Multi-stimulus response type photon thin film display material, preparation method and application of multi-stimulus response type photon thin film display material

Abstract

The invention discloses a preparation method of a multi-stimulus response type photon film display material, which comprises the following steps: uniformly dispersing monodisperse nanoparticles, anthracene fluorescent monomers, monomers and an initiator in ethanol to obtain a turbid liquid, placing the turbid liquid in a thermal environment to volatilize the ethanol to obtain a precursor solution, the anthracene fluorescent monomer simultaneously contains an anthryl group and a carbon-carbon double-bond end group; carrying out photopolymerization reaction on the obtained precursor solution to obtain a photon film; and performing secondary illumination treatment on different areas of the photon film to obtain the multi-stimulus response type photon film display material. According to the method, pattern drawing of different areas is achieved through the cycloaddition reaction of anthryl groups and the secondary illumination processing time of the different areas, a one-input-multiple-output display and encryption strategy can be achieved through various stimuli, and the method has wide application prospects in the fields of intelligent display, sensing, information encryption, anti-counterfeiting and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of stimulus-responsive polymer materials, and in particular to a multi-stimulus-responsive photonic thin film display material, a preparation method and an application thereof. Background Art

[0002] Stimuli-responsive colloidal photonic crystals, as a type of smart material, have excellent optical properties and the ability to sense and respond to environmental stimuli due to their unique self-assembled periodic nanostructures. They have attracted widespread attention from scientists because of their important application value in data storage, information encryption, and anti-counterfeiting.

[0003] The excellent optical stability of stimuli-responsive colloidal photonic crystals ensures their long-term and efficient color response under ambient stimuli, which has prompted extensive efforts to achieve structural colors in synthetic materials. In general, the generation of these eye-catching structural colors follows the Bragg law, which can be effectively adjusted by manipulating the species and proportion during the material preparation process. In addition, the structural colors of the prepared stimuli-responsive colloidal photonic crystals show flexible adjustability by changing the viewing angle and ambient environmental conditions, which is related to the stimuli-responsiveness and angle-dependent advantages of the host polymer matrix.

[0004] A variety of stimuli, including temperature, ions, pH, light, electricity, magnetism, humidity, chemical signals, and mechanical signals have been explored for regulating process structural colors, which shows great application prospects in anti-counterfeiting, sensors, information encryption / display, smart actuators, etc.

[0005] The Chinese patent document with publication number CN118707778A discloses a method for preparing a light-adjustable thermochromic film with information patterns: chiral nematic liquid crystal, polymer and photochromic monomer are mixed in a good solvent of the three to form a mixed solution; the mixed solution is coated on a substrate, dried to form a film; a light-transmissive mask plate with a target pattern is covered on the surface of the film, and the film surface is selectively irradiated with visible light or ultraviolet light, or the target pattern is used as a marking pattern by an ultraviolet laser marking machine to mark the film surface, so that the target pattern is marked on the surface of the thermochromic film. The present invention achieves a response to thermal stimulation by cleverly combining a reversible photochromic monomer with a reversible thermochromic cholesteric liquid crystal and a polymer matrix.

[0006] The Chinese patent document with publication number CN116813956A discloses a method for preparing a photonic crystal film with solvent responsiveness: first, monomers are mixed to obtain a pre-emulsion, then monodisperse polymer microspheres are obtained by semi-stepwise emulsion polymerization, and then the microspheres are evenly applied to the surface of the substrate to obtain a three-dimensional photonic crystal film. The photonic crystal film can detect a variety of solvents and solvent mixtures, and determine the specific solvent type based on different color responses, and the structural color is bright and the response speed is fast.

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

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

[0009] Although utilizing these non-visible light components to enrich the display channels of smart stimuli-responsive colloidal photonic crystal optical materials has great potential, their widespread application is hindered by various challenges, including complex preparation procedures, isolated and cumbersome regulation processes, and invasive stimuli residues.

[0010] In addition, light as a representative non-contact trigger can induce property changes of photopolymers with high spatiotemporal precision. These non-invasive techniques have attracted extensive attention and are used as alternatives to invasive regulatory triggers. Generally, the traditional method of regulating display channels individually has achieved interference-free multi-optical displays, which must ensure that stimulus transmission is not hindered. However, asynchronous display systems with cooperative programming 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 existing stimulus-responsive materials, such as complicated preparation process, difficult color separation, and single display channel. Summary of the invention

[0012] In order to solve the above technical problems, the present invention provides a method for preparing a multi-stimulus responsive photonic thin film display material. The preparation method has mild conditions, a short preparation process, and low cost. The prepared photonic thin film display material has good stimulus response characteristics and can realize information display of the photonic thin film display material through a variety of exogenous stimuli.

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

[0014] (1) uniformly dispersing monodisperse nanoparticles, anthracene fluorescent monomers, monomers and initiators in ethanol to obtain a suspension, placing the suspension in a hot environment to volatilize the ethanol, and obtaining a precursor solution, wherein the anthracene fluorescent monomers contain both an anthracene group and a carbon-carbon double bond end group;

[0015] (2) subjecting the precursor solution obtained in step (1) to a photopolymerization reaction to obtain a photonic film;

[0016] (3) Subjecting different regions of the photonic film obtained in step (2) to secondary illumination treatment to obtain a multi-stimulus responsive photonic film display material.

[0017] The present invention uses anthracene fluorescent monomers as the regulating functional body of fluorescence and structural color, dopes them into the precursor solution, and prepares the photonic film through a light-induced free radical polymerization reaction (i.e., photopolymerization reaction), and then performs secondary light treatment on different regions of the photonic film, so that a dimerization reaction occurs between the anthracene units on the polymer chain, that is, a [4+4] addition reaction occurs between the anthracene units to form a heterogeneous cross-linked structure, thereby realizing the spatiotemporal programming of different regions on the photonic film, and preparing a multi-stimulus responsive photonic film display material. The multi-stimulus responsive photonic film display material prepared by the present invention can distinguish the heterogeneous cross-linked structure through a variety of stimulus response modes (such as ultraviolet light response, external force stretching response, and solvent-assisted response, etc.), and realize color separation and pattern display.

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

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

[0020] In the present invention, monodisperse nanoparticles can self-assemble to form a non-tightly packed periodic structure, which has unique photonic band gap, angle-dependent color, slow photon effect, fluorescence enhancement and other advantages. After being mixed with anthracene fluorescent monomers, bright structural colors are produced.

[0021] The generation of the structural color of the present invention follows the Bragg law, and the effective refractive index and lattice distance can be regulated by adjusting the type, particle size, addition amount and observation angle of the monodisperse nanoparticles, thereby realizing the display of full-color spectrum structural color.

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

[0023] The structure of the anthracene fluorescent monomer is shown below:

[0024]

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

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

[0027] In the present invention, only a small amount of anthracene fluorescent monomers need to be added to the precursor solution to achieve high quantum yield fluorescence emission. The present invention can adjust the amount of anthracene fluorescent monomers added to adjust the dimerization ratio of anthracene fluorescent monomers, that is, it can achieve the regulation of fluorescence intensity, and then adjust the cross-linking degree of the polymer, and then synergistically affect / regulate the structural color.

[0028] Preferably, the monomer is 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-acrylic acid-2-(2-methoxyethoxy)ethyl ester (MEO 2 At least one of ethylene 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 above monomer is as follows:

[0030]

[0031] In the present invention, the above-mentioned monomers all contain carbon-carbon double bonds at their ends, and can undergo a photo-initiated free radical polymerization reaction 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-methylpropiophenone.

[0033] In the present invention, 2-hydroxy-2-methyl-1-phenyl-1-propanone and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone are both free radical photoinitiator molecules, which can initiate the cross-linking reaction of monomers after being irradiated by ultraviolet rays.

[0034] Preferably, the added amount of the initiator 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 method for preparing the photonic film is: firstly, the precursor solution is spontaneously infiltrated 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 film.

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

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

[0039] Preferably, the wavelength of light in the photopolymerization reaction is 260 to 380 nm, and the photopolymerization time is 5 to 10 minutes.

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

[0041] Preferably, the secondary illumination treatment is to perform illumination treatment for different time periods on different regions of the photonic film, the wavelength of light for the secondary illumination treatment is >300nm, and the illumination treatment time is 20 to 180min.

[0042] In the present invention, the [4+4] cycloaddition efficiency of the anthracene group is lower than that of photopolymerization. Therefore, the time of the secondary light treatment is longer than the time of the photopolymerization reaction. Sufficient secondary light treatment time is required to distinguish the addition area of ​​the anthracene group from the photopolymerization area only, and customized color separation and pattern drawing are achieved through the difference in areas.

[0043] The present invention also provides a multi-stimulus responsive photonic thin film display material prepared by the above preparation method, which has excellent stimulus responsiveness, high structural color reflectivity, narrow half-peak width, and high fluorescence intensity, and can achieve rapid response to multiple stimuli (including ultraviolet UV response, uniaxial stretching mechanical response, and solvent-assisted response). At the same time, based on the dimerization reaction of the anthracene group, the direct interaction between fluorescence and structural color can be avoided to achieve asynchronous multi-channel display.

[0044] The present invention also provides the application of the above-mentioned multi-stimulus responsive photonic film display material in the fields of information storage and display, information encryption and anti-counterfeiting, warning and sensing. The present invention utilizes the regionalized addition reaction of the anthracene group to synergistically affect the fluorescence and structural color properties of the multi-stimulus responsive photonic film display material, and can achieve interference-free multi-light channel display. By performing secondary illumination treatment on different areas of the photonic film, the degree of cross-linking of the multi-stimulus responsive photonic film display material is spatially adjusted to achieve customized color separation and patterning, and the display of patterns or encrypted information can be achieved through a variety of stimuli (including ultraviolet UV response, uniaxial stretching mechanical response, and solvent-assisted response).

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] (1) In the present invention, the cycloaddition reaction of the anthracene group is utilized, and the pattern drawing of different areas is achieved by changing the length of time of secondary light treatment in different areas. The preparation method is novel and ingenious, and light is used as a control means. This non-contact / non-invasive control method has high temporal and spatial resolution accuracy, and various types of texts / patterns can be remotely customized; the preparation method is low in cost, simple in preparation process, mild in reaction conditions, low in equipment requirements, and wide in applicability.

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

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

[0049] (4) The present invention performs secondary illumination treatment on different areas of the photonic film to spatially adjust the degree of cross-linking of the multi-stimulus responsive photonic film display material to achieve customized color separation and patterning. It can realize a "one-input, multiple-output" display and encryption strategy through a variety of stimuli (including ultraviolet UV response, uniaxial stretching mechanical response, and solvent-assisted response). It has broad application prospects in the fields of intelligent display, sensing, information encryption, and anti-counterfeiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a picture of the precursor solution prepared in Example 1.

[0051] Figure 2 This is a real picture 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 image of the cross section of the multi-stimulus responsive photonic thin film display material prepared in Example 1.

[0053] Figure 4 These are pictures 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 This is a reflection spectrum diagram of the multi-stimulus responsive photonic thin film display material prepared in Example 1 in areas with different illumination times.

[0055] Figure 6 This is a CIE diagram of the multi-stimulus responsive photonic thin film display material prepared in Example 1 at different illumination times.

[0056] Figure 7 These are 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 This is a steady-state fluorescence spectrum diagram of the multi-stimulus responsive photonic thin film display material prepared in Example 1 under ultraviolet light in areas with different illumination times.

[0058] Fig. 9 These are pictures displayed by the multi-stimulus responsive photonic thin film display material prepared in Example 1 under different stimuli.

[0059] Fig.10 This is an infrared spectrum diagram of the common photonic thin film material prepared in Comparative Example 1 at different illumination times. DETAILED DESCRIPTION

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

[0061] The raw materials used in the present invention are all commercially available.

[0062] Example 1

[0063] (1) Preparation of precursor solution

[0064] 1.2224 g SiO 2 Nanoparticles (197 nm), 15 mg 9-vinyl anthracene, 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 15 mL 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 the ethanol was completely evaporated to present a rainbow-colored precursor solution, the precursor solution being as shown in FIG. Figure 1 As shown;

[0065] (2) Preparation of photonic thin films

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

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

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

[0069] Example 2

[0070] (1) Preparation of precursor solution

[0071] 0.713 g of polymethyl methacrylate nanoparticles (207 nm), 15 mg of anthracene-9-methyl acrylate, 1.0 mL of diethylene glycol ethyl ether acrylate and 15 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 an oven at 85° C. for 24 h to evaporate the ethanol, until the ethanol was completely evaporated to present a rainbow-colored precursor solution;

[0072] (2) Preparation of photonic thin films

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

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

[0075] Different regions of the photonic film obtained in step (2) are subjected to differentiated secondary photon treatment, that is, the photonic 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 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-methyl acrylate, 1.0 mL of diethylene glycol ethyl ether acrylate and 10 μL of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone were uniformly dispersed in 20 mL of ethanol, and ultrasonically mixed to obtain a white suspension; the suspension was then placed in an oven at 85° C. for 24 h to evaporate the ethanol, until the ethanol was completely evaporated to present a rainbow-colored precursor solution;

[0079] (2) Preparation of photonic thin films

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

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

[0082] Different regions of the photonic film obtained in step (2) are subjected to differentiated secondary photon treatment, that is, the photonic 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 film display material.

[0083] Example 4

[0084] (1) Preparation of precursor solution

[0085] 1.23 g SiO 2Particles (195 nm), 15 mg of anthracene-9-methyl acrylate, 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 13 mL of ethanol and ultrasonically mixed to obtain a white suspension; the suspension was then placed in an oven at 100° C. for 12 h to evaporate the ethanol until the ethanol was completely evaporated to obtain a rainbow-colored precursor solution;

[0086] (2) Preparation of photonic thin films

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

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

[0089] Different regions of the photonic film obtained in step (2) are subjected to differentiated secondary photon treatment, that is, the photonic 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 film display material.

[0090] Comparative Example 1

[0091] (1) Preparation of precursor solution

[0092] 1.23 g SiO 2 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 until the ethanol was completely evaporated to obtain a rainbow-colored precursor solution;

[0093] (2) Preparation of photonic thin films

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

[0095] (3) Preparation of common photonic thin film display materials

[0096] Different regions of the photonic film obtained in step (2) are subjected to differentiated secondary photon treatment, that is, the photonic 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 common photonic film display material.

[0097] The obtained ordinary photonic film material was tested for its photophysical properties. The material did not have fluorescence properties. After adding the excitation light source, no fluorescence phenomenon was observed. Fig.10 As shown, for the prepared ordinary photonic thin film material, a microscopic infrared spectrometer (Micro-FTIR) was used to detect the changes in the corresponding molecular structure and chemical composition of the material at various ultraviolet treatment times, and it was found that the corresponding infrared spectrum line peak shape did not change, and the spectrum line did not detect the characteristic peak changes of the dimerization behavior of the anthracene characteristic peak, and the ordinary photonic thin film material has limited stimulus response and only has a single structural color characteristic.

[0098] Sample analysis

[0099] 1. 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 This is a scanning electron microscope image of a cross section of the multi-stimulus responsive photonic thin film display material prepared in Example 1. Figure 3 As shown, the silica nanoparticles are stacked in a hexagonal close-packed structure, and the polymers of 9-vinylanthracene and polyethylene glycol phenyl ether acrylate fill the gaps between the silica (d ~ 210nm), laying the foundation for the iridescent structural color. The polymer network is sufficient to fix the physical color unit in place in the initial stage of free radical polymerization, and may be accompanied by a very small amount of dimerization of the anthracene group.

[0102] 2. Photophysical performance test under natural light

[0103] The multi-stimulus responsive photonic thin film display material prepared in Example 1 is placed under natural light. Specifically, a digital camera is used to record digital photos under the corresponding natural light, and the color changes of the regions under different illumination times under natural light are observed. The reflectance spectrum of each region is detected with an ultraviolet-visible-near-infrared spectrophotometer (LAMBDA), and the corresponding reflectance spectrum is mapped to the CIE 1931 color space.

[0104] Figure 4 These are pictures 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 4As shown, the area treated with secondary light for 0 to 180 min all appeared bright red, and the naked eye could hardly discern any changes.

[0105] Figure 5 This is a reflection spectrum diagram of the multi-stimulus responsive photonic thin film display material prepared in Example 1 in areas with different illumination times. As shown in the figure, the maximum reflection wavelengths in the area of ​​secondary illumination treatment for 0 to 180 minutes are 644.43nm, 644.43nm, 644.09nm, 642.40nm, 646.11nm, 644.09nm and 643.42nm, respectively. The average maximum reflection wavelength is 644.14nm, and the standard deviation is less than 0.18%.

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

[0107] 3. Photophysical properties test 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, corresponding digital photos were recorded with a digital camera to observe the color changes of areas with different illumination times under non-visible light, and the steady-state fluorescence spectra of different areas were monitored with a fluorescence spectrometer (FL3-111).

[0109] Figure 7 and Figure 8 They are respectively the fluorescence images and steady-state fluorescence spectra of the regions of the multi-stimulus responsive photonic thin film display material prepared in Example 1 under ultraviolet light at different illumination times, as shown in Figure 7 As shown in the figure, the fluorescence intensity of the area treated with secondary light for 30 to 180 minutes is lower than that of the area without secondary light treatment. This is because the anthracene groups dimerize during the secondary light treatment, 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, and 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 the present invention can directly read the information in different illumination time areas during secondary illumination treatment under the excitation of ultraviolet light (365nm).

[0110] 4. Analysis of performance of multiple stimulus responses

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

[0112] Fig. 9 The pictures displayed by the multi-stimulus responsive photonic thin film display material prepared in Example 1 under different stimuli are shown in the figure. As shown in the figure, in the absence of stimulation, the multi-stimulus responsive photonic thin film display material does not show any exogenous information and always presents a bright red structural color; when stimulated by ultraviolet light (365nm), the hidden information 1 (two symmetrical swans with a crown on their heads) is revealed; then, under the action of external mechanical tension, when the overall strain of the multi-stimulus responsive photonic thin film display material reaches 25%, the hidden information 2 (an orange swan) is presented; finally, the multi-stimulus responsive photonic thin film display material is forced to undergo a swelling-de-swelling process using a stimulus response method assisted by DMSO solvent. During the de-swelling process, the hidden information 3 (two symmetrical swans) is also decrypted.

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in 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: The following steps are involved: (1) uniformly dispersing monodisperse nanoparticles, anthracene fluorescent monomers, monomers and initiators in ethanol to obtain a suspension, placing the suspension in a hot environment to volatilize the ethanol, and obtaining a precursor solution, wherein the anthracene fluorescent monomers contain both an anthracene group and a carbon-carbon double bond end group; (2) subjecting the precursor solution obtained in step (1) to a photopolymerization reaction to obtain a photonic film; (3) Subjecting different regions of the photonic film obtained in step (2) to secondary illumination treatment to obtain a multi-stimulus responsive photonic film display material.

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

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

4. The method for preparing a multi-stimulus responsive photonic thin film display material according to claim 1, characterized in that: The monodisperse nanoparticles are silicon dioxide, polystyrene or polymethyl methacrylate, and the particle size of the monodisperse nanoparticles is 200-300 nm; The monomer is at least one of polyethylene glycol methyl ether acrylate, ethylene glycol dimethacrylate, poly(ethylene glycol) dimethacrylate, diethylene glycol ethyl ether acrylate, 1,6-hexanediol diacrylate, 2-methyl-2-acrylic acid-2-(2-methoxyethoxy)ethyl ester, ethylene glycol phenyl ether methacrylate, polyethylene glycol phenyl ether acrylate, ethylene glycol phenyl ether acrylate, poly(ethylene glycol) diacrylate, and trimethylol propane ethoxylate triacrylate; 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 a multi-stimulus responsive photonic thin film display material according to claim 1, characterized in that: The added amount of the monodisperse nanoparticles is 30% to 74% of the monomer volume; the added amount of the initiator is 1% to 5% of the monomer mass.

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

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

8. The method for preparing a multi-stimulus responsive photonic thin film display material according to claim 1, characterized in that: The secondary illumination treatment is to perform illumination treatment for different time periods on different regions of the photonic film, the wavelength of light for the secondary illumination treatment is >300nm, and the illumination treatment time is 20 to 180 minutes.

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

10. 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.

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