Photoluminescent organic-inorganic hybrid photochromic coating and preparation method thereof

Abstract

The invention relates to the technical field of photoluminescence, in particular to a photoluminescence organic-inorganic hybrid photochromic coating and a preparation method thereof.The coating comprises an organic polymer network, heteropolyanions and rare earth ions, and the heteropolyanions and the rare earth ions are dispersed in the organic polymer network; the organic polymer network comprises structural units derived from an ethylenically unsaturated monomer and a boron-containing monomer. The coating is prepared through a photopolymerization reaction and an in-situ growth method, and heteropolyanions and rare earth ions are anchored in a polymer network through coordination. The coating provided by the invention has high visible light transmittance in an initial state, and presents rapid and reversible color change under the irradiation of ultraviolet light or sunlight, and meanwhile, the characteristic fluorescence intensity of rare earth ions is reversibly regulated and controlled along with the color change. The photochromic and photoluminescence composite material has double functions of photochromic and photoluminescence, is good in environmental stability and mild in preparation process, and can be applied to the fields of intelligent windows, security information encryption and the like.

Description

Technical Field

[0001] This invention relates to the field of photoluminescence technology, specifically to a photoluminescent organic-inorganic hybrid photochromic coating and its preparation method. Background Technology

[0002] Photochromism and photoluminescence play crucial roles in anti-counterfeiting, smart windows, and information storage. However, traditional inorganic photochromic materials typically require high-temperature synthesis and are difficult to effectively change color under sunlight irradiation, significantly limiting their application in practical scenarios such as smart windows. While organic photochromic and photoluminescent materials can be processed using solution methods at low temperatures, their inherent toxicity and poor environmental stability severely restrict their widespread adoption in practical applications. Integrating photochromism and photoluminescence into a single material system allows for reversible control of photoluminescence, thereby enhancing the level of information encryption. However, current research on this technology primarily focuses on inorganic material systems, which are typically limited by high ultraviolet response thresholds, long ultraviolet response times, and low visible light transmittance.

[0003] To address the aforementioned bottlenecks, this invention prepares a photoluminescent organic-inorganic hybrid photochromic coating (BAV-W-Eu) via photopolymerization and in-situ growth. This coating not only possesses excellent properties such as non-toxicity, good stability, high visible light transmittance, low ultraviolet light response threshold, and rapid light response, but its preparation process is also more energy-efficient and environmentally friendly compared to conventional methods, demonstrating significant comprehensive advantages. Importantly, its photochromic process allows for reversible control of luminescence intensity. This multifunctional organic-inorganic photochromic hybrid not only shows potential applications in fields such as smart windows and secure information encryption, but also provides a new design concept for integrating photochromic and photoluminescent functions into a single material system. Summary of the Invention

[0004] The purpose of this invention is to provide a photoluminescent organic-inorganic hybrid photochromic coating and its preparation method. The coating includes an organic polymer network and heteropoly anions and rare earth ions dispersed therein, which exhibit reversible color changes and reversibly adjustable fluorescence intensity under ultraviolet light or sunlight irradiation.

[0005] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution: A photoluminescent organic-inorganic hybrid photochromic coating, comprising: An organic polymer network comprising structural units derived from olefinic unsaturated monomers and boron-containing monomers; and heteropolyanions dispersed in the organic polymer network; The coating exhibits a reversible color change under ultraviolet light or sunlight.

[0006] Furthermore, the coating also includes rare earth ions dispersed in the organic polymer network, and the coating emits characteristic fluorescence under ultraviolet light excitation, the intensity of which varies with the reversible color change.

[0007] Furthermore, the olefinic unsaturated monomers include acrylate monomers or methacrylate monomers, as well as acrylic monomers or methacrylate monomers.

[0008] Furthermore, the molar ratio of the acrylate monomer or methacrylate monomer to the acrylate monomer or methacrylate monomer to the boron-containing monomer is (6-10):(1-3):(0.5-2).

[0009] Furthermore, the molar ratio is 8:2:1.

[0010] Furthermore, the boron-containing monomer is vinylphenylboronic acid.

[0011] Furthermore, the heteropoly anion is derived from phosphotungstic acid.

[0012] Furthermore, the rare earth ion is a europium ion.

[0013] Furthermore, the visible light transmittance of the coating in its initial state is not less than 80%.

[0014] On the other hand, the present invention provides a method for preparing the above-mentioned coating, comprising the following steps: S1: Mix olefinic unsaturated monomers and boron-containing monomers with a photoinitiator and carry out a polymerization reaction under ultraviolet light irradiation to form an organic polymer network; S2: The organic polymer network and heteropoly acid are mixed in a solvent and stirred at 100-120°C for 3-5 hours to form a homogeneous solution; S3: When the coating contains rare earth ions, rare earth salts are further added in step S2 to dissolve the heteropoly acid together in the solvent; S4: The uniform solution obtained in S2 or S3 is coated onto the substrate using a blade coating method, and then the solvent is evaporated at 50-70°C and vacuum dried at 80-120°C to obtain the coating.

[0015] The beneficial effects of this invention are: This invention regulates the molar ratio of butyl methacrylate, acrylic acid, and boron-containing monomers in an organic polymer network, enabling heteropoly anions to be dispersed at the molecular level in the polymer backbone in a coordinated manner. This avoids light scattering caused by inorganic phase aggregation, thereby achieving an initial visible light transmittance of not less than 80%. Simultaneously, the heteropoly anions form a tight electron transfer interface with electron-rich groups in the polymer, which can be rapidly reduced to heteropoly blue under ultraviolet light or sunlight irradiation, exhibiting a low ultraviolet light response threshold and rapid color development characteristics. This solves the problem of traditional photochromic materials struggling to balance transparent transmittance and color-changing sensitivity.

[0016] This invention employs a stepwise preparation strategy: first, photopolymerization forms an organic network containing carboxyl and boric acid groups; then, coordination reactions anchor heteropolyanions and rare earth ions. This process ensures that heteropolyanions and rare earth ions exist stably in the polymer network through chemical bonds, avoiding performance degradation caused by inorganic phase migration or agglomeration in physical blending. Furthermore, it achieves an environmentally stable organic-inorganic hybrid structure without high-temperature sintering, overcoming the dual limitations of poor stability in organic photochromic materials and the stringent film-forming conditions of inorganic materials.

[0017] This invention introduces both phosphotungstic acid heteropoly anions and trivalent europium ions into a single hybrid system. The heteropoly blue generated during photochromism exhibits characteristic absorption in the visible and near-infrared regions, overlapping with the emission spectrum and some excited-state energy levels of europium ions. This results in the reversible quenching of the characteristic fluorescence of europium ions through radiative and non-radiative energy transfer pathways. This mechanism enables the coating to simultaneously output two correlated response signals—color change and fluorescence intensity change—during photochromism, providing a composite anti-counterfeiting feature with both visual and spectral recognition capabilities for information encryption.

[0018] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 These are the proton nuclear magnetic resonance spectra of the BAV, BAV-W, and BAV-W-Eu materials prepared in this invention.

[0021] Figure 2 This refers to the liquid phase permeation gel chromatography of the BAV, BAV-W, and BAV-W-Eu materials prepared in this invention.

[0022] Figure 3 These are the near-infrared spectra of the BAV, BAV-W, and BAV-W-Eu materials prepared in this invention.

[0023] Figure 4 These are the transmission spectra of the BAV-W and BAV-W-Eu materials prepared in this invention after irradiation with 365nm ultraviolet light.

[0024] Figure 5 These are the transmission spectra of the BAV-W and BAV-W-Eu materials prepared in this invention after being irradiated by sunlight.

[0025] Figure 6 These are photographs of the BAV-W material prepared in this invention after being irradiated with ultraviolet light for different times and after self-fading.

[0026] Figure 7 This is the emission spectrum of the BAV-W-Eu material prepared in this invention.

[0027] Figure 8 This is a schematic diagram of the luminescence and color change of the BAV-W-Eu material prepared in this invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0029] The method for preparing the organic-inorganic photochromic coating (BAV-W) as described in this embodiment includes the following steps: : Mix butyl methacrylate (≥99.5%, 1270 μL, 8 mmol), acrylic acid (suitable for synthesis, 136 μL, 2 mmol), 4-vinylphenylboronic acid (≥96%, 15 μL, 1 mmol) and photoinitiator 1173 (≥97%, 15 μL, 0.1 mmol) in a glass bottle; S2: Expose the mixture to ultraviolet light (365 nm). Irradiation was performed for 15 min to obtain an organic network polymer (BAV). S3: Dissolve 0.1 g phosphotungstic acid (analytical grade) and 1 g organic network polymer in 2.6 mL N,N-dimethylformamide (≥99.9%), and then stir at 110 °C for 4 h to obtain a homogeneous and transparent solution; S4: The solution was uniformly coated onto a glass substrate using a blade coating method. The solvent was evaporated at 50°C for 30 min, and then dried under vacuum at 100°C for 12 h to obtain a photochromic coating (BAV-W).

[0030] Figure 1 , 2 Figures 3 and 4 show the 1H NMR spectrum, liquid-phase permeate gel chromatography and near-infrared spectroscopy of Example 1, confirming the successful coordination of phosphotungstic acid with BAV.

[0031] Figure 4 The figure shows the transmission spectrum of BAV-W after irradiation with 365 nm ultraviolet light. As can be seen from the figure, BAV-W has 90% visible light transmittance in the initial state, but the transmittance decreases rapidly under ultraviolet light irradiation.

[0032] Figure 5 The figure shows the transmission spectrum of BAV-W under sunlight. As can be seen from the figure, the transmittance of BAV-W decreases rapidly under solar irradiation.

[0033] Figure 6 These are photographs of the BAV-W material prepared in this invention after being irradiated with 365nm ultraviolet light for different times and after self-fading. As can be seen from the images, it rapidly changes from transparent to black under 365nm ultraviolet light irradiation and exhibits self-fading properties. Example 2

[0034] The method for preparing the organic-inorganic photochromic coating (BAV-W) as described in this embodiment includes the following steps: : Mix butyl methacrylate (≥99.5%, 1270 μL, 8 mmol), acrylic acid (suitable for synthesis, 136 μL, 2 mmol), 4-vinylphenylboronic acid (≥96%, 15 μL, 1 mmol) and photoinitiator 1173 (≥97%, 15 μL, 0.1 mmol) in a glass bottle; S2: Expose the mixture to ultraviolet light (365 nm). Irradiation was performed for 15 min to obtain an organic network polymer (BAV). S3: Add 0.1 g of phosphotungstic acid (analytical grade). 1 g of organic network polymer (≥99.9%) and 1 g of organic network polymer were dissolved in 2.6 mL of N,N-dimethylformamide (≥99.9%) and then stirred at 110 °C for 4 h to obtain a homogeneous and transparent solution.

[0035] S4: The solution was uniformly coated onto the glass substrate using a blade coating method. The solvent was evaporated at 50°C for 30 min, and then dried under vacuum at 100°C for 12 h to obtain a coating that combines photoluminescence and photochromism (BAV-W-Eu).

[0036] Figure 1 , 2 Figures 3 and 4 show the 1H NMR spectrum, liquid permeate gel chromatography and near-infrared spectroscopy of Example 1, confirming the successful coordination of phosphotungstic acid and europium ions with BAV.

[0037] Figure 4 The image shows the transmittance spectrum of BAV-W-Eu under 365nm ultraviolet light irradiation. As can be seen from the figure, BAV-W-Eu initially has 80% visible light transmittance, which rapidly decreases under ultraviolet irradiation.

[0038] Figure 5 The figure shows the transmission spectrum of BAV-W-Eu under sunlight. As can be seen from the figure, the transmittance of BAV-W-Eu decreases rapidly under sunlight.

[0039] Figure 7 The figure shows the emission spectrum of BAV-W-Eu under ultraviolet light excitation. As can be seen from the figure, BAV-W-Eu exhibits typical emission peaks characteristic of trivalent europium ions.

[0040] In summary, this invention proposes a photoluminescent organic-inorganic hybrid photochromic coating and its preparation method. The coating comprises an organic polymer network and heteropolyanions and rare earth ions dispersed therein; the organic polymer network contains structural units derived from olefinic unsaturated monomers and boron-containing monomers. This invention prepares the coating through photopolymerization and in-situ growth, with the heteropolyanions and rare earth ions anchored in the polymer network through coordination. The coating exhibits high visible light transmittance in its initial state and displays a rapid and reversible color change under ultraviolet or sunlight irradiation. Simultaneously, the characteristic fluorescence intensity of the rare earth ions is reversibly modulated with the color change. This invention combines photochromic and photoluminescent functions, exhibits good environmental stability, and uses a mild preparation process, making it suitable for applications such as smart windows and security information encryption.

[0041] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A photoluminescent organic-inorganic hybrid photochromic coating, characterized in that, include: An organic polymer network comprising structural units derived from olefinic unsaturated monomers and boron-containing monomers; and heteropolyanions dispersed in the organic polymer network; The coating exhibits a reversible color change under ultraviolet light or sunlight.

2. The coating as described in claim 1, characterized in that, The coating also includes rare earth ions dispersed in the organic polymer network. The coating emits characteristic fluorescence under ultraviolet light excitation, and the intensity of the characteristic fluorescence varies with the reversible color change.

3. The coating as described in claim 1 or 2, characterized in that, The olefinic unsaturated monomers include acrylate monomers or methacrylate monomers, as well as acrylic monomers or methacrylate monomers.

4. The coating as described in claim 3, characterized in that, The molar ratio of the acrylate monomer or methacrylate monomer to the acrylate monomer or methacrylate monomer to the boron-containing monomer is (6-10):(1-3):(0.5-2).

5. The coating as described in claim 4, characterized in that, The molar ratio is 8:2:

1.

6. The coating as described in claim 1 or 2, characterized in that, The boron-containing monomer is vinylphenylboronic acid.

7. The coating as described in claim 1 or 2, characterized in that, The heteropoly anion is derived from phosphotungstic acid.

8. The coating as described in claim 2, characterized in that, The rare earth ion is europium ion.

9. The coating as claimed in claim 1, characterized in that, The coating has a visible light transmittance of no less than 80% in its initial state.

10. A method for preparing the coating according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1: Mix olefinic unsaturated monomers and boron-containing monomers with a photoinitiator and carry out a polymerization reaction under ultraviolet light irradiation to form an organic polymer network; S2: The organic polymer network and heteropoly acid are mixed in a solvent and stirred at 100-120°C for 3-5 hours to form a homogeneous solution; S3: When the coating contains rare earth ions, rare earth salts are further added in step S2 to dissolve the heteropoly acid together in the solvent; S4: The uniform solution obtained in S2 or S3 is coated onto the substrate using a blade coating method, and then the solvent is evaporated at 50-70°C and vacuum dried at 80-120°C to obtain the coating.

Images