Intelligent long-afterglow coating with light-heat dual response and application of intelligent long-afterglow coating

Abstract

The invention provides a light-heat dual response intelligent long afterglow coating which is prepared from the following components in parts by mass: 15 to 25 parts of coated strontium europium dysprosium aluminate, 10 to 20 parts of thermochromic microcapsules, 5 to 15 parts of tungsten-copper heterojunction filler, 30 to 40 parts of organic silicon modified acrylic resin, 3 to 8 parts of interface bridging agent and 2 to 5 parts of modified boron nitride. According to the invention, stable long afterglow performance is ensured, organic unification of photo-thermal response and long-acting luminescence is successfully realized, and the technical problems of mutual interference of components and poor environmental stability in a traditional multifunctional coating are effectively solved.

Description

A smart long afterglow coating with dual photo-thermal response and its application Technical Field

[0001] This invention belongs to the field of new materials technology, specifically relating to a smart long afterglow coating with dual photo-thermal response and its application. Background Technology

[0002] Long-afterglow materials, as special functional materials that continue to emit light after the excitation light has ceased, have wide applications in safety signage, emergency lighting, and decoration. Traditional long-afterglow materials are mainly sulfide systems, but they suffer from short afterglow times, poor chemical stability, and susceptibility to environmental humidity. In recent years, aluminate-based long-afterglow materials, especially strontium europium dysprosium aluminate, have attracted widespread attention due to their excellent afterglow properties and chemical stability. However, these materials still face many challenges in practical applications.

[0003] In practical applications of building energy conservation, it has been found that traditional long-afterglow coatings exhibit significant performance degradation under high-temperature and high-humidity environments. Specifically, when the ambient temperature exceeds 40℃ and the relative humidity is greater than 80%, the afterglow brightness of strontium europium dysprosium aluminate materials decreases by more than 50% within 30 days, and the afterglow duration is shortened from the initial 8 hours to less than 3 hours. Simultaneously, hydrolysis easily occurs on the material surface, leading to further deterioration of luminescent performance. This problem severely restricts the widespread application of long-afterglow coatings in outdoor environments.

[0004] On the other hand, the single function of long afterglow is no longer sufficient to meet the development needs of modern smart materials. Thermochromic materials can change color according to changes in ambient temperature, offering unique advantages in temperature indication and intelligent control. However, simple composites of traditional thermochromic materials and long afterglow materials produce significant performance interference. For example, a new materials company in Zhejiang found that when thermochromic microcapsules were directly mixed with strontium europium dysprosium aluminate, ion exchange occurred between the microcapsule wall material and the surface of the long afterglow material, leading to a sharp decline in afterglow performance. Furthermore, thermochromic materials are prone to leakage during long-term use, affecting their service life.

[0005] In the field of photothermal conversion materials, existing fillers such as carbon nanotubes or metal nanoparticles, while possessing high photothermal conversion efficiency, often exhibit fluorescence quenching effects when combined with long-afterglow materials. Research from a coatings company in Jiangsu Province shows that when carbon nanotubes are blended with strontium europium dysprosium aluminate, the initial brightness of the long-afterglow material decreases by more than 40%, and the afterglow lifetime is shortened by approximately 60%. Furthermore, these photothermal conversion fillers exhibit poor dispersibility in the resin matrix, easily agglomerating and further affecting the overall performance of the coating.

[0006] Furthermore, existing technologies struggle to achieve the organic synergy of multiple functions, including long-afterglow luminescence, thermochromism, and photothermal conversion. When these functional materials are simply blended, the poor interfacial compatibility between the components leads to a decline in the coating's mechanical properties, making it prone to cracking and peeling. Research from a Shanghai-based research institution shows that after 100 thermal cycling tests, the adhesion of multifunctional coatings decreased by more than 30%, and significant phase separation occurred.

[0007] Therefore, there is a need to design a smart long afterglow coating with dual light and heat response and its application. Summary of the Invention

[0008] To overcome the shortcomings of existing technologies, a smart long afterglow coating with dual photo-thermal response and its application are provided.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a smart long afterglow coating with dual photo-thermal response, comprising the following components by mass: 15-25 parts of coated strontium europium dysprosium aluminate, 10-20 parts of thermochromic microcapsules, 5-15 parts of tungsten copper heterojunction filler, 30-40 parts of organosilicon modified acrylic resin, 3-8 parts of interface bridging agent, and 2-5 parts of modified boron nitride.

[0010] The coated strontium europium dysprosium aluminate is a strontium europium dysprosium aluminate material that has been treated with a double coating of silica and a silane coupling agent. The preparation method of the coated strontium europium dysprosium aluminate includes the following steps: dispersing strontium europium dysprosium aluminate powder in an ethanol aqueous solution with a volume fraction of 75%-85%, adding a mixed solution of silane coupling agent KH-560 and tetraethyl orthosilicate, adjusting the pH value to 8.5-9.5 with ammonia, reacting at 60°C for 6 hours, washing and drying, and annealing at 500-600°C for 2-3 hours under nitrogen protection. The mass ratio of silane coupling agent to tetraethyl orthosilicate in the mixed solution is 1:3 to 1:5, and the total amount of silane coupling agent and tetraethyl orthosilicate added is 8%-15% of the mass of strontium europium dysprosium aluminate powder; the doping amount of europium in the strontium europium dysprosium aluminate powder is 1-3 mol%, and the doping amount of dysprosium is 2-5 mol%; the annealing adopts programmed temperature control, and the heating rate is 2-5℃ / min.

[0011] In practical applications, it has been found that traditional long-afterglow materials are prone to performance degradation under high-temperature and high-humidity environments, especially in the field of building energy conservation. When the ambient temperature exceeds 40°C and the relative humidity is high, the afterglow performance of strontium europium dysprosium aluminate materials decreases significantly. Existing technologies typically use physical isolation methods to improve material stability, but this method often affects the material's luminescence performance. This application employs a dual coating treatment of strontium europium dysprosium aluminate materials with silica and a silane coupling agent to form a dense protective layer on the material surface. This coating structure not only blocks the penetration of water molecules from the environment but also enhances the interfacial bonding with the resin matrix through the bridging effect of the silane coupling agent. From a materials science perspective, this coating treatment can protect the luminescent centers on the surface of strontium europium dysprosium aluminate from environmental influences while maintaining the integrity of its crystal structure, thereby maintaining stable luminescence performance under complex environments.

[0012] The thermochromic microcapsules are core-shell structured microspheres formed by encapsulating a thermochromic complex with silica as the shell. The preparation method of the thermochromic microcapsules includes the following steps: crystal violet lactone, bisphenol A, and tetradecyl alcohol are mixed and melted in a mass ratio of 1:(1.1-1.3):(10-15) to form a core material, which is then dispersed and emulsified in an aqueous solution containing sodium dodecyl sulfate. Tetraethyl orthosilicate is added, and the pH value is adjusted to 9-10 with ammonia. The mixture is reacted at 40-60℃ for 4-8 hours to form a microcapsule intermediate with a silica shell. Subsequently, the system temperature is adjusted to 25-35℃, γ-aminopropyltriethoxysilane is added, the pH value is maintained at 9-10, and the reaction is continued with stirring for 4-8 hours. Finally, the mixture is centrifuged, washed, and dried to obtain the thermochromic microcapsules.

[0013] The amount of sodium dodecyl sulfate used is 1%-3% of the core material mass; the amount of γ-aminopropyltriethoxysilane added is 2%-5% of the total mass of the core material.

[0014] The tungsten-copper heterojunction filler is a composite nanoparticle of tungsten oxide and copper oxide prepared by hydrothermal synthesis and calcination. The preparation method of the tungsten-copper heterojunction filler includes the following steps: dissolving sodium tungstate and copper sulfate in deionized water, and adding citric acid as a complexing agent; transferring the resulting mixed solution into a high-pressure reactor, heating it to 180-220°C at a heating rate of 3-5°C / min, and holding it at that temperature for 12-24 hours; after washing and drying the reaction product, calcining it in air at 400-500°C for 2-4 hours, and cooling it to obtain the tungsten-copper heterojunction filler.

[0015] The molar ratio of sodium tungstate to copper sulfate is 1:1 to 1:2, and the ratio of citric acid to the total molar number of tungsten ions and copper ions in the solution is 1.2:1 to 1.8:1.

[0016] While the stability issue of long-afterglow materials has been resolved, practical applications have revealed that a single long-afterglow function is insufficient to meet the development needs of smart materials. Existing technologies attempt to simply combine thermochromic materials with long-afterglow materials, but this often leads to performance interference; for example, components of the thermochromic material readily interact with the surface of the long-afterglow material. This application employs a core-shell structure with silica as the shell to encapsulate the thermochromic composite. This structural design effectively prevents leakage and deterioration of the thermochromic components. Simultaneously, a tungsten-copper heterojunction filler is used, which achieves efficient photothermal conversion through its unique band structure. From an energy conversion perspective, the heterojunction structure promotes the separation of photogenerated electron-hole pairs, improving the conversion efficiency of light energy to heat energy, while the thermochromic microcapsules convert heat energy into visible color changes, enabling sensitive responses to external environmental conditions.

[0017] The interface bridging agent is a polyacrylic acid-b-polyethylene oxide block copolymer. The preparation method of the interface bridging agent includes the following steps: using acrylic acid as a monomer and a complex of copper bromide and pentamethyldiethylenetriamine as a catalytic system, wherein the molar ratio of pentamethyldiethylenetriamine to copper bromide is (1.5-2.5):1, the polyacrylic acid segment is synthesized by atom transfer radical polymerization reaction at 60-80℃ under inert gas protection for 6-12 hours; using the polyacrylic acid segment as a macromolecular initiator, the ring-opening polymerization of ethylene oxide is initiated at 80-100℃ under inert gas protection for 24-48 hours to obtain a polyacrylic acid-b-polyethylene oxide block copolymer with a molecular weight of 10000-30000, which is the interface bridging agent.

[0018] The mass ratio of the polyacrylic acid segment to the polyethylene oxide segment is 1:1 to 1:3; the degree of polymerization of the polyacrylic acid segment is 50-100, and the degree of polymerization of the polyethylene oxide segment is 100-200.

[0019] The modified boron nitride is a composite material formed by in-situ polymerization of dopamine to form a coating layer on the surface of boron nitride. The preparation method of the modified boron nitride includes the following steps: dispersing boron nitride in a 10 mM Tris-HCl buffer solution with a pH of 8.5; adding dopamine hydrochloride, wherein the mass ratio of dopamine hydrochloride to boron nitride is 1:5-1:10; stirring and polymerizing at 25-35°C for 12-24 hours, during which air is continuously purged; collecting the product by centrifugation, washing with water and ethanol, and drying under vacuum at 40-60°C to obtain modified boron nitride.

[0020] As research deepens, the introduction of multifunctional components has revealed new technical challenges, namely, the compatibility between the components. When multiple functional materials coexist in a coating system, phase separation easily occurs due to significant differences in surface properties, affecting the overall performance of the coating. Existing technologies typically use a single compatibilizer, but with limited effectiveness. This application innovatively employs a polyacrylic acid-b-polyethylene oxide block copolymer as an interfacial bridger. The polymer's molecular chain simultaneously contains highly polar polyacrylic acid segments and polyethylene oxide segments with good compatibility with the resin matrix. From an interface engineering perspective, this amphiphilic structure can form effective molecular bridges between inorganic fillers and organic resins, reducing interfacial energy through interfacial interactions, thereby improving the dispersion stability of each component in the system. Furthermore, the formation of a coating layer on the boron nitride surface through in-situ polymerization of dopamine not only improves its dispersibility in the resin but also utilizes the excellent thermal conductivity of boron nitride to promote the uniform distribution of heat within the system.

[0021] This invention employs a multi-layered structural design to enable the coated strontium europium dysprosium aluminate to provide sustained long-afterglow luminescence, thermochromic microcapsules to impart temperature-responsive color-changing capabilities, tungsten-copper heterojunction fillers to achieve photothermal conversion, and interfacial bridging agents and modified boron nitride to ensure the stable synergy of these functional components. This combination not only considers the individual functional characteristics of each component but, more importantly, focuses on the interactions between them. The heat generated by the tungsten-copper heterojunction filler effectively triggers the response of the thermochromic microcapsules, while the thermal conductivity of modified boron nitride facilitates rapid heat transfer and uniform distribution. The interfacial bridging agent maintains the stability of the entire system. This synergistic effect allows the coating to achieve an organic unity of photothermal dual response and long-afterglow luminescence.

[0022] Compared with existing technologies, the advantages and beneficial effects of this invention are as follows: 1. The photothermal dual-response intelligent long afterglow coating of this invention effectively improves the stability of the material in complex environments by using coated strontium europium dysprosium aluminate as the core luminescent material. Traditional strontium europium dysprosium aluminate materials are prone to interacting with water molecules in the environment, leading to a decrease in luminescent performance. However, this invention forms a dense protective layer on the material surface through a dual coating treatment of silica and silane coupling agent. This coating structure not only blocks the penetration of water molecules but also enhances the interfacial bonding force with the resin matrix through the bridging effect of the silane coupling agent, enabling the long afterglow material to maintain stable luminescent performance even in high temperature and high humidity environments.

[0023] 2. The synergistic effect of the thermochromic microcapsules and tungsten-copper heterojunction filler in this invention enables intelligent management of photothermal energy. The thermochromic microcapsules encapsulate the thermochromic composite with silica as the shell, and this core-shell structure effectively prevents leakage and deterioration of the thermochromic components. The tungsten-copper heterojunction filler achieves efficient photothermal conversion through its special band structure. When the ambient temperature changes, the thermochromic microcapsules can reversibly change color, while the tungsten-copper heterojunction filler ensures efficient utilization of photothermal energy. The combined use of these two components allows the coating to respond sensitively to changes in external photothermal conditions.

[0024] 3. The introduction of the interfacial bridging agent and modified boron nitride in this invention improves the compatibility and dispersion stability of the components. The polyacrylic acid-polyethylene oxide block copolymer, acting as an interfacial bridging agent, exhibits strong interactions between the polyacrylic acid segments of its molecular chain and the inorganic filler surface, while the polyethylene oxide segments demonstrate good compatibility with the organic resin matrix. This amphiphilic structure forms an effective molecular bridge between the inorganic filler and the organic resin, reducing phase separation. Modified boron nitride, through in-situ polymerization of dopamine, forms a coating layer on the surface, which not only improves its dispersibility in the resin but also promotes uniform heat distribution through its excellent thermal conductivity.

[0025] 4. The organic combination of the functional components of this invention enables the coating to exhibit multiple intelligent response characteristics. The encapsulated strontium europium dysprosium aluminate provides long-lasting afterglow luminescence, the thermochromic microcapsules endow the coating with temperature-responsive color-changing capabilities, the tungsten-copper heterojunction filler realizes photothermal conversion functionality, and the interface bridging agent and modified boron nitride ensure the stable synergy of these functional components. This multi-layered structural design solves the technical problem of mutual interference between components in traditional multifunctional coatings, while simultaneously achieving dual photothermal response and long afterglow luminescence. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0027] In the specific embodiments of this application, the sources of various main raw materials are briefly described as follows: Strontium europium dysprosium aluminate powder: Zhejiang Minghe New Material Co., Ltd., CAS No. 883150-73-0; Silane coupling agent KH-560: Nanjing Shuguang Chemical Group Co., Ltd., CAS No. 2530-83-8; Tetraethyl orthosilicate: Zhangjiagang Xinya Chemical Co., Ltd., CAS No. 78-10-4; Crystal violet lactone: Sinopharm Chemical Reagent Co., Ltd., CAS No. 1676-61-9; Bisphenol A: Sinopharm Chemical Reagent Co., Ltd., CAS No. 80-05-7; Tetradecyl alcohol: Shanghai Jizhi Biochemical Technology Co., Ltd., CAS No. 112-72-1; γ-aminopropyltriethoxysilane: Nanjing Jingtianwei Chemical Co., Ltd., CAS No. 919-30-2; Sodium tungstate: Sinopharm Chemical Reagent Co., Ltd., CAS No. 10213-10-2; Copper sulfate (pentahydrate): Sinopharm Chemical Reagent Co., Ltd. The technical solution of this application is: a smart long afterglow coating with dual photo-thermal response, which, by mass parts, comprises the following components: 15-25 parts of coated strontium europium dysprosium aluminate, 10-20 parts of thermochromic microcapsules, 5-15 parts of tungsten copper heterojunction filler, 30-40 parts of organosilicon modified acrylic resin, 3-8 parts of interface bridging agent, and 2-5 parts of modified boron nitride.

[0028] The coated strontium europium dysprosium aluminate is a strontium europium dysprosium aluminate material that has been treated with a double coating of silica and a silane coupling agent. The preparation method of the coated strontium europium dysprosium aluminate includes the following steps: dispersing strontium europium dysprosium aluminate powder in an ethanol aqueous solution with a volume fraction of 75%-85%, adding a mixed solution of silane coupling agent KH-560 and tetraethyl orthosilicate, adjusting the pH value to 8.5-9.5 with ammonia, reacting at 60°C for 6 hours, washing and drying, and annealing at 500-600°C for 2-3 hours under nitrogen protection.

[0029] The mass ratio of silane coupling agent to tetraethyl orthosilicate in the mixed solution is 1:3 to 1:5, and the total amount of silane coupling agent and tetraethyl orthosilicate added is 8%-15% of the mass of strontium europium dysprosium aluminate powder; the doping amount of europium in the strontium europium dysprosium aluminate powder is 1-3 mol%, and the doping amount of dysprosium is 2-5 mol%; the annealing adopts programmed temperature control, and the heating rate is 2-5℃ / min.

[0030] The thermochromic microcapsules are core-shell structured microspheres formed by encapsulating a thermochromic complex with silica as the shell. The preparation method of the thermochromic microcapsules includes the following steps: crystal violet lactone, bisphenol A, and tetradecyl alcohol are mixed and melted in a mass ratio of 1:(1.1-1.3):(10-15) to form a core material, which is then dispersed and emulsified in an aqueous solution containing sodium dodecyl sulfate. Tetraethyl orthosilicate is added, and the pH value is adjusted to 9-10 with ammonia. The mixture is reacted at 40-60℃ for 4-8 hours to form a microcapsule intermediate with a silica shell. Subsequently, the system temperature is adjusted to 25-35℃, γ-aminopropyltriethoxysilane is added, the pH value is maintained at 9-10, and the reaction is continued with stirring for 4-8 hours. Finally, the mixture is centrifuged, washed, and dried to obtain the thermochromic microcapsules.

[0031] The amount of sodium dodecyl sulfate used is 1%-3% of the core material mass; the amount of γ-aminopropyltriethoxysilane added is 2%-5% of the total mass of the core material.

[0032] The tungsten-copper heterojunction filler is a composite nanoparticle of tungsten oxide and copper oxide prepared by hydrothermal synthesis and calcination. The preparation method of the tungsten-copper heterojunction filler includes the following steps: dissolving sodium tungstate and copper sulfate in deionized water, and adding citric acid as a complexing agent; transferring the resulting mixed solution into a high-pressure reactor, heating it to 180-220°C at a heating rate of 3-5°C / min, and holding it at that temperature for 12-24 hours; after washing and drying the reaction product, calcining it in air at 400-500°C for 2-4 hours, and cooling it to obtain the tungsten-copper heterojunction filler.

[0033] The molar ratio of sodium tungstate to copper sulfate is 1:1 to 1:2, and the ratio of citric acid to the total molar number of tungsten ions and copper ions in the solution is 1.2:1 to 1.8:1.

[0034] The interface bridging agent is a polyacrylic acid-b-polyethylene oxide block copolymer. The preparation method of the interface bridging agent includes the following steps: using acrylic acid as a monomer and a complex of copper bromide and pentamethyldiethylenetriamine as a catalytic system, wherein the molar ratio of pentamethyldiethylenetriamine to copper bromide is (1.5-2.5):1, the polyacrylic acid segment is synthesized by atom transfer radical polymerization reaction at 60-80℃ under inert gas protection for 6-12 hours; using the polyacrylic acid segment as a macromolecular initiator, the ring-opening polymerization of ethylene oxide is initiated at 80-100℃ under inert gas protection for 24-48 hours to obtain a polyacrylic acid-b-polyethylene oxide block copolymer with a molecular weight of 10000-30000, which is the interface bridging agent.

[0035] The mass ratio of the polyacrylic acid segment to the polyethylene oxide segment is 1:1 to 1:3; the degree of polymerization of the polyacrylic acid segment is 50-100, and the degree of polymerization of the polyethylene oxide segment is 100-200.

[0036] The modified boron nitride is a composite material formed by in-situ polymerization of dopamine to form a coating layer on the surface of boron nitride. The preparation method of the modified boron nitride includes the following steps: dispersing boron nitride in a 10 mM Tris-HCl buffer solution with a pH of 8.5; adding dopamine hydrochloride, wherein the mass ratio of dopamine hydrochloride to boron nitride is 1:5-1:10; stirring and polymerizing at 25-35°C for 12-24 hours, during which air is continuously purged; collecting the product by centrifugation, washing with water and ethanol, and drying under vacuum at 40-60°C to obtain modified boron nitride.

[0037] The present invention will be described in detail below through examples and comparative examples, but the scope of protection of the present invention is not limited to these examples. Unless otherwise specified, the chemical reagents and raw materials used in the following examples and comparative examples are all conventional commercially available products.

[0038] Example 1 This example provides a smart long afterglow coating with dual photothermal response. By mass, the coating comprises the following components: 25 parts of coated strontium europium dysprosium aluminate, 15 parts of thermochromic microcapsules, 5 parts of tungsten copper heterojunction filler, 40 parts of organosilicon modified acrylic resin, 3 parts of interface bridging agent, and 2 parts of modified boron nitride.

[0039] The preparation process of coated strontium europium dysprosium aluminate is as follows: strontium europium dysprosium aluminate powder is dispersed in an 85% (v / v) ethanol aqueous solution, and a mixed solution of silane coupling agent KH-560 and tetraethyl orthosilicate is added, wherein the mass ratio of silane coupling agent to tetraethyl orthosilicate is 1:5, and the total amount added is 15% of the mass of strontium europium dysprosium aluminate powder. The pH value is adjusted to 9.5 with ammonia water, and the reaction is carried out at 60℃ for 6 hours. After washing and drying, it is annealed at 600℃ for 2 hours under nitrogen protection. The annealing process adopts programmed temperature control with a heating rate of 5℃ / min. The doping amount of europium in the strontium europium dysprosium aluminate powder is 3 mol%, and the doping amount of dysprosium is 2 mol%.

[0040] The preparation process of thermochromic microcapsules is as follows: crystal violet lactone, bisphenol A and tetradecyl alcohol are mixed and melted in a mass ratio of 1:1.3:10 to form a core material, which is then dispersed in an aqueous solution containing sodium dodecyl sulfate and emulsified. The amount of sodium dodecyl sulfate is 3% of the mass of the core material. Tetraethyl orthosilicate is added, and the pH value is adjusted to 10 with ammonia. The reaction is carried out at 60°C for 4 hours to form a microcapsule intermediate with a silica shell. Subsequently, the system temperature is adjusted to 35°C, and γ-aminopropyltriethoxysilane is added at 5% of the total mass of the core material. The pH value is maintained at 10, and the reaction is continued to be stirred for 4 hours. Finally, the microcapsules are obtained by centrifugation, washing and drying.

[0041] The preparation process of tungsten-copper heterojunction filler is as follows: Sodium tungstate and copper sulfate are dissolved in deionized water at a molar ratio of 1:2. Citric acid is added as a complexing agent. The molar ratio of citric acid to the total number of tungsten ions and copper ions in the solution is 1.8:1. The resulting mixed solution is transferred to a high-pressure reactor and heated to 220°C at a heating rate of 5°C / min. The temperature is maintained for 12 hours. After washing and drying, the reaction product is calcined at 500°C in air for 2 hours. After cooling, tungsten-copper heterojunction filler is obtained. The preparation process of the interface bridging agent is as follows: using acrylic acid as the monomer and a complex of copper bromide and pentamethyldiethylenetriamine as the catalytic system, wherein the molar ratio of pentamethyldiethylenetriamine to copper bromide is 2.5:1, the polyacrylic acid segment is synthesized by atom transfer radical polymerization reaction at 80℃ under inert gas protection for 6 hours. Using the polyacrylic acid segment as a macromolecular initiator, the ring-opening polymerization of ethylene oxide is initiated at 100℃ under inert gas protection for 24 hours to obtain a polyacrylic acid-b-polyethylene oxide block copolymer with a molecular weight of 30,000. The mass ratio of polyacrylic acid segment to polyethylene oxide segment is 1:3, the degree of polymerization of polyacrylic acid segment is 100, and the degree of polymerization of polyethylene oxide segment is 200.

[0042] The preparation process of modified boron nitride is as follows: boron nitride is dispersed in Tris-HCl buffer solution with a concentration of 10 mM and a pH of 8.5, dopamine hydrochloride is added, and the mass ratio of dopamine hydrochloride to boron nitride is 1:10. The mixture is stirred and polymerized at 35°C for 12 hours, during which air is continuously purged. The product is collected by centrifugation, washed with water and ethanol, and dried under vacuum at 60°C to obtain modified boron nitride.

[0043] Example 2 In this example, the similarities with Example 1 will not be repeated, and the differences are as follows: This example provides another intelligent long afterglow coating with dual photothermal response. By mass, the coating includes the following components: 15 parts of coated strontium europium dysprosium aluminate, 20 parts of thermochromic microcapsules, 15 parts of tungsten copper heterojunction filler, 30 parts of organosilicon modified acrylic resin, 8 parts of interface bridging agent, and 5 parts of modified boron nitride.

[0044] The preparation process of coated strontium europium dysprosium aluminate is as follows: strontium europium dysprosium aluminate powder is dispersed in a 75% (v / v) ethanol aqueous solution, and a mixed solution of silane coupling agent KH-560 and tetraethyl orthosilicate is added, wherein the mass ratio of silane coupling agent to tetraethyl orthosilicate is 1:3, and the total amount added is 8% of the mass of strontium europium dysprosium aluminate powder. The pH value is adjusted to 8.5 with ammonia water, and the reaction is carried out at 60℃ for 6 hours. After washing and drying, it is annealed at 500℃ for 3 hours under nitrogen protection. The annealing process adopts programmed temperature control, and the heating rate is 2℃ / min. The doping amount of europium in the strontium europium dysprosium aluminate powder is 1 mol%, and the doping amount of dysprosium is 5 mol%.

[0045] The preparation process of thermochromic microcapsules is as follows: crystal violet lactone, bisphenol A and tetradecyl alcohol are mixed and melted in a mass ratio of 1:1.1:15 to form a core material, which is then dispersed and emulsified in an aqueous solution containing sodium dodecyl sulfate. The amount of sodium dodecyl sulfate is 1% of the mass of the core material. Tetraethyl orthosilicate is added, and the pH value is adjusted to 9 with ammonia. The reaction is carried out at 40°C for 8 hours to form a microcapsule intermediate with a silica shell. Subsequently, the system temperature is adjusted to 25°C, and γ-aminopropyltriethoxysilane is added at 2% of the total mass of the core material. The pH value is maintained at 9, and the reaction is continued to be stirred for 8 hours. Finally, the microcapsules are obtained by centrifugation, washing and drying.

[0046] The preparation process of tungsten-copper heterojunction filler is as follows: Sodium tungstate and copper sulfate are dissolved in deionized water at a molar ratio of 1:1. Citric acid is added as a complexing agent. The ratio of the total molar number of tungsten ions and copper ions in the solution to that of citric acid is 1.2:1. The resulting mixed solution is transferred to a high-pressure reactor and heated to 180°C at a heating rate of 3°C / min. The temperature is maintained for 24 hours. After washing and drying, the reaction product is calcined at 400°C in air for 4 hours. After cooling, the tungsten-copper heterojunction filler is obtained.

[0047] The preparation process of the interface bridging agent is as follows: using acrylic acid as the monomer and a complex of copper bromide and pentamethyldiethylenetriamine as the catalytic system, wherein the molar ratio of pentamethyldiethylenetriamine to copper bromide is 1.5:1, the polyacrylic acid segment is synthesized by atom transfer radical polymerization reaction at 60℃ under inert gas protection for 12 hours. The polyacrylic acid segment is then used as a macromolecular initiator to initiate the ring-opening polymerization of ethylene oxide at 80℃ under inert gas protection for 48 hours to obtain a polyacrylic acid-b-polyethylene oxide block copolymer with a molecular weight of 10000. The mass ratio of polyacrylic acid segment to polyethylene oxide segment is 1:1, the degree of polymerization of the polyacrylic acid segment is 50, and the degree of polymerization of the polyethylene oxide segment is 100.

[0048] The preparation process of modified boron nitride is as follows: boron nitride is dispersed in Tris-HCl buffer with a concentration of 10 mM and a pH of 8.5, dopamine hydrochloride is added, and the mass ratio of dopamine hydrochloride to boron nitride is 1:5. The mixture is stirred and polymerized at 25°C for 24 hours, during which air is continuously purged. The product is collected by centrifugation, washed with water and ethanol, and dried under vacuum at 40°C to obtain modified boron nitride.

[0049] Example 3 In this example, the similarities with Example 1 will not be repeated, and the differences are as follows: This example provides another intelligent long afterglow coating with dual photothermal response. By mass parts, the coating includes the following components: 20 parts of coated strontium europium dysprosium aluminate, 10 parts of thermochromic microcapsules, 10 parts of tungsten copper heterojunction filler, 35 parts of organosilicon modified acrylic resin, 5 parts of interface bridging agent, and 3 parts of modified boron nitride.

[0050] The preparation process of coated strontium europium dysprosium aluminate is as follows: strontium europium dysprosium aluminate powder is dispersed in an 80% (v / v) ethanol aqueous solution. A mixed solution of silane coupling agent KH-560 and tetraethyl orthosilicate is added, wherein the mass ratio of silane coupling agent to tetraethyl orthosilicate is 1:4, and the total amount added is 12% of the mass of the strontium europium dysprosium aluminate powder. The pH value is adjusted to 9.0 with ammonia water, and the reaction is carried out at 60℃ for 6 hours. After washing and drying, it is annealed at 550℃ for 2.5 hours under nitrogen protection. The annealing process adopts programmed temperature control with a heating rate of 3℃ / min. The doping amount of europium in the strontium europium dysprosium aluminate powder is 2 mol%, and the doping amount of dysprosium is 3 mol%.

[0051] The preparation process of thermochromic microcapsules is as follows: crystal violet lactone, bisphenol A and tetradecyl alcohol are mixed and melted in a mass ratio of 1:1.2:12 to form a core material, which is then dispersed in an aqueous solution containing sodium dodecyl sulfate and emulsified. The amount of sodium dodecyl sulfate is 2% of the mass of the core material. Tetraethyl orthosilicate is added, and the pH value is adjusted to 9.5 with ammonia. The reaction is carried out at 50°C for 6 hours to form a microcapsule intermediate with a silica shell. Subsequently, the system temperature is adjusted to 30°C, and γ-aminopropyltriethoxysilane is added at a mass of 3% of the total mass of the core material. The pH value is maintained at 9.5, and the reaction is continued to be stirred for 6 hours. Finally, the microcapsules are obtained by centrifugation, washing and drying.

[0052] The preparation process of tungsten-copper heterojunction filler is as follows: Sodium tungstate and copper sulfate are dissolved in deionized water at a molar ratio of 1:1.5. Citric acid is added as a complexing agent. The molar ratio of citric acid to the total number of tungsten ions and copper ions in the solution is 1.5:1. The resulting mixed solution is transferred to a high-pressure reactor and heated to 200°C at a heating rate of 4°C / min. The temperature is maintained for 18 hours. After washing and drying, the reaction product is calcined at 450°C in air for 3 hours. After cooling, tungsten-copper heterojunction filler is obtained.

[0053] The preparation process of the interface bridging agent is as follows: using acrylic acid as the monomer and a complex of copper bromide and pentamethyldiethylenetriamine as the catalytic system, wherein the molar ratio of pentamethyldiethylenetriamine to copper bromide is 2.0:1, the polyacrylic acid segment is synthesized by atom transfer radical polymerization reaction at 70℃ under inert gas protection for 9 hours. Using the polyacrylic acid segment as a macromolecular initiator, the ring-opening polymerization of ethylene oxide is initiated at 90℃ under inert gas protection for 36 hours to obtain a polyacrylic acid-b-polyethylene oxide block copolymer with a molecular weight of 20,000. The mass ratio of polyacrylic acid segment to polyethylene oxide segment is 1:2, the degree of polymerization of polyacrylic acid segment is 75, and the degree of polymerization of polyethylene oxide segment is 150.

[0054] The preparation process of modified boron nitride is as follows: boron nitride is dispersed in Tris-HCl buffer with a concentration of 10 mM and a pH of 8.5, dopamine hydrochloride is added, and the mass ratio of dopamine hydrochloride to boron nitride is 1:7. The mixture is stirred and polymerized at 30°C for 18 hours, during which air is continuously purged. The product is collected by centrifugation, washed with water and ethanol, and dried under vacuum at 50°C to obtain modified boron nitride.

[0055] Comparative Example 1: The similarities to Example 1 will not be repeated here. The differences are as follows: Uncoated strontium europium dysprosium aluminate powder is used instead of coated strontium europium dysprosium aluminate.

[0056] In Comparative Example 2, the similarities to Example 2 will not be repeated, and the differences are as follows: ordinary copper oxide powder is used instead of tungsten copper heterojunction filler.

[0057] In Comparative Example 3, the similarities to Example 3 will not be repeated, but the differences are as follows: no interface bridging agent is used.

[0058] In Comparative Example 4, the similarities to Example 1 will not be repeated, and the differences are as follows: unmodified boron nitride was used instead of modified boron nitride.

[0059] In Comparative Example 5, the similarities with Example 2 will not be repeated here. The differences are as follows: γ-aminopropyltriethoxysilane is not used for surface modification during the preparation of thermochromic microcapsules.

[0060] In Comparative Example 6, the similarities with Example 3 will not be repeated here. The differences are as follows: ordinary acrylic resin is used instead of silicone-modified acrylic resin.

[0061] Performance testing results and analysis: The performance testing methods included: coating samples prepared in each embodiment and comparative example were coated onto a standard substrate to form a dry film thickness of 100 μm, and cured at 85°C for 50 minutes. Afterglow performance testing involved exciting the coating with an ultraviolet light source at a wavelength of 365 nm for 30 minutes, and then measuring the brightness values ​​at different time points after excitation was stopped using an afterglow brightness meter. Thermochromic performance testing involved observing the color change of the coating within a temperature range of 25°C to 65°C using a hot-stage microscope, and recording the color difference values ​​using a colorimeter. Photothermal conversion performance testing involved irradiating the coating surface with simulated sunlight, and recording the surface temperature change using an infrared thermal imager. Environmental resistance testing involved placing the coating samples in an environment of 40°C and 85% relative humidity, and periodically monitoring changes in various performance characteristics. Coating adhesion was tested using the standard cross-cut test, and thermal cycling testing was performed for 100 cycles within a temperature range of -20°C to 80°C before detecting the coating state. Specific test results are shown in Table 1.

[0062] Table 1 Analysis of Test Results As shown in Table 1, all three embodiments exhibit excellent performance across all indicators, verifying the effectiveness of the technical solution of this invention. Comparative Example 1, using uncoated strontium europium dysprosium aluminate, showed a significantly lower afterglow retention rate (68%) after 30 days compared to the embodiments (over 90%). This is mainly because the trap energy levels on the surface of the strontium europium dysprosium aluminate material readily interact with water molecules in high humidity environments, leading to the filling or destruction of the traps and accelerating afterglow decay. This invention, through double coating with silica and a silane coupling agent, forms a dense protective layer on the material surface, effectively blocking the penetration and erosion of water molecules and other components in the air, protecting these critical trap energy levels, and thus maintaining stable afterglow performance. This demonstrates that the application of coated strontium europium dysprosium aluminate significantly improves the environmental stability and afterglow performance of the coating.

[0063] Test results show that Comparative Example 2, using ordinary copper oxide, has a significantly lower photothermal conversion efficiency (72%) than the Example (over 86%). According to the photothermal conversion principle of materials, copper oxide alone has limited absorption and utilization efficiency for near-infrared photons. However, the tungsten oxide / copper oxide heterojunction prepared through hydrothermal synthesis and calcination forms a built-in electric field at the interface of the two semiconductor materials. When exposed to light, photogenerated electron-hole pairs can effectively separate under the influence of the built-in electric field, greatly improving the lifetime and concentration of charge carriers. This allows more light energy to be converted into heat energy through non-radiative transitions, exhibiting a higher photothermal conversion efficiency. This demonstrates that the introduction of filler material into the tungsten-copper heterojunction is key to achieving efficient photothermal conversion.

[0064] The interfacial bridging agent of this invention is crucial for maintaining the uniformity of the coating's microstructure and its macroscopic durability. Comparative Example 3, without the interfacial bridging agent, showed a decreased adhesion grade (level 2) and localized peeling after thermal cycling. This verifies the role of the amphiphilic structure of the block copolymer: its polyacrylic acid segments can anchor to the surface of inorganic fillers such as coated strontium europium dysprosium aluminate and tungsten copper heterojunction fillers, while the polyethylene oxide segments are well-compatible with the silicone-modified acrylic resin matrix and may entangle. This "bridging" effect significantly improves the interfacial compatibility between the inorganic filler and the organic resin, reduces phase separation and stress concentration caused by differences in thermal expansion coefficients, thereby enhancing coating integrity and adhesion, enabling it to withstand thermal cycling.

[0065] The thermal energy converted by the tungsten-copper heterojunction filler can more effectively trigger the reversible color change of the thermochromic microcapsules (whose silica shell provides stable protection). In Comparative Example 5, the microcapsules were not surface-modified with γ-aminopropyltriethoxysilane, which may lead to poor bonding with the matrix or reduced encapsulation, affecting the accuracy and durability of the thermal response.

[0066] Modified boron nitride coated by in-situ polymerization of dopamine not only improves dispersion in the resin, but its good thermal conductivity may also contribute to the uniform distribution of heat within the coating, avoiding localized overheating and indirectly protecting the trapping stability of long-afterglow materials. Comparative Example 4, using unmodified boron nitride, showed slight blistering after thermal cycling, illustrating the importance of interfacial bonding.

[0067] Comparative Example 6 used ordinary acrylic resin, and all properties decreased, proving that the silicone-modified acrylic resin provides more stable support for the entire functional system due to its higher thermal stability and better film-forming properties.

[0068] This invention achieves a synergistic effect of coated strontium europium dysprosium aluminate, thermochromic microcapsules, tungsten copper heterojunction filler, interfacial bridging agent, and modified boron nitride, ensuring stable long afterglow performance while successfully unifying photothermal response and long-lasting luminescence. This effectively solves the technical problems of mutual interference and poor environmental stability among components in traditional multifunctional coatings.

[0069] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A smart long afterglow coating with dual photo-thermal response, characterized in that, By weight, the coating comprises the following components: 15-25 parts of coated strontium europium dysprosium aluminate, 10-20 parts of thermochromic microcapsules, 5-15 parts of tungsten copper heterojunction filler, 30-40 parts of silicone-modified acrylic resin, 3-8 parts of interfacial bridging agent, and 2-5 parts of modified boron nitride.

2. The intelligent long afterglow coating with dual photo-thermal response according to claim 1, characterized in that, The coated strontium europium dysprosium aluminate is a strontium europium dysprosium aluminate material that has been treated with a double coating of silica and a silane coupling agent. The preparation method of the coated strontium europium dysprosium aluminate includes the following steps: dispersing strontium europium dysprosium aluminate powder in an ethanol aqueous solution with a volume fraction of 75%-85%, adding a mixed solution of silane coupling agent KH-560 and tetraethyl orthosilicate, adjusting the pH value to 8.5-9.5 with ammonia, reacting at 60°C for 6 hours, washing and drying, and annealing at 500-600°C for 2-3 hours under nitrogen protection.

3. The intelligent long afterglow coating with dual photo-thermal response according to claim 2, characterized in that, The mass ratio of silane coupling agent to tetraethyl orthosilicate in the mixed solution is 1:3 to 1:5, and the total amount of silane coupling agent and tetraethyl orthosilicate added is 8%-15% of the mass of strontium europium dysprosium aluminate powder; the doping amount of europium in the strontium europium dysprosium aluminate powder is 1-3 mol%, and the doping amount of dysprosium is 2-5 mol%; the annealing adopts programmed temperature control, and the heating rate is 2-5℃ / min.

4. The intelligent long afterglow coating with dual photo-thermal response according to claim 1, characterized in that, The thermochromic microcapsules are core-shell structured microspheres formed by encapsulating a thermochromic complex with silica as the shell. The preparation method of the thermochromic microcapsules includes the following steps: crystal violet lactone, bisphenol A, and tetradecyl alcohol are mixed and melted in a mass ratio of 1:(1.1-1.3):(10-15) to form a core material, which is then dispersed and emulsified in an aqueous solution containing sodium dodecyl sulfate. Tetraethyl orthosilicate is added, and the pH value is adjusted to 9-10 with ammonia. The mixture is reacted at 40-60℃ for 4-8 hours to form a microcapsule intermediate with a silica shell. Subsequently, the system temperature is adjusted to 25-35℃, γ-aminopropyltriethoxysilane is added, the pH value is maintained at 9-10, and the reaction is continued with stirring for 4-8 hours. Finally, the mixture is centrifuged, washed, and dried to obtain the thermochromic microcapsules.

5. The intelligent long afterglow coating with dual photo-thermal response according to claim 4, characterized in that, The amount of sodium dodecyl sulfate used is 1%-3% of the core material mass; the amount of γ-aminopropyltriethoxysilane added is 2%-5% of the total mass of the core material.

6. The intelligent long afterglow coating with dual photo-thermal response according to claim 1, characterized in that, The tungsten-copper heterojunction filler is a composite nanoparticle of tungsten oxide and copper oxide prepared by hydrothermal synthesis and calcination. The preparation method of the tungsten-copper heterojunction filler includes the following steps: dissolving sodium tungstate and copper sulfate in deionized water, and adding citric acid as a complexing agent; transferring the resulting mixed solution into a high-pressure reactor, heating it to 180-220°C at a heating rate of 3-5°C / min, and holding it at that temperature for 12-24 hours; after washing and drying the reaction product, calcining it in air at 400-500°C for 2-4 hours, and cooling it to obtain the tungsten-copper heterojunction filler.

7. The intelligent long afterglow coating with dual photo-thermal response according to claim 6, characterized in that, The molar ratio of sodium tungstate to copper sulfate is 1:1 to 1:2, and the ratio of citric acid to the total molar number of tungsten ions and copper ions in the solution is 1.2:1 to 1.8:

1.

8. The intelligent long afterglow coating with dual photo-thermal response according to claim 1, characterized in that, The interface bridging agent is a polyacrylic acid-b-polyethylene oxide block copolymer. The preparation method of the interface bridging agent includes the following steps: using acrylic acid as a monomer and a complex of copper bromide and pentamethyldiethylenetriamine as a catalytic system, wherein the molar ratio of pentamethyldiethylenetriamine to copper bromide is (1.5-2.5):1, the polyacrylic acid segment is synthesized by atom transfer radical polymerization reaction at 60-80℃ under inert gas protection for 6-12 hours; using the polyacrylic acid segment as a macromolecular initiator, the ring-opening polymerization of ethylene oxide is initiated at 80-100℃ under inert gas protection for 24-48 hours to obtain a polyacrylic acid-b-polyethylene oxide block copolymer with a molecular weight of 10000-30000, which is the interface bridging agent.

9. The intelligent long afterglow coating with dual photo-thermal response according to claim 8, characterized in that, The mass ratio of the polyacrylic acid segment to the polyethylene oxide segment is 1:1 to 1:3; the degree of polymerization of the polyacrylic acid segment is 50-100, and the degree of polymerization of the polyethylene oxide segment is 100-200.

10. The intelligent long afterglow coating with dual photo-thermal response according to claim 1, characterized in that, The modified boron nitride is a composite material formed by in-situ polymerization of dopamine to form a coating layer on the surface of boron nitride. The preparation method of the modified boron nitride includes the following steps: dispersing boron nitride in a 10 mM Tris-HCl buffer solution with a pH of 8.5; adding dopamine hydrochloride, wherein the mass ratio of dopamine hydrochloride to boron nitride is 1:5-1:10; stirring and polymerizing at 25-35°C for 12-24 hours, during which air is continuously purged; collecting the product by centrifugation, washing with water and ethanol, and drying under vacuum at 40-60°C to obtain modified boron nitride.

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