A thermally responsive liquid smart window and its preparation method

Abstract

This invention discloses a thermoresponsive smart window and its preparation method. The method includes: using thermosensitive cyclodextrin as a solute and water and glycerol as solvents to prepare a thermoresponsive liquid system; injecting this system into the interlayer of a double-layer window panel to obtain a thermoresponsive liquid smart window. This invention adheres to the concept of green environmental protection, using safe, non-toxic, and environmentally friendly raw materials and a simple and feasible preparation method to obtain a thermoresponsive liquid smart window. The obtained smart window exhibits highly uniform liquid properties, significant antifreeze ability due to the presence of glycerol, high transparency in a cold state, and a rapid response speed upon heating, quickly becoming opaque, effectively modulating sunlight transmittance.

Description

Technical Field

[0001] This invention relates to the field of building energy conservation, specifically to a heat-responsive liquid smart window and its preparation method. Background Technology

[0002] According to a report released by the China Building Energy Conservation Association in 2021, building energy consumption accounted for 46.5% of the country's total energy consumption in 2018. Windows are a key component of building design, but they are also among the least energy-efficient parts. Because heat can easily be transferred through glass, windows have a significant impact on the heating and cooling costs of buildings. In the context of global energy shortages, the increase in building energy consumption has become a major obstacle to China's economic development. Therefore, new types of dynamically adjustable smart windows, capable of dynamically absorbing solar spectrum according to environmental changes, have attracted widespread attention. Smart windows can dynamically regulate the transmission and shielding of solar spectrum, thereby significantly reducing the energy consumed in regulating room temperature. This can not only alleviate the global energy crisis but also make a significant contribution to building a sustainable and harmonious society.

[0003] Smart windows can be classified according to different stimulus response types, including electrochromic, photochromic, and thermochromic smart windows. Among them, thermochromic smart windows are more conducive to large-scale applications in the future due to their low cost, simple structure, and lack of additional energy input, and better meet the requirements of building energy conservation for smart windows. The manufacture of thermochromic smart windows generally involves encapsulating thermochromic materials in a glass interlayer or coating the thermochromic material into a thin film onto the glass. Currently, many types of thermochromic materials have been discovered, which can be broadly divided into inorganic and organic categories. Among these, monoclinic VO2 and some perovskite-structured compounds are the most widely studied inorganic materials. VO2 can undergo a phase transition from monoclinic to rutile states at different temperatures, thereby adjusting the light transmittance. However, VO2 thin films have low visible light transmittance and high phase transition temperatures, making them unsuitable for practical applications. The poor stability of thermochromic perovskites is a problem faced by this material in the field of smart windows, and perovskites contain heavy metals, which may pose a health risk. Due to the aforementioned drawbacks of inorganic materials, organic thermochromic materials, particularly thermosensitive hydrogels, have attracted widespread attention in recent years, such as poly(N-isopropylacrylamide) (PNIPAM), hydroxypropyl cellulose (HPC), and their derivatives. The mechanism of action of thermosensitive hydrogels is their ability to respond to temperature and undergo reversible changes in phase or conformation. However, thermosensitive hydrogels are typically organic polymers, posing certain health risks and failing to meet the requirements of modern green and environmentally friendly smart windows. Most importantly, the thermal shrinkage and deformation of hydrogels can lead to unevenness in the window, resulting in a decreased ability to modulate light. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies in the field of smart windows by providing a thermoresponsive liquid smart window and its preparation method. Using environmentally friendly, non-toxic, and harmless thermosensitive cyclodextrin as a raw material, this invention creates a window essential to human life, avoiding harm to the human body and pollution to the environment. Furthermore, the interlayer of the smart window is a thermoresponsive liquid with extremely high uniformity, unlike materials such as hydrogels which shrink and deform upon heating, thus preventing a decrease in light-blocking ability.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A thermoresponsive liquid smart window includes: a thermoresponsive liquid and a double-layered window panel interlayer; the thermoresponsive liquid includes a solute portion and a solvent portion; the solute portion includes a thermosensitive cyclodextrin; the solvent portion includes water and glycerol; the double-layered window panel interlayer is used to contain the thermoresponsive liquid.

[0007] Optionally, the light transmittance of the thermally responsive liquid smart window decreases as the temperature increases.

[0008] Optionally, when the temperature is lower than a first temperature, the light transmittance of the thermally responsive liquid smart window can be greater than the first light transmittance. The first temperature can be between 10°C and 23°C. The first light transmittance can be no less than 75%; preferably, the first light transmittance can be no less than 80%.

[0009] Optionally, when the temperature is higher than the second temperature, the light transmittance of the thermally responsive liquid smart window can be lower than the second light transmittance. The second temperature can be between 28°C and 40°C. The second light transmittance can be no greater than 30%; preferably, the second light transmittance can be no greater than 20%.

[0010] Optionally, when the temperature is below 20°C, the light transmittance of the heat-responsive liquid smart window can be greater than 80%; when the temperature is above 30°C, the light transmittance of the heat-responsive liquid smart window can be less than 20%.

[0011] Optionally, the lower critical dissolution temperature of the thermosensitive cyclodextrin is 20℃-80℃, preferably 30℃-50℃, and more preferably 35℃-45℃.

[0012] Optionally, the volume ratio of water to glycerin is 10%:90%-90%:10%, preferably 40%:60%-70%:30%, and more preferably 50%:50%-60%:40%.

[0013] Optionally, the thickness of the double-layer window panel interlayer is 0.1nm-30mm, preferably 1nm-5nm, and more preferably 2nm-4nm.

[0014] Optionally, the material of the double-layer window panel interlayer is one or more combinations of silicate glass, borate glass, phosphate glass and aluminate glass, polyethylene plastic, polypropylene plastic, polystyrene plastic, and polyvinyl chloride plastic.

[0015] Optionally, the concentration of the thermally responsive liquid is 1 mg / mL-500 mg / mL, preferably 10 mg / mL-50 mg / mL, and more preferably 30 mg / mL-40 mg / mL.

[0016] Optionally, the thermosensitive cyclodextrin is represented by Formula 1:

[0017]

[0018] In Equation 1, x is a positive integer, y is a positive integer, and x+y is 6, 7, or 8; R1 is selected from one of the following structures:

[0019]

[0020] * indicates a bonding site with an adjacent atom.

[0021] A method for preparing a thermoresponsive liquid smart window includes: preparing a thermoresponsive liquid using thermosensitive cyclodextrin as a solute and water and glycerol as solvents, and injecting it into the interlayer of a double-layer window panel to obtain the thermoresponsive liquid smart window.

[0022] The significant advantages of this invention are:

[0023] This invention utilizes a safe, non-toxic, and environmentally friendly thermosensitive cyclodextrin to obtain a thermally responsive liquid smart window through a simple and feasible preparation process.

[0024] The thermally responsive liquid smart window produced by this invention is very uniform and will not shrink due to heat like traditional hydrogel smart windows, which would reduce the effective area of ​​the smart window and decrease its ability to modulate sunlight.

[0025] The thermally responsive liquid system prepared by this invention contains glycerol, thus exhibiting significant antifreeze capabilities and being suitable for a wider range of applications.

[0026] The thermally responsive liquid smart window produced by this invention has high transparency in a cold state and a fast response speed after being heated, quickly becoming opaque, which can effectively modulate the transmittance of sunlight. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the light transmittance of the thermally responsive liquid smart window obtained in Example 1.

[0029] Figure 2 The images show the transmission spectra of the thermally responsive liquid smart window obtained in Example 1 under different temperature conditions.

[0030] Figure 3 This is a diagram demonstrating the change in transparency of the thermally responsive liquid smart window obtained in Example 1 during the gradual heating process. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of one or more embodiments of this specification clearer, the technical solutions of one or more embodiments of this specification will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of them. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of one or more embodiments of this specification.

[0032] The fabrication of a thermally responsive liquid smart window includes the following steps:

[0033] A thermoresponsive liquid was prepared using thermosensitive cyclodextrin as the solute and water and glycerol as solvents. The liquid was then injected into the interlayer of a double-layer window panel to obtain the thermoresponsive liquid smart window.

[0034] The thermosensitive cyclodextrin has a lower critical dissolution temperature of 20℃-80℃. The lower critical dissolution temperature is the lowest temperature at which the solubility of the solute in the solvent decreases sharply. The volume ratio of water to glycerol is 10%:90% to 90%:10%. The thickness of the double-layer window panel interlayer is 0.1nm-30mm. The material of the double-layer window panel interlayer is one of silicate glass, borate glass, phosphate glass, aluminate glass, polyethylene plastic, polypropylene plastic, polystyrene plastic, or polyvinyl chloride plastic. The concentration of the thermally responsive liquid is 1mg / mL-500mg / mL.

[0035] The transmittance of the smart window is tested as follows: The smart window is placed in the sample cell of the UV-Vis-NIR spectrophotometer, and the wavelength range of 250nm-2500nm is selected for testing in transmittance mode.

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0037] Example 1

[0038] The fabrication of a thermally responsive liquid smart window includes the following steps:

[0039] 20 mg of thermosensitive cyclodextrin was used as the solute. The structure of the selected thermosensitive cyclodextrin is shown in Formula 2. 10 mL of water and glycerol in a volume ratio of 50%:50% were used as the solvent to dissolve the solute in the solvent to form a thermoresponsive liquid system. This system was injected into a silicate glass with a sandwich thickness of 5 mm. The injection port was sealed to obtain a thermoresponsive liquid smart window.

[0040] Equation 2 is as follows:

[0041]

[0042] Place the smart window in the sample cell of the UV-Vis-NIR spectrophotometer and select a wavelength range of 250nm-2500nm for testing in transmittance mode.

[0043] Tests showed that the smart window had a light transmittance of 80% at 15℃ and 15% at 32℃, which meets the actual usage requirements.

[0044] Figure 1 This is a photograph of the obtained thermally responsive liquid smart window. As can be seen from the image, the prepared smart window exhibits high light transmittance.

[0045] Figure 2 The figures show the transmittance spectra of the obtained thermally responsive liquid smart window under different temperature conditions. The transmittance curves, from bottom to top, correspond to 35℃, 32℃, 30℃ and 25℃ / 20℃ / 15℃, respectively. The curves corresponding to the three temperatures of 25℃, 20℃, and 15℃ overlap. As can be seen from the figures, it has excellent modulation capability for solar transmittance.

[0046] Figure 3 Optical images demonstrate the change in light transmittance of the obtained thermally responsive liquid smart window as temperature increases. As can be seen from the images, the smart window gradually changes from highly transparent to opaque as the ambient temperature gradually increases.

[0047] Example 2

[0048] The fabrication of a thermally responsive liquid smart window includes the following steps:

[0049] Using 50 mg of thermosensitive cyclodextrin as the solute (the structure of which is shown in Formula 2), and 2 mL of a solvent containing 70% water and 30% glycerol, the solute was dissolved to form a thermoresponsive liquid system. This system was then injected into a 3 mm thick silicate glass substrate, and the injection port was sealed to obtain a thermoresponsive liquid smart window. The smart window was placed in the sample cell of a UV-Vis-NIR spectrophotometer, and the wavelength range of 250 nm to 2500 nm was selected for testing in transmittance mode.

[0050] The test results showed that the light transmittance of the smart window was 82% at 10℃ and 10% at 35℃, which meets the actual usage requirements.

[0051] Example 3

[0052] The fabrication of a thermally responsive liquid smart window includes the following steps:

[0053] Using 30 mg of thermosensitive cyclodextrin as the solute (the structure of which is shown in Formula 2), and 10 mL of a solvent containing 60% water and 40% glycerol, the solute was dissolved to form a thermoresponsive liquid system. This system was then injected into a 5 mm thick silicate glass substrate, and the injection port was sealed to obtain a thermoresponsive liquid smart window. The smart window was placed in the sample cell of a UV-Vis-NIR spectrophotometer, and the wavelength range of 250 nm to 2500 nm was selected for testing in transmittance mode.

[0054] The test results showed that the light transmittance of the smart window was 81% at 12℃ and 12% at 34℃, which meets the actual usage requirements.

[0055] In summary, as can be seen from the above embodiments, the thermally responsive liquid smart window prepared by the present invention has a good modulation capability for sunlight, providing a new approach for building energy conservation.

[0056] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0057] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A thermally responsive liquid smart window, characterized in that, The thermally responsive liquid smart window includes: A thermoresponsive liquid; the thermoresponsive liquid comprises a solute portion and a solvent portion; the solute portion comprises a thermosensitive cyclodextrin; the solvent portion comprises water and glycerol; A double-layered window panel interlayer that contains the thermally responsive liquid; The thermosensitive cyclodextrin is represented by the following formula:

2. The thermally responsive liquid smart window as described in claim 1, characterized in that, The light transmittance of the thermally responsive liquid smart window decreases as the temperature increases.

3. The thermally responsive liquid smart window as described in claim 2, characterized in that, When the temperature is lower than a first temperature, the light transmittance of the thermally responsive liquid smart window is greater than the first light transmittance; the first temperature is 10°C to 23°C; the first light transmittance is not less than 75%; When the temperature is higher than the second temperature, the light transmittance of the thermally responsive liquid smart window is less than the second light transmittance; the second temperature is 28°C to 40°C; and the second light transmittance is no greater than 30%.

4. The thermally responsive liquid smart window as described in claim 1, characterized in that, The lower critical dissolution temperature of the thermosensitive cyclodextrin is 20℃-80℃.

5. The thermally responsive liquid smart window as described in claim 1, characterized in that, The volume ratio of water to glycerol is 10%:90% to 90%:10%.

6. The thermally responsive liquid smart window as described in claim 1, characterized in that, The concentration of the thermally responsive liquid is 1 mg / mL to 500 mg / mL.

7. The thermally responsive liquid smart window as described in claim 1, characterized in that, The material of the double-layer window panel interlayer is one or more combinations of silicate glass, borate glass, phosphate glass and aluminate glass, polyethylene plastic, polypropylene plastic, polystyrene plastic and polyvinyl chloride plastic.

8. The thermally responsive liquid smart window as described in claim 1, characterized in that, The thickness of the double-layer window panel interlayer is 0.1 nm-30 mm.

9. A method for preparing a thermally responsive liquid smart window, characterized in that, A thermoresponsive liquid was prepared using thermosensitive cyclodextrin as the solute and water and glycerol as solvents. The thermally responsive liquid is injected into the interlayer of the double-layer window panel to obtain the thermally responsive liquid smart window; The thermosensitive cyclodextrin is represented by the following formula:

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