Thermochromic material, method for preparing the same, smart film and smart glass

Abstract

The application discloses a kind of thermochromic materials and preparation method thereof, smart film and smart glass;The thermochromic material includes as follows: organic phase change material, deep eutectic solvent, photo initiator and crosslinking agent;Deep eutectic solvent is composed of hydrogen bond donor and hydrogen bond acceptor;Hydrogen bond donor includes donor I and donor II;At least one of the structural formula of donor I and donor II contains double bond structure;The application provides a novel thermochromic material, the preparation raw material of the material includes organic phase change material and deep eutectic solvent, wherein the first thermal response temperature point is provided by organic phase change material.Deep eutectic solvent provides second thermal response temperature point.Two thermal response temperature is wide.Therefore, the thermochromic material of the application can realize the effect of indoor lighting, shading and temperature adjustment by regulating two thermal response temperature points.

Description

Technical Field

[0001] This invention relates to the field of smart glass technology, and in particular to a thermochromic material and its preparation method, a smart film, and smart glass. Background Technology

[0002] Windows, as the interface between a building and the external environment, play a crucial role in regulating indoor light and heat, but they are also a "funnel" for building energy consumption. To improve building energy efficiency, researchers are dedicated to developing various types of smart glass. Among them, thermochromic smart glass can dynamically regulate visible and near-infrared light in a passive manner, without consuming additional energy. When the outdoor temperature rises, the window automatically darkens to reduce the influx of solar radiation heat and lower the indoor temperature; when the outdoor temperature is too low, the window darkens to prevent indoor heat loss, thereby reducing the load on temperature control equipment such as air conditioners and heating systems. This intelligent energy-saving method provides new ideas for building design.

[0003] Currently, the main research materials for thermochromic smart glass include inorganic oxide (vanadium dioxide) systems, perovskite systems, and hydrogel (NN dimethyl diacrylate) systems. These systems also have the following problems: inorganic oxide systems suffer from complex preparation processes, low light transmittance, poor stability, and heavy metal toxicity; perovskite systems have drawbacks such as high thermal response temperatures, poor environmental stability, low color contrast, and insufficient near-infrared modulation capabilities; hydrogel systems are costly, and aqueous systems are prone to water loss, making them unsuitable for outdoor environments. Inorganic oxide and perovskite systems require coating processes to achieve composite with glass, while hydrogel systems require glass interlayering processes to be incorporated into the glass. Both require additional costs and may even necessitate changes to the glass manufacturing process, making their application inconvenient. Furthermore, existing organic phase change materials have a single phase change point, which cannot meet the needs of applications in varying seasons.

[0004] Therefore, there is an urgent need to develop a new type of thermochromic material with multiple phase change points that can also be green and environmentally friendly, low in toxicity, easy to prepare, low in cost, convenient to use, highly stable, and capable of modulating sunlight. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the first aspect of the present invention proposes a thermochromic material having multiple phase transition points, which exhibits multiple dimming ranges with different transparency as the temperature changes.

[0006] A second aspect of the present invention also provides a method for preparing a thermochromic material.

[0007] A third aspect of the present invention also provides a smart thin film.

[0008] A fourth aspect of the present invention also provides a smart glass.

[0009] According to a first aspect of the present invention, a thermochromic material is provided, comprising the following raw materials for preparation: an organic phase change material, a deep eutectic solvent, a photoinitiator, and a crosslinking agent; wherein the deep eutectic solvent is composed of a hydrogen bond donor and a hydrogen bond acceptor;

[0010] The hydrogen bond donors include donor I and donor II;

[0011] At least one of the structural formulas of donor I and donor II contains a double bond structure;

[0012] The donor I is selected from at least one of acrylic acid, methacrylic acid, vinyl benzoic acid, or itaconic acid.

[0013] The donor II is selected from at least one of hydroxybutyl vinyl ether, hydroxyethyl acrylate, hydroxypropyl acrylate, carbamate acrylate, dimethylaminoethyl acrylate, ureidopyrimidinone, acrylamide, methacrylamide, or allylamine.

[0014] According to a preferred embodiment of the present invention, the hydrogen bond acceptor includes halide acceptors and / or amino acid acceptors.

[0015] According to a preferred embodiment of the present invention, the halide acceptor includes at least one of choline chloride, tetramethylammonium chloride, fluorinated choline, or chloroform.

[0016] According to a preferred embodiment of the present invention, the amino acid receptor includes at least one of proline, glycine, or glutamic acid.

[0017] According to a preferred embodiment of the present invention, the molar ratio of donor I to hydrogen bond acceptor and donor II is 1:(0.6~1.4):(4~6).

[0018] According to a preferred embodiment of the present invention, the relative molecular mass of the organic phase change material is 100~1000 g / mol.

[0019] According to a preferred embodiment of the present invention, the organic phase change material includes at least one of organic alcohol phase change materials, organic acid phase change materials, or alkane organic phase change materials.

[0020] According to a preferred embodiment of the present invention, the organic alcohol phase change material includes at least one of erythritol, n-hexadecyl alcohol, polyethylene glycol, or mannitol.

[0021] According to a preferred embodiment of the present invention, the organic acid phase change material includes at least one of palmitic acid, lauric acid, or octanoic acid.

[0022] According to a preferred embodiment of the present invention, the alkane-based organic phase change material includes at least one of tetradecane, n-octadecane, or n-eicosane.

[0023] According to a preferred embodiment of the present invention, the mass ratio of the organic phase change material to the deep eutectic solvent is (0.6~1.4):1.

[0024] According to a preferred embodiment of the present invention, the amount of photoinitiator is 0.01 wt.% to 0.2 wt.% based on the total mass of the deep eutectic solvent.

[0025] According to a preferred embodiment of the present invention, the amount of the crosslinking agent is 1 wt.% to 3 wt.% based on the total mass of the deep eutectic solvent.

[0026] According to a preferred embodiment of the present invention, the photoinitiator includes an organic photoinitiator and / or an inorganic photoactivated oxidant.

[0027] According to a preferred embodiment of the present invention, the organic photoinitiator includes at least one selected from 2-hydroxy-2-methyl-1-phenylpropanone, diphenyl ethyl ketone, azobisisobutyronitrile, and 1-hydroxycyclohexylphenylpropanone.

[0028] According to a preferred embodiment of the present invention, the inorganic photoactivated oxidant includes at least one of potassium persulfate, ammonium persulfate, or sodium persulfate.

[0029] According to a preferred embodiment of the present invention, the crosslinking agent includes an organic crosslinking agent and / or an inorganic crosslinking agent.

[0030] According to a preferred embodiment of the present invention, the organic crosslinking agent includes at least one of aluminum citrate, N,N-methylenebisacrylamide, ethylene glycol diacrylate, 2,2'-dimethyl-3,3',5,5'-triphenylmethane tetraisocyanate, or dicumyl peroxide.

[0031] According to a preferred embodiment of the present invention, the inorganic crosslinking agent includes at least one of calcium sulfate, magnesium hydroxide, magnesium oxide, magnesium silicate, or ammonium alum.

[0032] The thermochromic material according to embodiments of the present invention has at least the following beneficial effects:

[0033] This invention provides a novel thermochromic material. The raw materials for preparing this material include an organic phase change material and a deep eutectic solvent. The organic phase change material provides a first thermal response temperature point, where a phase change similar to water freezing occurs at low temperatures. The deep eutectic solvent provides a second thermal response temperature point. In the deep eutectic solvent, hydrogen bond acceptors combine with different hydrogen bond donors (donor I or donor II) at different temperatures (the second thermal response temperature point), resulting in a phase change. At high temperatures, the newly combined phase no longer forms a homogeneous phase with the organic phase change material, and phase separation occurs, leading to macroscopic color change. At room temperature, the hydrogen bond acceptors re-bind with the original donors, and the entire system returns to a homogeneous phase, i.e., a macroscopically transparent state.

[0034] In summary, the organic phase change material of this invention is a transparent liquid at room temperature, and undergoes a crystalline phase transition to form an opaque state at low temperatures. The deep eutectic solvent does not change color at room temperature, but at high temperatures, the competition between different hydrogen bond donors and acceptors reduces the compatibility between the deep eutectic solvent and the organic phase change material, leading to phase separation. This, in turn, causes a change in the transparency of the material at the second thermal response temperature. Therefore, the thermochromic material of this invention can achieve the effects of indoor lighting, shading, and temperature regulation by controlling the two thermal response temperature points.

[0035] According to a second aspect of the present invention, a method for preparing a thermochromic material as described in the first aspect of the present invention is provided, comprising the following steps:

[0036] S1. Mix the deep eutectic solvent, organic phase change material, initiator and crosslinking agent, remove bubbles to obtain precursor solution;

[0037] S2. The precursor solution is photocured to obtain the thermochromic material.

[0038] According to a preferred embodiment of the present invention, the deep eutectic solvent is prepared by the following method:

[0039] The hydrogen bond acceptor and hydrogen bond donor are obtained by stirring under heating.

[0040] According to a preferred embodiment of the present invention, the stirring rate is 400~1200 r / min.

[0041] According to a preferred embodiment of the present invention, the heating temperature is 40~100°C.

[0042] According to a preferred embodiment of the present invention, the defoaming method includes vacuum defoaming.

[0043] According to a preferred embodiment of the present invention, ultraviolet LED lamps are used for photocuring.

[0044] According to a preferred embodiment of the present invention, the photocuring time is 1 to 10 minutes.

[0045] A third aspect of the present invention provides a smart film comprising the thermochromic material described in the first aspect of the present invention.

[0046] A fourth aspect of the present invention provides a smart glass comprising the thermochromic material described in the first aspect of the present invention.

[0047] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0048] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0049] Figure 1 This is a thermal response diagram of the thermochromic material (smart film A) of Embodiment 1 of the present invention at different temperatures;

[0050] Figure 2 This is a graph showing the relationship between smart films with different hydrogen bond donor masses and their thermal response;

[0051] Figure 3 This is a graph showing the relationship between smart thin films and thermal responses of organic phase change materials with different relative molecular masses;

[0052] Figure 4 The thermal response diagrams of the thermochromic material (smart film B) in Comparative Example 1 at different temperatures are shown.

[0053] Figure 5 The thermal response diagrams of the thermochromic material (smart film C) in Comparative Example 2 at different temperatures are shown.

[0054] Figure 6 The thermal response diagrams of the thermochromic material (smart film D) in Comparative Example 3 at different temperatures are shown.

[0055] Figure 7 The thermal response diagrams of the thermochromic material (smart film H) in Comparative Example 4 at different temperatures are shown.

[0056] Figure 8 This is a solar spectral transmittance diagram of the thermochromic material (smart film A) of Embodiment 1 of the present invention in three thermal response ranges;

[0057] Figure 9 This is a thermal cycling stability test diagram of the thermochromic material (smart film A) of Embodiment 1 of the present invention;

[0058] Figure 10This is a photograph of a blank glass and a glass with the smart film A of Embodiment 1 of the present invention placed on a square hollow polystyrene foam box.

[0059] Figure 11 This is a graph showing the temperature and time relationship between a blank glass and a glass with the smart film A of Embodiment 1 of the present invention placed on a polystyrene foam square hollow box. Detailed Implementation

[0060] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0061] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0062] In some embodiments of the present invention, a thermochromic material is provided, comprising the following raw materials for preparation: an organic phase change material, a deep eutectic solvent, a photoinitiator, and a crosslinking agent; the deep eutectic solvent is composed of a hydrogen bond donor and a hydrogen bond acceptor;

[0063] Hydrogen bond donors include donor I and donor II;

[0064] At least one of the structural formulas of donor I and donor II contains a double bond structure;

[0065] Donor I is selected from at least one of acrylic acid, methacrylic acid, vinyl benzoic acid, or itaconic acid.

[0066] Donor II is selected from at least one of hydroxybutyl vinyl ether, hydroxyethyl acrylate, hydroxypropyl acrylate, carbamate acrylate, dimethylaminoethyl acrylate, ureidopyrimidinone, acrylamide, methacrylamide, or allylamine.

[0067] It is understood that this invention provides a novel thermochromic material, the raw materials for which include an organic phase change material and a deep eutectic solvent. The organic phase change material provides a first thermal response temperature point, at which a phase change similar to water freezing occurs at low temperatures. The deep eutectic solvent provides a second thermal response temperature point. In the deep eutectic solvent, hydrogen bond acceptors combine with different hydrogen bond donors (donor I or donor II) at different temperatures (the second thermal response temperature point), resulting in a change in phase state. At high temperatures, the newly combined phase state no longer forms a homogeneous phase with the organic phase change material, and phase separation occurs, resulting in macroscopic color change. At room temperature, the hydrogen bond acceptors re-bind with the original donors, and the entire system returns to a homogeneous phase, i.e., a macroscopically transparent state.

[0068] In summary, the organic phase change material of this invention is a transparent liquid at room temperature, and undergoes a crystalline phase transition to form an opaque state at low temperatures. The deep eutectic solvent does not change color at room temperature, but at high temperatures, the competition between different hydrogen bond donors and acceptors reduces the compatibility between the deep eutectic solvent and the organic phase change material, leading to phase separation. This, in turn, causes a change in the transparency of the material at the second thermal response temperature. Therefore, the thermochromic material of this invention can achieve the effects of indoor lighting, shading, and temperature regulation by controlling the two thermal response temperature points.

[0069] In some embodiments of the present invention, hydrogen bond acceptors include halide acceptors and / or amino acid acceptors.

[0070] In some embodiments of the present invention, the halide acceptor includes at least one of choline chloride, tetramethylammonium chloride, fluorinated choline, or chloroform.

[0071] In some embodiments of the present invention, the amino acid receptor includes at least one of proline, glycine, and / or glutamic acid.

[0072] In some embodiments of the present invention, the molar ratio of donor I to hydrogen bond acceptor and donor II is 1:(0.6~1.4):(4~6). Therefore, by controlling the molar ratio of donor I, donor II, and hydrogen bond acceptor, the range of the second response temperature point can be controlled.

[0073] In some embodiments of the present invention, the relative molecular mass of the organic phase change material is 100~1000 g / mol. For example, it includes 100 g / mol, 150 g / mol, 198 g / mol, 200 g / mol, 300 g / mol, 400 g / mol, 500 g / mol, 600 g / mol, 700 g / mol, 800 g / mol, 900 g / mol, 1000 g / mol, or any sub-range composed of two of the above values.

[0074] The thermal response temperature is influenced by the chain segment length of the organic phase change material, i.e., the average molecular weight of the organic material. Organic materials with higher molecular weights are more prone to crystallization, resulting in a higher first thermal response temperature. Therefore, this invention controls the temperature range of the first response temperature by adjusting the relative molecular weight of the organic phase change material.

[0075] In some embodiments of the present invention, the organic phase change material includes at least one of organic alcohol phase change materials, organic acid phase change materials, and alkane organic phase change materials.

[0076] In some embodiments of the present invention, the organic alcohol phase change material includes at least one of erythritol, n-hexadecyl alcohol, polyethylene glycol, or mannitol.

[0077] In some embodiments of the present invention, the organic acid phase change material includes at least one of palmitic acid, lauric acid, or octanoic acid.

[0078] In some embodiments of the present invention, the alkane-based organic phase change material includes at least one of tetradecane, n-octadecane, or n-eicosane.

[0079] In some embodiments of the present invention, the mass ratio of the organic phase change material to the deep eutectic solvent is (0.6~1.4):1. For example, it includes sub-ranges of mass ratios of 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, or any two of the above values.

[0080] In some embodiments of the present invention, the amount of photoinitiator is 0.01 wt.% to 0.2 wt.%, calculated based on the total mass of the deep eutectic solvent. For example, it includes 0.01 wt.%, 0.02 wt.%, 0.04 wt.%, 0.06 wt.%, 0.08 wt.%, 0.1 wt.%, 0.12 wt.%, 0.14 wt.%, 0.16 wt.%, 0.18 wt.%, 0.2 wt.%, or any sub-range consisting of two of the above values.

[0081] In some embodiments of the present invention, the amount of the crosslinking agent is 1 wt.% to 3 wt.% based on the total mass of the deep eutectic solvent. For example, it includes 1 wt.%, 1.2 wt.%, 1.4 wt.%, 1.6 wt.%, 1.8 wt.%, 2.0 wt.%, 2.2 wt.%, 2.4 wt.%, 2.4 wt.%, 2.6 wt.%, 2.8 wt.%, 3 wt.%, or any sub-range consisting of any two of the above values.

[0082] In some embodiments of the present invention, the photoinitiator includes an organic photoinitiator and / or an inorganic photoactivated oxidant.

[0083] In some embodiments of the present invention, the organic photoinitiator includes at least one of 2-hydroxy-2-methyl-1-phenylpropanone, diphenyl ethyl ketone, azobisisobutyronitrile, or 1-hydroxycyclohexylphenylpropanone.

[0084] In some embodiments of the present invention, the inorganic photoactivated oxidant includes at least one of potassium persulfate, ammonium persulfate, or sodium persulfate.

[0085] In some embodiments of the present invention, the crosslinking agent includes organic crosslinking agents and / or inorganic crosslinking agents.

[0086] In some embodiments of the present invention, the organic crosslinking agent includes at least one of aluminum citrate, N,N-methylenebisacrylamide, ethylene glycol diacrylate, 2,2'-dimethyl-3,3',5,5'-triphenylmethane tetraisocyanate, or dicumyl peroxide.

[0087] In some embodiments of the present invention, the inorganic crosslinking agent includes at least one of calcium sulfate, magnesium hydroxide, magnesium oxide, magnesium silicate, or ammonium alum.

[0088] In some embodiments of the present invention, a method for preparing a thermochromic material as described in the first aspect of the present invention is provided, comprising the following steps:

[0089] S1. Mix the deep eutectic solvent, organic phase change material, initiator and crosslinking agent, remove bubbles to obtain precursor solution;

[0090] S2. The precursor solution is photocured to obtain the thermochromic material.

[0091] In some embodiments of the present invention, the deep eutectic solvent is prepared by the following method:

[0092] The hydrogen bond acceptor and hydrogen bond donor are obtained by stirring under heating.

[0093] In some embodiments of the present invention, the stirring rate is 400~1200 r / min. For example, it includes 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min, 900 r / min, 1000 r / min, 1100 r / min, 1200 r / min or any sub-range of two of the above values.

[0094] In some embodiments of the present invention, the heating temperature is 40~100°C. For example, it includes a sub-range of temperature such as 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, or any two of the above values.

[0095] In some embodiments of the present invention, the defoaming method includes vacuum defoaming.

[0096] In some embodiments of the present invention, ultraviolet LED lamps are used for photocuring.

[0097] In some embodiments of the present invention, the photocuring time is 1 to 10 minutes. For example, it includes 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, or any sub-range composed of two of the above values.

[0098] In some embodiments of the present invention, a smart film is provided, comprising the thermochromic material described in the first aspect of the present invention.

[0099] Therefore, the smart film of this invention possesses all the effects of thermochromic materials, having two thermal response temperatures and exhibiting three dimming ranges as the temperature changes. In the low-temperature region (below the first thermal response temperature), the smart film appears white, which can be used for privacy protection. In the medium-temperature region (between the first and second thermal response temperatures), the smart film appears transparent, which can be used for indoor lighting. In the high-temperature region (above the second thermal response temperature), the smart film appears white, which can be used for indoor shading and temperature regulation.

[0100] Furthermore, the smart film of the present invention has a much lower near-infrared light transmittance in the low-temperature and high-temperature regions than in the medium-temperature region, and can be used for indoor temperature regulation to achieve energy saving.

[0101] In some embodiments of the present invention, a smart glass is provided, comprising the thermochromic material described in the first aspect of the present invention.

[0102] Therefore, the smart glass of the present invention has all the effects of the smart film of the present invention.

[0103] Example 1

[0104] This example provides a thermochromic material, the preparation method of which is as follows:

[0105] Preparation of deep eutectic solvent: 16 mmol of fluorinated choline, 70 mmol of hydroxyethyl acrylate and 16 mmol of methacrylic acid were mixed and then magnetically stirred at 400 rpm at 70 °C to obtain a homogeneous deep eutectic solvent.

[0106] S1. The above-mentioned deep eutectic solvent, 14g of PEG700, 0.015g of 1-hydroxycyclohexylphenyl ketone and 0.5g of ethylene glycol diacrylate are mixed to obtain a precursor solution.

[0107] S2. Remove air bubbles from the precursor solution by vacuum drying at 60°C, drop the precursor solution onto a silicone mold, and perform photo-initiated polymerization for 1 minute using a 45W 365nm ultraviolet LED to obtain a thermochromic material (denoted as: smart film A) on the silicone mold.

[0108] Furthermore, the prepared smart film A was placed on the surface of a transparent glass sheet and heated to a specified temperature in a temperature-controlled oven. The transmittance change of the smart film A at different temperatures was tested, and the transparency of the smart film A at the corresponding temperatures was observed by placing it through a window. The results are as follows: Figure 1As shown, as the temperature rises from 0℃ to 50℃, three thermal response ranges appear sequentially. The first thermal response range is white (corresponding to a shooting temperature of 3℃), the second thermal response range is the background outside the window (the gel becomes transparent) (corresponding to a shooting temperature of 23℃), and the third thermal response range is white (corresponding to a shooting temperature of 35℃). This indicates that the thermochromic material (smart film A) has two thermal response temperature points, i.e., three thermal response ranges.

[0109] Example 2

[0110] This example investigates the effect of the molar ratio of hydrogen bond donors and acceptors on the thermal response temperature. Specifically, based on Example 1, the molar ratio of methacrylic acid to fluorinated choline was changed sequentially to 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.1, 1:1.2, 1:1.3, and 1:1.4. The remaining raw materials and preparation methods remained the same as in Example 1. A thermochromic material (smart film E) was obtained, and the results are as follows... Figure 2 As shown, with the increase of the mass of the hydrogen bond acceptor, the first thermal response temperature of the smart film E is around 19.6℃, and the second thermal response temperature changes from 26.3℃ to 38℃.

[0111] Example 3

[0112] This example investigates the effect of the relative molecular weight of organic phase change materials on the thermal response temperature. The preparation method and raw materials are the same as in Example 1, except that PEG 400, PEG 500, and PEG 600 are used instead of PEG 700, respectively. A thermochromic material (smart film F) is obtained. The results are as follows... Figure 3 As shown, with the increase of the molecular weight of the organic phase change material, the first thermal response point of the smart thin film F changes from 3℃ to 19.6℃.

[0113] Example 4

[0114] This example provides a thermochromic material, which is prepared in the same way as in Example 1. The difference is that n-tetradecane and n-hexadecane are used to replace PEG 700, respectively, to obtain thermochromic materials (denoted as smart film G and smart film H); the first thermal response temperatures are 6°C and 20°C, respectively.

[0115] Example 5

[0116] This example provides a thermochromic material, prepared using the same method as in Example 1, except that 9g of hydroxyethyl acrylate and 1.2g of acrylic acid are used as hydrogen bond donors, and 2.5g of choline chloride is used as a hydrogen bond acceptor. The resulting thermochromic material (denoted as smart film J) has a first thermal response temperature of 20°C and a second thermal response temperature of 32°C.

[0117] Comparative Example 1

[0118] This example provides a thermochromic material, prepared using the same method as in Example 1, except that no organic phase change material or hydrogen bond donor is added. The resulting thin film B is observed through a window, and the results are as follows... Figure 4 As shown, as the temperature rises from 0 ℃ to 50 ℃, the color of film B only appears in the background, indicating that film B does not have two thermal response temperature points (corresponding to shooting temperatures of 3 ℃, 23 ℃, and 45 ℃ respectively).

[0119] Comparative Example 2

[0120] This example provides a thermochromic material, prepared using the same method as in Example 1, except that no organic phase change material is added. The resulting thin film C is observed through a window, and the results are as follows... Figure 5 As shown, as the temperature rises from 0 ℃ to 50 ℃, the color of the smart film C only appears in the background, indicating that the smart film C does not have two thermal response temperature points (corresponding to shooting temperatures of 3 ℃, 23 ℃, and 45 ℃ respectively).

[0121] Comparative Example 3

[0122] This example provides a thermochromic material, prepared using the same method as in Example 1, except that no hydrogen bond donor is added. The resulting thin film D is observed through a window, and the results are as follows... Figure 6 As shown, as the temperature rises from 0 ℃ to 50 ℃, the color of the smart film D changes from white to the background in sequence, indicating that the film D only has a first thermal response temperature point and no second thermal response temperature point (corresponding to shooting temperatures of 3℃, 23℃, and 45℃ respectively).

[0123] Comparative Example 4

[0124] This example provides a thermochromic material, prepared using the same method as in Example 1, except that methacrylic acid is not added. The thermochromic material (denoted as smart film H) is obtained. Film H is observed through a window, and the results are as follows... Figure 7 As shown, as the temperature increases from 0 ℃ to 50 ℃, the color of film H changes sequentially from white to transparent with impurities precipitated, and then back to white, indicating that film H has two phase transition points. However, in the transparent state at room temperature, the fluorinated choline receptor will precipitate impurities because there is no suitable hydrogen bond donor for binding.

[0125] Performance testing

[0126] The smart thin film A prepared in Example 1 of this invention was used for performance testing of solar light modulation. The solar spectral transmittance of smart thin film A in three thermal response ranges (380 nm-2500 nm) was tested, and the results are as follows. Figure 8As shown, the solar transmittance calculated using the AM 1.5 solar irradiance spectrum is 7.72%, 86.66%, and 39.99% in the three thermal response ranges, respectively; the visible light transmittance (380 nm-780 nm) is 2.65%, 92.95%, and 34.59% in the ranges, respectively; and the near-infrared light transmittance (780 nm-2500 nm) is 14.06%, 78.80%, and 46.81% in the ranges, respectively.

[0127] like Figure 9 As shown, the smart film A was placed in a temperature-controlled oven and heated or cooled to a specified temperature. The transmittance of the smart film A was then tested using a transmittance meter. After 100 cycles at temperatures ranging from 3°C to 45°C, the transmittance of the smart film A remained highly stable across the three thermal response ranges. Therefore, the smart film exhibits high visible light transmittance (92.95%), good near-infrared light modulation capability, and excellent cycling stability.

[0128] Furthermore, the blank glass and the glass with the smart film A of Embodiment 1 of the present invention were placed on a square hollow polystyrene foam box and sealed with tape. Then, the other sides except the glass side were wrapped with tin foil (see actual picture). Figure 10 As shown in the image, the left image is a blank glass pane, and the right image is a glass pane with the smart film A attached. A thermometer was inserted inside the box, and it was placed under a xenon lamp simulating sunlight for vertical illumination. The relationship between temperature and time was recorded, and the results are as follows. Figure 11 As shown, the temperatures of both the blank glass group and the glass group of smart film A increased over time, with the temperature of the blank glass group being significantly higher than that of the smart glass group. This is because the smart film can simulate the transmittance of near-infrared light in sunlight by regulating temperature, thereby reducing temperature fluctuations inside the box.

[0129] The present invention has been described in detail above with reference to the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A thermochromic material, characterized in that, The raw materials used in its preparation include: organic phase change material, deep eutectic solvent, photoinitiator, and crosslinking agent; the deep eutectic solvent is composed of a hydrogen bond donor and a hydrogen bond acceptor; the hydrogen bond acceptor is fluorinated choline. The hydrogen bond donors include donor I and donor II; The donor I is selected from acrylic acid and / or methacrylic acid; The donor II is selected from hydroxyethyl acrylate and / or hydroxypropyl acrylate; The molar ratio of donor I to hydrogen bond acceptor and donor II is 1:(0.6~1.4):(4~6). The relative molecular mass of the organic phase change material is 100~1000 g / mol; the organic phase change material includes at least one of organic alcohol phase change materials, organic acid phase change materials, and alkane organic phase change materials.

2. The thermochromic material according to claim 1, characterized in that, The mass ratio of the organic phase change material to the deep eutectic solvent is (0.6~1.4):

1.

3. The thermochromic material according to claim 1, characterized in that, Based on the total mass of the deep eutectic solvent, the amount of photoinitiator used is 0.01 wt.%~0.2 wt.%; And / or, based on the total mass of the deep eutectic solvent and the organic phase change material, the amount of the crosslinking agent is 1 wt.% to 3 wt.%.

4. The thermochromic material according to claim 1, characterized in that, The photoinitiator is an organic photoinitiator.

5. A method for preparing the thermochromic material as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Mix the deep eutectic solvent, organic phase change material, photoinitiator and crosslinking agent, remove bubbles, and obtain the precursor solution; S2. The precursor solution is photocured to obtain the thermochromic material.

6. A smart thin film, characterized in that, Includes the thermochromic material as described in any one of claims 1 to 4.

7. A type of smart glass, characterized in that, It includes the thermochromic material according to any one of claims 1 to 4 or the smart film according to claim 6.

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