Photoluminescent multistage form radiation cooling coating and preparation method thereof

Abstract

The invention discloses a photoluminescent multilevel form radiation cooling coating and a preparation method thereof, which innovatively introduces photoluminescent silicon quantum dots and multilevel structure design to realize high solar reflectivity and high and medium infrared emissivity, and enhances heat insulation through low thermal conductivity of hollow glass beads. The high solar reflectivity is realized through multi-scale roughness generated by micron-sized hollow glass beads and nano-sized mesoporous silicon dioxide particles, so that the overall solar reflectivity is improved through scattering and reflection of sunlight by a formed graded form; meanwhile, the silicon quantum dots which have photoluminescence performance and are packaged by mesoporous silica are synthesized in situ through a one-pot method, and ultraviolet light can be absorbed and converted into visible light, so that the reflectivity is further improved. The high and intermediate infrared emissivity is realized through relatively high emission in an intermediate infrared band by an organic silicon prepolymer matrix and a filler molecular structure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of daytime radiative cooling and heat dissipation, and particularly relates to a photoluminescence multistage radiative cooling coating and a preparation method thereof. BACKGROUND

[0002] With the increasingly serious energy and environmental problems, it is urgent to develop energy-saving and environment-friendly cooling technology. Radiative cooling materials and technology have the characteristics of radiative cooling without energy consumption, and have become a research field attracting much attention in recent years. In recent years, photonic structures, dielectric materials, polymers and metal-dielectric-metal composite materials have been reported as radiative cooling materials, and have shown excellent cooling performance. However, these materials have high manufacturing cost, are prone to corrosion and have fixed shape, and cannot be applied to complex-shaped roofs or walls. Coating refers to a kind of material coated on the surface of an object by a specific construction process, which forms a continuous solid film with protection, decoration or special properties after solidification. As a kind of solar energy conversion functional coating, the radiative cooling coating has the advantages of simple preparation, low cost and convenient application, and shows important scientific research value and great engineering application prospect.

[0003] Traditional radiative cooling coating (usually white high-reflective coating) mainly relies on high solar reflectance (reducing heat absorption) and high emissivity in the mid-infrared window (enhancing heat dissipation). However, when the sunlight is very strong, even if the reflectivity is very high, a small amount of absorption will cause significant temperature rise. According to the structure of the coating, it can be divided into single-coat radiative cooling coating and double-coat radiative cooling coating. It is worth mentioning that the functional materials used in white radiative cooling coating are mainly inorganic nanoparticles with different structures and fluorine / silicon polymers and their composites. Due to aesthetic or functional reasons, white color is limited as a coating for buildings or other outdoor facilities, and high-brightness white color also brings light pollution. In addition, the introduction of traditional pigments and dyes will bring additional solar energy absorption, and it is still a big challenge to color the radiative cooling coating without affecting its cooling performance. Therefore, it is very important to develop a photoluminescence radiative cooling coating with high radiative cooling efficiency for the thermal management field of buildings, vehicles and electronic devices. SUMMARY

[0004] The purpose of the present application is to provide a photoluminescence multistage radiative cooling coating and a preparation method thereof. The method combines in-situ preparation and encapsulation technology of quantum dots, and through simple physical blending, hollow glass microspheres and mesoporous silica with different sizes are constructed in the presence of silicone resin to realize the controllable adjustment of the wettability and roughness of functional fillers on the substrate surface. The heat insulation performance of the coating is avoided to improve the cooling performance of the coating.

[0005] In order to solve the above technical problems, the following technical solutions are adopted:

[0006] A photoluminescent multi-level morphology radiative cooling coating and a preparation method thereof, characterized by comprising the following steps:

[0007] (1) Dissolve the template agent in a reaction bottle containing deionized water, heat and stir in an oil bath, then add a reducing agent and a catalyst, continue stirring for a certain time, then add tetraethyl orthosilicate dropwise for hydrolysis and condensation reaction; after the reaction solution cools to room temperature, the product is centrifuged, then washed with ethanol and deionized water twice to obtain a precipitate;

[0008] (2) Disperse the precipitate in a mixture of ethanol and concentrated hydrochloric acid (37%) at 60°C and 500 rpm overnight to remove the template agent, then wash with ethanol and water twice, freeze the obtained mesoporous silica encapsulated silicon quantum dots with liquid nitrogen, and then place them in a freeze dryer overnight to obtain mesoporous silica encapsulated silicon quantum dot powder;

[0009] (3) Ultrasonically disperse the mesoporous silica encapsulated silicon quantum dot powder obtained in step (2) in anhydrous ethanol, add a catalyst and deionized water, then heat and stir the mixed solution in an oil bath, then add a silane coupling agent and react for a certain time; after the mixed solution cools to room temperature, centrifuge the product, then wash it with ethanol and deionized water twice to remove unreacted nanoparticles and silane coupling agent, and then place it in a vacuum oven at 40-80°C to dry to constant weight to obtain modified mesoporous silica / silicon quantum dot composite particles;

[0010] (4) Add organosilicon prepolymer A and curing agent B (wherein the mass of the curing agent is 10% of the organosilicon prepolymer) to ethyl acetate, magnetically stir at room temperature to obtain a mixed solution; then add hollow glass microbeads and mesoporous silica / silicon quantum dot composite particles to the mixed solution, stir well to disperse to obtain a mixed slurry, coat the mixed slurry on a substrate, dry in air for 1 h, then dry in an oven at 80°C for 2-24 h to obtain a photoluminescent multi-level morphology coating for daytime passive radiative cooling.

[0011] Preferably, in step (1), the template agent is selected from one of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, and tetrapropylammonium hydroxide.

[0012] Preferably, in step (1), the oil bath temperature is 60-90°C, the stirring speed is 300-1000 rpm, and the stirring time is 20-40 min.

[0013] Preferably, in step (1), the addition rate of tetraethyl orthosilicate is 0.5-2 mL / min, and the hydrolysis and condensation reaction time is 3-6 h.

[0014] Preferably, in the step (1), the molar ratio of the template agent to tetraethyl orthosilicate is 0.01-0.5:1, and more preferably 0.05-0.2:1.

[0015] Preferably, in the step (1), the volume ratio of the deionized water to tetraethyl orthosilicate used for dissolving and dispersing the reactants is 5-100:1, and more preferably 10-50:1.

[0016] Preferably, in the step (1), the reducing agent is at least one of sodium salicylate, sodium citrate, sodium ascorbate, sodium borohydride, potassium borohydride, and sodium glutamate, and more preferably at least one of sodium salicylate, sodium citrate, and sodium ascorbate.

[0017] Preferably, in the step (1), the molar ratio of the reducing agent to tetraethyl orthosilicate is 0.01-1:1, and more preferably 0.05-0.5:1.

[0018] Preferably, in the step (1), the catalyst is at least one of triethanolamine, triethylamine, dopamine, dicyandiamide, hexanediamine, and polyethylene glycol amine, and more preferably at least one of triethanolamine, triethylamine, and polyethylene glycol amine.

[0019] Preferably, in the step (1), the molar ratio of the catalyst to tetraethyl orthosilicate is 0.01-10:1.

[0020] Preferably, in the step (2), to completely remove the template agent, the volume ratio of the mixture of ethanol and concentrated hydrochloric acid (37%) is 5-15:1.

[0021] Preferably, in the step (3), the amount of anhydrous ethanol is controlled so that the concentration of the mesoporous silica encapsulating silicon quantum dot powder is 0.1-5wt%.

[0022] Preferably, in the step (3), the ultrasonic dispersion power is 30W-700W, and the time is 10-60min.

[0023] Preferably, in the step (3), the catalyst is at least one of dilute hydrochloric acid, glacial acetic acid, and ammonia water, and the mass ratio of the catalyst to the aqueous ethanol solution is 0.01-0.2:1.

[0024] Preferably, in the step (3), the molar ratio of the amount of deionized water to the silane coupling agent is 0.1-0.4:1.

[0025] Preferably, in the step (3), the heating temperature is 40℃-80℃, the reaction time is 2-24h, and the stirring speed is controlled to be 100-1000rpm.

[0026] Preferably, in the step (3), the silane coupling agent is at least one of 3-aminopropyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, octyltriethoxysilane, hexadecyltrimethoxysilane, octadecyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane. In consideration of the reactivity and dispersibility of the mesoporous silica, the silane coupling agent is further preferably 3-aminopropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane.

[0027] Preferably, in the step (3), the mass ratio of the silane coupling agent to the aqueous ethanol solution is 0.01-0.1:1.

[0028] Preferably, in the step (4), the initial mixing of the silicone prepolymer A and the curing agent B is performed at a rotation speed of 300-500 rpm for 30-60 min, and the mixing is performed at a rotation speed of 200-800 rpm for 1-4 h after the hollow glass beads are added as the filler.

[0029] Preferably, in the step (4), the silicone prepolymer A is at least one of a methyl triethoxysilane hydrolysis prepolymer, a hydroxyl-terminated PDMS, a silicone-modified epoxy acrylate, an acrylate group-containing silicone prepolymer, an alkylhydroxyl silicone oil-acrylate prepolymer, an epoxy-acrylate bifunctional silicone prepolymer, a vinyl ether-modified silicone, a vinyl-terminated polysiloxane, an amino-modified silicone, and an MQ resin-modified polyurethane acrylate.

[0030] Preferably, in the step (4), the curing agent B is at least one of NaOH-methanol solution, methyltriacetoxysilane, Darocur 1173 photoinitiator, platinum catalyst, TPO photoinitiator, diaryliodonium hexafluorophosphate, and 184 photoinitiator.

[0031] Preferably, in the step (4), the hollow glass beads are directly purchased from the market (with a wall thickness of 0.2-1 μm), and the average size is controlled to be 0.5-15 μm in consideration of the scattering effect and dispersion stability of the coating surface.

[0032] Preferably, in the step (4), the mass ratio of the mixed solution to the hollow glass beads is 1:0.43-1 in order to balance the cooling efficiency and mechanical properties.

[0033] Preferably, the step (4) is to achieve multi-scale scattering complementation, and the mass ratio of the hollow glass beads to the mesoporous silica / silicon quantum composite particle dots is 4-10:1.

[0034] With the above technical solution, the following beneficial effects are achieved:

[0035] The photoluminescence radiation cooling coating mainly converts the absorbed part of the sunlight energy into radiation through a photoluminescence conversion process, thereby actively reducing the net heat absorption, so that a lower temperature than the traditional white radiation coating can be achieved during the day, especially on sunny days. By reflecting most of the sunlight using a high-reflectivity substrate, the core photoluminescence material converts the absorbed residual harmful short-wave sunlight (such as UV) into lower-energy long-wave (such as NIR) light radiation, thereby avoiding the conversion of this part of energy into heat energy. At the same time, the coating has high emissivity in the entire mid-infrared atmospheric window band, and can efficiently dissipate its heat in the form of thermal radiation to the cold outer space. The synergistic effect of the two mechanisms enables the surface of the coating to achieve passive cooling below the ambient temperature.

[0036] The photoluminescence silicon quantum dots and the multi-level structure design are introduced innovatively to achieve high solar reflectance and high mid-infrared emissivity, and the low thermal conductivity of the hollow glass beads enhances the thermal insulation. The high solar reflectance is achieved by the multi-scale roughness produced by the micron-sized hollow glass beads and the nano-sized mesoporous silica particles. The hierarchical morphology formed thereby improves the overall solar reflectance by scattering and reflecting sunlight, and the in-situ synthesis of the mesoporous silica-encapsulated silicon quantum dots with photoluminescence properties can absorb ultraviolet light and convert it into visible light to further improve the reflectivity. The high mid-infrared emissivity is achieved by the high emissivity of the organic silicon prepolymer matrix and the filler molecular structure in the mid-infrared band.

[0037] The preparation method of the present application is simple, and the mesoporous silica-encapsulated silicon quantum dot composite particles are constructed through an integrated continuous process, which is beneficial to shorten the time, has mild conditions, does not require high temperature and high pressure conditions, has low energy consumption, and is easy to industrialize.

[0038] The solar reflectance and infrared emissivity of the radiation cooling coating prepared by the present application can both reach more than 95%, and the cooling amplitude in the actual environment is more than 6.5℃.

[0039] The radiation cooling coating prepared by the present application has good environmental adaptability and durability (high temperature resistance, low temperature resistance, stain resistance, corrosion resistance, ultraviolet radiation resistance, etc.). BRIEF DESCRIPTION OF DRAWINGS

[0040] The present application will be further described below with reference to the accompanying drawings:

[0041] Figure 1 The emission spectrum of the mesoporous silica / silicon quantum dot composite particles under different ultraviolet light excitation.

[0042] Figure 2 The perspective electron microscope photo of the mesoporous silica / silicon quantum dot composite particles.

[0043] Figure 3 The coating fluorescent digital photo of Comparative Example 1 (A) and Example 1 (B). DETAILED DESCRIPTION

[0044] The mesoporous silica / silicon quantum dot composite particles with photoluminescence performance are prepared by adopting a one-pot in-situ synthesis strategy. The composite particles significantly improve the solar reflectivity by absorbing ultraviolet light and converting it into visible light, in cooperation with the photoluminescence characteristics of the mesoporous silica / silicon quantum dot composite particles itself and the multi-level structure design. Meanwhile, the material realizes high and medium infrared emissivity, which is mainly derived from the vibration of the organic silicon resin and the filler skeleton molecules in the medium infrared band. In addition, the hollow glass microbeads are introduced to enhance the overall thermal insulation performance of the coating by utilizing their low thermal conductivity. The multi-scale rough surface formed by the micron and nanometer mesoporous silica particles in the composite coating further enhances the scattering and high reflectivity of the coating to sunlight.

[0045] The application will be described in detail below with specific examples:

[0046] Comparative Example 1

[0047] Into a single-necked round-bottom flask, 760 mg of cetyltrimethylammonium bromide and 50 mL of deionized water were added, and the temperature was raised to 90℃ in an oil bath, and stirred continuously at 800 rpm for 30 min, then 168 mg of sodium salicylate and 1 mL of an aqueous solution containing 136 mg of ethanolamine were added, and stirring was continued for 1 h. 4 mL of tetraethyl orthosilicate was added at a rate of 1 mL / min, and the reaction was continued for 4 h. After cooling to room temperature, centrifugation was performed, and washing was performed twice with ethanol and deionized water, respectively. The mixture was dispersed in 50 mL of ethanol and 5 mL of concentrated hydrochloric acid (37%), and stirred at 60℃ and 500 rpm overnight to remove the template cetyltrimethylammonium bromide. Centrifugation was performed and washing was performed twice with ethanol and water, respectively. After liquid nitrogen freeze-drying, the mesoporous silica / silicon quantum dot composite particles were obtained and placed in a freeze dryer overnight.

[0048] The above 100 mg mesoporous silica / silicon quantum dot powder was dispersed in 100 mL of anhydrous ethanol, 200 μL of ammonia water and 3 mL of deionized water were added, the mixed solution was heated to 80°C in an oil bath and stirred at 800 rpm for 30 min, then 200 μL of 3-aminopropyltrimethoxysilane was added, and the reaction was continued for 2 h. After cooling to room temperature, the product was centrifuged, washed twice with ethanol and deionized water respectively to remove unreacted nanoparticles and silane coupling agent, and placed in a 60°C oven for vacuum drying to constant weight to obtain the modified mesoporous silica encapsulated silicon quantum dot powder.

[0049] 5 g of methyl triethoxysilane hydrolysis prepolymer and 0.5 g of NaOH-methanol solution were added to 5.5 g of ethyl acetate, and a uniform solution was obtained by magnetic stirring at room temperature at a speed of 400 rpm for 1 h. 0.36 g of modified mesoporous silica encapsulated silicon quantum dots was added to the above solution, and a mixed slurry was obtained after stirring at a speed of 600 rpm for 3 h. The mixed slurry was coated on a substrate, dried in air for 1 h, and then dried in a 60°C oven for 4 h to obtain a photoluminescent hierarchical morphology film for daytime passive radiative cooling.

[0050] The modified mesoporous silica encapsulated quantum dot powder was redispersed in water to prepare an aqueous dispersion of mesoporous silica / quantum dot composite particles. The particle size of the mesoporous silica / quantum dot composite particles in the aqueous dispersion was determined by dynamic light scattering, and the results showed that the Z-average particle size was 25 nm at 25°C. The above mesoporous silica / quantum dot dispersion was prepared into a solution with a suitable concentration, and the ultraviolet absorbance (A1) and the fluorescence integral peak area (S1) were determined, respectively. The fluorescence quantum yield of the composite particles was calculated to be 62% using the reference method. The sample was tested for solar band (0.3-2.5 μm) reflectivity using an ultraviolet-visible-near infrared spectrophotometer equipped with a standard integrating sphere accessory, and the results showed that the solar spectrum weighted reflectivity of the radiative cooling film reached 93.2%. At the same time, the radiative properties of the film in the mid-infrared band (2.5-25 μm) were tested by a Fourier transform infrared spectrometer equipped with an integrating sphere accessory, and the weighted emissivity of the radiative cooling film was measured to be 94.9%. The thermal conductivity of the coating was measured according to GB / T 22588–2008 “Flash method for measuring thermal diffusivity or thermal conductivity”, wherein the total thickness of the dry film of the coating system was (110±2) μm, and the thermal conductivity of the coating was to 0.245 W / (m·K), which had no heat insulation effect.

[0051] Example 1

[0052] Into a single necked round bottom flask, 760 mg of cetyltrimethylammonium bromide and 50 mL of deionized water were added, heated to 90 °C in an oil bath, continuously stirred at 800 rpm for 30 min, then 168 mg of sodium salicylate and 1 mL of aqueous solution containing 136 mg of ethanolamine were added, and stirring was continued for 1 h. 4 mL of tetraethyl orthosilicate was added at a rate of 1 mL / min, and the reaction was continued for 4 h. After cooling to room temperature, centrifugation was performed, and washing was performed twice with ethanol and deionized water, respectively. The mixture was dispersed in a mixture of 50 mL of ethanol and 5 mL of concentrated hydrochloric acid (37%), and stirring was performed at 60 °C and 500 rpm overnight to remove the template cetyltrimethylammonium bromide. Centrifugation was performed, and washing was performed twice with ethanol and water, respectively. After being freeze-dried in liquid nitrogen, the product was placed in a freeze dryer overnight to obtain mesoporous silica / silicon quantum dot composite particles.

[0053] The above 100 mg of mesoporous silica / silicon quantum dot powder was dispersed in 100 mL of anhydrous ethanol, 200 μL of ammonia water and 3 mL of deionized water were added, and the mixed solution was heated to 80 °C in an oil bath and stirred at 800 rpm for 30 min. Subsequently, 200 μL of 3-aminopropyltrimethoxysilane was added, and the reaction was continued for 2 h. After cooling to room temperature, the product was centrifuged, and washing was performed twice with ethanol and deionized water, respectively, to remove unreacted nanoparticles and silane coupling agents. Vacuum drying was performed in an oven at 60 °C to a constant weight to obtain a modified mesoporous silica encapsulated silicon quantum dot powder.

[0054] 5 g of methyltriethoxysilane hydrolyzed prepolymer and 0.5 g of NaOH-methanol solution were added to 5.5 g of ethyl acetate, and magnetic stirring was performed at a speed of 400 rpm at room temperature for 1 h to obtain a uniform solution. 1.78 g of hollow glass microbeads and 0.36 g of modified mesoporous silica encapsulated silicon quantum dots were added to the above solution, and the mixed slurry was obtained after being stirred at a speed of 600 rpm for 3 h. The mixed slurry was coated on a substrate, dried in air for 1 h, and then dried in an oven at 60 °C for 4 h to obtain a photoluminescence hierarchical morphology film for daytime passive radiative cooling.

[0055] The results show that the Z-average particle size of the silica / quantum dot composite particles in the aqueous dispersion is 25 nm, and the fluorescence quantum yield of the composite particles is 62%. The solar spectrum weighted reflectance of the radiative cooling film reaches 93.7%, and the weighted emissivity of the radiative cooling coating is 95.2%. The thermal conductivity of the coating is to 0.043 W / (m·K), and the coating has good thermal insulation effect.

[0056] Example 2

[0057] 760 mg of hexadecyltrimethylammonium bromide and 50 mL of deionized water were added to a single-necked round-bottom flask, heated to 90°C in an oil bath, and stirred continuously at 800 rpm for 30 min. Then, 336 mg of sodium salicylate and 1 mL of an aqueous solution containing 136 mg of ethanolamine were added, and stirring was continued for 1 h. 4 mL of ethyl orthosilicate was added at a rate of 1 mL / min, and the reaction was continued for 4 h. The mixture was cooled to room temperature, centrifuged, washed twice with ethanol and deionized water, and dispersed in a mixture of 50 mL of ethanol and 5 mL of concentrated hydrochloric acid (37%). The mixture was stirred at 60°C and 500 rpm overnight to remove the template agent hexadecyltrimethylammonium bromide. The mixture was centrifuged and washed twice with ethanol and water, and then freeze-dried with liquid nitrogen and placed in a freeze dryer overnight to obtain mesoporous silica / silicon quantum dot composite particles.

[0058] 100 mg of the above mesoporous silica / silicon quantum dot powder was dispersed in 100 mL of anhydrous ethanol. 200 μL of ammonia and 3 mL of deionized water were added. The mixed solution was heated to 80°C in an oil bath and stirred at 800 rpm for 30 minutes. Subsequently, 200 μL of 3-aminopropyltriethoxysilane was added and the reaction continued for 2 hours. After cooling to room temperature, the product was centrifuged and washed twice with ethanol and deionized water to remove unreacted nanoparticles and silane coupling agent. The product was then dried in a vacuum oven at 60°C to constant weight to obtain the modified mesoporous silica-encapsulated silicon quantum dot powder.

[0059] 5g of silicone-modified epoxy acrylate and 0.5g of NaOH-methanol solution were added to 5.5g of ethyl acetate and magnetically stirred at 400 rpm at room temperature for 1 hour to obtain a homogeneous solution. 1.78g of hollow glass microspheres and 0.36g of modified mesoporous silica-encapsulated silicon quantum dots were added to the solution and stirred at 600 rpm for 3 hours to obtain a mixed slurry. The mixed slurry was coated on a substrate, dried in air for 1 hour, and then in a 60°C oven for 4 hours to obtain a photoluminescent graded morphology film for daytime passive radiative cooling.

[0060] Results showed that the z-average particle size of the silica / quantum dot composite particles in the aqueous dispersion was 32 nm, and the composite particles had a fluorescence quantum yield of 70%. The radiative cooling film achieved a weighted solar spectrum reflectivity of 94.8%, and the weighted emissivity of the radiative cooling coating was 95.3%. The coating also exhibited excellent thermal insulation properties, with a thermal conductivity of 0.037 W / (m·K).

[0061] Example 3:

[0062] Into a single necked round bottom flask, 760 mg of cetyltrimethylammonium bromide and 50 mL of deionized water were added, heated to 90 °C in an oil bath, continuously stirred at 800 rpm for 30 min, then 504 mg of sodium borohydride and 1 mL of aqueous solution containing 136 mg of ethanolamine were added, and stirring was continued for 1 h. 4 mL of tetraethyl orthosilicate was added at a rate of 1 mL / min, and the reaction was continued for 4 h. After cooling to room temperature, centrifugation was performed, and washing was performed twice with ethanol and deionized water, respectively. The mixture was dispersed in a mixture of 50 mL of ethanol and 5 mL of concentrated hydrochloric acid (37%), and stirring was performed at 60 °C and 500 rpm overnight to remove the template cetyltrimethylammonium bromide. Centrifugation was performed, and washing was performed twice with ethanol and water, respectively. After being freeze-dried in liquid nitrogen, the product was placed in a freeze dryer overnight to obtain mesoporous silica / silicon quantum dot composite particles.

[0063] The above 100 mg of mesoporous silica / silicon quantum dot powder was dispersed in 100 mL of anhydrous ethanol, 200 μL of ammonia water and 3 mL of deionized water were added, and the mixed solution was heated to 80 °C in an oil bath and stirred at 800 rpm for 30 min. Subsequently, 200 μL of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added, and the reaction was continued for 2 h. After cooling to room temperature, the product was centrifuged, and washing was performed twice with ethanol and deionized water, respectively, to remove unreacted nanoparticles and silane coupling agents. Vacuum drying was performed in an oven at 60 °C to a constant weight to obtain a modified mesoporous silica encapsulated silicon quantum dot powder.

[0064] 5 g of silicone-modified epoxy acrylate and 0.5 g of methyltriacetoxysilane were added to 5.5 g of ethyl acetate, and magnetic stirring was performed at room temperature at a speed of 400 rpm for 1 h to obtain a uniform solution. 1.78 g of hollow glass microbeads and 0.36 g of modified mesoporous silica encapsulated silicon quantum dots were added to the above solution, and stirring was performed at a speed of 600 rpm for 3 h to obtain a mixed slurry. The mixed slurry was coated on a substrate, dried in air for 1 h, and then dried in an oven at 60 °C for 4 h to obtain a photoluminescent hierarchical morphology film for daytime passive radiative cooling.

[0065] The results show that the Z-average particle size of the silica / quantum dot composite particles in the aqueous dispersion is 40 nm, and the fluorescence quantum yield of the composite particles is 83%. The solar spectrum weighted reflectance of the radiative cooling film reaches 94.2%, and the weighted emissivity of the radiative cooling coating is 94.7%. The thermal conductivity of the coating is to 0.028 W / (m·K), and the coating has good thermal insulation effect.

[0066] Example 4:

[0067] Into a single necked round bottom flask, 760 mg of cetyltrimethylammonium bromide and 50 mL of deionized water were added, and the temperature was raised to 90 °C in an oil bath with continuous stirring at 800 rpm for 30 min, then 504 mg of sodium salicylate and 1 mL of an aqueous solution containing 136 mg of triethylamine were added, and the stirring was continued for 1 h. 4 mL of tetraethyl orthosilicate was added at a rate of 1 mL / min, and the reaction was continued for 4 h. The temperature was cooled to room temperature, and the product was centrifuged and washed twice with ethanol and deionized water, respectively. The product was dispersed in a mixture of 50 mL of ethanol and 5 mL of concentrated hydrochloric acid (37%), and stirred at 60 °C and 500 rpm overnight to remove the template cetyltrimethylammonium bromide. The product was centrifuged and washed twice with ethanol and deionized water, respectively, and then freeze-dried in liquid nitrogen to obtain mesoporous silica / silicon quantum dot composite particles.

[0068] The above 100 mg of mesoporous silica / silicon quantum dot powder was dispersed in 100 mL of anhydrous ethanol, 200 μL of ammonia water and 3 mL of deionized water were added, and the mixed solution was heated to 80 °C in an oil bath and stirred at 800 rpm for 30 min, then 200 μL of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added, and the reaction was continued for 2 h. The temperature was cooled to room temperature, the product was centrifuged, and unreacted nanoparticles and silane coupling agent were removed by washing with ethanol and deionized water, respectively, and then vacuum dried in an oven at 60 °C to a constant weight to obtain modified mesoporous silica encapsulated silicon quantum dot powder.

[0069] 5 g of methyltriethoxysilane hydrolyzed prepolymer and 0.5 g of NaOH-methanol solution were added to 5.5 g of ethyl acetate, and a uniform solution was obtained by magnetic stirring at room temperature at a speed of 400 rpm for 1 h. 1.78 g of hollow glass microbeads and 0.36 g of modified mesoporous silica encapsulated silicon quantum dots were added to the above solution, and a mixed slurry was obtained by stirring at a speed of 600 rpm for 3 h. The mixed slurry was coated on a substrate, dried in air for 1 h, and then dried in an oven at 60 °C for 4 h to obtain a photoluminescent hierarchical morphology film for daytime passive radiative cooling.

[0070] The results show that the Z-average particle size of the silica / quantum dot composite particles in the aqueous dispersion is 48 nm, and the fluorescence quantum yield of the composite particles is 90%. The solar spectrum weighted reflectance of the radiative cooling film reaches 96.2%, and the weighted emissivity of the radiative cooling coating is 95.9%. The thermal conductivity of the coating is to 0.033 W / (m·K), which has good thermal insulation effect.

[0071] Example 5

[0072] Into a single necked round bottom flask, 760 mg of cetyltrimethylammonium bromide and 50 mL of deionized water were added, heated to 90 °C in an oil bath, continuously stirred at 800 rpm for 30 min, then 336 mg of sodium citrate and 1 mL of aqueous solution containing 136 mg of ethanolamine were added, and stirring was continued for 1 h. 4 mL of tetraethyl orthosilicate was added at a rate of 1 mL / min, and the reaction was continued for 4 h. After cooling to room temperature, centrifugation was performed, and washing was performed twice with ethanol and deionized water, respectively. The mixture was dispersed in a mixture of 50 mL of ethanol and 5 mL of concentrated hydrochloric acid (37%), stirred at 60 °C and 500 rpm overnight to remove the template cetyltrimethylammonium bromide, centrifuged, and washed twice with ethanol and water, respectively. After being frozen and dried in liquid nitrogen, the mesoporous silica / silicon quantum dot composite particles were obtained by placing them in a freeze dryer overnight.

[0073] The above 100 mg of mesoporous silica / silicon quantum dot powder was dispersed in 100 mL of anhydrous ethanol, 200 μL of ammonia water and 3 mL of deionized water were added, and the mixed solution was heated to 80 °C in an oil bath and stirred at 800 rpm for 30 min. Then 200 μL of 3-aminopropyltrimethoxysilane was added, and the reaction was continued for 2 h. After cooling to room temperature, the product was centrifuged, and washing was performed twice with ethanol and deionized water, respectively, to remove unreacted nanoparticles and silane coupling agents. The modified mesoporous silica encapsulated silicon quantum dot powder was obtained by vacuum drying to constant weight in an oven at 60 °C.

[0074] 5 g of methyl triethoxysilane hydrolyzed prepolymer and 0.5 g of methyl triacetoxy silane were added to 5.5 g of ethyl acetate, and a uniform solution was obtained by magnetic stirring at a speed of 400 rpm at room temperature for 1 h. 2.24 g of hollow glass microbeads and 0.45 g of modified mesoporous silica encapsulated silicon quantum dots were added to the above solution, and a mixed slurry was obtained by stirring at a speed of 600 rpm for 3 h. The mixed slurry was coated on a substrate, dried in air for 1 h, and then dried in an oven at 60 °C for 4 h to obtain a fluorescent hierarchical morphology film for daytime passive radiative cooling.

[0075] The results show that the Z-average particle size of the silica / quantum dot composite particles in the aqueous dispersion is 33 nm, and the fluorescence quantum yield of the composite particles is 72%. The solar spectrum weighted reflectance of the radiative cooling film reaches 95.6%. At the same time, the radiative properties of the film in the mid-infrared band (2.5-25 μm) were tested by a Fourier transform infrared spectrometer equipped with an integrating sphere accessory, and the weighted emissivity of the radiative cooling film was measured to be 95.7%. The thermal conductivity of the coating is to 0.039 W / (m·K), which has good thermal insulation effect.

[0076] Example 6

[0077] Into a single necked round bottom flask, 760 mg of cetyltrimethylammonium bromide and 50 mL of deionized water were added, heated to 90 °C in an oil bath, continuously stirred at 800 rpm for 30 min, then 336 mg of sodium borohydride and 1 mL of aqueous solution containing 136 mg of triethylamine were added, and stirring was continued for 1 h. 4 mL of tetraethyl orthosilicate was added at a rate of 1 mL / min, and the reaction was continued for 4 h. After cooling to room temperature, centrifugation was performed, and washing was performed twice with ethanol and deionized water, respectively. The mixture was dispersed in a mixture of 50 mL of ethanol and 5 mL of concentrated hydrochloric acid (37%), and stirring was performed at 60 °C and 500 rpm overnight to remove the template cetyltrimethylammonium bromide. Centrifugation was performed, and washing was performed twice with ethanol and water, respectively. After being freeze-dried in liquid nitrogen, the product was placed in a freeze dryer overnight to obtain mesoporous silica / silicon quantum dot composite particles.

[0078] The above 100 mg of mesoporous silica / silicon quantum dot powder was dispersed in 100 mL of anhydrous ethanol, 200 μL of ammonia water and 3 mL of deionized water were added, and the mixed solution was heated to 80 °C in an oil bath and stirred at 800 rpm for 30 min. Subsequently, 200 μL of 3-aminopropyltrimethoxysilane was added, and the reaction was continued for 2 h. After cooling to room temperature, the product was centrifuged, and washing was performed twice with ethanol and deionized water, respectively, to remove unreacted nanoparticles and silane coupling agents. The product was placed in a 60 °C oven and dried to constant weight under vacuum to obtain modified mesoporous silica encapsulated silicon quantum dot powder.

[0079] 5 g of alkylhydroxysilicone-acrylate pre-polymer and 0.5 g of NaOH-methanol solution were added to 5.5 g of ethyl acetate, and magnetic stirring was performed at room temperature at a speed of 400 rpm for 1 h to obtain a uniform solution. 2.77 g of hollow glass microbeads and 0.56 g of modified mesoporous silica encapsulated silicon quantum dots were added to the above solution, and the mixture was stirred at a speed of 600 rpm for 3 h to obtain a mixed slurry. The mixed slurry was coated on a substrate, dried in air for 1 h, and then dried in a 60 °C oven for 4 h to obtain a fluorescent hierarchical morphology film for daytime passive radiative cooling.

[0080] The results show that the Z-average particle size of the silica / quantum dot composite particles in the aqueous dispersion is 35 nm, and the fluorescence quantum yield of the composite particles is 76%. The solar spectrum weighted reflectance of the radiative cooling film reaches 95.3%. At the same time, the radiative properties of the film in the mid-infrared band (2.5-25 μm) were tested by a Fourier transform infrared spectrometer equipped with an integrating sphere accessory, and the weighted emissivity of the radiative cooling film was measured to be 96.1%. The thermal conductivity of the coating is to 0.021 W / (m·K), which has good thermal insulation effect.

[0081] Example 7

[0082] Into a single necked round bottom flask, 760 mg of cetyltrimethylammonium bromide and 50 mL of deionized water were added, heated to 90 °C in an oil bath, continuously stirred at 800 rpm for 30 min, then 336 mg of sodium salicylate and 1 mL of aqueous solution containing 136 mg of ethanolamine were added, and stirring was continued for 1 h. 4 mL of tetraethyl orthosilicate was added at a rate of 1 mL / min, and the reaction was continued for 4 h. After cooling to room temperature, centrifugation, washing with ethanol and deionized water twice, dispersion in a mixture of 50 mL of ethanol and 5 mL of concentrated hydrochloric acid (37%), stirring at 60 °C and 500 rpm overnight to remove the template cetyltrimethylammonium bromide, centrifugation and washing with ethanol and water twice, and lyophilization in liquid nitrogen, the mesoporous silica / silicon quantum dot composite particles were obtained.

[0083] The above 100 mg of mesoporous silica / silicon quantum dot powder was dispersed in 100 mL of anhydrous ethanol, 200 μL of ammonia water and 3 mL of deionized water were added, and the mixed solution was heated to 80 °C in an oil bath and stirred at 800 rpm for 30 min, then 200 μL of γ-(methacryloyloxy)propyltrimethoxysilane was added, and the reaction was continued for 2 h. After cooling to room temperature, the product was centrifuged, washed with ethanol and deionized water twice to remove unreacted nanoparticles and silane coupling agent, and placed in a 60 °C oven for vacuum drying to constant weight to obtain modified mesoporous silica encapsulated silicon quantum dot powder.

[0084] Into a single necked round bottom flask, 760 mg of cetyltrimethylammonium bromide and 50 mL of deionized water were added, heated to 90 °C in an oil bath, continuously stirred at 800 rpm for 30 min, then 336 mg of sodium salicylate and 1 mL of aqueous solution containing 136 mg of ethanolamine were added, and stirring was continued for 1 h. 4 mL of tetraethyl orthosilicate was added at a rate of 1 mL / min, and the reaction was continued for 4 h. After cooling to room temperature, centrifugation, washing with ethanol and deionized water twice, dispersion in a mixture of 50 mL of ethanol and 5 mL of concentrated hydrochloric acid (37%), stirring at 60 °C and 500 rpm overnight to remove the template cetyltrimethylammonium bromide, centrifugation and washing with ethanol and water twice, and lyophilization in liquid nitrogen, the mesoporous silica / silicon quantum dot composite particles were obtained.

[0085] The results show that the Z-average particle size of the silica / quantum dot composite particles in the aqueous dispersion is 38 nm, and the fluorescence quantum yield of the composite particles is 65%. The solar spectrum weighted reflectivity of the radiative cooling film reaches 96.5%. At the same time, the radiative properties of the film in the mid-infrared band (2.5-25 μm) were tested by a Fourier transform infrared spectrometer equipped with an integrating sphere accessory, and the weighted emissivity of the radiative cooling film was measured to be 96.3%. The thermal conductivity of the coating is to 0.025 W / (m·K), which has good thermal insulation effect.

[0086] Example 8

[0087] Into a single necked round bottom flask, 760 mg of cetyltrimethylammonium bromide and 50 mL of deionized water were added, heated to 90 °C in an oil bath, continuously stirred at 800 rpm for 30 min, then 336 mg of sodium salicylate and 1 mL of aqueous solution containing 136 mg of ethanolamine were added, and stirring was continued for 1 h. 4 mL of tetraethyl orthosilicate was added at a rate of 1 mL / min, and the reaction was continued for 4 h. After cooling to room temperature, centrifugation, washing with ethanol and deionized water twice, dispersion in a mixture of 50 mL of ethanol and 5 mL of concentrated hydrochloric acid (37%), stirring at 60 °C and 500 rpm overnight to remove the template cetyltrimethylammonium bromide, centrifugation and washing with ethanol and water twice, and lyophilization in liquid nitrogen, the mesoporous silica / silicon quantum dot composite particles were obtained.

[0088] The above 100 mg of mesoporous silica / silicon quantum dot powder was dispersed in 100 mL of anhydrous ethanol, 200 μL of ammonia water and 3 mL of deionized water were added, and the mixed solution was heated to 80 °C in an oil bath and stirred at 800 rpm for 30 min, then 200 μL of γ-mercaptopropyltrimethoxysilane was added, and the reaction was continued for 2 h. After cooling to room temperature, the product was centrifuged, washed with ethanol and deionized water twice to remove unreacted nanoparticles and silane coupling agent, and placed in a 60 °C oven for vacuum drying to constant weight to obtain the modified mesoporous silica encapsulated silicon quantum dot powder.

[0089] Into a single necked round bottom flask, 760 mg of cetyltrimethylammonium bromide and 50 mL of deionized water were added, heated to 90 °C in an oil bath, continuously stirred at 800 rpm for 30 min, then 336 mg of sodium salicylate and 1 mL of aqueous solution containing 136 mg of ethanolamine were added, and stirring was continued for 1 h. 4 mL of tetraethyl orthosilicate was added at a rate of 1 mL / min, and the reaction was continued for 4 h. After cooling to room temperature, centrifugation, washing with ethanol and deionized water twice, dispersion in a mixture of 50 mL of ethanol and 5 mL of concentrated hydrochloric acid (37%), stirring at 60 °C and 500 rpm overnight to remove the template cetyltrimethylammonium bromide, centrifugation and washing with ethanol and water twice, and lyophilization in liquid nitrogen, the mesoporous silica / silicon quantum dot composite particles were obtained.

[0090] The results show that the Z-average particle size of the silica / quantum dot composite particles in the aqueous dispersion is 35 nm, and the fluorescence quantum yield of the composite particles is 87%. The solar spectrum weighted reflectivity of the radiation cooling film reaches 96.2%. At the same time, the radiation characteristics of the film in the mid-infrared band (2.5-25 μm) were tested by a Fourier transform infrared spectrometer equipped with an integrating sphere accessory, and the weighted emissivity of the radiation cooling film was measured to be 97.4%. The thermal conductivity of the coating is to 0.018 W / (m·K), which has good thermal insulation effect.

[0091] Table 1 Comparison of test results of comparative examples and examples

[0092] Aperture (nm) Quantum yield (%) Reflectance (%) Emissivity (%) Thermal conductivity (W / m-K) Comparative Example 1 25 62 93.2 94.9 0.245 Example 1 25 62 93.7 95.2 0.043 Example 2 32 70 94.8 95.3 0.037 Example 3 40 83 94.2 94.7 0.038 Example 4 48 90 96.2 95.9 0.041 Example 5 33 72 95.6 95.7 0.039 Example 6 57 94 95.3 96.1 0.131 Example 7 38 65 96.5 96.3 0.025 Example 8 35 87 96.2 97.4 0.018

[0093] As shown in Table 1 and the examples, the amount of the reducing agent used in the preparation of the mesoporous silica / quantum dot composite particles, the amount and type of the modifier are directly related to the pore size and quantum yield of the mesoporous silica / quantum dot powder. In Comparative Example 1, the amount of the reducing agent sodium salicylate is 168 mg, the pore size of the synthesized mesoporous silica / quantum dot composite particles is 25 nm, and due to the small amount of the modified mesoporous silica / quantum dot composite particles used, the reflectivity and emissivity of the coating are 93.2% and 94.9%, respectively. In addition, since no hollow glass microbeads are added in Comparative Example 1, the thermal conductivity of the prepared silicone coating is 0.245 W / m·K, and there is almost no heat insulation effect. In Examples 1, 2, and 4, as the amount of the reducing agent increases, the pore size gradually increases to 40 nm, and the corresponding quantum yield also increases from 62% to 83%. For Example 3, when the catalyst is changed to triethylamine, increasing the amount of the reducing agent, the pore size of the synthesized mesoporous silica / quantum dot composite particles increases to 48 nm, and the quantum yield reaches 90%. At this time, the reflectivity and emissivity of the coating are 96.2% and 95.9%, respectively, and the thermal conductivity of the coating is 0.041 W / m·K, which has good heat insulation effect. In Example 6, as the amount of the reducing agent continues to increase, the quantum yield of the mesoporous silica / quantum dot composite particles reaches 94%, which has excellent fluorescence emission performance, but the high pore size leads to a decline in the heat insulation performance of the coating, which is not worth the loss. In order to comprehensively consider the radiation cooling and heat insulation performance, it can be seen that the amount of the reducing agent and the catalyst in Example 2 is the best, so in Examples 7 and 8, the catalyst and the reducing agent in Example 2 are used, and the type of the modifier and the content of the hollow glass microbeads are changed. However, it is obvious that the pore size and quantum yield of the mesoporous silica / quantum dot composite particles are lower than those in Example 2, and it can be seen that the silicone composite coating in Example 2 has the best heat insulation effect while maintaining high ultraviolet reflectivity and infrared emissivity.

[0094] The above merely describes specific embodiments of the present application, but the technical features of the present application are not limited thereto. Any simple change, equivalent replacement, or modification made on the basis of the present application to solve the basically same technical problem and achieve the basically same technical effect is included in the protection scope of the present application.

Claims

1. A method for preparing a photoluminescent multi-level morphological radiation cooling coating: characterized in that The steps include: (1) The template is dissolved in a reaction bottle filled with deionized water, and the reaction bottle is placed in an oil bath for heating and stirring. Then, a reducing agent and a catalyst are added thereto. After stirring for a certain period of time, ethyl orthosilicate is added dropwise to carry out a hydrolysis and condensation reaction. After the reaction solution is cooled to room temperature, the product is centrifuged and then washed twice with ethanol and deionized water to obtain a precipitate. (2) The precipitate was dispersed in a mixture of ethanol and concentrated hydrochloric acid, stirred at 60°C and 500 rpm overnight to remove the template, and then washed twice with ethanol and water by centrifugation. The obtained mesoporous silica-encapsulated silicon quantum dots were frozen with liquid nitrogen and placed in a freeze dryer overnight to obtain mesoporous silica-encapsulated silicon quantum dot powder; (3) ultrasonically dispersing the mesoporous silica encapsulated silicon quantum dot powder obtained in step (2) in anhydrous ethanol, adding a catalyst and deionized water, heating and stirring the mixed solution in an oil bath, and then adding a silane coupling agent to react for a certain time; after the mixed solution is cooled to room temperature, centrifuging the product, washing it twice with ethanol and deionized water respectively to remove unreacted nanoparticles and silane coupling agent, and drying it in a vacuum oven at 40-80° C. to constant weight to obtain modified mesoporous silica / silicon quantum dot composite particles; (4) Adding silicone prepolymer A and curing agent B to ethyl acetate in a mass ratio of 1:10, and magnetically stirring at room temperature to obtain a mixed solution; then adding hollow glass microspheres and mesoporous silica / silicon quantum composite particles to the above mixed solution, stirring and dispersing them thoroughly to obtain a mixed slurry, coating the mixed slurry on a substrate, drying it in air for 1 hour, and then drying it in an oven at 80°C for 2-24 hours to obtain a photoluminescent graded morphology coating for daytime passive radiation cooling.

2. The method for preparing a photoluminescent multi-level morphological radiation cooling coating according to claim 1, characterized in that: In the step (1), the template agent is selected from one of dodecyltrimethoxyammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, and tetrapropylammonium hydroxide.

3. The method for preparing a photoluminescent multi-level morphological radiation cooling coating according to claim 1, characterized in that: In the step (1), the oil bath temperature is 60-90° C., the stirring speed is 300-1000 rpm, the stirring time is 20-40 min, the dropping speed of tetraethyl orthosilicate is 0.5-2 mL / min, and the hydrolysis condensation reaction time is 3-6 h.

4. The method for preparing a photoluminescent multi-level morphological radiation cooling coating according to claim 1, characterized in that: In the step (1), the molar ratio of the template to tetraethyl orthosilicate is 0.01-0.5:1, the volume ratio of deionized water used to dissolve and disperse the reactants to tetraethyl orthosilicate is 5-100:1; the molar ratio of the reducing agent to tetraethyl orthosilicate is 0.01-1:1; and the molar ratio of the catalyst to tetraethyl orthosilicate is 0.01-10:

1.

5. The method for preparing a photoluminescent multi-level morphological radiation cooling coating according to claim 1, characterized in that: In the step (1), the reducing agent is selected from sodium salicylate, sodium citrate, sodium ascorbate, sodium borohydride, potassium borohydride, and sodium glutamate, preferably at least one of sodium salicylate, sodium citrate, and sodium ascorbate; and the catalyst is selected from triethanolamine, triethylamine, dopamine, dicyandiamide, hexamethylenediamine, and polyethylene glycolamine, preferably at least one of triethanolamine, triethylamine, and polyethylene glycolamine.

6. The method for preparing a photoluminescent multi-level morphology radiation cooling coating according to claim 1, characterized in that: In the step (3), the concentration of the mesoporous silica encapsulated silicon quantum dot powder is controlled to be 0.1-5wt% by controlling the amount of anhydrous ethanol; the molar ratio of the amount of deionized water to the silane coupling agent is 0.1-0.4:1, the heating temperature is 40°C-80°C, the reaction time is 2-24h, and the stirring speed is controlled at 100-1000rpm.

7. The method for preparing a photoluminescent multi-level morphology radiation cooling coating according to claim 1, characterized in that: In the step (3), the catalyst is selected from at least one of dilute hydrochloric acid, glacial acetic acid, and ammonia water, and the mass ratio of the catalyst to the ethanol aqueous solution is 0.01-0.2:

1.

8. The method for preparing a photoluminescent multi-level radiation cooling coating according to claim 1, characterized in that: In the step (3), the silane coupling agent is selected from at least one of 3-aminopropyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, octyltriethoxysilane, hexadecyltrimethoxysilane, octadecyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane, and the mass ratio of the silane coupling agent to the ethanol aqueous solution is 0.01-0.1:

1.

9. The method for preparing a photoluminescent multi-level morphology radiation cooling coating according to claim 1, characterized in that: In the step (4), the organosilicon prepolymer A is selected from at least one of methyltriethoxysilane hydrolyzed prepolymer, hydroxyl-terminated PDMS, organosilicon-modified epoxy acrylate, organosilicon prepolymer containing acrylate group, alkoxy silicone oil-acrylate prepolymer, epoxy-acrylate bifunctional organosilicon prepolymer, vinyl ether modified organosilicon, vinyl-terminated polysiloxane, amino-modified organosilicon, and MQ resin modified polyurethane acrylate; and the curing agent B is selected from at least one of NaOH-methanol solution, methyltriacetoxysilane, Darocur 1173 photoinitiator, platinum catalyst, TPO photoinitiator, diaryliodonium hexafluorophosphate, and 184 photoinitiator.

10. The method for preparing a photoluminescent multi-level radiation cooling coating according to claim 1, characterized in that: In the step (4), the rotation speed of the initial mixing of the silicone prepolymer A and the curing agent B is 300-500 rpm, and the mixing time is 30-60 min; the rotation speed after adding the filler hollow glass microspheres is 200-800 rpm, and the stirring time is 1-4 h; the mass ratio of the mixed solution to the hollow glass microspheres is 1:0.43-1; and the mass ratio of the hollow glass microspheres to the mesoporous silica / silicon quantum composite particles is 4-10:1.

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