An ultra-insulating aerogel exterior wall coating and a method for preparing the same

Abstract

The application provides an ultrathermal aerogel outer wall paint and a preparation method thereof, and belongs to the technical field of outer wall paint. In the application, the silica aerogel is modified by a modifier HY-6085, and has excellent thermal insulation and hydrophobicity; the rare earth doped tungsten trioxide realizes thermochromism through oxygen vacancy regulation, and the aging resistance is improved by combining silica coating and fluorine-containing polymer modification; the graphene / manganese dioxide porous network provides high strength and multi-stage pore structure, and realizes self-cleaning performance through surface modification; the ionic liquid modified LDH nanosheet forms an ordered water blocking channel through interlayer expansion effect, and is compounded with polyacrylonitrile fibers to synergistically enhance the mechanical properties of the coating film. The synergistic effect of multiple components and multiple mechanisms constructs a high-performance coating system integrating thermal insulation, water resistance, corrosion resistance and mechanical stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of exterior wall coatings and relates to a super-insulation aerogel exterior wall coating and a preparation method thereof. BACKGROUND

[0002] In today's construction industry, the thermal insulation performance of exterior wall coatings is increasingly valued, especially in the context of global climate change and rapid increase in energy consumption. Reasonable exterior wall insulation design not only can significantly reduce the energy consumption of buildings, but also can improve the comfort of living, becoming an important consideration in modern architectural design. Traditional exterior wall coatings usually rely on reflective materials, although they can reflect part of the solar radiation, but their thermal insulation effect is generally limited, especially in extreme temperature conditions, often cannot meet the comfort requirements of living environment.

[0003] Existing thermal insulation materials, such as polyurethane foam and polystyrene, although have some performance in thermal insulation, but have obvious shortcomings in fire resistance, environmental stability and service life. These materials are easily degraded in high temperature or humid environment, leading to the decline of thermal insulation effect, and even may release harmful substances, affecting indoor air quality. In addition, many traditional coatings are easily aged, peeled off when exposed to ultraviolet light and climate change, increasing the maintenance cost, and have insufficient ability to adapt to environmental changes, limiting their wide application.

[0004] Under this background, aerogel gradually becomes a new favorite of building materials due to its ultra-low thermal conductivity and lightweight characteristics. Aerogel is a kind of porous material with extremely high specific surface area, which can achieve significant thermal insulation effect in a relatively thin coating. However, the brittleness and hygroscopicity of aerogel significantly limit its application potential in building exterior wall coatings. Therefore, it is an urgent task to develop a new type of aerogel modified exterior wall coating to improve its strength and waterproof performance. SUMMARY

[0005] In view of the above problems, the purpose of the present application is to provide a super thermal insulation aerogel exterior wall coating and a preparation method thereof. The present application comprehensively utilizes silica aerogel, graphene / manganese dioxide porous network, rare earth doped tungsten trioxide particles and ionic liquid modified LDH nanosheets, combines multiple modification methods and synergistic effects, and significantly improves the thermal insulation, water resistance, weather resistance and comprehensive performance of the coating. The silica aerogel is modified by the modifier HY-6085 and has excellent thermal insulation and hydrophobicity; the rare earth doped tungsten trioxide realizes thermochromic response by adjusting lattice defects, and the silica coating and fluorine-containing polymer modification improve the anti-aging performance; the graphene / manganese dioxide porous network provides high strength and multi-level pore structure, and realizes super hydrophobicity and self-cleaning performance through surface modification; the ionic liquid modified LDH nanosheet forms a dense barrier structure by expanding the interlayer spacing, and is compounded with polyacrylonitrile fibers to enhance the mechanical properties of the coating film. The synergistic effect of multiple components and multiple mechanisms constructs a high-performance coating system integrating thermal insulation, water resistance, corrosion resistance and mechanical stability.

[0006] To achieve this purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a preparation method of a super thermal insulation aerogel exterior wall coating, which comprises:

[0008] S1: silica aerogel is added to an ethanol solution of a modifier HY-6085, and after reaction under a nitrogen atmosphere, deionized water and dibutyltin dimethylsilane are added to obtain a second modified solution, and the reaction and treatment obtain pre-modified silica aerogel powder;

[0009] S2: a leveling agent, a defoaming agent and a preservative are added to a silicone oil emulsion, and after stirring uniformly, pre-modified silica aerogel powder, super-hydrophobic graphene / manganese dioxide porous network, tungsten trioxide thermochromic particles and LDH-fiber nanosheets are sequentially added, and after uniform dispersion, vacuum degassing is performed to obtain a super thermal insulation aerogel exterior wall coating.

[0010] The preparation method of the tungsten trioxide thermochromic particles is:

[0011] S21: an ammonium tungstate solution is prepared, a rare earth oxide is dissolved in nitric acid to obtain a rare earth ion solution, the rare earth ion solution is mixed with the ammonium tungstate solution to obtain a mixed solution, ammonia water is used to adjust the pH to obtain a reaction liquid A, microwave reaction is performed, and after treatment, a rare earth doped tungsten trioxide gel is obtained, and calcination and grinding obtain rare earth doped tungsten trioxide;

[0012] Disperse it with tetraethyl orthosilicate in ethanol / water solution to obtain dispersion B. Adjust the pH with ammonia to obtain reaction solution C. Stir the reaction and process to obtain silica-coated tungsten trioxide. Add it to the modified dispersion to obtain reaction solution D. After the reaction, dry it in a supercritical carbon dioxide device to obtain tungsten trioxide thermochromic particles.

[0013] The preparation method of the superhydrophobic graphene / manganese dioxide porous network is as follows:

[0014] S22: Place nickel foam in a CVD furnace and pass in a mixed gas to obtain three-dimensional graphene-nickel foam. Immerse it in ferric chloride solution to obtain a three-dimensional graphene framework. Prepare an electrolyte with manganese sulfate and sulfuric acid. Use the three-dimensional graphene framework as the working electrode and a platinum sheet as the counter electrode to perform constant current deposition to obtain a graphene / manganese dioxide porous network.

[0015] A graphene / manganese dioxide porous network was immersed in a dopamine hydrochloride solution, and its pH was maintained using Tris buffer. After reaction and treatment, a polydopamine-coated porous network was obtained. The network was then immersed in an ethanol solution of dodecafluoroheptyl methacrylate, and a photoinitiator was added to obtain reaction solution E. The network was then cured under nitrogen protection to obtain a superhydrophobic graphene / manganese dioxide porous network.

[0016] The preparation method of LDH-fiber nanosheets is as follows:

[0017] S23: Prepare a mixed metal salt solution, add sodium hydroxide solution to adjust the pH to obtain reaction solution F, and after aging, obtain LDH powder; mix it with ionic liquid [EMIM][BF4] in acetonitrile to obtain intercalation modified solution, and after ultrasonic treatment, obtain intercalation modified LDH;

[0018] An N,N-dimethylformamide solution of polyacrylonitrile was prepared, and polyacrylonitrile fiber membranes were prepared by electrospinning. An intercalated modified LDH suspension was sprayed onto the surface of the polyacrylonitrile fiber membrane, and after drying, LDH-fiber nanosheets were obtained.

[0019] Specifically, S1: Prepare an ethanol solution of modifier HY-6085, add silica aerogel to obtain an aerogel modification solution, stir at room temperature under a nitrogen atmosphere, add deionized water and dibutyltin disilicate to obtain a second modification solution, react at a constant temperature, filter, wash and dry to obtain pre-modified silica aerogel powder.

[0020] S2: Add leveling agent, defoamer and preservative to silicone oil emulsion, stir evenly, and then add pre-modified silica aerogel powder, superhydrophobic graphene / manganese dioxide porous network, tungsten trioxide thermochromic particles and LDH-fiber nanosheets in sequence. After even dispersion, vacuum degassing is performed to obtain super heat-insulating aerogel exterior wall coating.

[0021] The preparation method of the tungsten trioxide thermochromic particles is as follows:

[0022] S21: An ammonium tungstate solution is prepared, a rare earth oxide is dissolved in nitric acid to obtain a rare earth ion solution, the rare earth ion solution is mixed with the ammonium tungstate solution to obtain a mixed solution, ammonia water is used to adjust the pH to obtain a reaction liquid A, after microwave reaction and cooling, centrifugal separation, washing and drying, a rare earth doped tungsten trioxide gel is obtained, and calcination and grinding are performed to obtain a rare earth doped tungsten trioxide; the tungsten trioxide is dispersed in an ethanol / water solution, tetraethyl orthosilicate is added to obtain a dispersion liquid B, ammonia water is used to adjust the pH to obtain a reaction liquid C, and stirring reaction is performed at room temperature, and after centrifugal separation, washing and drying, a silica coated tungsten trioxide is obtained; a vinylidene fluoride-hexafluoropropylene copolymer is dispersed in N-methyl pyrrolidone to obtain a modified dispersion liquid, and the silica coated tungsten trioxide is added to obtain a reaction liquid D, and after stirring at a constant temperature, the reaction liquid D is placed in a supercritical carbon dioxide device for drying to obtain the tungsten trioxide thermochromic particles;

[0023] The preparation method of the super-hydrophobic graphene / manganese dioxide porous network is as follows:

[0024] S22: The nickel foam is placed in a CVD furnace, mixed gas is introduced, and heat preservation is performed, and after natural cooling, a three-dimensional graphene-nickel foam is obtained, the three-dimensional graphene-nickel foam is immersed in a ferric chloride solution, and filtration, washing and drying are performed to obtain a three-dimensional graphene skeleton; an electrolyte is prepared by taking manganese sulfate and sulfuric acid, a three-dimensional graphene skeleton is used as a working electrode, and a platinum plate is used as a counter electrode for constant current deposition, and after washing and vacuum drying, a graphene / manganese dioxide porous network is obtained; the graphene / manganese dioxide porous network is immersed in a dopamine hydrochloride solution to obtain a dopamine modified solution, and a Tris buffer solution is used to maintain the pH, and after stirring at room temperature, centrifugal separation and drying are performed to obtain a polydopamine coated porous network; the polydopamine coated porous network is immersed in a dodecafluoroheptyl methacrylate ethanol solution, and a photoinitiator is added to obtain a reaction liquid E, and ultraviolet curing is performed under nitrogen protection to obtain the super-hydrophobic graphene / manganese dioxide porous network;

[0025] The preparation method of the LDH-fiber nanosheet is as follows:

[0026] S23: A mixed metal salt solution is prepared by taking magnesium nitrate and aluminum nitrate, and a sodium hydroxide solution is added dropwise under stirring to adjust the pH to obtain a reaction liquid F, and after maturation, centrifugal separation, washing and drying, an LDH powder is obtained; the LDH powder is mixed with an ionic liquid [EMIM][BF4] in acetonitrile to obtain an intercalation modification liquid, ultrasonic treatment is performed at a constant temperature, and after centrifugal separation, washing and drying, an intercalation modified LDH is obtained; a polyacrylonitrile N,N-dimethylformamide solution is prepared, and a polyacrylonitrile fiber membrane is prepared by electrospinning; an intercalation modified LDH suspension is sprayed onto the surface of the polyacrylonitrile fiber membrane, and after drying, an LDH-fiber nanosheet is obtained;

[0027] As a preferred technical solution of the present application, in step S1, the mass fraction of the ethanol solution of the modifier HY-6085 is 2-5 wt.%, for example, it can be 2 wt.%, 2.3 wt.%, 2.6 wt.%, 2.9 wt.%, 3.2 wt.%, 3.5 wt.%, 3.8 wt.%, 4.1 wt.%, 4.4 wt.%, 4.7 wt.%, or 5 wt.%, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0028] In some optional embodiments, the mass ratio of the silica aerogel to the ethanol solution of the modifier HY-6085 is 1:5-10, for example, it can be 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, or 1:10, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0029] In some optional embodiments, the volume ratio of the ethanol to the deionized water is 3-5:1, for example, it can be 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1, or 5:1, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0030] In some optional embodiments, the amount of dibutyltin dilaurate added is 0.1-0.2% of the mass of the modifier HY-6085, for example, it can be 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, or 0.2%, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0031] In some optional embodiments, the temperature of the constant-temperature reaction of the second modification solution is 50-60°C, for example, it can be 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, or 60°C, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0032] In some optional embodiments, the time of the constant-temperature reaction of the second modification solution is 1-2h, for example, it can be 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0033] As a preferred technical solution of the present application, in step S2, the leveling agent is any one or a combination of BYK-310 and BYK-345;

[0034] In some optional embodiments, the feeding amount of the leveling agent is 0.2-0.5% of the total amount of the coating, for example, it can be 0.2%, 0.23%, 0.26%, 0.29%, 0.32%, 0.35%, 0.38%, 0.41%, 0.44%, 0.47% or 0.5%, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0035] The defoaming agent is any one or a combination of BYK-024 and BYK-025;

[0036] In some optional embodiments, the feeding amount of the defoaming agent is 0.1-0.3% of the total amount of the coating, for example, it can be 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, 0.20%, 0.22%, 0.24%, 0.26%, 0.28% or 0.3%, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0037] The preservative is any one or a combination of RocimaTM and ActicideMBS;

[0038] In some optional embodiments, the feeding amount of the preservative is 0.1-0.2% of the total amount of the coating, for example, it can be 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19% or 0.2%, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0039] The silicone oil emulsion is any one of Wacker Shin-Etsu KF-96L;

[0040] The mass ratio of the silicone oil emulsion, pre-modified silica aerogel powder, super-hydrophobic graphene / manganese dioxide porous network, tungsten trioxide thermochromic particles, and LDH-fiber nanosheet is (40-60):(20-30):(5-8):(3-5):(3-5);

[0041] As a preferred technical solution of the present application, in step S21, the concentration of the ammonium tungstate solution is 0.1-0.2M, for example, it can be 0.1M, 0.11M, 0.12M, 0.13M, 0.14M, 0.15M, 0.16M, 0.17M, 0.18M, 0.19M or 0.2M, but not limited to the listed values, other values not listed in this range are also applicable.

[0042] The rare earth oxide is lanthanum oxide or cerium oxide;

[0043] In some alternative embodiments, the concentration of the rare earth ion solution is 0.05-0.1M, for example, it can be 0.05M, 0.055M, 0.06M, 0.065M, 0.07M, 0.075M, 0.08M, 0.085M, 0.09M, 0.095M or 0.1M, but not limited to the listed values, other values not listed in this range are also applicable.

[0044] In some alternative embodiments, the molar ratio of tungsten ions to rare earth ions in the mixed solution is 1:0.01-0.05, for example, it can be 1:0.01, 1:0.014, 1:0.018, 1:0.022, 1:0.026, 1:0.03, 1:0.034, 1:0.038, 1:0.042, 1:0.046 or 1:0.05, but not limited to the listed values, other values not listed in this range are also applicable.

[0045] In some alternative embodiments, the mixed solution is adjusted to a pH of 7-9 using ammonia water, for example, it can be 7, 7.2, 7.4, 7.6, 7.8, 8, 8.2, 8.4, 8.6, 8.8 or 9, but not limited to the listed values, other values not listed in this range are also applicable.

[0046] In some alternative embodiments, the temperature of the microwave reaction of the reaction solution A is 195-205℃, for example, it can be 195℃, 196℃, 197℃, 198℃, 199℃, 200℃, 201℃, 202℃, 203℃, 204℃ or 205℃, but not limited to the listed values, other values not listed in this range are also applicable.

[0047] In some alternative embodiments, the power of the microwave reaction of the reaction solution A is 700-800W, for example, it can be 700W, 710W, 720W, 730W, 740W, 750W, 760W, 770W, 780W, 790W or 800W, but not limited to the listed values, other values not listed in this range are also applicable.

[0048] In some optional embodiments, the reaction liquid A is subjected to microwave reaction for 1-2 h, for example, 1 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, or 2 h, but not limited to the listed values, and other values not listed in the range are also applicable.

[0049] In some optional embodiments, the tungsten trioxide gel is calcined at a temperature of 500-600 °C, for example, 500 °C, 510 °C, 520 °C, 530 °C, 540 °C, 550 °C, 560 °C, 570 °C, 580 °C, 590 °C, or 600 °C, but not limited to the listed values, and other values not listed in the range are also applicable.

[0050] In some optional embodiments, the tungsten trioxide gel is calcined for 2-3 h, for example, 2 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h, 2.5 h, 2.6 h, 2.7 h, 2.8 h, 2.9 h, or 3 h, but not limited to the listed values, and other values not listed in the range are also applicable.

[0051] In some optional embodiments, the particle size of the rare earth doped tungsten trioxide gel is 0.5-1 μm, for example, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.8 μm, 0.85 μm, 0.9 μm, 0.95 μm, or 1 μm, but not limited to the listed values, and other values not listed in the range are also applicable.

[0052] In some optional embodiments, the mass fraction of the rare earth doped tungsten trioxide gel dispersed in the ethanol / water solution is 1-5 wt.%, for example, 1 wt.%, 1.5 wt.%, 2 wt.%, 2.5 wt.%, 3 wt.%, 3.5 wt.%, 4 wt.%, 4.5 wt.%, or 5 wt.%, but not limited to the listed values, and other values not listed in the range are also applicable.

[0053] In some optional embodiments, the volume ratio of ethanol to water in the ethanol / water solution is 3-4:1, for example, 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, or 4:1, but not limited to the listed values, and other values not listed in the range are also applicable.

[0054] In some optional embodiments, the mass ratio of the rare earth doped tungsten trioxide gel to tetraethyl orthosilicate is 1:0.1-0.2, for example, it can be 1:0.1, 1:0.11, 1:0.12, 1:0.13, 1:0.14, 1:0.15, 1:0.16, 1:0.17, 1:0.18, 1:0.19, or 1:0.2, but not limited to the listed values, other values not listed in the range are also applicable.

[0055] In some optional embodiments, the dispersion liquid B is adjusted to a pH of 10-11 with ammonia water, for example, it can be 10, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, or 11, but not limited to the listed values, other values not listed in the range are also applicable.

[0056] In some optional embodiments, the reaction liquid C is stirred at room temperature for 1-2h, for example, it can be 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h, but not limited to the listed values, other values not listed in the range are also applicable.

[0057] In some optional embodiments, the mass fraction of the vinylidene fluoride-hexafluoropropylene copolymer dispersed in the N-methyl pyrrolidone in the modified dispersion liquid is 3-5wt.%, for example, it can be 3wt.%, 3.2wt.%, 3.4wt.%, 3.6wt.%, 3.8wt.%, 4wt.%, 4.2wt.%, 4.4wt.%, 4.6wt.%, 4.8wt.%, or 5wt.%, but not limited to the listed values, other values not listed in the range are also applicable.

[0058] In some optional embodiments, the mass ratio of the silicon dioxide coated tungsten trioxide to the modified dispersion liquid is 1:10-20, for example, it can be 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, or 1:20, but not limited to the listed values, other values not listed in the range are also applicable.

[0059] In some optional embodiments, the temperature of the constant temperature stirring of the reaction liquid D is 40-60℃, for example, it can be 40℃, 42℃, 44℃, 46℃, 48℃, 50℃, 52℃, 54℃, 56℃, 58℃, or 60℃, but not limited to the listed values, other values not listed in the range are also applicable.

[0060] In some optional embodiments, the reaction solution D is stirred at a constant temperature for 2-3h, for example, 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3h, but not only limited to the listed values, other values not listed in the range are also applicable.

[0061] In some optional embodiments, the supercritical carbon dioxide drying temperature is 40-50℃, for example, 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃ or 50℃, but not only limited to the listed values, other values not listed in the range are also applicable.

[0062] In some optional embodiments, the supercritical carbon dioxide drying time is 1-2h, for example, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2h, but not only limited to the listed values, other values not listed in the range are also applicable.

[0063] As a preferred technical solution of the present application, in step S22, the volume ratio of methane:hydrogen:argon in the mixed gas is 1:5:20.

[0064] In some optional embodiments, the CVD furnace works at a temperature of 900-1000℃, for example, 900℃, 910℃, 920℃, 930℃, 940℃, 950℃, 960℃, 970℃, 980℃, 990℃ or 1000℃, but not only limited to the listed values, other values not listed in the range are also applicable.

[0065] In some optional embodiments, the CVD furnace works for 30-40min, for example, 30min, 31min, 32min, 33min, 34min, 35min, 36min, 37min, 38min, 39min or 40min, but not only limited to the listed values, other values not listed in the range are also applicable.

[0066] In some optional embodiments, the concentration of ferric chloride is 1-2M, for example, 1M, 1.1M, 1.2M, 1.3M, 1.4M, 1.5M, 1.6M, 1.7M, 1.8M, 1.9M or 2M, but not only limited to the listed values, other values not listed in the range are also applicable.

[0067] In some optional embodiments, the time for immersing the three-dimensional graphene-foam nickel in the ferric chloride solution is 2-4h, for example, can be 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 3.2h, 3.4h, 3.6h, 3.8h or 4h, but not limited to the listed values, other values not listed in the range of values are also applicable.

[0068] In some optional embodiments, the concentration of manganese sulfate in the electrolyte is 0.1-0.2M, for example, can be 0.1M, 0.11M, 0.12M, 0.13M, 0.14M, 0.15M, 0.16M, 0.17M, 0.18M, 0.19M or 0.2M, but not limited to the listed values, other values not listed in the range of values are also applicable.

[0069] In some optional embodiments, the concentration of sulfuric acid in the electrolyte is 0.05-0.1M, for example, can be 0.05M, 0.055M, 0.06M, 0.065M, 0.07M, 0.075M, 0.08M, 0.085M, 0.09M, 0.095M or 0.1M, but not limited to the listed values, other values not listed in the range of values are also applicable.

[0070] In some optional embodiments, the deposition current of the constant current deposition is 1-2mA / cm 2 , for example, can be 1mA / cm 2 , 1.1mA / cm 2 , 1.2mA / cm 2 , 1.3mA / cm 2 , 1.4mA / cm 2 , 1.5mA / cm 2 , 1.6mA / cm 2 , 1.7mA / cm 2 , 1.8mA / cm 2 , 1.9mA / cm 2 or 2mA / cm 2 , but not limited to the listed values, other values not listed in the range of values are also applicable.

[0071] In some optional embodiments, the time for the constant current deposition is 20-30min, for example, can be 20min, 21min, 22min, 23min, 24min, 25min, 26min, 27min, 28min, 29min or 30min, but not limited to the listed values, other values not listed in the range of values are also applicable.

[0072] In some alternative embodiments, the dopamine hydrochloride solution has a concentration of 1-2 g / L, such as 1 g / L, 1.1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L, 1.5 g / L, 1.6 g / L, 1.7 g / L, 1.8 g / L, 1.9 g / L, or 2 g / L, but is not limited to the recited values, as other unrecited values within this range are also applicable.

[0073] In some alternative embodiments, the graphene / manganese dioxide porous network has a mass ratio to dopamine hydrochloride of 50-100: 1, such as 50: 1, 55: 1, 60: 1, 65: 1, 70: 1, 75: 1, 80: 1, 85: 1, 90: 1, 95: 1, or 100: 1, but is not limited to the recited values, as other unrecited values within this range are also applicable.

[0074] In some alternative embodiments, the dopamine-modified solution has a pH of 8.5-9.5 using Tris buffer, such as 8.5, 8.6, 8.7, 8.8, 8.9, 9, 9.1, 9.2, 9.3, 9.4, or 9.5, but is not limited to the recited values, as other unrecited values within this range are also applicable.

[0075] In some alternative embodiments, the stirring at room temperature is performed for 20-24 h, such as 20 h, 20.5 h, 21 h, 21.5 h, 22 h, 22.5 h, 23 h, 23.5 h, or 24 h, but is not limited to the recited values, as other unrecited values within this range are also applicable.

[0076] In some alternative embodiments, the ethanol solution of dodecafluoroheptyl methacrylate has a mass fraction of 10-15 wt.%, such as 10 wt.%, 10.5 wt.%, 11 wt.%, 11.5 wt.%, 12 wt.%, 12.5 wt.%, 13 wt.%, 13.5 wt.%, 14 wt.%, 14.5 wt.%, or 15 wt.%, but is not limited to the recited values, as other unrecited values within this range are also applicable.

[0077] In some alternative embodiments, the polydopamine-coated porous network has a mass ratio to dodecafluoroheptyl methacrylate of 1:0.01-0.1, such as 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, or 1:0.1, but is not limited to the recited values, as other unrecited values within this range are also applicable.

[0078] In some optional embodiments, the photoinitiator is Irgacure 2959, and the amount of the photoinitiator is 1-2% of the mass of the dodecafluoroheptyl methacrylate, for example, it can be 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0079] In some optional embodiments, the intensity of the ultraviolet light for the ultraviolet curing of the reaction solution E under nitrogen protection is 10-20 mW / cm 2 , for example, it can be 10 mW / cm 2 , 11 mW / cm 2 , 12 mW / cm 2 , 13 mW / cm 2 , 14 mW / cm 2 , 15 mW / cm 2 , 16 mW / cm 2 , 17 mW / cm 2 , 18 mW / cm 2 , 19 mW / cm 2 , or 20 mW / cm 2 , but is not limited to the listed values, and other values not listed in the range are also applicable.

[0080] In some optional embodiments, the time for the ultraviolet curing of the reaction solution E under nitrogen protection is 10-15 min, for example, it can be 10 min, 10.5 min, 11 min, 11.5 min, 12 min, 12.5 min, 13 min, 13.5 min, 14 min, 14.5 min, or 15 min, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0081] As a preferred technical solution of the present application, in step S23, in some optional embodiments, the concentration of the mixed metal salt solution is 0.1-0.2 M, for example, it can be 0.1 M, 0.11 M, 0.12 M, 0.13 M, 0.14 M, 0.15 M, 0.16 M, 0.17 M, 0.18 M, 0.19 M, or 0.2 M, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0082] In some alternative embodiments, the molar ratio of magnesium nitrate to aluminum nitrate in the mixed metal salt solution is 2-3: 1, for example, it can be 2: 1, 2.1: 1, 2.2: 1, 2.3: 1, 2.4: 1, 2.5: 1, 2.6: 1, 2.7: 1, 2.8: 1, 2.9: 1, or 3: 1, but not limited to the listed values, other values not listed in the range are also applicable.

[0083] In some alternative embodiments, the concentration of the sodium hydroxide solution is 1-2M, for example, it can be 1M, 1.1M, 1.2M, 1.3M, 1.4M, 1.5M, 1.6M, 1.7M, 1.8M, 1.9M, or 2M, but not limited to the listed values, other values not listed in the range are also applicable.

[0084] In some alternative embodiments, the pH of the mixed metal salt solution is adjusted to 9-10 by adding the sodium hydroxide solution dropwise, for example, it can be 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, or 10, but not limited to the listed values, other values not listed in the range are also applicable.

[0085] In some alternative embodiments, the temperature of the reaction solution F maturation is 60-80℃, for example, it can be 60℃, 62℃, 64℃, 66℃, 68℃, 70℃, 72℃, 74℃, 76℃, 78℃, or 80℃, but not limited to the listed values, other values not listed in the range are also applicable.

[0086] In some alternative embodiments, the time of the reaction solution F maturation is 10-12h, for example, it can be 10h, 10.2h, 10.4h, 10.6h, 10.8h, 11h, 11.2h, 11.4h, 11.6h, 11.8h, or 12h, but not limited to the listed values, other values not listed in the range are also applicable.

[0087] In some alternative embodiments, the mass ratio of the LDH powder to the ionic liquid [EMIM] [BF4] is 1:0.1-0.3, for example, it can be 1:0.1, 1:0.12, 1:0.14, 1:0.16, 1:0.18, 1:0.2, 1:0.22, 1:0.24, 1:0.26, 1:0.28, or 1:0.3, but not limited to the listed values, other values not listed in the range are also applicable.

[0088] In some optional embodiments, the mass ratio of the LDH powder to acetonitrile is 1:10-20, for example, can be 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19 or 1:20, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0089] In some optional embodiments, the temperature of the intercalation modification liquid constant temperature ultrasonic is 50-60℃, for example, can be 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, 59℃ or 60℃, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0090] In some optional embodiments, the time of the intercalation modification liquid constant temperature ultrasonic is 2-3h, for example, can be 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3h, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0091] In some optional embodiments, the mass fraction of the polyacrylonitrile N,N-dimethylformamide solution is 10-15wt.%, for example, can be 10wt.%, 10.5wt.%, 11wt.%, 11.5wt.%, 12wt.%, 12.5wt.%, 13wt.%, 13.5wt.%, 14wt.%, 14.5wt.% or 15wt.%, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0092] In some optional embodiments, the concentration of the intercalation modified LDH suspension is 5-10mg / mL, for example, can be 5mg / mL, 5.5mg / mL, 6mg / mL, 6.5mg / mL, 7mg / mL, 7.5mg / mL, 8mg / mL, 8.5mg / mL, 9mg / mL, 9.5mg / mL or 10mg / mL, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0093] In some optional embodiments, the mass ratio of LDH in the LDH-fiber nanosheet is 15-20%, for example, can be 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5% or 20%, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0094] In a second aspect, the present application provides a super-insulating aerogel exterior wall coating. The super-insulating aerogel exterior wall coating comprises a silicone oil emulsion, a pre-modified silica aerogel powder, a super-hydrophobic graphene / manganese dioxide porous network, tungsten trioxide thermochromic particles, and LDH-fiber nanosheets.

[0095] In the present application, silica aerogel is introduced. Silica aerogel is a highly dispersed porous material prepared by nanoscale silica particles through sol-gel method and supercritical drying process, and its structure has unique micro characteristics. First, the specific surface area and porosity of silica aerogel are high, and the internal pores are mainly nanoscale network structure, which gives it extremely low density. The three-dimensional network structure formed by the connection of nanoparticles makes the thermal conductivity of aerogel much lower than that of traditional materials, so that the occurrence of solid heat conduction can be significantly inhibited. At the same time, the free volume inside its nanopores limits the freedom of movement of gas molecules, reduces the average free path of gas molecules, and effectively hinders the convective heat transfer and thermal diffusion of gas, thereby further reducing the thermal conductivity of gas. These characteristics make silica aerogel an excellent thermal insulation material, which can provide the main thermal insulation function in coatings.

[0096] In addition, the light weight of silica aerogel is also an important advantage of its application in building coatings. Because most of the volume of aerogel is filled with air, its density is only a small part of that of traditional thermal insulation materials, which makes the coating significantly reduce the load of the building structure when applied, thereby improving the overall structural safety and durability of the building.

[0097] However, silica aerogel still faces some key problems in practical application, which limits the full play of its performance. First, the surface of aerogel contains a large number of silanol groups, which make its surface have strong hydrophilicity, so that the aerogel is easy to adsorb water in a humid environment. Once water enters the pore structure inside the aerogel, it will greatly increase its thermal conductivity, seriously weakening its thermal insulation performance. In addition, the polar nature of silanol groups also leads to poor interfacial compatibility between aerogel and hydrophobic organic emulsion systems. This interfacial incompatibility can cause problems such as poor dispersion, local aggregation and performance uniformity of the coating. Second, because the essence of aerogel is inorganic material, its surface energy is high, which is easy to cause interfacial segregation with organic matrix, thereby reducing the overall stability of the composite coating.

[0098] To this end, a modifier HY-6085 is used in the present application to modify the surface of the silica aerogel. Its molecular chain contains both hydrophilic polyether segments and hydrophobic polydimethylsiloxane segments, forming an amphiphilic structure. The polyether segment is composed of repeating ethoxy units, which have high hydrophilicity and can interact with polar groups in the emulsion system through hydrogen bonding or van der Waals forces, thereby significantly enhancing the interfacial compatibility between inorganic aerogel particles and the organic emulsion matrix. On the other hand, the polydimethylsiloxane segment is composed of siloxane bonds and methyl groups, which exhibit low surface energy and high hydrophobicity, effectively shielding the silica hydroxyl groups on the surface of the aerogel, significantly improving its hydrophobicity.

[0099] HY-6085 reacts with the silica hydroxyl groups on the surface of the silica aerogel through hydrolysis-condensation at the end of its molecular chain, forming stable covalent bonds and a layer of chemically bonded organic-inorganic composite shell on the surface of the aerogel.

[0100] The surface of the modified aerogel changes from hydrophilic to hydrophobic. Due to the presence of the hydrophobic layer, water molecules are difficult to penetrate into the internal pores of the aerogel, effectively preventing the increase in thermal conductivity caused by water intrusion, ensuring the stability of its thermal insulation performance in humid environments; secondly, the introduction of the amphiphilic shell reduces the polarity and surface energy of the aerogel surface, allowing it to better disperse in the organic emulsion, avoiding particle agglomeration and improving the uniformity and stability of the coating system; in addition, the presence of the modified shell provides the aerogel particles with a certain degree of flexibility, reducing the fragmentation or pulverization phenomenon caused by brittleness during the mixing and coating of the coating, thereby improving the overall mechanical properties and durability of the coating.

[0101] In the present application, tungsten trioxide particles are introduced as fillers to give the coating the function of dynamically adjusting heat management. Tungsten trioxide is a typical transition metal oxide with unique thermochromic properties. The tungsten atoms in its crystal structure usually exist in a six-coordinated form. When the material is subjected to external stimuli such as heating or light, the electronic structure of the tungsten-oxygen bond changes significantly, with the conduction band electrons jumping within the crystal. This transition directly affects the absorption or reflection ability of tungsten trioxide to near-infrared light, thereby achieving dynamic adjustment of near-infrared optical properties. This property manifests itself as a thermochromic effect in the coating, and by adjusting the near-infrared reflectivity, tungsten trioxide can effectively reduce the absorption of solar radiation heat by the coating, allowing the building surface to maintain a dynamic balance with the environment temperature, thereby significantly reducing the heat load inside the building. However, the thermochromic response temperature of traditional tungsten trioxide materials is usually high, which limits its application at room temperature. Therefore, in order to achieve a thermochromic response at a lower temperature than traditional tungsten trioxide, the present application modifies the tungsten trioxide particles through rare earth doping technology.

[0102] The introduction of rare earth elements can significantly improve the thermochromic performance of tungsten trioxide. The mechanism lies in the partial substitution of tungsten atoms in the tungsten trioxide lattice by rare earth ions during the doping process. Due to the large ionic radius and low oxidation state of rare earth ions, this lattice substitution inevitably introduces oxygen vacancies to maintain the electrical neutrality balance of the crystal. The formation of oxygen vacancies has a significant impact on the localized electron concentration of tungsten trioxide. Specifically, as electron donor centers, oxygen vacancies can significantly enhance the electron mobility and carrier concentration within the crystal, thereby accelerating the electron transition and rearrangement during the thermochromic process. The introduction of this lattice defect improves the thermochromic sensitivity of tungsten trioxide. In addition, rare earth element doping can also reduce the band gap of tungsten trioxide by adjusting its energy band structure. This narrowing of the energy band allows tungsten trioxide to have improved near-infrared optical response sensitivity in the appropriate temperature range, thereby meeting the dynamic management needs of building exterior coatings in high-temperature environments.

[0103] To further optimize the dispersibility and environmental stability of rare earth-doped tungsten trioxide particles, the present invention uses a silica shell to coat them, forming a dense silica shell on the particle surface. This inorganic shell has multiple functions: first, the silica shell can effectively isolate the direct contact between rare earth-doped tungsten trioxide particles, preventing particle agglomeration during coating preparation and storage, thereby significantly improving particle dispersibility; second, the silica shell can protect the particles on both physical and chemical levels, isolating the damage to the tungsten trioxide lattice caused by ultraviolet light, and slowing down the performance degradation of the material due to photochemical reactions or environmental oxidation. This coating strategy not only improves the environmental stability of the particles, but also provides a guarantee for their long-term performance in complex coating matrices.

[0104] Based on the silica shell, the present invention further introduces a fluorine-containing polymer outer layer on its surface to further enhance the hydrophobicity and weather resistance of the particles. Specifically, a vinylidene fluoride-hexafluoropropylene copolymer is used as the modification material and is adsorbed on the surface of the silica shell through intermolecular forces. The low surface energy property of vinylidene fluoride-hexafluoropropylene copolymer is derived from the large number of fluorine atoms in its molecular structure, which endows the material with high chemical inertness and excellent ultraviolet aging resistance. During the grafting process, the vinylidene fluoride-hexafluoropropylene copolymer is combined with the silica shell surface through van der Waals forces, ensuring the stability of the modified layer. The fluorine-containing polymer outer layer not only further reduces the surface energy of the particles, making them super-hydrophobic, but also effectively prevents the intrusion of water molecules and other corrosive substances, significantly improving the weather resistance and anti-aging performance of the particles.

[0105] In the present invention, graphene / manganese dioxide porous network is introduced as a functional filler for coating, whose unique structure and excellent performance significantly improve the thermal insulation and mechanical properties of the coating. The preparation of the material first constructs a three-dimensional graphene skeleton by chemical vapor deposition method. CVD method forms intercrosslinked graphene layers by cracking and depositing carbon atoms on the foam nickel substrate at high temperature with methane as carbon source. This three-dimensional graphene skeleton has a very high specific surface area, and its unique honeycomb structure endows the material with excellent mechanical strength and pressure resistance, which can provide mechanical reinforcement for the overall structure in the coating system. In addition, the porous network structure of the three-dimensional graphene skeleton provides an ideal carrier and support framework for subsequent manganese dioxide deposition.

[0106] On the surface of the graphene skeleton, manganese dioxide nanowires are introduced by electrochemical deposition method to further improve the specific surface area and porosity of the material. During the electrochemical deposition process, manganese ions are reduced to one-dimensional manganese dioxide nanowires in the electrolyte, which are uniformly deposited on the surface of graphene to form a hierarchical porous structure. The introduction of manganese dioxide not only increases the number and total pore volume of the material, but also provides multiple scattering effects of infrared radiation through its unique hierarchical pore channels. This scattering effect significantly prolongs the propagation path of infrared thermal radiation in the coating, thereby effectively reducing the heat transfer efficiency and enhancing the thermal insulation performance of the coating. In addition, the synergistic effect of graphene and manganese dioxide is produced: the graphene skeleton provides a high-strength three-dimensional support framework, and its porous structure provides the basis for heat scattering and absorption. The introduction of manganese dioxide further refines the pore structure, increases the scattering path of heat in the pore channel, and inhibits the direct transfer effect of heat.

[0107] In order to further improve the waterproofness, self-cleaning performance and environmental stability of graphene / manganese dioxide porous network, the surface of the present invention is modified. First, a uniform polydopamine coating is formed on the surface of the porous network by the oxidative self-polymerization of dopamine. Dopamine molecules can spontaneously undergo oxidation and polymerization under weak alkaline conditions, and finally form a uniform polydopamine coating layer. The polydopamine coating is rich in various active functional groups on its surface, including amino, hydroxyl and phenolic hydroxyl groups, which provide abundant reaction sites for subsequent chemical grafting.

[0108] On the basis of the polydopamine coating, a hydrophobic fluoropolymer coating is introduced on the surface of the porous network by UV-induced radical polymerization of fluorine-containing monomers. Specifically, the fluorine-containing monomers generate free radicals under UV irradiation, which undergo polymerization with the active groups on the surface of polydopamine, forming a chemically bonded hydrophobic coating. Due to the presence of a large number of C-F bonds in the fluorine-containing monomer molecules, this coating exhibits extremely low surface energy and excellent chemical stability. The contact angle of the modified graphene / manganese dioxide porous network surface is significantly improved, achieving superhydrophobic properties. This superhydrophobic surface can effectively prevent water penetration, thereby reducing the erosion of the internal structure of the coating by rainwater and avoiding structural collapse due to water absorption. In addition, the superhydrophobicity significantly improves the self-cleaning ability of the coating, making it difficult for rainwater or dust to adhere to the surface of the coating, thereby maintaining the long-term cleanliness and aesthetics of the coating.

[0109] More importantly, this surface modification not only improves the waterproofing and self-cleaning performance of the porous network, but also significantly enhances the weather resistance of the material. The low surface energy and chemical inertness of the fluoropolymer coating enable the material to withstand strong UV radiation and harsh environmental chemical corrosion, thereby maintaining the long-term stability of its performance.

[0110] In the present invention, layered double hydroxide nanosheets are introduced as functional fillers, which significantly enhance the water resistance and overall durability of the coating due to their unique layered structure and adjustable chemical properties. LDH is a typical two-dimensional layered material, with a basic structure of a sheet-like crystal structure formed by stacking positively charged metal hydroxide layers, and the interlayer is filled with exchangeable anions and water molecules. This unique layered property enables LDH to form a dense water-resistant barrier in the coating, and the arrangement of its layers effectively extends the diffusion path of water molecules and corrosive ions in the coating film through the "brick wall effect", thereby preventing the penetration of water and corrosive media, significantly improving the durability and corrosion resistance of the coating film. However, the original LDH has a small interlayer spacing, which limits its compatibility with the organic matrix in the coating, as well as the dispersion and water resistance of LDH in the coating. Therefore, it is necessary to modify the LDH nanosheets by intercalation to adjust their interlayer spacing and interfacial chemical properties.

[0111] In the present application, ionic liquid is used as intercalating agent to modify the interlayer of LDH through ion exchange. Ionic liquid is a kind of molten salt composed of organic cations and inorganic or organic anions, which has high chemical stability, low volatility and good thermal stability. During the intercalation reaction, the original anions in the interlayer of LDH are gradually replaced by the action of ionic liquid, and the bulky organic cations in the ionic liquid are introduced into the interlayer of LDH, which significantly expands the interlayer spacing. The expansion of the interlayer spacing not only improves the dispersibility of LDH nanosheets in the coating matrix, but also forms a more compact physical barrier structure by expanding the interlayer spacing, further improving the performance of LDH as a water-blocking barrier. In addition, the introduction of ionic liquid also changes the surface chemical properties of LDH, reducing its surface energy and improving its interfacial compatibility with the organic coating matrix. The modified LDH nanosheets can form a highly uniform dispersion state in the coating, avoiding the agglomeration between the layers, and further optimizing the water-blocking performance of the coating and the mechanical stability of the coating film.

[0112] In order to further improve the application performance of LDH in coatings, the present application also introduces polyacrylonitrile fibers to form a nanoscale fiber network through electrospinning technology, and combines with LDH nanosheets to construct a high-strength composite network structure. Polyacrylonitrile fibers have excellent mechanical properties and chemical stability, and their nanofiber network not only provides additional mechanical reinforcement to the coating, but also acts as a "scaffold" for LDH nanosheets at the microscale. Specifically, polyacrylonitrile fibers are combined with modified LDH nanosheets through physical entanglement to form a highly stable organic-inorganic composite structure. This composite structure effectively avoids the sedimentation or re-aggregation of LDH layers in the coating, and at the same time gives the coating film higher tensile strength and toughness. In addition, the presence of polyacrylonitrile fibers further prolongs the diffusion path of water and corrosive ions in the coating film, forming a synergistic effect with the barrier effect of the LDH layered structure, thereby significantly improving the overall water resistance and corrosion resistance of the coating.

[0113] There is also a synergistic enhancement effect in the present application. The graphene / manganese dioxide porous network and the LDH nanosheet respectively play a barrier role in the coating through different physical and chemical mechanisms, but the functional complementarity between the two can produce a significant synergistic effect. The main role of the graphene / manganese dioxide porous network is to provide a three-dimensional support framework with high mechanical strength, while scattering infrared radiation through its multi-level channels and extending the heat transfer path, thereby achieving thermal insulation function. The LDH nanosheet forms a "brick wall effect" through its layered structure, effectively preventing the penetration of moisture and corrosive ions. The synergistic effect of the two additives is reflected in the following two aspects: the channel structure of graphene / manganese dioxide and the sheet structure of LDH work together to hinder the transmission path of heat and moisture in the coating, respectively. The porous network of graphene / manganese dioxide provides optical scattering of heat, while the dense sheet of LDH further extends the diffusion path of moisture and corrosive ions, thereby forming multiple protection in physical barrier function; secondly, the LDH nanosheet has a certain tendency to aggregate in the coating system, while the graphene / manganese dioxide porous network acts as a three-dimensional support framework, which can effectively disperse the LDH nanosheet and avoid its aggregation. At the same time, the introduction of LDH nanosheet can fill the small pores of graphene / manganese dioxide porous network, thereby further optimizing the overall density and barrier performance.

[0114] The rare earth doped tungsten trioxide particles and the graphene / manganese dioxide porous network have different mechanisms in thermal insulation function, the former dynamically regulates the near-infrared reflectivity through the thermochromic property, and the latter extends the heat radiation path through the multi-level channel structure. The synergistic effect of the two is mainly reflected in the following aspects: the rare earth doped tungsten trioxide particles can adjust the reflectivity of near-infrared light according to the change of external temperature, thereby reducing the absorption of solar radiation heat. This dynamic thermal management function can actively regulate heat in high temperature environment. While the graphene / manganese dioxide porous network further reduces the heat transfer efficiency through its static multi-level channel structure and infrared scattering effect. The combination of this dynamic and static thermal insulation mechanism enables the coating to exhibit more excellent thermal insulation performance in complex environments; secondly, the graphene / manganese dioxide porous network provides a high-strength support framework for the rare earth doped tungsten trioxide particles, which can effectively prevent the particles from settling and aggregating in the coating, while enhancing the dispersibility of the particles in the coating matrix. This synergistic effect ensures the thermochromic performance and dispersion stability of the coating in long-term use.

[0115] The LDH nanosheets and the rare earth doped tungsten trioxide particles respectively play the functions of water blocking barrier and dynamic thermal management, and the two in the coating system complement each other through different mechanisms to form a synergistic effect of heat shielding and durability improvement. Specifically, the rare earth doped tungsten trioxide particles need to maintain long-term stability in the dynamic thermal management process, and the layered barrier effect of the LDH nanosheets not only prevents the penetration of external moisture and corrosive ions, but also provides uniform distribution in the coating matrix, effectively slowing down the aging and performance degradation of the particles; the LDH nanosheets prolong the diffusion path of moisture and corrosive ions through the "brick wall effect", and in combination with the dynamic thermal management function of the rare earth doped tungsten trioxide particles, a multifunctional barrier system integrating heat insulation, water blocking and corrosion resistance is constructed.

[0116] Compared with the prior art, the present application has the following advantages:

[0117] The present application significantly improves the comprehensive performance of the coating by introducing silica aerogel and using modifier HY-6085 for surface modification. Aerogel provides excellent thermal insulation performance and lightweight characteristics due to its high specific surface area and porous structure, but its strong hygroscopicity and poor interfacial compatibility due to the surface silicon hydroxyl limit its application effect. The modifier enhances the compatibility of aerogel with organic matrix through amphiphilic molecular structure, and imparts hydrophobicity by shielding silicon hydroxyl. The modified aerogel maintains thermal insulation performance in a humid environment, and the dispersibility and mechanical properties are significantly improved, ensuring the stability and durability of the coating;

[0118] The present application imparts dynamic thermal management function and high environmental stability to the coating by rare earth doped tungsten trioxide particles and silica coating and fluorine-containing polymer modification. The introduction of oxygen vacancies and the adjustment of energy band structure by rare earth doping enable tungsten trioxide to realize thermochromic response at a lower temperature than traditional tungsten trioxide; the silica shell layer prevents particle agglomeration and improves ultraviolet resistance and oxidation resistance; the fluorine-containing polymer further enhances hydrophobicity and weather resistance. Multiple modifications synergistically optimize the thermal insulation, durability and stability of the coating;

[0119] The present application significantly improves the thermal insulation, waterproofness and weather resistance of the coating by constructing a graphene / manganese dioxide porous network and surface modification. The three-dimensional graphene skeleton provides high specific surface area and mechanical strength, and the electrochemically deposited manganese dioxide nanowires form hierarchical pores, enhancing thermal radiation scattering and achieving excellent thermal insulation. Through modification by polydopamine coating and fluorine-containing polymer coating, the network surface obtains superhydrophobicity, self-cleaning ability and ultraviolet aging resistance, comprehensively improving the stability and durability of the coating;

[0120] The present application significantly improves the water resistance, corrosion resistance and durability of the coating by introducing ionic liquid modified LDH nanosheets and polyacrylonitrile fiber composite network. The ionic liquid intercalation expands the LDH interlayer spacing, improves the dispersibility and interfacial compatibility, and forms a dense physical barrier structure through interlayer spacing expansion, so as to form a high-efficiency 'brick wall effect' water barrier; the polyacrylonitrile fiber builds a nanofiber network through electrospinning, which not only improves the mechanical properties of the coating film, but also provides a scaffold for LDH, effectively avoiding sheet aggregation. The synergistic effect of the two further prolongs the diffusion path of water and corrosive ions, and optimizes the comprehensive performance of the coating.

[0121] The present application significantly improves the heat insulation, water resistance and durability of the coating through the synergistic effect of graphene / manganese dioxide porous network, LDH nanosheet and rare earth doped tungsten trioxide particles. The graphene / manganese dioxide porous network provides a high-strength support framework and infrared scattering, the LDH nanosheet hinders the penetration of water and ions through the 'brick wall effect', and the two synergistically form a multiple physical barrier to optimize the compactness and barrier performance of the coating; the rare earth doped tungsten trioxide particles dynamically regulate the near-infrared reflectivity through dynamic thermal management, combined with the static heat insulation effect of graphene / manganese dioxide, to enhance the comprehensive heat insulation function of the coating; at the same time, the LDH nanosheet and the rare earth doped tungsten trioxide particles jointly construct a multifunctional barrier integrating heat insulation, water resistance and corrosion resistance, to ensure the stability and long-term effectiveness of the coating. DETAILED DESCRIPTION

[0122] The technical solutions of the present application will be described in detail below in combination with specific examples. The examples described herein are specific embodiments of the present application, which are used to illustrate the concept of the present application; these descriptions are all explanatory and exemplary, and should not be understood as limiting the embodiments of the present application and the protection scope of the present application. In addition to the examples described herein, those skilled in the art can also employ other technical solutions that are obvious based on the disclosure of the claims and the specification of the present application, which include technical solutions that make any obvious substitutions and modifications to the examples described herein.

[0123] The chemical reagents used in the examples and comparative examples of the present application are all commercially available without further purification or treatment.

[0124] Example 1

[0125] The present example provides a super-insulating aerogel exterior wall coating and a preparation method thereof, and the preparation method of the super-insulating aerogel exterior wall coating specifically comprises the following steps:

[0126] S1: an ethanol solution of modifier HY-6085 with a concentration of 3wt.% was prepared, and silica aerogel was added to obtain a modified solution of aerogel, wherein the mass ratio of silica aerogel to the ethanol solution of modifier HY-6085 was 1:8, deionized water and dibutyltin dilaurate were added after stirring at room temperature under a nitrogen atmosphere for 0.8h to obtain a second modified solution, wherein the volume ratio of ethanol to deionized water was 4:1, the amount of dibutyltin dilaurate was 0.15% of the mass of the modifier HY-6085, and the reaction was carried out at a constant temperature of 50℃ for 1h, and then the pre-modified silica aerogel powder was obtained by filtration, washing and drying;

[0127] S2: leveling agent BYK-310, defoaming agent BYK-024 and preservative RocimaTM were added to the silicone oil emulsion Wacker , wherein the amount of leveling agent was 0.4% of the total amount of paint; the amount of defoaming agent was 0.2% of the total amount of paint; the amount of preservative was 0.15% of the total amount of paint, and then the pre-modified silica aerogel powder, super-hydrophobic graphene / manganese dioxide porous network, tungsten trioxide thermochromic particles and LDH-fiber nanosheet were added in sequence and uniformly dispersed, and then vacuum degassing was performed to obtain the super-insulation aerogel exterior wall coating, wherein the mass ratio of the silicone oil emulsion, the pre-modified silica aerogel powder, the super-hydrophobic graphene / manganese dioxide porous network, the tungsten trioxide thermochromic particles and the LDH-fiber nanosheet was 50:28:7:4:4.7.

[0128] The preparation method of the tungsten trioxide thermochromic particles is as follows:

[0129] S21: prepare an ammonium tungstate solution with a concentration of 0.1 M, dissolve lanthanide oxide lanthanum oxide in nitric acid to obtain a lanthanide ion solution with a concentration of 0.08 M, mix the ammonium tungstate solution and the lanthanide ion solution to obtain a mixed solution, wherein the molar ratio of tungsten ions to lanthanide ions is 1:0.03, adjust the pH to 7 using ammonia water to obtain reaction liquid A, after microwave reaction at 200 ℃ and a power of 700 W for 1.6 h, centrifugal, washing, drying to obtain a lanthanide-doped tungsten trioxide gel, calcining at 550 ℃ for 2 h, grinding to obtain lanthanide-doped tungsten trioxide with a particle size of 0.8 μm; disperse it in an ethanol / water solution with a mass fraction of 2 wt.%, wherein the volume ratio of ethanol to water is 3:1, add tetraethyl orthosilicate to obtain dispersion liquid B, wherein the mass ratio of tungsten trioxide to tetraethyl orthosilicate is 1:0.15, adjust the pH to 10.6 using ammonia water to obtain reaction liquid C, stir at room temperature for 1 h, centrifugal, washing, drying to obtain silica-coated tungsten trioxide; disperse vinylidene fluoride-hexafluoropropylene copolymer in N-methylpyrrolidone to obtain a modified dispersion liquid with a mass fraction of 3 wt.%, add silica-coated tungsten trioxide to obtain reaction liquid D, wherein the mass ratio of silica-coated tungsten trioxide to the modified dispersion liquid is 1:15, stir at 40 ℃ for 2 h, and then place it in a supercritical carbon dioxide device to dry at 40 ℃ for 1 h to obtain tungsten trioxide thermochromic particles;

[0130] The preparation method of the super-hydrophobic graphene / manganese dioxide porous network is as follows:

[0131] S22: place the nickel foam in a CVD furnace, and pass a mixed gas at 900 ℃ for 30 min, wherein the volume ratio of methane to hydrogen to argon in the mixed gas is 1:5:20, and the three-dimensional graphene-nickel foam is obtained after natural cooling; immerse the three-dimensional graphene skeleton in a 1 M ferric chloride solution for 2 h, and filter, wash, and dry to obtain the three-dimensional graphene skeleton; prepare an electrolyte by taking manganese sulfate and sulfuric acid, wherein the concentration of manganese sulfate is 0.15 M, and the concentration of sulfuric acid is 0.07 M; use the three-dimensional graphene skeleton as a working electrode, and use a platinum sheet as a counter electrode to perform constant current deposition, wherein the deposition current is 1 mA / cm 2, and the graphene / manganese dioxide porous network is immersed in a dopamine hydrochloride solution with a concentration of 1.8 g / L to obtain a dopamine modified solution, wherein the mass ratio of the graphene / manganese dioxide porous network to the dopamine hydrochloride is 80:1, and a Tris buffer is used to maintain the pH of the solution at 8.5, and the solution is stirred at room temperature for 20 h, and then centrifuged and dried to obtain a polydopamine coated porous network; the polydopamine coated porous network is immersed in an ethanol solution of dodecafluoroheptyl methacrylate with a mass fraction of 10 wt.%, wherein the mass ratio of the polydopamine coated porous network to the dodecafluoroheptyl methacrylate is 1:0.07, and a photoinitiator Irgacure 2959 is added to obtain a reaction solution E, and the amount of the photoinitiator is 1% of the mass of the dodecafluoroheptyl methacrylate, and the reaction solution E is ultraviolet cured under the protection of nitrogen, and the ultraviolet intensity is 10 mW / cm 2 , and the curing time is 10 min, to obtain a super-hydrophobic graphene / manganese dioxide porous network.

[0132] The preparation method of the LDH-fiber nanosheet is as follows:

[0133] S23: magnesium nitrate and aluminum nitrate are weighed to prepare a mixed metal salt solution with a concentration of 0.1 M, wherein the molar ratio of magnesium nitrate to aluminum nitrate is 2:1, and a 1, 1.5, 1.3, or 2 M sodium hydroxide solution is added dropwise under stirring to adjust the pH to 9 to obtain a reaction solution F, and after aging at 60°C for 10 h, the reaction solution F is centrifuged, washed, and dried to obtain LDH powder; the LDH powder is mixed with an ionic liquid [EMIM][BF4] in acetonitrile at a mass ratio of 1:0.2 to obtain an intercalation modification solution, wherein the mass ratio of the LDH powder to the acetonitrile is 1:10, and the intercalation modification solution is ultrasonically treated at a constant temperature of 50°C for 2 h, and then centrifuged, washed, and dried to obtain intercalation modified LDH; a polyacrylonitrile solution with a mass fraction of 10 wt.% in N,N-dimethylformamide is prepared, and a polyacrylonitrile fiber membrane is prepared by electrospinning; and an intercalation modified LDH suspension with a concentration of 8 mg / mL is sprayed onto the surface of the polyacrylonitrile fiber membrane, and dried to obtain an LDH-fiber nanosheet, wherein the mass fraction of the LDH in the LDH-fiber nanosheet is 15%.

[0134] Example 2

[0135] The present embodiment provides a super-insulation aerogel exterior wall coating and a preparation method thereof, and the preparation method of the super-insulation aerogel exterior wall coating specifically comprises the following steps:

[0136] S1: an ethanol solution of modifier HY-6085 with a concentration of 4wt.% was prepared, and silica aerogel was added to obtain a modified aerogel solution, with a mass ratio of silica aerogel to the ethanol solution of modifier HY-6085 being 1:5, deionized water and dibutyltin dilaurate were added after stirring at room temperature under a nitrogen atmosphere for 0.7h to obtain a second modified solution, with a volume ratio of ethanol to deionized water being 3:1, the amount of dibutyltin dilaurate was 0.18% of the mass of the modifier HY-6085, and the reaction was carried out at a constant temperature of 55℃ for 1.8h, and then the pre-modified silica aerogel powder was obtained by filtration, washing and drying;

[0137] S2: leveling agent BYK-345, defoaming agent BYK-025 and preservative Acticide MBS were added to the silicone oil emulsion Shin-Etsu KF-96L, with the amount of leveling agent being 0.3% of the total amount of the coating, the amount of defoaming agent being 0.25% of the total amount of the coating, and the amount of preservative being 0.1% of the total amount of the coating, and then the pre-modified silica aerogel powder, super-hydrophobic graphene / manganese dioxide porous network, tungsten trioxide thermochromic particles and LDH-fiber nanosheets were added in sequence and uniformly dispersed, and then vacuum degassing was performed to obtain the super-insulation aerogel exterior wall coating, with the mass ratio of the silicone oil emulsion, the pre-modified silica aerogel powder, the super-hydrophobic graphene / manganese dioxide porous network, the tungsten trioxide thermochromic particles and the LDH-fiber nanosheets being 40:25:5:4.6:3.

[0138] The preparation method of the tungsten trioxide thermochromic particles is as follows:

[0139] S21: prepare an ammonium tungstate solution with a concentration of 0.18 M, dissolve rare earth oxide cerium oxide in nitric acid to obtain a rare earth ion solution with a concentration of 0.05 M, mix the ammonium tungstate solution and the rare earth ion solution to obtain a mixed solution, wherein the molar ratio of tungsten ions to rare earth ions is 1:0.04, adjust the pH to 8 using ammonia water to obtain reaction liquid A, after microwave reaction at 195°C and a power of 750 W for 1 h, centrifugal, washing, drying to obtain a rare earth doped tungsten trioxide gel, calcining at 500°C for 2.5 h, grinding to obtain a rare earth doped tungsten trioxide with a particle size of 0.7 μm; disperse it in an ethanol / water solution with a mass fraction of 4 wt.%, wherein the volume ratio of ethanol to water is 3.5:1, add tetraethyl orthosilicate to obtain dispersion liquid B, wherein the mass ratio of tungsten trioxide to tetraethyl orthosilicate is 1:0.18, adjust the pH to 10.8 using ammonia water to obtain reaction liquid C, stir at room temperature for 1.7 h, centrifugal, washing, drying to obtain silica-coated tungsten trioxide; disperse vinylidene fluoride-hexafluoropropylene copolymer in N-methylpyrrolidone to obtain a modified dispersion liquid with a mass fraction of 4 wt.%, add the silica-coated tungsten trioxide to obtain reaction liquid D, wherein the mass ratio of silica-coated tungsten trioxide to modified dispersion liquid is 1:18, stir at a constant temperature of 50°C for 2.6 h, and then place it in a supercritical carbon dioxide device to dry at 45°C for 1.5 h to obtain tungsten trioxide thermochromic particles;

[0140] The preparation method of the super-hydrophobic graphene / manganese dioxide porous network is as follows:

[0141] S22: place the nickel foam in a CVD furnace, pass in a mixed gas at 950°C for 35 min, wherein the volume ratio of methane:hydrogen:argon in the mixed gas is 1:5:20, and obtain three-dimensional graphene-nickel foam after natural cooling, immerse it in a 1.5 M ferric chloride solution for 3 h, filter, wash, and dry to obtain a three-dimensional graphene skeleton; take manganese sulfate and sulfuric acid to prepare an electrolyte, wherein the concentration of manganese sulfate is 0.18 M and the concentration of sulfuric acid is 0.05 M, use the three-dimensional graphene skeleton as a working electrode and a platinum sheet as a counter electrode to perform constant current deposition, wherein the deposition current is 1.6 mA / cm 2, and the graphene / manganese dioxide porous network is immersed in a dopamine hydrochloride solution with a concentration of 1.5 g / L to obtain a dopamine modified solution, wherein the mass ratio of the graphene / manganese dioxide porous network to the dopamine hydrochloride is 95:1, and a Tris buffer is used to maintain the pH of the solution at 9, and the solution is stirred at room temperature for 22 h, and then centrifuged and dried to obtain a polydopamine coated porous network; the polydopamine coated porous network is immersed in an ethanol solution of dodecafluoroheptyl methacrylate with a mass fraction of 12 wt.%, wherein the mass ratio of the polydopamine coated porous network to the dodecafluoroheptyl methacrylate is 1:0.05, and a photoinitiator Irgacure 2959 is added to obtain a reaction solution E, and the amount of the photoinitiator is 1.6% of the mass of the dodecafluoroheptyl methacrylate, and the reaction solution E is ultraviolet cured under the protection of nitrogen, and the ultraviolet intensity of the curing is 18 mW / cm 2 , and the curing time is 12 min, to obtain a super-hydrophobic graphene / manganese dioxide porous network.

[0142] The preparation method of the LDH-fiber nanosheet is as follows:

[0143] S23: magnesium nitrate and aluminum nitrate are weighed to prepare a mixed metal salt solution with a concentration of 0.1, 0.15, 0.18, and 0.2 M, wherein the molar ratio of the magnesium nitrate to the aluminum nitrate is 2.7:1, and a sodium hydroxide solution with a concentration of 1, 1.5, 1.3, and 2 M is added dropwise under stirring to adjust the pH to 9.7 to obtain a reaction solution F, and the reaction solution F is aged at 70°C for 11 h, and then centrifuged, washed, and dried to obtain LDH powder; the LDH powder is mixed with an ionic liquid [EMIM][BF4] in acetonitrile at a mass ratio of 1:0.1 to obtain an intercalation modification solution, wherein the mass ratio of the LDH powder to the acetonitrile is 1:15, and the intercalation modification solution is ultrasonically treated at a constant temperature of 55°C for 2.5 h, and then centrifuged, washed, and dried to obtain intercalation modified LDH; a polyacrylonitrile solution with a mass fraction of 13 wt.% in N,N-dimethylformamide is prepared, and a polyacrylonitrile fiber membrane is prepared by electrospinning; and an intercalation modified LDH suspension with a concentration of 5 mg / mL is sprayed onto the surface of the polyacrylonitrile fiber membrane, and then dried to obtain an LDH-fiber nanosheet, wherein the mass fraction of the LDH in the LDH-fiber nanosheet is 18%.

[0144] Example 3

[0145] The present embodiment provides a super-insulation aerogel exterior wall coating and a preparation method thereof, and the preparation method of the super-insulation aerogel exterior wall coating specifically comprises the following steps:

[0146] S1: an ethanol solution of modifier HY-6085 with a concentration of 2wt.% was prepared, and silica aerogel was added to obtain a modified aerogel solution, with a mass ratio of silica aerogel to the ethanol solution of modifier HY-6085 being 1:10, deionized water and dibutyltin dilaurate were added after stirring for 0.5h at room temperature under a nitrogen atmosphere to obtain a second modified solution, with a volume ratio of ethanol to deionized water being 4.8:1, the amount of dibutyltin dilaurate was 0.1% of the mass of the modifier HY-6085, and the reaction was carried out at a constant temperature of 58℃ for 1.5h, and then the pre-modified silica aerogel powder was obtained by filtration, washing and drying;

[0147] S2: leveling agent BYK-310, defoaming agent BYK-024 and preservative RocimaTM were added to the silicone oil emulsion Wacker , wherein the amount of leveling agent was 0.2% of the total amount of paint; the amount of defoaming agent was 0.1% of the total amount of paint; the amount of preservative was 0.18% of the total amount of paint, and then the pre-modified silica aerogel powder, super-hydrophobic graphene / manganese dioxide porous network, tungsten trioxide thermochromic particles and LDH-fiber nanosheets were added in sequence and uniformly dispersed, and then vacuum degassing was performed to obtain the super-insulation aerogel exterior wall coating, wherein the mass ratio of the silicone oil emulsion, the pre-modified silica aerogel powder, the super-hydrophobic graphene / manganese dioxide porous network, the tungsten trioxide thermochromic particles and the LDH-fiber nanosheets was 55:20:8:3:5.

[0148] The preparation method of the tungsten trioxide thermochromic particles is as follows:

[0149] S21: prepare an ammonium tungstate solution with a concentration of 0.15 M, dissolve lanthanide oxide lanthanum oxide in nitric acid to obtain a lanthanide ion solution with a concentration of 0.07 M, mix the ammonium tungstate solution and the lanthanide ion solution to obtain a mixed solution, wherein the molar ratio of tungsten ions to lanthanide ions is 1:0.01, adjust the pH to 8.5 using ammonia water to obtain reaction liquid A, microwave at 203 ℃ and a power of 780 W for 2 h, then centrifuge, wash, and dry to obtain a lanthanide-doped tungsten trioxide gel, calcine at 580 ℃ for 2.7 h, and grind to obtain lanthanide-doped tungsten trioxide with a particle size of 0.5 μm; disperse the lanthanide-doped tungsten trioxide in an ethanol / water solution at a mass fraction of 1 wt.%, wherein the volume ratio of ethanol to water is 3.8:1, add tetraethyl orthosilicate to obtain dispersion liquid B, wherein the mass ratio of tungsten trioxide to tetraethyl orthosilicate is 1:0.1, and adjust the pH to 10 using ammonia water to obtain reaction liquid C, stir at room temperature for 1.5 h, centrifuge, wash, and dry to obtain silica-coated tungsten trioxide; disperse vinylidene fluoride-hexafluoropropylene copolymer in N-methylpyrrolidone at a mass fraction of 4.6 wt.% to obtain a modified dispersion liquid, add the silica-coated tungsten trioxide to obtain reaction liquid D, wherein the mass ratio of silica-coated tungsten trioxide to the modified dispersion liquid is 1:10, stir at a constant temperature of 55 ℃ for 2.8 h, and then place in a supercritical carbon dioxide device to dry at 48 ℃ for 1.8 h to obtain tungsten trioxide thermochromic particles;

[0150] The preparation method of the super-hydrophobic graphene / manganese dioxide porous network is as follows:

[0151] S22: place the nickel foam in a CVD furnace, pass in a mixed gas at 980 ℃ for 38 min, wherein the volume ratio of methane to hydrogen to argon in the mixed gas is 1:5:20, and obtain three-dimensional graphene-nickel foam after natural cooling, immerse the three-dimensional graphene-nickel foam in a 1.8 M ferric chloride solution for 3.6 h, filter, wash, and dry to obtain a three-dimensional graphene skeleton; prepare an electrolyte by taking manganese sulfate and sulfuric acid, wherein the concentration of manganese sulfate is 0.1 M and the concentration of sulfuric acid is 0.08 M, use the three-dimensional graphene skeleton as a working electrode and a platinum sheet as a counter electrode to perform constant-current deposition, wherein the deposition current is 1.8 mA / cm 2, and the graphene / manganese dioxide porous network is immersed in a dopamine hydrochloride solution with a concentration of 1 g / L to obtain a dopamine modified solution, wherein the mass ratio of the graphene / manganese dioxide porous network to the dopamine hydrochloride is 50:1, and a Tris buffer is used to maintain the pH of the solution at 9.2, and the solution is stirred at room temperature for 23 h, and then centrifuged and dried to obtain a polydopamine coated porous network; the polydopamine coated porous network is immersed in an ethanol solution of dodecafluoroheptyl methacrylate with a mass fraction of 13 wt.%, wherein the mass ratio of the polydopamine coated porous network to the dodecafluoroheptyl methacrylate is 1:0.01, and a photoinitiator Irgacure 2959 is added to obtain a reaction solution E, and the amount of the photoinitiator is 1.8% of the mass of the dodecafluoroheptyl methacrylate, and the reaction solution E is ultraviolet cured under the protection of nitrogen, and the ultraviolet intensity of the curing is 20 mW / cm 2 , and the curing time is 14 min, to obtain a super-hydrophobic graphene / manganese dioxide porous network.

[0152] The preparation method of the LDH-fiber nanosheet is as follows:

[0153] S23: magnesium nitrate and aluminum nitrate are weighed to prepare a mixed metal salt solution with a concentration of 0.18 M, wherein the molar ratio of the magnesium nitrate to the aluminum nitrate is 2.5:1, and a 1, 1.5, 1.3, or 2 M sodium hydroxide solution is added dropwise under stirring to adjust the pH to 10 to obtain a reaction solution F, and after aging at 75 °C for 11.5 h, the reaction solution F is centrifuged, washed, and dried to obtain LDH powder; the LDH powder is mixed with an ionic liquid [EMIM][BF4] in acetonitrile at a mass ratio of 1:0.25 to obtain an intercalation modification solution, wherein the mass ratio of the LDH powder to the acetonitrile is 1:18, and the intercalation modification solution is ultrasonically treated at a constant temperature of 58 °C for 2.8 h, and then centrifuged, washed, and dried to obtain intercalation modified LDH; a polyacrylonitrile solution with a mass fraction of 12 wt.% in N,N-dimethylformamide is prepared, and a polyacrylonitrile fiber membrane is prepared by electrospinning; and a suspension of the intercalation modified LDH with a concentration of 6 mg / mL is sprayed onto the surface of the polyacrylonitrile fiber membrane, and after drying, an LDH-fiber nanosheet is obtained, wherein the mass fraction of the LDH in the LDH-fiber nanosheet is 17%.

[0154] Example 4

[0155] The present embodiment provides a super-insulating aerogel exterior wall coating and a preparation method thereof, and the preparation method of the super-insulating aerogel exterior wall coating specifically comprises the following steps:

[0156] S1: an ethanol solution of modifier HY-6085 with a concentration of 5wt.% was prepared, and silica aerogel was added to obtain an aerogel modification solution, wherein the mass ratio of silica aerogel to the ethanol solution of modifier HY-6085 was 1:7, deionized water and dibutyltin dilaurate were added after stirring at room temperature for 1h under a nitrogen atmosphere to obtain a second modification solution, wherein the volume ratio of ethanol to deionized water was 5:1, the amount of dibutyltin dilaurate was 0.2% of the mass of modifier HY-6085, and the reaction was carried out at a constant temperature of 60℃ for 2h, and then the pre-modified silica aerogel powder was obtained by filtration, washing and drying;

[0157] S2: leveling agent BYK-345, defoaming agent BYK-025 and preservative Acticide MBS were added to the silicone oil emulsion Shin-Etsu KF-96L, wherein the amount of leveling agent was 0.5% of the total amount of coating, the amount of defoaming agent was 0.3% of the total amount of coating, and the amount of preservative was 0.2% of the total amount of coating, and then the pre-modified silica aerogel powder, super-hydrophobic graphene / manganese dioxide porous network, tungsten trioxide thermochromic particles and LDH-fiber nanosheets were added in sequence and uniformly dispersed, and then vacuum degassing was performed to obtain the super-insulation aerogel exterior wall coating, wherein the mass ratio of silicone oil emulsion, pre-modified silica aerogel powder, super-hydrophobic graphene / manganese dioxide porous network, tungsten trioxide thermochromic particles and LDH-fiber nanosheets was 60:30:6:5:4.

[0158] The preparation method of the tungsten trioxide thermochromic particles is as follows:

[0159] S21: prepare an ammonium tungstate solution with a concentration of 0.2 M, dissolve rare earth oxide cerium oxide in nitric acid to obtain a rare earth ion solution with a concentration of 0.1 M, mix the ammonium tungstate solution and the rare earth ion solution to obtain a mixed solution, wherein the molar ratio of tungsten ions to rare earth ions is 1:0.05, adjust the pH to 9 using ammonia water to obtain reaction liquid A, microwave at 205°C and a power of 800 W for 1.8 h, then centrifuge, wash, and dry to obtain a rare earth-doped tungsten trioxide gel, calcine at 600°C for 3 h, and grind to obtain a rare earth-doped tungsten trioxide with a particle size of 1 μm; disperse the rare earth-doped tungsten trioxide in an ethanol / water solution at a mass fraction of 5 wt.%, wherein the volume ratio of ethanol to water is 4:1, add tetraethyl orthosilicate to obtain dispersion liquid B, wherein the mass ratio of tungsten trioxide to tetraethyl orthosilicate is 1:0.2, adjust the pH to 11 using ammonia water to obtain reaction liquid C, stir at room temperature for 2 h, centrifuge, wash, and dry to obtain silica-coated tungsten trioxide; disperse a vinylidene fluoride-hexafluoropropylene copolymer in N-methylpyrrolidone at a mass fraction of 5 wt.% to obtain a modified dispersion liquid, add the silica-coated tungsten trioxide to obtain reaction liquid D, wherein the mass ratio of silica-coated tungsten trioxide to modified dispersion liquid is 1:20, stir at a constant temperature of 60°C for 3 h, and then place in a supercritical carbon dioxide device and dry at 50°C for 2 h to obtain tungsten trioxide thermochromic particles;

[0160] The preparation method of the super-hydrophobic graphene / manganese dioxide porous network is as follows:

[0161] S22: place the nickel foam in a CVD furnace, pass in a mixed gas at 1000°C for 40 min, wherein the volume ratio of methane:hydrogen:argon in the mixed gas is 1:5:20, and naturally cool to obtain three-dimensional graphene-nickel foam, immerse the three-dimensional graphene-nickel foam in a 2 M ferric chloride solution for 4 h, filter, wash, and dry to obtain a three-dimensional graphene skeleton; prepare an electrolyte by taking manganese sulfate and sulfuric acid, wherein the concentration of manganese sulfate is 0.2 M and the concentration of sulfuric acid is 0.1 M, use the three-dimensional graphene skeleton as a working electrode and a platinum sheet as a counter electrode to perform constant current deposition, wherein the deposition current is 2 mA / cm 2, and the graphene / manganese dioxide porous network was obtained by washing and vacuum drying for 30 min; the graphene / manganese dioxide porous network was immersed in a dopamine hydrochloride solution with a concentration of 2 g / L to obtain a dopamine modified solution, wherein the mass ratio of the graphene / manganese dioxide porous network to the dopamine hydrochloride was 100:1, and a Tris buffer was used to maintain the pH of the solution at 9.5, and the solution was stirred at room temperature for 24 h, and then centrifuged and dried to obtain a polydopamine coated porous network; the polydopamine coated porous network was immersed in an ethanol solution of dodecafluoroheptyl methacrylate with a mass fraction of 15 wt.%, wherein the mass ratio of the polydopamine coated porous network to the dodecafluoroheptyl methacrylate was 1:0.1, and a photoinitiator Irgacure 2959 was added to obtain a reaction solution E, and the amount of the photoinitiator was 2% of the mass of the dodecafluoroheptyl methacrylate, and the reaction solution E was ultraviolet cured under the protection of nitrogen, and the ultraviolet intensity of the curing was 15 mW / cm 2 , and the curing time was 15 min, to obtain a super-hydrophobic graphene / manganese dioxide porous network.

[0162] The preparation method of the LDH-fiber nanosheet was as follows:

[0163] S23: magnesium nitrate and aluminum nitrate were weighed to prepare a mixed metal salt solution with a concentration of 0.2 M, wherein the molar ratio of the magnesium nitrate to the aluminum nitrate was 3:1, and a 1, 1.5, 1.3, or 2 M sodium hydroxide solution was added dropwise under stirring to adjust the pH to 9.4 to obtain a reaction solution F, and the reaction solution F was aged at 80 °C for 12 h, and then centrifuged, washed, and dried to obtain LDH powder; the LDH powder was mixed with an ionic liquid [EMIM][BF4] in acetonitrile at a mass ratio of 1:0.3 to obtain an intercalation modification solution, wherein the mass ratio of the LDH powder to the acetonitrile was 1:20, and the intercalation modification solution was ultrasonically treated at a constant temperature of 60 °C for 3 h, and then centrifuged, washed, and dried to obtain intercalation modified LDH; a polyacrylonitrile solution with a mass fraction of 15 wt.% in N,N-dimethylformamide was prepared, and a polyacrylonitrile fiber membrane was prepared by electrospinning; a 10 mg / mL intercalation modified LDH suspension was sprayed onto the surface of the polyacrylonitrile fiber membrane, and then dried to obtain an LDH-fiber nanosheet, wherein the mass fraction of the LDH in the LDH-fiber nanosheet was 20%.

[0164] Comparative Example 1

[0165] This comparative example provided a super-insulation aerogel exterior wall coating, which was different from Example 1 in that the step of modifying the silica aerogel in step S1 was omitted, and the other operation steps and process parameters were the same as those of Example 1.

[0166] Comparative Example 2

[0167] The comparative example provides an ultra-thermal insulation aerogel exterior wall coating, which is different from example 1 in that the step of modifying the tungsten trioxide by rare earth doping in step S21 is omitted, and the tungsten trioxide is directly prepared, and the other operation steps and process parameters are completely same as example 1.

[0168] Comparative example 3

[0169] The comparative example provides an ultra-thermal insulation aerogel exterior wall coating, which is different from example 1 in that the step of modifying the porous network coated with polydopamine by using fluorine-containing polymer in S22 is omitted, and the other operation steps and process parameters are completely same as example 1.

[0170] Comparative example 4

[0171] The comparative example provides an ultra-thermal insulation aerogel exterior wall coating, which is different from example 1 in that in S2, no super-hydrophobic graphene / manganese dioxide porous network is added, and the other operation steps and process parameters are completely same as example 1.

[0172] Comparative example 5

[0173] The comparative example provides an ultra-thermal insulation aerogel exterior wall coating, which is different from example 1 in that in S2, no tungsten trioxide thermochromic particles are added, and the other operation steps and process parameters are completely same as example 1.

[0174] Comparative example 6

[0175] The comparative example provides an ultra-thermal insulation aerogel exterior wall coating, which is different from example 1 in that in S2, no LDH-fiber nanosheet is added, and the other operation steps and process parameters are completely same as example 1.

[0176] The ultra-thermal insulation aerogel exterior wall coatings of examples 1-4 and comparative examples 1-6 are tested for performance, and the specific process is as follows:

[0177] According to GB / T25261-2018, the thermal conductivity of the sample is tested;

[0178] According to the industry standard JG / T235-2014, the sample is tested;

[0179] The test results are shown in Table 1.

[0180] Table 1: Performance test results of the ultra-thermal insulation aerogel exterior wall coatings of examples 1-4 and comparative examples 1-6

[0181]

[0182]

[0183] From the test results of Example 1 and Comparative Example 1, it can be seen that when the aerogel modification step in S1 is omitted, the thermal conductivity of the coating increases to 0.25 W / (m·K), because the unmodified aerogel has poor dispersibility in the fluorosilicone emulsion and forms agglomerates, increasing the heat conduction channels; the solar reflectance decreases to 75%, and the hemispherical emissivity decreases to 82%, because the aerogel agglomeration leads to uneven light scattering, reducing the optical performance of the coating; obvious discoloration and peeling occur in the acid and alkali resistance test, and bubbling, rusting, and cracking occur in the salt spray resistance test, because the interfacial bonding force between the aerogel and the matrix is weak, and local damage is easily formed in the corrosive environment;

[0184] From the test results of Example 1 and Comparative Example 2, it can be seen that when the tungsten trioxide rare earth doping step in S21 is omitted, the thermal conductivity of the coating increases to 0.18 W / (m·K), because the agglomeration of undoped tungsten trioxide particles increases the local heat conduction; the solar reflectance decreases to 70%, and the hemispherical emissivity decreases to 78%, because the undoped tungsten trioxide has decreased optical performance and thermochromic response sensitivity, affecting the regulation effect of radiation heat transfer; the acid and alkali resistance and salt spray resistance do not change significantly;

[0185] From the test results of Example 1 and Comparative Example 3, it can be seen that when the fluoropolymer modification step in S22 is omitted, the thermal conductivity of the coating increases to 0.19 W / (m·K), because the interfacial performance has deteriorated, increasing the heat conduction; the solar reflectance decreases to 73%, and the hemispherical emissivity decreases to 80%, because the increased surface wettability affects the light reflection and emission characteristics; obvious discoloration and peeling occur in the acid and alkali resistance test, and bubbling, rusting, and cracking occur in the salt spray resistance test, because the loss of the hydrophobic protective layer makes it easier for water and corrosive media to penetrate into the coating;

[0186] From the test results of Example 1 and Comparative Example 4, it can be seen that without adding the superhydrophobic graphene / manganese dioxide porous network, the thermal conductivity of the coating increases to 0.21 W / (m·K), because the lack of the porous network provides a heat conduction barrier; the solar reflectance decreases to 76%, and the hemispherical emissivity decreases to 83%, because the loss of the porous structure's scattering effect on infrared radiation; discoloration and peeling occur in the acid and alkali resistance test, and obvious bubbling, rusting, and cracking occur in the salt spray resistance test, because the overall structural stability of the coating has decreased;

[0187] From the test results of Example 1 and Comparative Example 5, it can be seen that without adding the tungsten trioxide thermochromic particles, the thermal conductivity of the coating increases to 0.17 W / (m·K), because the temperature response regulation mechanism is lost; the solar reflectance decreases to 72%, and the hemispherical emissivity decreases to 81%, because the lack of selective regulation components for visible and infrared light; the acid and alkali resistance and salt spray resistance do not change significantly;

[0188] From the test results of Example 1 and Comparative Example 6, it can be seen that, without the addition of LDH-fiber nanosheets, the thermal conductivity of the coating increases to 0.16 W / (m·K), which is due to the lack of the heat conduction detour path provided by the layered structure; the solar reflectance decreases to 77%, and the hemispherical emissivity decreases to 85%, which is because the LDH layered structure loses the effect of extending the heat conduction path; obvious discoloration and peeling occur in the acid and alkali resistance test, and obvious blistering, rusting, and cracking occur in the salt spray resistance test, which is due to the lack of the fiber reinforcing phase, resulting in a decrease in the stability of the coating structure.

[0189] The above merely provides a specific implementation of the present application, but the protection scope of the present application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily conceived by those skilled in the art, and all such changes and replacements fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing a super-insulating aerogel exterior wall coating, characterized in that, The preparation method comprises: S1: adding the silica aerogel into an ethanol solution of a modifier HY-6085, adding deionized water and dibutyltin dilaurate after reaction under a nitrogen atmosphere to obtain a second modification solution, and obtaining a pre-modified silica aerogel powder after reaction and treatment; S2: adding a leveling agent, a defoaming agent and a preservative into a silicone oil emulsion, stirring uniformly, then sequentially adding the pre-modified silica aerogel powder, the super-hydrophobic graphene / manganese dioxide porous network, the tungsten trioxide thermochromic particle and the LDH-fiber nanosheet, uniformly dispersing, and vacuum deaerating to obtain the super-insulation aerogel exterior wall coating; The preparation method of the tungsten trioxide thermochromic particle is: S21: preparing an ammonium tungstate solution, dissolving a rare earth oxide in nitric acid to obtain a rare earth ion solution, mixing the rare earth ion solution with the ammonium tungstate solution to obtain a mixed solution, adjusting the pH with ammonia water to obtain a reaction liquid A, treating after microwave reaction to obtain a rare earth doped tungsten trioxide gel, calcining and grinding to obtain the rare earth doped tungsten trioxide; dispersing the tungsten trioxide and tetraethyl orthosilicate into an ethanol / water solution to obtain a dispersion liquid B, adjusting the pH with ammonia water to obtain a reaction liquid C, stirring and reacting, and treating to obtain the silica coated tungsten trioxide; and adding the silica coated tungsten trioxide into a modified dispersion liquid to obtain a reaction liquid D, drying in a supercritical carbon dioxide device after reaction to obtain the tungsten trioxide thermochromic particle; The mass fraction of the vinylidene fluoride-hexafluoropropylene copolymer dispersed in the N-methyl pyrrolidone in the modified dispersion liquid is 3-5 wt.%; The preparation method of the super-hydrophobic graphene / manganese dioxide porous network is: S22: placing a nickel foam into a CVD furnace, treating by introducing a mixed gas to obtain a three-dimensional graphene-nickel foam, immersing the three-dimensional graphene-nickel foam in a ferric chloride solution to obtain a three-dimensional graphene skeleton, preparing an electrolyte by using manganese sulfate and sulfuric acid, using the three-dimensional graphene skeleton as a working electrode and a platinum sheet as a counter electrode to perform constant current deposition, and treating to obtain the graphene / manganese dioxide porous network; immersing the graphene / manganese dioxide porous network in a dopamine hydrochloride solution, using a Tris buffer to maintain the pH, and obtaining a polydopamine coated porous network after reaction and treatment; immersing the polydopamine coated porous network in an ethanol solution of dodecafluoroheptyl methacrylate, adding a photoinitiator to obtain a reaction liquid E, and ultraviolet curing under nitrogen protection to obtain the super-hydrophobic graphene / manganese dioxide porous network; The preparation method of the LDH-fiber nanosheet is: S23: preparing a mixed metal salt solution, adding a sodium hydroxide solution to adjust the pH to obtain a reaction liquid F, and treating after aging to obtain an LDH powder; mixing the LDH powder and an ionic liquid [EMIM][BF4] in acetonitrile to obtain an intercalation modification solution, and treating after ultrasonic to obtain the intercalation modification LDH; preparing a polyacrylonitrile N,N-dimethylformamide solution, preparing a polyacrylonitrile fiber membrane by electrospinning, spraying the intercalation modification LDH suspension onto the surface of the polyacrylonitrile fiber membrane, and drying to obtain the LDH-fiber nanosheet.

2. The preparation method of the super-insulation aerogel exterior wall coating according to claim 1, wherein in S1: The mass fraction of the ethanol solution of the modifier HY-6085 is 2-5 wt.%; ​ The mass ratio of the silica aerogel to the ethanol solution of the modifier HY-6085 is 1:5-10; In S2: The leveling agent is any one of BYK-310, BYK-345 or a combination of the two; The feeding amount of the leveling agent is 0.2-0.5% of the total amount of the paint; The defoaming agent is any one of BYK-024, BYK-025 or a combination of the two; The feeding amount of the defoaming agent is 0.1-0.3% of the total amount of the paint; The preservative is any one of RocimaTM, ActicideMBS or a combination of the two; The feeding amount of the preservative is 0.1-0.2% of the total amount of the paint; The silicone oil emulsion is SILRES BS692; The mass ratio of the silicone oil emulsion, the pre-modified silica aerogel powder, the super-hydrophobic graphene / manganese dioxide porous network, the tungsten trioxide thermochromic particles, and the LDH-fiber nanosheet is (40-60):(20-30):(5-8):(3-5):(3-5).

3. The method for preparing a super-insulating aerogel exterior wall coating according to claim 1, characterized in that, In S21: The rare earth oxide is lanthanum oxide or cerium oxide; The molar ratio of tungsten ions to rare earth ions in the mixed solution is 1:0.01-0.05; The mixed solution is adjusted to a pH of 7-9 using ammonia water; The particle size of the rare earth-doped tungsten trioxide gel is 0.5-1 μm.

4. The method for preparing a super-insulating aerogel exterior wall coating according to claim 1, characterized in that, In S21: The mass ratio of the rare earth-doped tungsten trioxide gel to tetraethyl orthosilicate is 1:0.1-0.2; The dispersion liquid B is adjusted to a pH of 10-11 using ammonia water; The mass ratio of the silica-coated tungsten trioxide to the modified dispersion liquid is 1:10-20.

5. The method for preparing a super-insulating aerogel exterior wall coating according to claim 1, characterized in that, In S22: The volume ratio of methane:hydrogen:argon in the mixed gas is 1:5:20; The mass ratio of the graphene / manganese dioxide porous network to dopamine hydrochloride is 50-100:1; The dopamine-modified solution is maintained at a pH of 8.5-9.5 using a Tris buffer; The mass ratio of the polydopamine-coated porous network to dodecafluoroheptyl methacrylate is 1:0.01-0.1; The photoinitiator is Irgacure 2959, and the feeding amount of the photoinitiator is 1-2% of the mass of dodecafluoroheptyl methacrylate.

6. The method of claim 1, wherein the aerogel exterior wall coating is prepared by the steps of: In S23: The molar ratio of magnesium nitrate to aluminum nitrate in the mixed metal salt solution is 2-3:1; The mixed metal salt solution is adjusted to a pH of 9-10 by adding sodium hydroxide solution dropwise; The mass ratio of the LDH powder to the ionic liquid [EMIM][BF4] is 1:0.1-0.3; The mass ratio of the LDH powder to acetonitrile is 1:10-20; The concentration of the intercalation-modified LDH suspension is 5-10 mg / mL; The mass ratio of the LDH-fiber nanosheet to the ionic liquid [EMIM][BF4] is 1:0.1-0.

3.

7. A super-insulating aerogel exterior wall coating prepared by the method of any one of claims 1-6.

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