Intelligent window and preparation method thereof

Abstract

The invention discloses an intelligent window and a preparation method thereof and belongs to the technical field of energy conservation. A first cavity and a second cavity which are isolated from each other are formed in a window body of the intelligent window in the thickness direction of the window body, and the first cavity is filled with a thermal response phase change material solution containing polyisopropylacrylamide and a first small molecule additive. And the second chamber is filled with a supercooled phase change material solution containing inorganic hydrated salt and a second small molecule additive. The mass ratio of the first small molecule additive in the thermal response phase change material solution is 0-50wt%, the mass ratio of the second small molecule additive in the supercooled phase change material solution is 0-20wt%, and both the first small molecule additive and the second small molecule additive contain electron donating or electron withdrawing groups. The intelligent window can automatically adjust the transparency and store heat, and can trigger the supercooled phase change material to crystallize in a mechanical triggering mode and the like, release heat and adjust the indoor temperature.

Description

Technical Field

[0001] The present application relates to the technical field of smart windows, and more specifically, to a smart window and a method for preparing the same. Background Art

[0002] Of the total energy consumption, about 40% is used in the building sector, of which about 50% is consumed through doors and windows. Therefore, windows are regarded as the least energy-efficient part of the building envelope and become a key focus for improving the energy performance of buildings. Fortunately, smart window technology provides a solution. This technology can automatically adjust light transmittance according to environmental conditions or user needs, maximize the use of natural light and control indoor temperature, significantly reduce the demand for heating and air conditioning, and improve living comfort.

[0003] At present, the research frontier of smart windows is mainly focused on the modulation of transmittance, and energy efficiency is improved by adopting a variety of modulation technologies, such as electrochromic, photochromic, mechanochromic and thermochromic methods. In the field of building energy conservation, the thermochromic method has unique zero energy input, excellent energy-saving performance, reasonable optical regulation and low cost.

[0004] However, these studies have overlooked the potential use of excess solar energy, which, if efficiently collected, can be used to meet indoor energy needs, especially for temperature compensation on cold nights, further reducing the energy consumption of heating equipment. Summary of the invention

[0005] The present application provides a smart window and a preparation method thereof, which can automatically adjust light transmittance and store energy, and release heat and adjust temperature as needed, thereby reducing the demand for heating and air conditioning.

[0006] This application is implemented as follows:

[0007] In the first aspect, the example of the present application provides a smart window, including a transparent window body. Along the thickness direction of the window body, the interior of the window body is provided with a first chamber and a second chamber isolated from each other, the first chamber is filled with a thermally responsive phase change material solution, and the second chamber is filled with a supercooled phase change material solution. The thermally responsive phase change material solution includes polyisopropylacrylamide and a first small molecule additive, and the mass proportion of the first small molecule additive in the thermally responsive phase change material solution is 0 to 50wt%. The supercooled phase change material solution includes an inorganic hydrated salt and a second small molecule additive, and the mass proportion of the second small molecule additive in the supercooled phase change material solution is 0 to 20wt%. Both the first small molecule additive and the second small molecule additive contain electron donating or electron withdrawing groups.

[0008] In the above implementation process, the two chambers of the window body are filled with a thermal responsive phase change material solution and a supercooled phase change material solution respectively. When the ambient temperature is higher than the phase transition temperature of the thermal responsive phase change material solution, the thermal responsive phase change material undergoes a phase transition, so that the smart window presents a translucent foggy white state with reduced transparency, which can block light and thermal radiation, thereby reducing the indoor temperature and reducing the energy consumption of indoor air conditioning. When the ambient temperature is lower than the phase transition temperature of the thermal responsive phase change material, the smart window can present high transparency to meet the indoor lighting needs, and the supercooled phase change material can store energy and maintain a stable supercooled state. When the room temperature is too low and heat needs to be released, the supercooled phase change material can be triggered by mechanical triggering or needle tip triggering, so that the inorganic hydrated salt in the supercooled phase change material crystallizes and releases heat, thereby increasing the indoor temperature and reducing the energy consumption of indoor heating equipment.

[0009] In addition, the thermal responsive phase change material solution contains polyisopropylacrylamide, and the phase transition temperature of the thermal responsive phase change material can be adjusted according to user needs by adjusting the amount of the first small molecule additive containing an electron donating or electron withdrawing group. The phase transition temperature of the supercooled phase change material can be adjusted as needed by adding a second small molecule additive containing an electron donating or electron withdrawing group to the supercooled phase change material.

[0010] In combination with the first aspect, in an optional embodiment of the present application, the electron donating or electron withdrawing group includes at least one of a hydroxyl group, an amino group, a carbonyl group, a carboxyl group, a urea group, an amide group, a sulfonyl group, a cyano group, a nitro group or a sulfonyl group.

[0011] In combination with the first aspect, in an optional embodiment of the present application, the first small molecule additive and the second small molecule additive can be independently selected from at least one of urea, acetamide, methyl urea, ethanol, methanol, acetone, isopropanol, ammonia water, acetic acid, tartaric acid, citric acid, dimethylacetamide and dimethyl urea.

[0012] Optionally, the first small molecule additive and the second small molecule additive are independently selected from at least one of urea, acetamide, methyl urea, ethanol, methanol, acetone, isopropanol, ammonia, acetic acid, tartaric acid or citric acid.

[0013] Optionally, the first small molecule additive and the second small molecule additive are independently selected from at least one of dimethylacetamide or dimethylurea.

[0014] In the above implementation process, electron donating or electron withdrawing groups such as hydroxyl, amino, carbonyl, carboxyl, urea, amide, sulfonyl, cyano, nitro or sulfonyl can affect the electron cloud density of thermally responsive phase change materials and supercooled phase change materials, adjust the strength of hydrogen bonds in the phase change materials, and then adjust their phase transition temperature to meet the needs of users in different climatic regions for the response temperature of smart windows.

[0015] When the first small molecule additive and the second small molecule additive are selected from at least one of urea, acetamide, methyl urea, ethanol, methanol, acetone, isopropanol, ammonia, acetic acid, tartaric acid or citric acid, the phase transition temperature gradually decreases with the addition amount of the additives.

[0016] When the first small molecule additive and the second small molecule additive are selected from at least one of dimethylacetamide and dimethylurea, the phase transition temperature gradually increases with the amount of additives added.

[0017] In combination with the first aspect, in an optional embodiment of the present application, the inorganic hydrated salt includes at least one of sodium acetate trihydrate, sodium sulfate decahydrate, sodium carbonate decahydrate, calcium chloride hexahydrate, sodium thiosulfate pentahydrate, sodium hydrogen phosphate dodecahydrate, lithium nitrate trihydrate, magnesium chloride hexahydrate, zinc nitrate hexahydrate or magnesium nitrate hexahydrate.

[0018] In the above implementation process, the above-mentioned inorganic hydrated salt can maintain a stable supercooled state under the action of the second small molecule additive to store energy. When heat release is required, the above-mentioned inorganic hydrated salt can be crystallized and release heat through triggering methods such as mechanical triggering or needle tip triggering.

[0019] In combination with the first aspect, in an optional embodiment of the present application, the mass ratio of polyisopropylacrylamide to the first small molecule additive is 1:10-100.

[0020] Optionally, the mass proportion of the first small molecule additive in the thermal responsive phase change material solution is 5wt% to 50wt%.

[0021] In the above implementation process, the phase transition temperature of the thermal responsive phase change material can be adjusted by adjusting the amount of the first small molecule additive added. The mass ratio of polyisopropylacrylamide to the first small molecule additive is 1:10-100, which can make the phase transition temperature of the thermal responsive phase change material adjustable at 5°C-70°C.

[0022] In combination with the first aspect, in an optional embodiment of the present application, the mass ratio of the inorganic hydrated salt to the second small molecule additive is 1:0.05-0.2.

[0023] Optionally, the mass proportion of the second small molecule additive in the supercooled phase change material solution is 5wt% to 20wt%.

[0024] In the above implementation process, the phase transition temperature of the supercooled phase change material can be adjusted by adjusting the addition amount of the second small molecule additive.

[0025] In combination with the first aspect, in an optional embodiment of the present application, the polyisopropylacrylamide contains isopropylacrylamide monomers and methylenebisacrylamide monomers. And / or, the material of the window body includes at least one of glass, polydimethylsiloxane or polymethyl methacrylate.

[0026] In the above implementation process, the introduction of methylene bisacrylamide monomer into polyisopropyl acrylamide can improve the transparency of the smart window when the temperature environment is lower than the phase transition temperature of the thermal responsive phase change material. The window body is made of glass, polydimethylsiloxane or polymethyl methacrylate, which has high transparency and can further improve the user's comfort. A flexible smart window can be obtained by using a window body made of polydimethylsiloxane.

[0027] In a second aspect, an example of the present application provides a method of a smart window, comprising:

[0028] A transparent window body is obtained. A heat-responsive phase-change material solution is injected into the first chamber of the window body, and a supercooled phase-change material solution is injected into the second chamber, and then sealed.

[0029] In the above implementation process, a thermal responsive phase change material solution is injected into the first chamber of the window body, and a supercooled phase change material solution is injected into the second chamber, and a multi-layer smart window is sealed. When the ambient temperature is lower than the phase transition temperature of the thermal responsive phase change material, the smart window has a high transparency and can meet the indoor lighting needs. When the ambient temperature is higher than the phase transition temperature of the thermal responsive phase change material, the thermal responsive phase change material undergoes a phase change, and the transparency of the smart window decreases, becoming a translucent foggy white state, which can block light and heat radiation and reduce the indoor temperature. When the ambient temperature is too low, the supercooled phase change material can be triggered to change phase by mechanical triggering or needle tip triggering, so that the supercooled phase change material crystallizes and releases heat.

[0030] In conjunction with the second aspect, in an optional embodiment of the present application, a method for preparing a thermally responsive phase change material solution includes:

[0031] Dissolve isopropyl acrylamide and methylene bisacrylamide in water, add initiator and catalyst, react for 12h to 24h, add the first small molecule additive, and stir to mix.

[0032] Optionally, the mass ratio of isopropyl acrylamide, methylene bisacrylamide, initiator, catalyst and water is 3-4:0.5-1:0.5-2:6-8:100.

[0033] Optionally, the initiator includes ammonium persulfate.

[0034] Optionally, the catalyst comprises tetramethylethylenediamine.

[0035] In the above implementation process, isopropyl acrylamide and methylene bisacrylamide are dissolved in water, and ammonium persulfate initiator and tetramethylethylenediamine catalyst are added to make isopropyl acrylamide monomer and methylene bisacrylamide monomer undergo polymerization reaction to form polyisopropyl acrylamide. Adding the first small molecule additive to the solution of polyisopropyl acrylamide can adjust the phase transition temperature.

[0036] In conjunction with the second aspect, in an optional embodiment of the present application, a method for preparing a supercooled phase change material solution includes:

[0037] The inorganic hydrated salt is heated and melted to obtain a salt solution; the second small molecule additive is added into the salt solution, and the mixture is mixed and stirred.

[0038] In the above implementation process, the inorganic hydrated salt is heated and melted to obtain a salt solution, and the second small molecule additive is added to the salt solution, mixed and stirred, which can maintain a stable supercooled state, store energy, and crystallize and release energy after mechanical triggering. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0040] Figure 1 A cross-sectional schematic diagram of a smart window provided in an embodiment of the present application;

[0041] Figure 2 A physical picture of the smart window provided in Example 1 of the present application when the temperature is lower than the phase transition temperature of the thermally responsive phase change material;

[0042] Figure 3 A physical picture of the smart window provided in Example 1 of the present application when the temperature is higher than the phase transition temperature of the thermally responsive phase change material;

[0043] Figure 4 A physical picture of the smart window provided in Example 1 of the present application before triggering the crystallization of the supercooled phase change material;

[0044] Figure 5 A physical picture of the smart window provided in Example 1 of the present application after the supercooled phase change material is triggered to crystallize;

[0045] Figure 6 A statistical graph of phase transition temperatures of the thermally responsive phase change material of the smart window provided in Examples 1 to 16 of the present application;

[0046] Figure 7 A schematic diagram of the thermal cycle of the supercooled phase change material in the smart window provided in Example 1 of the present application;

[0047] Figure 8A schematic diagram of light transmittance of the smart window provided in Example 1 of the present application in different states;

[0048] Fig. 9 A schematic diagram of the thermal response rate of the smart window provided in Example 1 of the present application;

[0049] Fig.10 Schematic diagram of the triggered crystallization response rate of the smart window provided in Example 1 of the present application.

[0050] Icon: 100-smart window; 101-window body; 102-first chamber; 103-second chamber; 104-thermal responsive phase change material solution; 105-supercooled phase change material solution. DETAILED DESCRIPTION

[0051] The embodiments of the present application will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0052] At present, the research frontier of smart windows is mainly focused on the modulation of transmittance, and energy efficiency is improved by adopting a variety of modulation technologies, such as electrochromic, photochromic, mechanochromic and thermochromic. Among them, in the field of building energy conservation, the thermochromic method perfectly fits the concept of carbon neutrality due to its unique zero energy input, excellent energy-saving performance, reasonable optical regulation and low cost.

[0053] However, these studies have overlooked the potential use of excess solar energy, which, if efficiently collected, can be used to meet indoor energy needs, especially for temperature compensation on cold nights, further reducing the energy consumption of heating equipment.

[0054] In order to collect this energy, photovoltaic modules can be introduced into the window body to prepare photovoltaic smart windows. However, the photoelectric efficiency of photovoltaic smart windows is low, and it will affect the light transmittance of the smart windows and the lighting conditions. In addition, the structure of photovoltaic smart windows is relatively complex and the preparation process is cumbersome, which further limits the development of photovoltaic smart windows.

[0055] The inventors believe that thermal energy storage, as a means of energy utilization, if combined with thermally responsive smart window technology, can effectively reduce dependence on air conditioning and refrigeration and significantly improve energy utilization.

[0056] By embedding energy storage materials in smart windows, precise regulation of indoor lighting can be achieved while efficiently storing excess heat. During the day, these materials absorb and store thermal energy, then release it at night or when needed to help maintain a balanced indoor temperature. This integrated approach is expected to improve the overall energy efficiency of buildings while reducing reliance on traditional heating and cooling systems.

[0057] Based on this, the present application further improves the smart window, so that the problems of automatic light transmittance adjustment, energy storage and release of the smart window can be met to a certain extent. In order to make the purpose, technical solution and advantages of the embodiment of the present application clearer, the technical solution in the embodiment of the present application will be clearly and completely described in conjunction with the drawings in the embodiment of the present application.

[0058] The present application embodiment provides a method for preparing a smart window, comprising:

[0059] S1. Obtain a transparent window body. In the thickness direction of the window body, a first chamber and a second chamber isolated from each other are arranged inside the window body.

[0060] S2. Inject a thermally responsive phase change material solution into the first chamber of the window body, inject a supercooled phase change material solution into the second chamber, and seal.

[0061] The thermal responsive phase change material solution includes polyisopropylacrylamide and a first small molecule additive, the mass proportion of the first small molecule additive in the thermal responsive phase change material solution is 0-50wt%. The supercooled phase change material solution includes an inorganic hydrated salt and a second small molecule additive, the mass proportion of the second small molecule additive in the supercooled phase change material solution is 0-20wt%.

[0062] The first small molecule additive and the second small molecule additive both contain electron donating or electron withdrawing groups.

[0063] In step S1 , in some embodiments, the material of the transparent window body may include at least one of glass, polydimethylsiloxane (PDMS) or polymethyl methacrylate.

[0064] As an example, the material of the window body may be glass.

[0065] Furthermore, in some possible embodiments, the method for preparing a window body made of glass material includes:

[0066] The three pieces of glass are sealed with glass glue to form a three-layer glass structure.

[0067] As an example, the material of the window body may be polydimethylsiloxane.

[0068] Furthermore, in some embodiments, the method for preparing the window body made of polydimethylsiloxane includes:

[0069] Polydimethylsiloxane is injected into the mold and the desired three-layer structure is obtained through a curing process.

[0070] By using polydimethylsiloxane to prepare the window body, a flexible smart window can be obtained.

[0071] In step S2, a thermal responsive phase change material solution is injected into the first chamber of the window body. When the ambient temperature is lower than the phase transition temperature of the thermal responsive phase change material, the thermal responsive phase change material solution maintains a relatively high light transmittance. When the ambient temperature is higher than the phase transition temperature of the thermal responsive phase change material, the thermal responsive phase change material in the thermal responsive phase change material solution undergoes a phase change, which reduces the transparency of the smart window and turns it into a translucent foggy white state. The reduced transparency can block light and heat radiation, thereby reducing the indoor temperature and reducing the energy consumption of indoor air conditioning and refrigeration equipment.

[0072] Furthermore, in some embodiments, the method for preparing the thermally responsive phase change material solution includes:

[0073] S21, dissolving isopropyl acrylamide and methylene bisacrylamide in water, adding an initiator and a catalyst, reacting for 12 hours to 24 hours, adding a first small molecule additive, stirring and mixing, and obtaining a thermal responsive phase change material solution.

[0074] In some embodiments, isopropyl acrylamide and methylene bisacrylamide can be dissolved in deionized water to obtain a monomer solution. Then add a catalyst to the monomer solution and ultrasonically vibrate for more than 30 minutes. Then add an initiator, stir and mix at room temperature at a speed of 30r / min0 to 600r / min, and react the mixed solution at room temperature for 12h to 24h. After the reaction is complete, the solution is freeze-dried for 48h to 72h to obtain a freeze-dried powder. The obtained freeze-dried powder is dissolved in deionized water, the first small molecule additive is added, and the mixture is stirred and mixed at room temperature at a speed of 600r / min for more than 30min to obtain a uniform thermal response phase change material solution.

[0075] In some embodiments, the mass ratio of isopropyl acrylamide, methylene bisacrylamide, initiator, catalyst, and water is 3-4:0.5-1:0.5-2:6-8:100.

[0076] In one embodiment, the initiator includes ammonium persulfate.

[0077] In one embodiment, the catalyst includes tetramethylethylenediamine.

[0078] Adding a first small molecule additive containing an electron donating or electron withdrawing group into the thermal responsive phase change material solution can adjust the phase transition temperature of the thermal responsive phase change material as required.

[0079] For example, if the phase transition temperature of the thermally responsive phase change material solution in the smart window is too low, the smart window will always be in an opaque state during the day, which will affect the lighting. If the phase transition temperature of the thermally responsive phase change material solution in the smart window is too high, when it is necessary to block sunlight for shading during the day, the smart window will always be in a transparent state, and the transmittance cannot be automatically adjusted to achieve temperature regulation. Therefore, it is necessary to select smart windows containing different amounts of the first small molecule additive according to the average temperature conditions of the area of ​​use.

[0080] The first small molecule additive contains an electron donating or electron withdrawing group. The electron donating group is also called an electron supplying group, which is a concept opposite to the electron withdrawing group.

[0081] In some embodiments, the electron donating or electron withdrawing group of the first small molecule additive includes at least one of a hydroxyl group, an amino group, a carbonyl group, a carboxyl group, a urea group, an amide group, a sulfonyl group, a cyano group, a nitro group, or a sulfonyl group.

[0082] Exemplarily, the first small molecule additive may be selected from at least one of urea, acetamide, methyl urea, ethanol, methanol, acetone, isopropanol, ammonia, acetic acid, tartaric acid, citric acid, dimethylacetamide and dimethyl urea.

[0083] In some embodiments, the mass ratio of polyisopropylacrylamide to the first small molecule additive is 1:10-100, which can make the phase transition temperature of the thermally responsive phase change material adjustable within the range of 5°C to 70°C.

[0084] As an example, the mass ratio of polyisopropylacrylamide to the first small molecule additive may be 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90 or 1:100 or a range between any two of them.

[0085] Furthermore, in some embodiments, the mass percentage of the first small molecule additive in the thermal responsive phase change material solution is 5 wt % to 50 wt %.

[0086] As an example, the mass proportion of the first small molecule additive in the thermally responsive phase change material solution can be one of 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt% or 50wt%, or a range between any two of them.

[0087] In some embodiments, the first small molecule additive is selected from at least one of urea, acetamide, methyl urea, ethanol, methanol, acetone, isopropanol, ammonia, acetic acid, tartaric acid or citric acid. When the phase change temperature of the thermal responsive phase change material solution needs to be increased, the amount of the first small molecule additive added to the thermal responsive phase change material solution can be reduced. Similarly, when the phase change temperature of the thermal responsive phase change material solution needs to be reduced, the amount of the first small molecule additive added to the thermal responsive phase change material solution can be increased.

[0088] As an example, 0.5 wt% polyisopropylacrylamide (PNIPAM) can be dissolved in deionized water to prepare a PNIPAM aqueous solution, and then 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt% and 50 wt% of tartaric acid (TA) are respectively added and dissolved in the PNIPAM solution to obtain a thermally responsive phase change material solution having a phase transition point temperature between 30°C and 5°C.

[0089] For example, 0.5 wt% polyisopropylacrylamide (PNIPAM) can be dissolved in deionized water to prepare a PNIPAM aqueous solution, and then 5 wt% tartaric acid (TA) is added and dissolved in the PNIPAM solution to obtain a thermally responsive phase change material solution with a phase transition point temperature of approximately 30°C to 35°C.

[0090] For example, 0.5 wt% polyisopropylacrylamide (PNIPAM) can be dissolved in deionized water to prepare a PNIPAM aqueous solution, and then 30 wt% tartaric acid (TA) is added and dissolved in the PNIPAM solution to obtain a thermally responsive phase change material solution with a phase transition point temperature of approximately 20°C to 30°C.

[0091] For example, 0.5 wt% polyisopropylacrylamide (PNIPAM) can be dissolved in deionized water to prepare a PNIPAM aqueous solution, and then 40 wt% tartaric acid (TA) is added and dissolved in the PNIPAM solution to obtain a thermally responsive phase change material solution with a phase transition point temperature of approximately 10°C to 20°C.

[0092] In some embodiments, the first small molecule additive is selected from dimethylacetamide or dimethylurea, and when the phase change temperature of the thermally responsive phase change material solution needs to be increased, the amount of the first small molecule additive added to the thermally responsive phase change material solution can be increased. Similarly, when the phase change temperature of the thermally responsive phase change material solution needs to be reduced, the amount of the first small molecule additive added to the thermally responsive phase change material solution can be reduced.

[0093] As an example, 0.5 wt% polyisopropylacrylamide (PNIPAM) can be dissolved in deionized water to prepare a PNIPAM aqueous solution, and then 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt% and 50 wt% of dimethylacetamide DMA are added and dissolved in the PNIPAM solution respectively to obtain a thermally responsive phase change material solution having a phase transition point temperature between 30°C and 70°C.

[0094] For example, 0.5 wt% polyisopropylacrylamide (PNIPAM) can be dissolved in deionized water to prepare a PNIPAM aqueous solution, and then 5 wt% dimethylacetamide DMA is added and dissolved in the PNIPAM solution to obtain a thermally responsive phase change material solution with a phase transition point temperature approximately at 30°C to 35°C.

[0095] For example, 0.5 wt% polyisopropylacrylamide (PNIPAM) can be dissolved in deionized water to prepare a PNIPAM aqueous solution, and then 10 wt% dimethylacetamide DMA is added and dissolved in the PNIPAM solution to obtain a thermally responsive phase change material solution with a phase transition point temperature of approximately 40°C to 50°C.

[0096] For example, 0.5 wt% polyisopropylacrylamide (PNIPAM) can be dissolved in deionized water to prepare a PNIPAM aqueous solution, and then 20 wt% dimethylacetamide DMA is added and dissolved in the PNIPAM solution to obtain a thermally responsive phase change material solution with a phase transition point temperature of approximately 50°C to 60°C.

[0097] In step S2, a supercooled phase change material solution is injected into the second chamber of the window body. When the temperature is high, the supercooled phase change material can store excess heat. When the temperature is low, the supercooled phase change material can be crystallized by mechanical triggering or needle tip triggering to release latent heat and adjust the temperature.

[0098] Furthermore, in some embodiments, the method for preparing the supercooled phase change material solution includes:

[0099] The inorganic hydrated salt is heated and melted to obtain a salt solution. The second small molecule additive is added to the salt solution, mixed and stirred to obtain a supercooled phase change material solution.

[0100] The inorganic hydrated salt in the supercooled phase change material solution has the advantages of high energy storage density and small phase change volume. Adding a second small molecule additive containing an electron donating group to the supercooled phase change material solution can adjust the phase transition temperature of the supercooled phase change material.

[0101] In some embodiments, the inorganic hydrated salt includes at least one of sodium acetate trihydrate, sodium sulfate decahydrate, sodium carbonate decahydrate, calcium chloride hexahydrate, sodium thiosulfate pentahydrate, sodium hydrogen phosphate dodecahydrate, lithium nitrate trihydrate, magnesium chloride hexahydrate, zinc nitrate hexahydrate or magnesium nitrate hexahydrate.

[0102] As an example, the inorganic hydrated salt can be selected from calcium chloride hexahydrate.

[0103] As an example, the inorganic hydrated salt can be selected from sodium acetate trihydrate.

[0104] For example, if the phase transition temperature of the supercooled phase change material solution in the smart window is too high, and the transition temperature from the supercooled state to the crystalline state is relatively high, the phase transition may occur during the day, affecting the transparency of the smart window and the lighting. If the phase transition temperature of the supercooled phase change material solution in the smart window is too low, and the transition temperature from the supercooled state to the crystalline state is relatively low, the crystallization of the supercooled phase change material may not be effectively triggered to release heat. Therefore, it is necessary to select smart windows with different addition amounts of the second small molecule additive according to the average temperature conditions of the use area and the like.

[0105] In some embodiments, the electron-donating or electron-withdrawing group of the second small molecule additive can include at least one of hydroxyl, amino, carbonyl, carboxyl, ureido, amido, sulfonyl, cyano, nitro or sulfo group.

[0106] Exemplarily, the second small molecule additive can be selected from at least one of urea, acetamide, methylurea, ethanol, methanol, acetone, isopropanol, ammonia water, acetic acid, tartaric acid, citric acid, dimethylacetamide and dimethylurea.

[0107] In some embodiments, the mass ratio of the inorganic hydrated salt to the second small molecule additive is 1:0.05 to 0.2.

[0108] As an example, the mass ratio of the inorganic hydrated salt to the second small molecule additive can be one of 1:0.05, 1:0.1, 1:0.15 or 1:0.2, or within the range between any two of them.

[0109] Further, in some embodiments, the mass percentage of the second small molecule additive in the supercooled phase change material solution is 5wt% to 20wt%.

[0110] As an example, the mass percentage of the second small molecule additive in the supercooled phase change material solution can be one of 5wt%, 10wt%, 15wt% or 20wt%, or within the range between any two of them.

[0111] For example, when preparing the supercooled phase change material solution, CaCl can be added to deionized water 2(The mass ratio of calcium chloride to deionized water is 111:108), stir magnetically for more than 30 minutes at 90°C to make CaCl 2 Completely dissolve to prepare calcium chloride hexahydrate (abbreviated as CCH). Subsequently, 0.238 mol of ethanol (abbreviated as EtOH) is added to 1 mol of calcium chloride hexahydrate, and heated and stirred at 90°C for more than 10 minutes to completely dissolve it, so as to prepare a CCH-EtOH solution. In the obtained CCH-EtOH solution, 5wt%, 10wt%, 15wt% and 20wt% of urea are added respectively, and magnetic stirring is carried out at 90°C for more than 30 minutes until the urea is completely dissolved in the supercooled phase change material solution with different phase transition temperatures.

[0112] Furthermore, in some embodiments, in order to facilitate triggering the supercooled phase change material in the smart window, a triggering member such as a needle tip for triggering crystallization may be pre-set in the second chamber.

[0113] For further information, see Figure 1 The embodiment of the present application provides a smart window 100. The smart window 100 includes a transparent window body 101. Along the thickness direction of the window body 101, the interior of the window body 101 is provided with a first chamber 102 and a second chamber 103 isolated from each other. The first chamber 102 is filled with a thermally responsive phase change material solution 104, and the second chamber 103 is filled with a supercooled phase change material solution 105.

[0114] The thermal responsive phase change material solution includes polyisopropylacrylamide and a first small molecule additive, the mass proportion of the first small molecule additive in the thermal responsive phase change material solution is 0-50wt%. The supercooled phase change material solution includes an inorganic hydrated salt and a second small molecule additive, the mass proportion of the second small molecule additive in the supercooled phase change material solution is 0-20wt%.

[0115] The first small molecule additive and the second small molecule additive both contain electron donating or electron withdrawing groups.

[0116] Furthermore, the smart window 100 provided in the embodiment of the present application further includes a triggering member (not shown in the figure) disposed in the second chamber 103. The triggering member is, for example, a needle tip.

[0117] When using the smart window provided in the embodiment of the present application, the side filled with the thermal responsive phase change material is facing outward, and the side filled with the supercooled phase change material solution is facing inward, so that sunlight enters from the side filled with the thermal responsive phase change material solution.

[0118] The smart window and its preparation method of the present application are further described in detail below in conjunction with embodiments.

[0119] Example 1

[0120] Embodiment 1 provides a smart window, and the preparation method thereof comprises:

[0121] (1) Preparation of thermal responsive phase change material solution

[0122] 3.164g (about 0.28mol) of N-isopropylacrylamide monomer (NIPAM for short) and 862.4mg (about 0.056mol) of methylenebisacrylamide monomer (MBA for short) were dissolved in deionized water at 25°C to obtain 400mL of homogeneous aqueous solution. Then 6.15mL of catalyst tetramethylethylenediamine (TEMED for short) was added and stirred at 600rpm for 30min. Finally, 12.3mL of 10wt% initiator sodium persulfate (APS for short) was added. To complete the reaction, the solution was stirred for 24h, and then the homogeneous liquid was pre-frozen with liquid nitrogen and vacuum freeze-dried for 72h to obtain PNIPAM powder.

[0123] 0.5 wt% of PNIPAM powder was dissolved in deionized water to prepare liquid PNIPAM hydrogel. Subsequently, 5 wt% of the first small molecule additive dimethylacetamide (DMA) was dissolved in the PNIPAM solution to obtain a thermal responsive phase change material solution, which was recorded as PNIPAM-DMA solution.

[0124] (2) Preparation of supercooled phase change material solution

[0125] Add CaCl to deionized water 2 (The mass ratio of calcium chloride to deionized water is 111:108), and magnetic stirring is performed at 90°C for 30 min to make CaCl 2 Then, 0.238 mol of ethanol (EtOH) was added to 1 mol of CCH, and the mixture was heated and stirred at 90° C. for 10 min to completely dissolve the mixture, thereby obtaining a CCH-EtOH solution.

[0126] 5 wt % of the second small molecule additive urea was added to the obtained CCH-EtOH solution, and the mixture was magnetically stirred at 90° C. for 30 min until the urea was completely dissolved.

[0127] (3) Preparation of smart windows

[0128] The three sheets of glass are sealed with glass glue to form a three-layer glass structure containing two chambers. The thermal response phase change material solution prepared in step (1) and the supercooled phase change material solution prepared in step (2) are respectively injected into the two chambers to form a smart window.

[0129] Example 2

[0130] Embodiment 2 provides a smart window, which is different from Embodiment 1 in that:

[0131] In step (1), the amount of the first small molecule additive added is 10 wt %.

[0132] Example 3

[0133] Embodiment 3 provides a smart window, which is different from Embodiment 1 in that:

[0134] In step (1), the amount of the first small molecule additive added is 15 wt %.

[0135] Example 4

[0136] Embodiment 4 provides a smart window, which is different from Embodiment 1 in that:

[0137] In step (1), the amount of the first small molecule additive added is 20 wt%.

[0138] Example 5

[0139] Embodiment 5 provides a smart window, which is different from Embodiment 1 in that:

[0140] In step (1), the amount of the first small molecule additive added is 25 wt %.

[0141] Example 6

[0142] Embodiment 6 provides a smart window, which is different from Embodiment 1 in that:

[0143] In step (1), the amount of the first small molecule additive added is 30 wt%.

[0144] Example 7

[0145] Embodiment 7 provides a smart window, which is different from Embodiment 1 in that:

[0146] In step (1), the amount of the first small molecule additive added is 35 wt%.

[0147] Example 8

[0148] Embodiment 8 provides a smart window, which is different from Embodiment 1 in that:

[0149] In step (1), the amount of the first small molecule additive added is 40 wt%.

[0150] Example 9

[0151] Embodiment 9 provides a smart window, which is different from Embodiment 1 in that:

[0152] In step (1), the amount of the first small molecule additive added is 45 wt%.

[0153] Example 10

[0154] Embodiment 10 provides a smart window, which is different from Embodiment 1 in that:

[0155] In step (1), the amount of the first small molecule additive added is 50 wt%.

[0156] Embodiment 11

[0157] Embodiment 11 provides a smart window, which is different from Embodiment 1 in that:

[0158] In step (1), the first small molecule additive is tartaric acid (TA for short).

[0159] Example 12

[0160] Embodiment 12 provides a smart window, which is different from Embodiment 11 in that:

[0161] In step (1), the amount of the first small molecule additive tartaric acid (TA for short) added is 10 wt%.

[0162] Example 13

[0163] Embodiment 13 provides a smart window, which is different from Embodiment 11 in that:

[0164] In step (1), the amount of the first small molecule additive tartaric acid (TA for short) added is 15 wt%.

[0165] Embodiment 14

[0166] Embodiment 14 provides a smart window, which is different from Embodiment 11 in that:

[0167] In step (1), the amount of the first small molecule additive tartaric acid (TA for short) added is 20 wt%.

[0168] Embodiment 15

[0169] Embodiment 15 provides a smart window, which is different from Embodiment 11 in that:

[0170] In step (1), the amount of the first small molecule additive tartaric acid (TA for short) added is 25 wt%.

[0171] Example 16

[0172] Embodiment 16 provides a smart window, which is different from Embodiment 11 in that:

[0173] In step (1), the addition amount of the first small molecule additive tartaric acid (TA for short) is 30 wt%.

[0174] Embodiment 17

[0175] Embodiment 17 provides a smart window, which is different from Embodiment 11 in that:

[0176] In step (1), the amount of the first small molecule additive tartaric acid (TA for short) added is 35 wt%.

[0177] Embodiment 18

[0178] Embodiment 18 provides a smart window, which is different from Embodiment 11 in that:

[0179] In step (1), the addition amount of the first small molecule additive tartaric acid (TA for short) is 40 wt%.

[0180] Embodiment 19

[0181] Embodiment 19 provides a smart window, which is different from Embodiment 11 in that:

[0182] In step (1), the amount of the first small molecule additive tartaric acid (TA for short) added is 45 wt%.

[0183] Embodiment 20

[0184] Embodiment 20 provides a smart window, which is different from Embodiment 11 in that:

[0185] In step (1), the addition amount of the first small molecule additive tartaric acid (TA for short) is 50 wt%.

[0186] Embodiment 21

[0187] Embodiment 21 provides a smart window, which is different from Embodiment 1 in that:

[0188] In step (2), the amount of the second small molecule additive urea added is 10 wt%.

[0189] Embodiment 22

[0190] Embodiment 22 provides a smart window, which is different from Embodiment 1 in that:

[0191] In step (2), the amount of the second small molecule additive urea added is 15 wt%.

[0192] Embodiment 23

[0193] Embodiment 23 provides a smart window, which is different from Embodiment 1 in that:

[0194] In step (2), the amount of the second small molecule additive urea added is 20 wt%.

[0195] Embodiment 24

[0196] Embodiment 24 provides a smart window, which is different from Embodiment 1 in that:

[0197] In step (2), the second small molecule additive is ethanol.

[0198] Embodiment 25

[0199] Embodiment 25 provides a smart window, which is different from Embodiment 1 in that:

[0200] In step (2), 1 mol of sodium acetate trihydrate (SAT) was taken and magnetically stirred at 90° C. for 30 min to form a sodium acetate solution. Subsequently, 0.238 mol of acetic acid was added to 1 mol of SAT and heated and stirred at 90° C. for 10 min to completely dissolve the solution, thereby preparing SAT-CH3COOH.

[0201] Embodiment 26

[0202] Embodiment 26 provides a smart window, which is different from Embodiment 1 in that:

[0203] In step (3), polydimethylsiloxane (PDMS for short) is injected into the mold and cured to form a window body.

[0204] Some parameters of Examples 1 to 26 are shown in Table 1.

[0205] Table 1

[0206]

[0207]

[0208] Test Case

[0209] (1) The smart window prepared in Example 1 is placed below the phase transition temperature of the thermal responsive phase change material and above the phase transition temperature of the thermal responsive phase change material, and the transparency of the smart window is observed. Figure 2 and Figure 3 shown.

[0210] (2) Observe the transparency of the smart window prepared in Example 1 before and after triggering crystallization. The actual pictures are as follows: Figure 4 and Figure 5 shown.

[0211] (3) The phase transition temperatures of the thermally responsive phase change materials of the smart windows provided in Examples 1 to 20 are counted. The statistical results are as follows: Figure 6 shown.

[0212] (4) Detect the change in light transmittance of the smart window provided in Example 1 during the thermal cycle. Figure 7 shown.

[0213] (5) Detect the light transmittance of the smart window provided in Example 1 in different states. Figure 8 shown.

[0214] (6) Detect the response rate of the thermal response phase change material of the smart window provided in Example 1. Fig. 9 .

[0215] (7) Detect the response rate of the smart window provided in Example 1 when crystallization is triggered. See the crystallization response diagram Fig.10 .

[0216] Result analysis:

[0217] from Figure 2 It can be seen that when the ambient temperature is lower than the phase transition temperature of the thermal responsive phase change material, the smart window has a higher transparency and can meet the lighting needs of users. Figure 3 It can be seen that when the ambient temperature is higher than the phase transition temperature of the thermally responsive phase change material, the transparency of the smart window decreases and becomes translucent and foggy, which can block light and heat radiation, thereby lowering the indoor temperature and reducing the energy consumption of indoor air conditioning and refrigeration equipment.

[0218] from Figure 4 It can be seen that when the temperature of the smart window drops at night, before the crystallization is triggered, the supercooled phase change material can maintain a stable supercooled state and maintain a high degree of transparency. Figure 5 It can be seen that after triggered crystallization, the supercooled phase change material will undergo phase change crystallization, and the transparency of the smart window will decrease.

[0219] from Figure 6 It can be seen that the addition of different contents of dimethylacetamide (DMA) as the first small molecule additive in Examples 1 to 10 of the present application can adjust the phase transition temperature of the thermally responsive phase change material. As the amount of DMA added increases, the phase transition temperature of the thermally responsive phase change material gradually increases. The addition of different contents of tartaric acid (TA) as the first small molecule additive in Examples 11 to 20 of the present application can adjust the phase transition temperature of the thermally responsive phase change material. As the amount of TA added increases, the phase transition temperature of the thermally responsive phase change material gradually decreases.

[0220] from Figure 7It can be seen that in the smart window provided by the example of this application, the supercooled phase change material gradually changes from a solid crystalline state to a liquid state as the temperature increases, and the transparency of the smart window gradually increases. As the temperature decreases, the supercooled phase change material can maintain a stable supercooled state, and the smart window can still maintain a high transparency. After triggering crystallization, the supercooled phase change material gradually changes from a supercooled state to a crystalline state, and the light transmittance of the smart window gradually decreases.

[0221] from Figure 8 It can be seen that the smart window provided in Example 1 of the present application has a low transmittance of light of different wavelengths when the temperature is higher than the phase transition temperature of the thermally responsive phase change material, and can effectively block light and thermal radiation. When the supercooled phase change material is in a supercooled state, it has a high transmittance for light with a wavelength below 1500nm. After the supercooled deformation material is triggered to crystallize, the transparency of the smart window decreases when the supercooled phase change material is in a crystalline state.

[0222] from Fig. 9 It can be seen that for the smart window provided in Example 1 of the present application, at 0s, the temperature is lower than the phase transition temperature of the thermal responsive phase change material, and the smart window has a higher transparency. At 10s, the temperature rises above the phase transition temperature of the thermal responsive material, and the transparency of the smart window decreases rapidly, presenting a foggy white state. At 15s, the temperature is lowered to below the phase transition temperature of the thermal responsive phase change material, and the smart window can quickly transform into a highly transparent state again. This indicates that the smart window provided in the embodiment of the present application has a higher thermal response rate.

[0223] from Fig.10 It can be seen that at 0s, the temperature is roughly below 15°C, which is a supercooled state, and the smart window has a higher transparency. Crystallization begins to be triggered at 0s, and at 3s, the crystals grow and dissipate heat. The crystallized area becomes opaque. As time goes by, at 6s, 9s, and 12s, the crystals grow further and dissipate heat further. At 15s, the crystallization is complete and the temperature rises to above 30°C. This shows that the embodiment of the present application provides a smart window that can store heat well, trigger crystallization when needed, can quickly dissipate heat, can quickly heat up in a short time, and has a fast response speed.

[0224] In summary, the embodiment of the present application fills the first chamber of the window body with a thermally responsive phase change material solution containing polyisopropylacrylamide and a first small molecule additive, and fills the second chamber of the window body with an inorganic hydrated salt and a second small molecule additive. When the temperature is high, the transparency of the smart window can be automatically and quickly adjusted to block light and thermal radiation. The supercooled phase change material solution can store heat. When the temperature is low, the supercooled phase change material can be triggered to crystallize by mechanical triggering and the like to release heat, and the response speed is fast. By adjusting the addition amount of the first small molecule additive and the second small molecule additive containing electron donating or electron withdrawing groups, the response temperature of the smart window can be adjusted as needed to meet the usage needs of users in different climatic regions.

[0225] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A smart window, characterized in that: include: A transparent window body, wherein a first chamber and a second chamber isolated from each other are arranged inside the window body along the thickness direction of the window body, the first chamber is filled with a thermal response phase change material solution, and the second chamber is filled with a supercooled phase change material solution; The thermally responsive phase change material solution includes polyisopropylacrylamide and a first small molecule additive, the mass proportion of the first small molecule additive in the thermally responsive phase change material solution is 0 to 50 wt %; the supercooled phase change material solution includes an inorganic hydrated salt and a second small molecule additive, the mass proportion of the second small molecule additive in the supercooled phase change material solution is 0 to 20 wt %; the first small molecule additive and the second small molecule additive both contain electron donating or electron withdrawing groups.

2. The smart window according to claim 1, characterized in that: The electron donating or electron withdrawing group includes at least one of a hydroxyl group, an amino group, a carbonyl group, a carboxyl group, a urea group, an amide group, a sulfonyl group, a cyano group, a nitro group or a sulfonyl group.

3. The smart window according to claim 1, characterized in that: The first small molecule additive and the second small molecule additive can be independently selected from at least one of urea, acetamide, methyl urea, ethanol, methanol, acetone, isopropanol, ammonia, acetic acid, tartaric acid, citric acid, dimethylacetamide or dimethyl urea; Optionally, the first small molecule additive and the second small molecule additive are independently selected from at least one of urea, acetamide, methyl urea, ethanol, methanol, acetone, isopropanol, ammonia, acetic acid, tartaric acid or citric acid; Optionally, the first small molecule additive and the second small molecule additive are independently selected from at least one of dimethylacetamide and dimethylurea.

4. The smart window according to claim 1, characterized in that: The inorganic hydrated salt includes at least one of sodium acetate trihydrate, sodium sulfate decahydrate, sodium carbonate decahydrate, calcium chloride hexahydrate, sodium thiosulfate pentahydrate, sodium hydrogen phosphate dodecahydrate, lithium nitrate trihydrate, magnesium chloride hexahydrate, zinc nitrate hexahydrate or magnesium nitrate hexahydrate.

5. The smart window according to any one of claims 1 to 4, characterized in that: The mass ratio of the polyisopropylacrylamide to the first small molecule additive is 1:10-100; Optionally, the mass percentage of the first small molecule additive in the thermal responsive phase change material solution is 5wt% to 50wt%.

6. The smart window according to any one of claims 1 to 4, characterized in that: The mass ratio of the inorganic hydrated salt to the second small molecule additive is 1:0.05-0.2; Optionally, the mass percentage of the second small molecule additive in the supercooled phase change material solution is 5wt% to 20wt%.

7. The smart window according to claim 1, characterized in that: The polyisopropylacrylamide contains isopropylacrylamide monomer and methylenebisacrylamide monomer; And / or, the material of the window body includes at least one of glass, polydimethylsiloxane or polymethyl methacrylate.

8. A method for preparing the smart window according to any one of claims 1 to 7, characterized in that: include: Obtaining the transparent window body; The thermal response phase change material solution is injected into the first chamber of the window body, and the supercooled phase change material solution is injected into the second chamber, and then sealed.

9. The method according to claim 8, characterized in that The method for preparing the thermal responsive phase change material solution comprises: Dissolve isopropyl acrylamide and methylene bisacrylamide in water, add initiator and catalyst, and react for 12 to 24 hours; add the first small molecule additive, and stir to mix; Optionally, the mass ratio of the isopropyl acrylamide, the methylene bisacrylamide, the initiator, the catalyst, and the water is 3-4:0.5-1:0.5-2:6-8:100; Optionally, the initiator includes ammonium persulfate; Optionally, the catalyst comprises tetramethylethylenediamine.

10. The method according to claim 8, characterized in that The method for preparing the supercooled phase change material solution comprises: The inorganic hydrated salt is heated and melted to obtain a salt solution; the second small molecule additive is added into the salt solution, and the mixture is mixed and stirred.

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