A structural color composite film containing a dynamic diselenide bond, a preparation method thereof and application thereof in optical anti-counterfeiting

Abstract

The application belongs to the technical field of high polymer materials, and discloses a structural color composite film containing a dynamic diselenide bond, a preparation method of the structural color composite film and application of the structural color composite film in optical anti-counterfeiting. The composite film is polystyrene or polymethyl methacrylate / SiO2 / polyurethane polymer or a multiple hydrogen bond polymer. The structural color composite film is obtained by filling a polyurethane shape memory film prepolymer solution or a multiple hydrogen bond shape memory film prepolymer solution into a photonic crystal template, heating and polymerizing at 70-90 DEG C. The core-shell structure monodisperse microspheres are self-assembled into the photonic crystal template through interface induction. In combination with the application of the birefringence effect and the double-layer patterned anti-counterfeiting label of structural color under the light mask technology, the film can be applied to the field of optical anti-counterfeiting.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and more specifically, relates to a type of structural color composite film containing dynamic diselenyl bonds, its preparation method, and its application in optical anti-counterfeiting. Background Technology

[0002] In the realms of commodity circulation and literary appreciation, counterfeit goods and misappropriation of names are frequent occurrences, undoubtedly posing a significant threat to the development of my country's market economy and the protection of consumer rights. With the rapid growth of China's economy and the emergence of its development model, creating a healthy market competition environment that protects intellectual property rights, combating counterfeit goods, and researching and developing sophisticated anti-counterfeiting label systems have become hot topics in market economic development. Currently, existing anti-counterfeiting technologies mainly fall into six categories: anti-counterfeiting materials, structural and packaging anti-counterfeiting technologies, anti-counterfeiting labels, biological product anti-counterfeiting technologies, laser anti-counterfeiting technologies, and computer security technologies. Among these technologies, label anti-counterfeiting materials have a particularly long history of development. Due to their advantages in commodity protection, such as being small, portable, and easily identifiable, they are widely used in protecting currency, high-value goods, and anti-cancer drugs.

[0003] In the production of various advanced anti-counterfeiting labels, the advantage lies in making genuine products easier to identify and making the anti-counterfeiting module more difficult to replicate. For example, CN201911234700.6 discloses a rewritable anti-counterfeiting film based on photonic crystal structural colors, its preparation method, and its application. This structural color anti-counterfeiting film, in its natural state, carries a hidden pattern and responds with complete pattern information upon water stimulation. Immersing the anti-counterfeiting film in a soluble chloride solution allows the hidden pattern to be wiped away, achieving information erasure and re-encoding.

[0004] However, the single stimulus-response color development mechanism is a common technical challenge for structural color materials. Simple decoding processes cannot provide sufficient security for products, undoubtedly hindering their marketization. Therefore, we propose an innovative composite material strategy that introduces a three-dimensional polymer network structure and a dynamic bond exchange process, enabling the composite material to simultaneously possess structural color and shape memory birefringence color effects. The structural color effect originates from photonic crystal structures, possessing unique color signals and exhibiting excellent performance in signal storage and authenticity verification. Furthermore, the thin-film birefringence effect caused by polymer shape changes can serve as an encrypted signal for depicting the stress-strain distribution of an object. Simultaneously, under the influence of dynamic molecular bonds (DCB), a fourth-dimensional (4D) time-dependent optical image display process is developed, resulting in more interesting changes in the recognition of the color-developed image. This demonstrates the significant developmental advantages of this type of composite material in the research and development of advanced anti-counterfeiting labels. Summary of the Invention

[0005] To address the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide a structural color composite film containing dynamic diselenyl bonds. This film utilizes two different shape memory functional blocks, and the glass transition temperature T is achieved by controlling the rigidity of polymer chain segments. g Shape memory capabilities that reach above room temperature; or reshapeable shape memory capabilities formed by strong non-covalent interactions of quadruple hydrogen bonds.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned structural color composite film containing dynamic diselenylene bonds. This method combines the polymer birefringence effect with a dual optical anti-counterfeiting strategy of structural color. Based on the interaction between stress-strain tension and dynamic diselenylene bonds, this type of combination can be endowed with great flexibility and can produce more complex, precise and high-dimensional anti-counterfeiting patterns.

[0007] Another objective of this invention is to provide applications for the above-mentioned structural color composite film containing dynamic diselenyl bonds; by studying the changes of patterns under visible light or temperature modes through the shape memory and dynamic stress relaxation of hybrid materials, the prepared structural color polymer has strong applicability and is easy to prepare. It is a low-cost dual anti-counterfeiting polymer material and is expected to serve as an advanced portable optical anti-counterfeiting label.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A structural color composite film containing dynamic diselenyl bonds, wherein the structural color composite film is polystyrene or polymethyl methacrylate@SiO2 / polyurethane polymer or multi-hydrogen bonded polymer; the structural color composite film is obtained by filling a polyurethane shape memory film prepolymer solution or a multi-hydrogen bonded shape memory film prepolymer solution into a photonic crystal template and heating and polymerizing it at 70-90°C.

[0010] Preferably, the photonic crystal template is composed of monodisperse microspheres of a polymer encapsulated in a core-shell structure of silica, wherein the polymer is polystyrene or polymethyl methacrylate, and the particle size of the monodisperse microspheres is 180–320 nm.

[0011] Preferably, the polyurethane shape memory film prepolymer solution is obtained by mixing 3,3'-dihydroxydipropyl diselenyl ether and diisocyanate monomer B1, and then adding linear prepolymer monomer C1.

[0012] More preferably, the mass ratio of the 3,3'-dihydroxydipropyldiselelenide, diisocyanate monomer B1, and linear prepolymer monomer C1 is (30-150) mg:(75-175) mg:1 g.

[0013] Preferably, the multi-hydrogen bond shape memory film prepolymer solution is obtained by mixing 3,3'-diacrylate diselenyl ether, tetra-arm thiol monomer B2 and UPyA monomer, and adding linear prepolymer monomer C2 and triethylamine.

[0014] More preferably, the mass ratio of propyl diacrylate diselenyl ether, tetra-arm thiol monomer B2, UPyA monomer and linear prepolymer monomer C2 is (100-500) mg: 600 mg: (400-600) mg: 1 g.

[0015] The method for preparing the structural color composite film containing dynamic diselenyl bonds includes the following specific steps:

[0016] S1. Core-shell structured monodisperse nanoparticles are prepared into periodic photonic crystal templates under solvent evaporation conditions. The outer shell of the monodisperse microspheres is wrapped with silica, and the core is polystyrene or polymethyl methacrylate.

[0017] S2. Preparation of dynamic diselenyl bond small molecules: Na2Se2 was obtained by reducing elemental selenium with sodium borohydride under anaerobic conditions, followed by chemical modification with 3-bromopropanol for 8-12 h to prepare 3,3'-dihydroxydipropyl diselenyl ether. Subsequently, 3,3'-dihydroxydipropyl diselenyl ether was reacted with acryloyl chloride to obtain 3,3'-propyl diacrylate diselenyl ether.

[0018] S3. Mix 3,3'-dihydroxydipropyldiselenoether and diisocyanate monomer B1, add linear prepolymer monomer C1, and mix to obtain a polyurethane shape memory film prepolymer solution;

[0019] S4. Mix 3,3'-diacrylate diselenyl ether, tetra-arm thiol monomer B2 and UPyA monomer, and introduce linear prepolymer monomer C2. Add triethylamine catalyst in the two-step mixing process to obtain a prepolymer solution of multiple hydrogen bond shape memory film.

[0020] S5. Fill the prepolymer solution of polyurethane shape memory film in step S3 or the prepolymer solution of multi-hydrogen bond shape memory film in step S4 into a photonic crystal template that has been pretreated by heating and dehumidifying under vacuum at 60-80℃, and then heat and polymerize at 70-90℃ to obtain a structural color composite film containing dynamic diselenide bonds.

[0021] Preferably, the self-assembly of the monodisperse nanoparticles in step S1 is prepared by vertical deposition, natural sedimentation, or dip coating to control colloidal crystal microspheres.

[0022] Preferably, in step S2, the molar ratio of sodium borohydride to selenium powder is 1:1, and the mass ratio of selenium powder, sodium borohydride, and 3-bromopropanol is (5-10):(2.4-4.8):(8.8-17.6); the molar ratio of acryloyl chloride to 3,3'-dihydroxydipropyldiselenoether is (2-4):1.

[0023] Preferably, the diisocyanate monomer B1 in step S3 is toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, or isophorone diisocyanate; the linear prepolymer monomer C1 is a prepolymer with multi-hydroxyl functionality or a similar hydroxyl-containing linear condensation molecule prepared by reacting epoxy resin 2,2-bis(4-glycidoxyphenyl)-propane and 3-amino-1-propanol at 100-120°C, and the molecular weight of the linear prepolymer monomer C1 is 12,000-14,000;

[0024] Preferably, in step S4, the four-armed thiol monomer B2 is tetra(mercaptopropionic acid)-3-pentaerythritol ester or a similar molecular derivative containing four-armed thiol end-capsulation; the UPyA monomer is methacrylate-modified 2-amino-4-hydroxy-6-methylpyrimidine; and the linear prepolymer monomer C2 is poly(ethylene glycol) diacrylate or poly(caprolactone) diacrylate.

[0025] The application of the structural color composite film containing dynamic diselenyl bonds in optical anti-counterfeiting.

[0026] In this invention, isocyanate-based polyurethanes with alternating soft and hard segments can increase the chain rigidity of molecules by increasing the benzene ring content, which is a commonly used method to increase the glass transition temperature (Tg). A polyurethane-based shape memory polymer was prepared by using a linear polymer with polyhydroxyl functionality and benzene rings as the soft segment, combined with a photonic crystal via template filling, to create a polyurethane-based shape memory structural color composite film. Furthermore, covalently cross-linked elastomers with high UPy content also possess strong dynamic mechanical properties. Shape fixation is achieved by controlling the UPy content of quadruple hydrogen bonds. During this process, the hybrid supramolecular network undergoes a transition from elasticity to plasticity. The high UPy content provides a large number of non-covalently cross-linked hydrogen bond networks, providing strong stress dissipation energy for polymer stretching, thus enhancing the shape memory capability. A multi-hydrogen bonded shape memory polymer was also prepared by combining a photonic crystal with a template filling method to create a multi-hydrogen bonded shape memory structural color composite film.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The structural color composite film with shape memory function of the present invention has a bright structural color. Under stretching, its structure can be fixed through a high-temperature-cooling process and return to its original state after heating. When the heating process exceeds the maximum transesterification temperature, the polymer exhibits shape reconfigurability. This structural color composite film can also be used to prepare color-producing materials in any visible light band using photonic crystal templates assembled from monodisperse nanoparticles of different particle sizes. The film exhibits a unique birefringence effect under stretching. Combined with polarized light and an analyzer, the color information of tensile strain in different regions can be identified. This optical behavior, based on material properties to depict the stress-strain distribution of an object, combined with photomasking, enables the hiding and identification of patterns.

[0029] 2. In the preparation process of the structural color composite film containing dynamic diselenyl bonds, the dynamic changes of diselenyl bonds and the polymer shape memory ability of the present invention exhibit excellent patterning loading ability.

[0030] 3. The preparation method of this invention is reliable and the conditions are mild and controllable. The structural color composite film containing dynamic diselenyl bonds has both the structural color observed under sunlight and the color of birefringence effect under the action of polarizer, while the shape memory stress relaxation brings a richer Bragg diffraction effect to the photonic crystal.

[0031] 4. The structural color composite film containing dynamic diselenyl bonds of this invention can be applied to signal encoding and decoding, and its unique reflectance spectral information can be used as a basis for digital judgment.

[0032] 5. The structural color composite film containing dynamic diselenyl bonds of the present invention can be used for time-dimensional (4D) sunlight-driven patterned erasure. Different light-driven times have different time-dimensional encoded signals, and the specific recognition signal can be obtained by image observation or by reflectance spectrum detection. Attached Figure Description

[0033] Figure 1 This is an optical schematic diagram and a schematic diagram of dynamic reversible bond exchange for the structural color composite thin film containing dynamic diselenide bonds of the present invention.

[0034] Figure 2 This is a transmission electron microscope (TEM) image of the PS@SiO2 core-shell structured monodisperse microspheres in Example 1.

[0035] Figure 3 In Example 1, (a) shows the reflection spectrum of photonic crystal microspheres with different structures and (b) shows the concentration normalization statistics, and (c) shows the physical image of the reflection spectrum of (a).

[0036] Figure 4 The images show the green (a) and yellow (b) photonic crystal templates deposited in the glass culture dish in Example 2.

[0037] Figure 5 The NMR spectra of the diselenyl bond small molecules 3,3'-dihydroxydipropyl diselenyl ether and 3,3'-propyl diacrylate diselenyl ether in Example 3 are shown in the 1H NMR spectrum.

[0038] Figure 6 The images show scanning electron microscope (SEM) images of the PS@SiO2 / photonic crystal template and the PS@SiO2 / polyurethane-based shape memory structural color composite film in Example 4, as well as the infrared absorption spectrum of the PS@SiO2 / polyurethane-based shape memory structural color composite film.

[0039] Figure 7 This is a physical image of the PS@SiO2 / polyurethane shape memory structural color composite film (a) in Example 4, which exhibits a significant angle-dependent (b) structural color property.

[0040] Figure 8 The infrared absorption spectrum of the PS@SiO2 / multiple hydrogen bond shape memory structural color composite film in Example 5 is shown.

[0041] Figure 9 This is a schematic diagram showing the specific encrypted information (QR code) displayed on the patterned PS@SiO2 / polyurethane shape memory structural color composite film in Application Example 1 under polarized film detection. Detailed Implementation

[0042] The present invention will be further described below with reference to specific embodiments, but these should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0043] Composite materials composed of photonic crystal thin films and polymer thin films are called structural color composite thin films. Figure 1 This invention relates to the optical principle of the structural color composite thin film containing dynamic diselenyl bonds. Figure 1 Three-dimensional photonic crystals with periodically arranged structures exhibit specific specular reflection of a particular wavelength of visible light when sunlight strikes their surface, creating a visible structural color. Photonic crystals with structural colors require monodisperse micro- and nano-sized spheres ranging from 180 to 320 nm in size. This process can be explained by Bragg's diffraction law. A schematic diagram of the dynamic reversible bond exchange process of diselenylene is also included. Since the dynamic bond energy of diselenylene is 172 kJ / mol, it is a type of chemical covalent bond that can be broken by visible light or heat. Therefore, under certain light or heating conditions, diselenylene bonds in polymers can undergo dissociation and rearrangement, thereby achieving molecular chain exchange.

[0044] Example 1

[0045] An emulsion polymerization method for PS@SiO2 core-shell structured microspheres was developed, which prepared micro-nano structured microspheres with visible light reflectivity in the range of 180–320 nm by adjusting different reaction conditions.

[0046] 1. Add sodium dodecyl sulfate, a surfactant, to a three-necked flask, followed by 135 mL of deionized water. Maintain the temperature at 80°C in an oil bath, then add 10–15 g of styrene monomer. Under N2 protection throughout the process, mechanically stir for 10 min. After the reaction solvent is stirred evenly, add 0.15 g of potassium persulfate to initiate polymerization. Stop the reaction after 3–6 h. Transfer the reaction solution to a beaker and leave it open for 5–7 days to quench free radical reactions, thus obtaining polystyrene emulsion (PS). The size of polystyrene colloidal microspheres can be adjusted by changing the amount of sodium dodecyl sulfate.

[0047] 2. First, transfer 3-6 mL of the prepared PS emulsion to a 250 mL three-necked flask, add 60 mL of deionized water, ammonia, and vinyltriethoxysilane, and stir continuously for 3-5 h. The size of the PS@SiO2 microspheres can be controlled by adjusting the amount of ammonia or vinyltriethoxysilane added. Then, transfer the reaction solution to a beaker and heat it in an 80 °C oven for 2 days until the solvent is completely evaporated to obtain a PS@SiO2 core-shell structured photonic crystal.

[0048] 3. Add 20-40 mL of anhydrous ethanol solution to the dried PS@SiO2 core-shell photonic crystal and sonicate for 0.5 h. Repeat centrifugation and ultrasonic washing three times. Calculate the concentration and dilute with ethanol to obtain an ethanol dispersion of PS@SiO2 with a concentration of 4% (mass volume fraction).

[0049] Figure 2 The image shown is a transmission electron microscope (TEM) image of the monodisperse microspheres with the PS@SiO2 core-shell structure in Example 1, showing that the PS core particle size is 200 nm and the SiO2 shell thickness is 19 nm. Figure 3 In Example 1, (a) shows the reflection spectra of photonic crystal microspheres with different structural colors prepared by controlling different ammonia water ratios; (b) is a concentration-normalized statistical graph; and (c) is a physical image of the reflection spectrum of (a). Figure 3 As can be seen, photonic crystals with reflection wavelengths of 468–634 nm were successfully prepared, and the relationship between different amounts of ammonia added and the reflection peaks of the resulting photonic crystals showed a single linear relationship. PS@SiO2 photonic crystal microspheres capable of assembling different reflected light from purple to red were obtained.

[0050] Example 2

[0051] A method for inducing self-assembly of photonic crystals at an interface on a fixed culture dish includes the following steps:

[0052] 1. Preparation of transparent PDMS polymer-isolated substrates using a thermosetting method: A PDMS base solution containing vinyl-active polydimethylsiloxane and a curing agent containing hydrogen-containing polydimethylsiloxane were mixed at a mass ratio of 10:1 and stirred for 5 min. The mixture was then centrifuged at 8000 rpm for 5 min to remove air bubbles generated during stirring. The PDMS mixture was poured evenly onto clean glass petri dishes and coated evenly using a coater. The glass petri dishes were then placed in an oven and heated at 100℃ for 3 h to allow the film to crosslink.

[0053] 2. Monodisperse PS@SiO2 microsphere ethanol solutions with particle sizes of 200nm, 220nm, 240nm, and 260nm were poured onto PDMS-based culture dishes with diameters of 60mm, 75mm, and 100mm, respectively. The solvent was dried by heating at 60℃, and finally thin PS@SiO2 structural color photonic crystals with iridescent phenomena were obtained.

[0054] Figure 4 Images show the yellow photonic crystal template deposited in the glass culture dish in Example 2, and green photonic crystal templates of different particle sizes. (a) shows a 240nm green photonic crystal template deposited in a 100mm diameter glass culture dish in Example 2, and (b) shows a 260nm yellow photonic crystal template. Figure 4 As can be seen from the text, complete PS@SiO2 structural color photonic crystals with bright structural colors of 200-260 nm are stacked at the bottom of the culture dish, indicating that a complete (111) lattice stacked photonic crystal template morphology is obtained. This shows that the deposition effect of photonic crystal microspheres with different particle sizes is significant. The following examples will use a 240 nm green photonic crystal template as a typical example of a structural color template to illustrate this.

[0055] Example 3

[0056] A method for preparing reversible dynamic diselenide small molecules includes the following steps:

[0057] Preparation of 1,3,3'-dihydroxydipropyldiselenoether (diseleno-bonded small molecule A1):

[0058] (1) Selenium powder was added to a 250 mL dry three-necked flask, the mouth was sealed with a rubber stopper, and the flask was treated with nitrogen three times to remove oxygen. Sodium borohydride was added to 30 mL of pure water and then very slowly added dropwise to the three-necked flask using a 10 mL syringe at room temperature. The mixture was reacted at 50 °C for 0.5 h to obtain wine-red Na2Se2.

[0059] (2) 3-Bromo-1-propanol was first dissolved in 40 mL of tetrahydrofuran, then injected into Na2Se2 solution, and then heated to 60 °C overnight. The reaction solution was extracted twice with 25 mL of DCM and once with 50 mL of saturated brine. The organic phase was dried over anhydrous Na2SO4. The solution was further purified by column chromatography using a dichloromethane:methanol mixture as eluent. A portion of the tetrahydrofuran was removed by rotary evaporation at 35 °C, and then dried under vacuum for 24 h to obtain a pure golden oily liquid, namely 3,3'-dihydroxydipropyldiselenoether, with a yield of 70%.

[0060] Preparation of 2,3,3'-propyl diacrylate diselenyl ether (diselenyl bond small molecule A2):

[0061] (1) Add 4g of the prepared 3,3'-dihydroxydipropyldiselenoether, 3-5g of triethylamine, and 150mL of dry tetrahydrofuran to a 250mL three-necked flask. Under a nitrogen atmosphere, add 3 equivalents of acryloyl chloride dropwise to the above solution. Seal the flask with a rubber stopper, stir the mixture at 0℃ for 24h, and then heat to room temperature;

[0062] (2) The precipitated salt was removed by filtration, the filtrate was washed with 0.1 mol / L sodium carbonate aqueous solution, the organic layer was dried on MgSO4 and concentrated on a rotary evaporator; the crude oil was further purified by column chromatography using a mixture of dichloromethane, methanol, petroleum ether and ethyl acetate as eluent to obtain 3,3'-diacrylate diselenyl ether in 75% yield.

[0063] Figure 5 These are the 1H NMR spectra and infrared absorption spectra of the diselenyl bonded small molecules 3,3'-dihydroxydipropyldiselenyl ether and 3,3'-propyl diacrylate diselenyl ether in Example 3. (a) is the 1H NMR spectrum of 3,3'-dihydroxydipropyldiselenyl ether, and (b) is the 1H NMR spectrum of 3,3'-propyl diacrylate diselenyl ether. Figure 5 It can be seen that two target diselenyl crosslinked small molecules were successfully prepared.

[0064] Example 4

[0065] The preparation method of PS@SiO2 / polyurethane shape memory structural color composite film includes the following steps:

[0066] 1. Preparation of photonic crystal template: PS@SiO2 particles with a particle size of 240 nm were dispersed in an ethanol solution to prepare a dispersion with a concentration of 2% by mass volume; the PS@SiO2 ethanol dispersion was dropped onto a hydrophilically treated PDMS-glass culture dish, and after the solvent evaporated, a 240 nm green structural color PS@SiO2 photonic crystal template was deposited.

[0067] 2. Preparation of PS@SiO2 / polyurethane shape memory structural color composite films:

[0068] (1) 20 g of 2,2-bis(4-glycidoxyphenyl)-propane and 4 g of 3-aminopropanol were dissolved in 50 mL of ultra-dry N,N'-dimethylformamide and placed together in a 250 mL three-necked flask. The mixture was reacted at 120 °C for 12 h to synthesize a hydroxyl-containing prepolymer solution (C1). The prepolymer solution was divided into 32 bottles for the next crosslinking process.

[0069] (2) Then, 150-350 mg of 4,4'-diphenylmethane diisocyanate and 60-300 mg of 3,3'-dihydroxydipropyl diselenide were added to 1-5 mL of anhydrous N,N'-dimethylformamide, and the mixture was reacted in an oil bath at 70 °C for 3 h to obtain diseleninated crosslinked oligomers.

[0070] (3) The diselenyl crosslinked oligomer was completely dissolved in 2g of hydroxyl-containing prepolymer solution. After stirring at room temperature for 2min, it was added to the PS@SiO2 photonic crystal template with 240nm green structural color prepared in Example 3. It was then penetrated into the stacking gap of the PS@SiO2 photonic crystal by capillary force and uniformly coated on the polydimethylsiloxane (PDMS) based culture dish.

[0071] (4) The petri dish was placed in an oven at 60°C for 4 hours for pre-curing, and then transferred to a vacuum oven at 70°C for 24 hours for further curing. After demolding, a PS@SiO2 / polyurethane shape memory structural color composite film with a thickness of 0.33 mm was obtained.

[0072] Figure 6 These are scanning electron microscope (SEM) images of the PS@SiO2 photonic crystal template and the PS@SiO2 / polyurethane shape memory structural color composite film in Example 4, as well as the infrared absorption spectrum of the PS@SiO2 / polyurethane shape memory structural color composite film. (a) is the SEM image of the photonic crystal template; (b) is the SEM image of the PS@SiO2 / polyurethane shape memory structural color composite film; and (c) is the infrared absorption spectrum of the PS@SiO2 / polyurethane shape memory structural color composite film. Figure 6 As can be seen from the data, the PS@SiO2 photonic crystal exhibits a (1,0,0) stacking morphology, consistent with the long-range ordered stacking pattern of photonic crystals; the introduction of polyurethane-based shape memory polymers can completely encapsulate the photonic crystal structure; 1719 cm⁻¹ -1 and 1662cm -1 The peak value at 3342 cm⁻¹ is assigned to carbamate; -1 and 1509cm -1 The peak value at the point was assigned to the imino group, demonstrating the successful preparation of polyurethane-based shape memory polymers. Figure 7 These are physical images of the polyurethane-based shape memory structural color composite film in Example 4. (a) shows the structural color composite film at a 90° viewing angle, and (b) shows the structural color composite film at a 120° viewing angle. As can be seen, the structural color composite film is orange at a 90° viewing angle and green at a 120° viewing angle. The phenomenon of color change with the viewing angle indicates that the structural color composite film has the unique angle-dependent property of structural color. This shows that the shape memory polymer film with photonic crystal template still has a significant structural color effect and shows a structural color change from orange to yellow to green at different viewing angles.

[0073] Example 5

[0074] The preparation method of PS@SiO2 / multiple hydrogen bond shape memory structural color composite film includes the following steps:

[0075] 1. Preparation of photonic crystal thin film: PS@SiO2 particles with a particle size of 240 nm were dispersed in an ethanol solution to prepare a dispersion with a concentration of 2% by mass volume; the PS@SiO2 ethanol dispersion was dropped onto a hydrophilically treated PDMS-glass culture dish, and after the solvent evaporated, a PS@SiO2 photonic crystal template was deposited.

[0076] 2. Preparation of PS@SiO2 / multiple hydrogen bond shape memory structural color composite films:

[0077] (1) In a 100 mL three-necked flask, 1-4 g of 6-methylisocytosine (MIS) was completely dissolved in dimethyl sulfoxide (DMSO) under oil bath heating at 170 °C. The flask was then lifted above the liquid surface, and immediately 3-6 g of 2-isocyanoethyl (meth)acrylate (ICEMA) was added to the flask, resulting in a vigorous reaction. After maintaining this reaction for 15 min, the polymerization was rapidly quenched using an ice-water bath to inhibit polymerization. A white solid, UPyA, precipitated, was obtained by H+ filtration. 1 Its structure was verified by NMR spectroscopy.

[0078] (2) In a 100 mL three-necked flask, N,N'-dimethylformamide (DMF) was added as a solvent, followed by 600 mg of pentaerythritol tetrakis(3-mercaptopropionic acid) ester (PETMP) and 400–600 mg of UPyA. Then, triethylamine (TEA) (10% of the total monomer mass) was added as a catalyst. The resulting mixture was heated to 80 °C until UPyA was completely dissolved. Then, 1 g of poly(ethylene glycol) diacrylate (PEGDA) and 200–500 mg of propyl 3,3'-diacrylate diselenyl ether were added, and the mixture was stirred until homogeneous to obtain a prepolymer solution for curing. For these samples, the concentration of total monomers (UpyA, PEGDA, and propyl 3,3'-diacrylate diselenyl ether) was maintained at 30 wt%.

[0079] (3) The prepolymer solution from step 2 was added to the PS@SiO2 photonic crystal template with a 240nm green structural color prepared in Example 3. It was then penetrated into the stacking gaps of the PS@SiO2 photonic crystal by capillary force and uniformly coated onto a polydimethylsiloxane (PDMS) based culture dish.

[0080] (4) The precursor was cured in an oven at 80°C for 6 hours. It was then dried in a vacuum oven at 80°C for 24 hours until a constant weight was achieved. After demolding, a PS@SiO2 / multi-hydrogen bond shape memory structure color composite film with a thickness of 0.33 mm was obtained. The composite film contained 40 wt% UPyA.

[0081] Figure 8 The image shows the infrared absorption spectrum of the PS@SiO2 / multiple hydrogen bond shape memory structural color composite film in Example 5. From... Figure 8 From this, we can know that it is 1733cm -1 and 1644cm -1 The two absorption peaks correspond to the carbonyl hydrogen bond and urea hydrogen bond of the polymer, respectively, proving that the multi-hydrogen bond shape memory polymer was successfully synthesized. Its structural color composite film phenomenon is similar to the final result obtained in Example 4.

[0082] Application Example 1

[0083] Photolithographic patterning of structural color composite films with shape memory function and dynamic diselenylene bonds and their application as anti-counterfeiting identification labels. The PS@SiO2 / polyurethane shape memory structural color composite film prepared in Example 4 or the PS@SiO2 / multiple hydrogen bond shape memory structural color composite film prepared in Example 5 were designed to obtain composite films with different structural colors from purple to red. The stress of the film was relaxed by photoreversible crosslinking of dynamic diselenylene bonds, and patterning was performed using a photomask strategy to obtain a QR code anti-counterfeiting pattern that simultaneously possesses structural color and birefringence. Figure 9This is a schematic diagram showing the dense information (QR code) displayed on the patterned PS@SiO2 / polyurethane shape memory structural color composite film under polarizer detection, as described in Application Example 1. In (a), the pattern is shown with the analyzer angle parallel to the linearly polarized light, and in (b), the pattern is shown with the analyzer angle perpendicular to the linearly polarized light. Figures (c) and (d) are images of the film with localized surface wrinkles under white light, corresponding to magnified high-resolution images of a specific area in (a) and (b), respectively. Both images show the surface of the polymer film displaying an orange structural color under white light illumination, and wrinkles on the patterned surface can be observed.

[0084] Furthermore, changes in structural color also provide another layer of authentication for QR code verification. Within the area illuminated by the structural color, the QR code image can change with the angle from 0° to 90°. The structural color region of the thin film can exhibit a blue shift in visible light, and the results can be compared by examining the reflection spectral peaks.

[0085] The resulting structural color composite film was used with a specially designed photomask to produce an anti-counterfeiting label after 5 minutes of illumination. The pattern prepared using the photomask method has a clear outline, demonstrating the speed and feasibility of the photomask patterning lithography method. Furthermore, a dynamic bond crosslinking process that can be driven by sunlight to erase the pattern over time provides a multi-dimensional (4D) anti-counterfeiting security feature. This also reflects the rich and tunable optical properties of the material, making it suitable for preparation and application as a high-security material.

[0086] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A structural color composite film containing dynamic diselenyl bonds, characterized in that, The structural color composite film is a polymer@SiO2 / multi-hydrogen bonded polymer; the structural color composite film is obtained by filling a multi-hydrogen bonded shape memory film prepolymer solution into a photonic crystal template and then heating and polymerizing it at 70~90℃; the photonic crystal template is composed of monodisperse microspheres of polymer encapsulated in a core-shell structured silica, and the polymer is polystyrene or polymethyl methacrylate, with a particle size of 180~320 nm for the monodisperse microspheres; The multi-hydrogen bond shape memory film prepolymer solution is obtained by mixing 3,3'-diacrylate diselenyl ether, four-arm thiol monomer B2 and UPyA monomer, and adding linear prepolymer monomer C2 and triethylamine; the mass ratio of 3,3'-diacrylate diselenyl ether, four-arm thiol monomer B2, UPyA monomer and linear prepolymer monomer C2 is (100~500) mg:600 mg:(400~600) mg:1 g; the four-arm thiol monomer B2 is tetra(mercaptopropionic acid)-3-pentaerythritol ester or a similar molecular derivative containing four-arm thiol end caps; the UPyA monomer is methacrylate-modified 2-amino-4-hydroxy-6-methylpyrimidine; and the linear prepolymer monomer C2 is poly(ethylene glycol) diacrylate or poly(caprolactone) diacrylate.

2. The method for preparing a structural color composite film containing dynamic diselenyl bonds according to claim 1, characterized in that, The specific steps include the following: S1. Core-shell structured monodisperse nanoparticles are prepared into periodic photonic crystal templates under solvent evaporation conditions. The outer shell of the monodisperse microspheres is wrapped with silica, and the core is polystyrene or polymethyl methacrylate. S2. Preparation of dynamic diselenyl bond small molecules: Na2Se2 was obtained by reducing elemental selenium with sodium borohydride under anaerobic conditions, followed by chemical modification with 3-bromopropanol for 8-12 h to prepare 3,3'-dihydroxydipropyl diselenyl ether. Subsequently, 3,3'-dihydroxydipropyl diselenyl ether was reacted with acryloyl chloride to obtain 3,3'-propyl diacrylate diselenyl ether. S3. Mix 3,3'-diacrylate diselenyl ether, tetra-arm thiol monomer B2 and UPyA monomer, and introduce linear prepolymer monomer C2. Add triethylamine catalyst in the two-step mixing process to obtain a prepolymer solution of multi-hydrogen bond shape memory film. S4. The prepolymer solution of the multi-hydrogen bond shape memory film from step S3 is filled into a photonic crystal template that has been pretreated by heating and dehumidifying under vacuum at 60~80℃, and then polymerized at 70~90℃ to obtain a structural color composite film containing dynamic diselenide bonds.

3. The method for preparing a structural color composite film containing dynamic diselenyl bonds according to claim 2, characterized in that, The monodisperse nanoparticles described in step S1 are prepared by vertical deposition, natural sedimentation, or dip coating to control colloidal crystal microspheres.

4. The method for preparing a structural color composite film containing dynamic diselenyl bonds according to claim 2, characterized in that, In step S2, the molar ratio of sodium borohydride to selenium powder is 1:1, and the mass ratio of selenium powder, sodium borohydride, and 3-bromopropanol is (5~10):(2.4~4.8):(8.8~17.6); the molar ratio of acryloyl chloride to 3,3'-dihydroxydipropyldiselenoether is (2~4):

1.

5. The application of the structural color composite film containing dynamic diselenyl bonds as described in claim 1 in optical anti-counterfeiting.

Images