus responsive photonic thin-film display material prepared in Example 1 under different illumination times. Specifically, the above... Figure 5 Each measured reflectance spectrum data point was mapped to CIE coordinates for visualization. As shown in the figure, the coordinate span of each mapped point is almost very small, eliminating the influence of errors and verifying the same optical state of the multi-stimulus responsive photonic thin film display material under white light, which is beneficial for hiding secret information under visible light.

[0107] III. Photophysical performance testing under ultraviolet light

[0108] The multi-stimulus responsive photonic thin film display material prepared in Example 1 was placed under ultraviolet light (365nm ultraviolet light excitation). Specifically, digital photos were recorded using a digital camera to observe the color changes of the region under different illumination times in non-visible light, and the steady-state fluorescence spectrum of different regions was monitored using a fluorescence spectrometer (FL3-111).

[0109] Figure 7 and Figure 8 The images show fluorescence images and steady-state fluorescence spectra of the multi-stimulus responsive photonic thin-film display material prepared in Example 1 under ultraviolet light at different illumination times. Figure 7 As shown, the fluorescence intensity of the region treated with secondary light for 30–180 min was lower than that of the region without secondary light treatment. This is because during secondary light treatment, the anthracene groups dimerize, and the fluorescence intensity of the dimerized anthracene groups weakens. The degree of dimerization gradually increases with the extension of the secondary light treatment time, while the fluorescence intensity gradually decreases with the extension of the secondary light treatment time. Figure 8 Therefore, the multi-stimulus responsive photonic thin film display material prepared by this invention can directly read information from different illumination time regions during secondary illumination processing under ultraviolet light (365nm) excitation.

[0110] IV. Performance Analysis of Multiple Stimulus Responses

[0111] Different external stimuli were applied to the multi-stimuli responsive photonic thin film display material of Example 1, and digital photos were recorded under different stimuli to observe multiple hidden secret information.

[0112] Figure 9 The images shown are of the multi-stimulus responsive photonic thin-film display material prepared in Example 1 under different stimuli. As shown, without any stimulus, the prepared multi-stimulus responsive photonic thin-film display material does not display any external information and always exhibits a bright red structural color. When stimulated by ultraviolet light (365nm), hidden information 1 (two symmetrical swans with a crown on their heads) is revealed. Then, under external mechanical tension, when the overall strain of the prepared multi-stimulus responsive photonic thin-film display material reaches 25%, hidden information 2 (an orange swan) is revealed. Finally, using a DMSO solvent-assisted stimulus response method, the prepared multi-stimulus responsive photonic thin-film display material is forced to undergo a swelling-deswelling process. During the deswelling process, hidden information 3 (two symmetrical swans) is also deciphered.

[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a multi-stimulus responsive photonic thin-film display material, characterized in that, Includes the following steps: (1) Monodisperse nanoparticles, anthracene fluorescent monomers, monomers and initiators are uniformly dispersed in ethanol to obtain a suspension. The suspension is placed in a hot environment to evaporate the ethanol to obtain a precursor solution. The anthracene fluorescent monomers contain both anthracene groups and carbon-carbon double bond end groups. The monodisperse nanoparticles are silica, polystyrene, or polymethyl methacrylate; The monomer is at least one of the following: polyethylene glycol methyl ether acrylate, ethylene glycol dimethacrylate, poly(ethylene glycol) dimethacrylate, diethylene glycol ethyl ether acrylate, 1,6-hexanediol diacrylate, 2-methyl-2-acrylate-2-(2-methoxyethoxy)ethyl acrylate, ethylene glycol phenyl ether methacrylate, polyethylene glycol phenyl ether acrylate, ethylene glycol phenyl ether acrylate, poly(ethylene glycol) diacrylate, and trimethylolpropane ethoxy acrylate triacrylate. (2) The precursor solution obtained in step (1) is subjected to photopolymerization to obtain a photonic thin film; (3) The different regions of the photonic thin film obtained in step (2) are subjected to secondary light irradiation to obtain a multi-stimulus responsive photonic thin film display material.

2. The method for preparing the multi-stimulus responsive photonic thin-film display material according to claim 1, characterized in that, The anthracene fluorescent monomers are 9-vinylanthracene, methyl anthracene-9-acrylate, or methyl anthracene-9-methacrylate.

3. The method for preparing the multi-stimulus responsive photonic thin-film display material according to claim 1, characterized in that, The amount of anthracene fluorescent monomer added is 1% to 5% of the monomer mass.

4. The method for preparing the multi-stimulus responsive photonic thin-film display material according to claim 1, characterized in that, The monodisperse nanoparticles have a particle size of 200~300 nm; The initiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone or 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.

5. The method for preparing the multi-stimulus responsive photonic thin-film display material according to claim 1, characterized in that, The amount of monodisperse nanoparticles added is 30% to 74% of the monomer volume; the amount of initiator added is 1% to 5% of the monomer mass.

6. The method for preparing the multi-stimulus responsive photonic thin-film display material according to claim 1, characterized in that, The method for preparing the photonic thin film is as follows: first, the precursor solution is spontaneously permeated into the gap between two glass slides separated by a spacer layer under the action of capillary force, and then a photopolymerization reaction is carried out to obtain the photonic thin film.

7. The method for preparing the multi-stimulus responsive photonic thin-film display material according to claim 1 or 6, characterized in that, The wavelength of the photopolymerization reaction is 260~380 nm, and the photopolymerization time is 5~10 min.

8. The method for preparing the multi-stimulus responsive photonic thin-film display material according to claim 1, characterized in that, The secondary illumination process involves illuminating different regions of the photonic thin film for varying durations, with the wavelength of the light used in the secondary illumination process being >300 nm and the illumination time being 20~180 min.

9. The multi-stimulus responsive photonic thin film display material prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the multi-stimulus responsive photonic thin film display material according to claim 9 in the fields of information storage and display, information encryption and anti-counterfeiting, or warning and sensing.

Images