A low-freezing-point small-molecule thermal response color-changing intelligent window and a preparation method and application thereof

Abstract

This invention discloses a low-freezing-point small-molecule thermoresponsive color-changing smart window, its preparation method, and its applications. The small molecule has the structure of Formula 1, where R is independently selected from [−(CH2)]. a ] b -OCH3, a is 1 or 2; b is 2 to 10. This invention encapsulates a molecular aqueous solution of Formula 1 with specific concentrations of different metal cations within two glass layers to create a smart dynamic window capable of modulating light and heat transfer. The phase transition temperature of the smart dynamic window can be controlled by complexing specific metal ions with the crown ether cavity, and it possesses a low freezing point under the influence of salt ions, allowing it to be used in relatively harsh environmental conditions. By using simple and economical raw materials, the smart dynamic window of this invention represents a technological leap towards expanding into intelligent management systems in modern buildings.

Description

Technical Field

[0001] This invention relates to the field of smart window materials, specifically to a low freezing point small molecule thermo-responsive color-changing smart window, its preparation method, and its application. Background Technology

[0002] Materials exhibiting responsiveness to external stimuli have always attracted widespread attention. External stimuli can be divided into two main categories: chemical stimuli such as pH, solvent, ionic strength, and redox reactions, and physical stimuli such as light, heat, electricity, and mechanical force. Thermal stimuli are readily available; thermally responsive materials disperse uniformly within a certain temperature range, and phase separation occurs above this temperature (LCST) or below it (UCST), causing the system to become turbid. Current research on LCST behavior mainly focuses on high-molecular polymers based on polyethylene glycol, polypropylene glycol, poly(N-isopropylacrylamide), and polyvinylpyrrolidone. Research on small molecule systems is relatively limited. Small molecules with LCST properties not only bring greater flexibility to LCST systems and thermosensitive materials but also enable material functionalization; therefore, it is essential to develop small molecule systems with LCST properties.

[0003] Compared to polymer systems, small molecules offer the advantage of precise and controllable synthesis. Furthermore, compared to small molecule systems that require additional energy to control LCST behavior, LCST-type thermosensitive materials based on naturally temperature-controlled small molecules have enormous application potential, potentially being used as responsive materials for smart windows. Chinese Patent Publication No. CN118963033A discloses an electro / thermal dual-response color-changing smart window and its preparation method. However, the chemical structure of this disclosed window is complex, and the preparation method is cumbersome. Moreover, the smart window's transmittance is only 80% in its natural state below LCST, affecting visibility, and even above LCST, the transmittance remains at 40%, resulting in poor visual obstruction. Additionally, the aqueous solution of the thermally responsive molecules in this disclosed window does not switch between transparency and turbidity quickly enough, exhibiting poor sensitivity, and the average transmittance change is not significant enough, limiting its application to harsh environments. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing small-molecule LCST-type thermosensitive materials, such as cumbersome synthesis, interference of solution color with visibility in the natural state, poor thermosensitivity, and limited operating temperature range. It provides a low-freezing-point small-molecule thermoresponsive color-changing smart window, its preparation method, and its applications. This low-freezing-point small molecule, based on a crown ether system, is simple to synthesize. Its aqueous solution is colorless and transparent in the natural state. Through complexation with metal cations, it forms novel and diverse amphiphilic supramolecular assemblies, allowing control of a series of minimum phase transition temperatures and the type of cation. It exhibits excellent thermosensitivity, a low freezing point, and a wide operating temperature range. Its freezing point can reach approximately -10 degrees Celsius, making it suitable for most southern environments. The invention also provides a synthesis method and its application in creating a smart dynamic window capable of modulating light and heat transmission.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A low freezing point small molecule thermo-responsive color-changing smart window, wherein the thermo-responsive color-changing smart window has a sandwich structure, comprising two transparent glass pieces with a sandwich layer between the two transparent glass pieces, the sandwich layer being prepared from a temperature-responsive mixed solution, the temperature-responsive mixed solution comprising: temperature-responsive small molecules, electrolytes, and solvents; The first aspect of this invention relates to a molecule of Formula 1, which is a temperature-responsive small molecule: Wherein, R is independently selected from [-(CH2)]. a ] b -OY, where a is 1 or 2; b is an integer from 2 to 10; Y is selected from -CH3, -CH2CH3, -CH2CH2CH3, -CH(CH3)2.

[0006] The concentration of temperature-responsive small molecules in the temperature-responsive mixed solution is 15 mM-30 mM.

[0007] The electrolyte salt is potassium chloride, sodium chloride, cesium chloride, or barium chloride. The concentration of the electrolyte salt in the temperature-responsive mixed solution is 1-4 mol / L.

[0008] The solvent is water, and the mass ratio of the solvent to the temperature-responsive small molecule system is 98-99%.

[0009] The preparation method of the low freezing point small molecule thermo-responsive color-changing smart window includes the following steps: (1) Add the temperature-responsive small molecules to the solvent and stir to disperse them completely; (2) Add electrolyte salts to the solution obtained in step (1) and sonicate to disperse them completely; (3) Clamp two pieces of transparent glass and seal three sides with UV curing adhesive to obtain a double-layered glass window. Seal the fourth side of the mixture obtained in step (2) in the interlayer with UV curing adhesive to obtain an intelligent dynamic window.

[0010] A method for preparing a molecule with thermally responsive formula 1 includes the following steps: Under a nitrogen atmosphere, intermediate 1 Dissolve and stir until homogeneous. Add the activator under ice bath conditions to carry out the first step of the reaction, followed by the addition of intermediate 2. The second step of the reaction is carried out, and the product is separated. The R in intermediate 2 has the same meaning as the R in the structure of Equation 1.

[0011] In this reaction, the activator is sodium hydride, and the molar ratio of intermediate 1 to intermediate 2 is 1:1 to 1.5; the reaction temperature of intermediate 1 and activator is 0 to 5°C, and the reaction time is 1 to 2 hours; the molar ratio of intermediate 1 to activator is 1:3 to 4; the reaction temperature after adding intermediate 2 is 20 to 30°C, and the reaction time is 24 to 48 hours. Intermediate 1 and intermediate 2 are directly synthesized into the molecule of formula 1 in one step, with a yield of 84%. The synthesis method is efficient and simple.

[0012] Furthermore, the preparation method of intermediate 1 includes the following steps: (1) 3,4-Dihydroxybenzaldehyde, an acid-binding agent, and a catalyst were dissolved in a solvent, and 2-chloroethoxy-2-ethoxydiethanol was added. The mixture was heated under a nitrogen atmosphere to react and the resulting compound 1 was obtained. ; (2) Dissolve compound 1 obtained in step (1) with the catalyst and acid-binding agent in a solvent, stir and cool to 0~5℃. o C, p-toluenesulfonyl chloride was added, and the reaction was carried out at room temperature for 24 hours to obtain compound 2. ; (3) Dissolve compound 2 obtained in step (2) in a solvent, add an activator, then add catechol, and react under a nitrogen atmosphere for 24 hours to separate compound 3. ; (4) Dissolve compound 3 obtained in step (3) in a solvent, add a reducing agent, stir the reaction at low temperature for 24 hours, and separate to obtain intermediate 1. .

[0013] Furthermore, in step (1), the acid-binding agent is potassium carbonate, the catalyst is lithium bromide, and the molar ratio of 3,4-dihydroxybenzaldehyde:2-chloroethoxy-2-ethoxydiethanol:catalyst:template is 1:2~2.5:2.5~3:1~1.5, the reaction temperature is 100℃, and the reaction time is 48~72 hours; The catalyst in step (2) is 4-dimethylaminopyridine, the acid-binding agent is triethylamine, the molar ratio of compound 1: p-toluenesulfonyl chloride: catalyst: acid-binding agent is 1:3~3.5:2~2.5:8~10, the reaction temperature is 0~5℃, and the reaction time is 12~24 hours; The activator in step (3) is cesium carbonate, the molar ratio of compound 2:catechol:activator is 1:1~1.2:2.5~3, the reaction temperature is 90~100℃, and the reaction time is 12~24 hours.

[0014] The reducing agent in step (4) is sodium borohydride, the molar ratio of compound to reducing agent is 1:3 to 3.5, the reaction temperature is 0 to 10°C, and the reaction time is 12 to 24 hours.

[0015] Furthermore, the preparation method of intermediate 2 includes the following steps: (5) HO-[(CH2) a -O] b -Y, catalyst, and acid-binding agent are dissolved in a solvent, and p-toluenesulfonyl chloride is added to react, yielding TsO-[(CH2)] by separation. a -O] b -Y; Furthermore, in step (5), the catalyst is sodium hydroxide or potassium hydroxide, the acid-binding agent is triethylamine, and HO-[(CH2)] a -O] b The molar ratio of -Y: p-toluenesulfonyl chloride: catalyst: acid-binding agent is 1:1~2:2~2.5:0.1~0.2, the reaction temperature is 20~40℃, and the reaction time is 24~48 hours.

[0016] A second aspect of the invention relates to a solution comprising molecules of formula 1, wherein R is selected from [-(CH2)]. a ] b -OY, where a is 1 or 2, b is 2 to 10, and Y is selected from -CH3, -CH2CH3, -CH2CH2CH3, -CH(CH3)2. In the molecule of Formula 1, when Y is selected from -CH3, -CH2CH3, -CH2CH2CH3, -CH(CH3)2, the minimum critical dissolution temperature of the molecule of Formula 1 in solution can be significantly controlled due to the change in the ratio of hydrophilic and hydrophobic segments. The temperature is in the range of 20°C to 50°C.

[0017] A third aspect of the invention relates to solutions comprising molecules of formula 1, wherein R is selected from [-(CH2)]. a ] b -OY, where a is 1 or 2, b is 2 to 10, and Y is selected from -CH3, -CH2CH3, -CH2CH2CH3, -CH(CH3)2. The concentration of the molecule of Formula 1 in the solvent is in the range of 20 mM to 30 mM, wherein the solvent is selected from water. The solution exhibits temperature-adjustable transparency and is colorless and transparent below its minimum critical dissolution temperature (LCST) and becomes opaque above its minimum critical dissolution temperature (LCST), wherein the temperature is in the range of 20°C to 50°C.

[0018] A fourth aspect of the invention relates to a molecule of formula 1 exhibiting thermally responsive behavior, wherein the molecule is colorless, clear and transparent in its aqueous solution and exhibits a minimum critical solution temperature (LCST) phase transition close to room temperature. The solution, when prepared as a smart dynamic window, can achieve rapid switching of transparency and haze within 1.5 to 5 °C, thereby modulating light and heat transfer through rapid and reversible switching of optical transparency.

[0019] The fifth aspect of this invention relates to the characteristic that aqueous solutions containing formula 1 can utilize the cavity energy of crown ethers to form stable complexes with ions of different sizes through host-guest interactions, thereby enabling K... + Na + Cs + Ba 2+ Metal ions are added to an aqueous solution of a molecule of Formula 1 to form novel and diverse amphiphilic supramolecular assemblies, thereby achieving adjustable phase transition temperatures. The molar ratio of the molecule of Formula 1 to the metal ion is 1:5 to 200. The concentration of the metal complex of the molecule of Formula 1 in the solvent is in the range of 10 mM to 20 mM. The solvent is selected from water. The solution exhibits temperature-adjustable transparency and becomes opaque above its lowest critical dissolution temperature (LCST), which is in the range of 25°C to 60°C.

[0020] The sixth aspect of this invention relates to a molecular aqueous solution comprising Formula 1 whose phase transition temperature can be controlled by utilizing the salt-dissolution effect between the crown ether and the metal cation, as well as the salt-precipitation effect between the crown ether, the cation, and water, so that it first increases and then decreases with increasing salt concentration. Simultaneously, the freezing point of the molecular aqueous solution of Formula 1 can be significantly reduced by utilizing the hydration effect of the metal cation, preventing it from freezing at around -10 degrees Celsius, thus broadening its application scenarios and enabling it to function in more extreme environments.

[0021] This invention is based on a crown ether system, specifically a crown ether-type small molecule with a lowest critical solution temperature (LCST). An aqueous solution of the molecule of formula 1, with a specific concentration of electrolyte added, is encapsulated within two glass layers to create a smart dynamic window capable of modulating light and heat transfer. The phase transition temperature of the smart dynamic window can be controlled by adding different types and concentrations of metal cations. Using simple and economical raw materials, the smart dynamic window of this invention represents a technological leap towards intelligent management systems in modern buildings.

[0022] This overview aims to briefly introduce the main contents of the present invention. The following specific embodiments will describe the features and advantages of the present invention in detail to help understand the subject matter of the present invention. Attached Figure Description

[0023] Figure 1 It is the structural formula of Formula 1 of this invention.

[0024] Figure 2 yes Figure 1 The hydrogen NMR spectrum.

[0025] Figure 3 These are the transmittance-temperature curves and cloud point diagrams of aqueous solutions of molecules of Formula 1 at different concentrations according to the present invention.

[0026] Figure 4 The transmittance-temperature curves of the aqueous solution of Formula 1 with a concentration of 30 mM of the present invention during heating and cooling cycles, and the transmittance-temperature curves during cycling between 25 °C and 40 °C.

[0027] Figure 5 The graphs show the transmittance-temperature curves and cloud point diagrams of aqueous solutions containing different concentrations of potassium chloride added to molecules of Formula 1 according to the present invention.

[0028] Figure 6 This is a transparent-turbidity switching diagram of the intelligent dynamic window of the present invention containing an aqueous solution of a 20 mM molecule of Formula 1 with added 3.5 M potassium chloride.

[0029] Table 1 shows the overall performance of thermochromic smart windows with different concentrations of potassium chloride. Detailed Implementation

[0030] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0031] In one embodiment of this disclosure, an example of a molecule of thermally responsive formula 1 is provided. This disclosure is not limited to the specific methods and experimental conditions described, as such methods and conditions may be applicable.

[0032] Test methods Optical properties were tested using a UV-Vis spectrophotometer. The transmittance of a thermochromic smart window in the 200-800 nm range was measured at 1°C intervals between 20°C and 60°C using a temperature-responsive small-molecule aqueous solution. Temperature response performance was assessed by timing and recording the transmittance changes when the smart window was placed in a constant-temperature heating bath. Cyclic performance was tested under different conditions as needed.

[0033] Example 1. Synthesis of Compound 1 Take a clean 250 mL three-necked flask and add a magnetic stir bar. Under nitrogen protection, add 10.0 g (72.4 mmol) of 3,4-dihydroxybenzaldehyde dissolved in anhydrous N,N-dimethylformamide (30 mL), followed by the addition of potassium carbonate (25.0 g, 181.0 mmol) and anhydrous lithium bromide (6.3 g, 72.4 mmol) and stirring until homogeneous. Then, dissolve 16.9 g (159.3 mmol) of 2-[(2-chloroethoxy)ethoxy]ethanol in anhydrous N,N-dimethylformamide (20 mL) and slowly add it dropwise to the mixture while stirring at 100 °C. Continue the reaction for 2–3 days. After the reaction was complete, the mixture was separated into liquid and liquid phases using dichloromethane (60 mL) and water (60 mL). The organic phase was washed with 10% potassium carbonate solution (3 x 60 mL). Finally, the organic phase was collected and dried by rotary evaporation to obtain a light brown oily crude product. The crude product was purified by silica gel column chromatography to obtain a light brown oily product 1 (26.2 g, 90%). TLC (evolving solvent: dichloromethane: methanol = 20:1 / v:v), R f = 0.36, 1 H NMR (600 MHz, CDCl3, 298 K)δ (ppm): 9.83 (s, 1H), 7.45-7.43 (m, 2H), 6.99 (d, J = 8.6 Hz, 1H), 4.26-4.23(m, 4H), 3.94-3.90 (m, 4H), 3.77-3.68 (m, 16H), 3.61(m, 4H), 2.99(s, 3H); 13 CNMR (151 MHz, CDCl3, 298 K) δ (ppm): 190.82, 154.13, 149.03, 130.28, 126.80,112.31, 111.57, 72.68, 71.96, 70.88, 70.33, 69.48, 69.33, 68.60, 61.68. Example 2. Synthesis of Compound 2 Take a clean 350 mL round-bottom flask and dissolve compound 1 (6.0 g, 14.9 mmol), triethylamine (15.1 g, 20.8 mL, 149.2 mmol), and 4-dimethylaminopyridine (364 mg, 10%) in dichloromethane (30 mL). Stir and cool to 0–5 °C. Under ice-water bath conditions, slowly add a dichloromethane solution (60 mL) of p-toluenesulfonyl chloride (8.6 g, 44.8 mmol) to the reaction system over 3 h. After the addition is complete, continue the reaction at low temperature for 1 h, then return to room temperature and stir overnight. Monitor the reaction progress using a TLC plate. After the reaction is complete, add 2 M hydrochloric acid solution (20 mL) to acidify the system to pH = 5–6, and then wash the organic phase with 2 M hydrochloric acid solution (20 mL) and saturated brine (2 × 20 mL). The organic phase was dried and purified by silica gel column chromatography to give a pale yellow oily compound 2 (8.6 g, 81%). TLC (electrolyte: ethyl acetate: petroleum ether = 3:1 / v:v), R f = 0.44, 1 H NMR (600 MHz, CDCl3, 298 K) δ (ppm): 9.84(s,1H), 7.79 (d, J = 8.2 Hz, 4H), 7.46-7.43 (m, 2H), 7.33 (d, J = 8.2 Hz, 4H), 7.00 (d, J = 8.2Hz, 1H), 4.25-4.14 (m, 8H), 3.87 (m, 4H), 3.71-3.61 (m, 12H), 2.43 (s, 6H); 13 C NMR (151 MHz, CDCl3, 298 K): δ (ppm): 190.83, 154.30,149.14, 144.81, 132.97, 130.27, 129.82, 127.94, 126.74, 112.51, 111.82,70.86, 70.83, 70.81, 69.59, 69.46, 69.28, 69.24, 68.72, 68.65, 21.61. Example 3. Synthesis of Compound 3 Under nitrogen protection, cesium carbonate (11.5 g, 20.2 mmol) was dissolved in anhydrous N,N-dimethylformamide (30 mL). The reaction system was stirred and heated to 100 °C. Compound 2 (5.0 g, 7.0 mmol) and catechol (775 mg, 7.0 mmol) were dissolved in anhydrous N,N-dimethylformamide (20 mL) and transferred to a constant pressure dropping funnel. The solution was added dropwise to the reaction system. After the addition was complete, the reaction temperature was maintained and stirring continued for 24 h. The reaction progress was monitored by TLC plate, and the reaction was stopped when the reactants had completely reacted. Excess solvent was removed by rotary evaporation. The mixture was separated into aqueous and aqueous phases using dichloromethane (40 mL) and 10% w / v potassium carbonate (40 mL). The aqueous phase was extracted with dichloromethane (3 × 40 mL), and the organic phase was collected and concentrated. The mixture was then washed with 10% w / v potassium carbonate (20 mL) solution, and the solvent was evaporated to dryness. The crude product was then purified by silica gel column chromatography and recrystallized from ethanol to give compound 3 (2.2 g, 67%) as a white solid. TLC (electrolyte: ethyl acetate), R f = 0.37, mp: 87-88 o C, 1 H NMR (600MHz, CDCl3, 298 K) δ (ppm): 9.82 (s, 1H), 7.42 (d, J = 8.0 Hz, 1H), 7.38 (s,1H), 6.95 (d, J = 8.2 Hz, 1H), 6.90-6.87 (m, 4H), 4.23-4.19 (m, 8H), 3.97-3.91 (m, 8H), 3.85-3.83 (m, 8H); 13 C NMR (151 MHz, CDCl3, 298 K): δ (ppm):190.95, 154.40, 149.28, 149.00, 130.29, 126.90, 121.52, 114.07, 111.98,111.16, 71.65, 71.54, 71.42, 70.05, 69.79, 69.63, 69.56, 69.52, 69.43. Example 4. Synthesis of Intermediate 1 Compound 3 (2.0 g, 4.2 mmol) was added to a 100 mL single-necked flask and dissolved in 40 mL of anhydrous ethanol:anhydrous dichloromethane = 1:1. The solution was then cooled to 0–5 °C in an ice-water bath and stirred for 30 min. Sodium borohydride (476 mg, 12.6 mmol) was added in small, multiple portions. The mixture was stirred at low temperature for 1 h, then brought to room temperature and stirred overnight. After the reaction was complete, the solution was concentrated, and 1 M hydrochloric acid was slowly added under ice-water bath conditions to acidify the system to pH 5–6. The mixture was then allowed to stand and separated. The organic phase was washed successively with 1 M sodium bicarbonate solution (3 × 20 mL) and water (2 × 20 mL). The organic phase was collected and the solvent was removed by rotary evaporation. The crude product was purified by silica gel column chromatography to give a white solid intermediate 1 (1.9 g, 95%). TLC (electrolyte: ethyl acetate:methanol = 70:1 / v:v), R f = 0.5, mp: 94-95 o C. 1 H NMR (400 MHz, CDCl3,298 K) δ (ppm): 6.87 (m, 7H), 4.58 (s, 2H), 4.16 (m, 8H), 3.96-3.87 (m, 8H), 3.83 (s, 8H); 13 C NMR (151 MHz, CDCl3, 298 K): δ (ppm): 149.01, 148.91,148.39, 134.21, 121.41, 119.91, 114.07, 113.89, 113.00, 71.24, 69.89, 69.53,69.36, 65.17. Example 5. Synthesis of Intermediate 2 Tetraethylene glycol monomethyl ether (1.0 g, 4.8 mmol) was dissolved in anhydrous tetrahydrofuran (10 mL), followed by the addition of p-toluenesulfonyl chloride (1.83 g, 9.6 mmol) and sodium hydroxide catalyst (0.4 g, 9.6 mmol). The solution was stirred overnight at room temperature. Excess solvent was removed by rotary evaporation, and the mixture was separated by dichloromethane (40 mL) and water (40 mL). The aqueous phase was extracted with dichloromethane (3 × 40 mL), and the organic phase was collected and the solvent was removed by rotary evaporation. The solution was purified by column chromatography to give intermediate 1 (1.26 g, 72.5%), a yellow oily liquid. TLC (electrolyte: petroleum ether: ethyl acetate = 2:1 / v:v), R f = 0.5. 1HNMR (400 MHz, CDCl3, 298 K) δ (ppm): 7.81 (s, 2H), 7.36 (s, 2H), 3.71-3.54(m, 16H), 3.39 (s, 3H), 2.46 (s, 3H). Example 6. Synthesis of Formula 1 molecule Under ice bath conditions, sodium hydride (22 mg, 0.91 mmol) was dissolved in anhydrous tetrahydrofuran (5 mL), and intermediate 1 (174 mg, 0.364 mmol) was dissolved in anhydrous THF (5 mL) and slowly added dropwise. Intermediate 2 (158 mg, 0.437 mmol) was added at the same temperature, and the solution was heated to room temperature and stirred for 24 h under a nitrogen atmosphere. After the reaction was complete, a saturated ammonium chloride solution (10 mL) was added to quench the reaction. Excess solvent was removed by rotary evaporation. The mixture was separated by dichloromethane (40 mL) and water (40 mL). The aqueous phase was extracted with dichloromethane (3 × 40 mL), and the organic phase was dried over anhydrous sodium sulfate and the solvent was removed by rotary evaporation. The resulting yellow oily liquid of formula 1 (206 mg, 83.5%) was purified by column chromatography. TLC (electrolyte: ethyl acetate: methanol = 10:1 / v:v), R f = 0.3. 1 H NMR (400 MHz, CDCl3, 298 K) δ (ppm):6.91-6.82 (q, 7H), 4.49 (s, 2H), 4.2-4.15 (m, 8H), 3.96-3.91 (m, 8H), 3.87-3.82 (m, 8H), 3.7-3.55 (m,16H), 3.39 (s,3H). 13 C NMR (151 MHz, CDCl3, 298 K): δ(ppm):162.57, 148.91, 130.95, 121.41, 110.04, 95.56, 93.10,77.41, 77.09,76.77, 72.60, 71.92, 71.26, 70.46, 69.92, 69.88, 69.51, 69.38, 66.87, 59.03,36.50, 31.43. In one embodiment of the present invention, the manufacturing method of the intelligent dynamic window is as follows: at room temperature (25°C), temperature-responsive small molecules are added to a solvent and stirred to disperse them completely; an electrolyte salt is added to the resulting solution and ultrasonically treated for 20 minutes to disperse them completely; three 5×55×1 mm polytetrafluoroethylene strips are sandwiched between the three sides of two 60×60×3 mm ordinary glass pieces, and the three sides are sealed with UV-curable adhesive to obtain a double-glazed window with a 1 mm interlayer; after injecting an aqueous solution of the molecule of formula 1 into the interlayer, the fourth side is sealed with 5×55×1 mm polytetrafluoroethylene and UV-curable adhesive to obtain an intelligent dynamic window.

[0034] like Figure 3 As shown, the permeability-temperature curve of the aqueous solution of the molecule of Formula 1 indicates that the minimum critical dissolution temperature can be controlled from 30℃ to 42℃ when the concentration ranges from 20 mM to 30 mM, and the permeability of the 30 mM solution can be completely converted from 100% to 0% within 1.5℃, showing excellent sensitivity.

[0035] like Figure 4 As shown, the permeability-temperature curves of aqueous solutions of Formula 1 molecules with different concentrations of potassium chloride added indicate that, at a concentration of 20 mM, the addition of potassium chloride can cause the phase transition temperature to first increase and then decrease. By changing the concentration of potassium chloride, the cloud point temperature can be controlled from 27.5℃ to 47℃. Furthermore, after adding potassium chloride, the permeability of the solution can be completely converted from 100% to 0% within 1.5℃ to 3℃, demonstrating excellent sensitivity.

[0036] like Figure 5 As shown, the intelligent dynamic window prepared by the present invention exhibits a transparent-opaque transition under natural conditions. The intelligent dynamic window is completely transparent and visible below the minimum critical dissolution temperature, and becomes opaque above the minimum critical dissolution temperature, thus possessing temperature responsiveness.

[0037] In another embodiment of the invention, the aqueous solution of Formula 1 contained in the intelligent dynamic window interlayer can utilize the characteristic that the cavity of the crown ether can form stable complexes with ions of different sizes through host-guest interactions, thereby enabling K... + Na + Cs + Ba 2+Adding metal ions to an aqueous solution of Formula 1 molecules forms novel and diverse amphiphilic supramolecular assemblies, thereby achieving adjustable phase transition temperatures. The molar ratio of Formula 1 molecules to metal ions is 1:5 to 200. The concentration of the metal complex of Formula 1 molecules in the solvent is in the range of 10 mM to 20 mM, where the solvent is selected from water. The solution exhibits temperature-adjustable transparency and becomes opaque above its lowest critical solution temperature (LCST), which is in the range of 25°C to 60°C. Furthermore, the addition of metal ions significantly lowers the freezing point of the smart window, allowing it to maintain excellent performance under more extreme conditions. After adding 0 M to 4 M potassium chloride, its freezing point can be lowered from 0°C to -13°C, making it suitable for use under most environmental conditions.

[0038] In another embodiment of the invention, the intelligent dynamic window is colorless and transparent below the lowest critical melting temperature (LCST) and exhibits a significant change in transmittance when approaching the LCST temperature (27.5°C to 47°C). The intelligent dynamic window can achieve a rapid change in transparency within 1.5 to 5°C, thereby modulating light and heat transmission through rapid and reversible switching of optical transparency.

[0039] In another embodiment of the invention, the intelligent dynamic window has reversible transparency control at near room temperature (27.5°C to 40°C) for the effective management and utilization of energy in the building's indoor environment.

[0040] Table 1

Claims

1. A low-freezing-point small-molecule thermo-responsive color-changing smart window, characterized in that, The heat-responsive color-changing smart window has a sandwich structure, comprising two transparent glass panes with a sandwich layer between them. The sandwich layer is prepared from a temperature-responsive mixed solution, which includes: temperature-responsive small molecules, electrolytes, and solvents. The temperature-responsive small molecule described has the structure of Formula 1: Wherein, R is independently selected from [-(CH2)]. a ] b -OY, where a is 1 or 2; b is an integer from 2 to 10; Y is selected from -CH3, -CH2CH3, -CH2CH2CH3, -CH(CH3)2.

2. The low freezing point small molecule thermochromic smart window according to claim 1, characterized in that, The concentration of temperature-responsive small molecules in the temperature-responsive mixed solution is 15 mM-30 mM.

3. The low freezing point small molecule thermo-responsive color-changing smart window according to claim 1, characterized in that, The electrolyte salt is potassium chloride, sodium chloride, cesium chloride, or barium chloride.

4. The low freezing point small molecule thermo-responsive color-changing smart window according to claim 1, characterized in that, The concentration of the electrolyte salt in the temperature-responsive mixed solution is 1-4 mol / L.

5. The preparation method of the low freezing point small molecule thermo-responsive color-changing smart window according to claim 1, characterized in that, Includes the following steps: (1) Add the temperature-responsive small molecules to the solvent and stir to disperse them completely; (2) Add electrolyte salts to the solution obtained in step (1) and sonicate to disperse them completely; (3) Clamp two pieces of transparent glass and seal three sides with UV curing adhesive to obtain a double-layered glass window. Seal the fourth side of the mixture obtained in step (2) in the interlayer with UV curing adhesive to obtain an intelligent dynamic window.

6. The preparation method of the low freezing point small molecule thermo-responsive color-changing smart window according to claim 5, characterized in that, In step (1), the preparation of the temperature-responsive small molecule specifically includes: Under a nitrogen atmosphere, intermediate 1 Dissolve and stir the activator until homogeneous, proceed with the first step of the reaction, and then add intermediate 2. The second step reaction was carried out to separate low-freezing-point small molecules based on the crown ether system of Formula 1. The R in intermediate 2 has the same meaning as the R in the structure of Equation 1.

7. The preparation method of the low freezing point small molecule thermo-responsive color-changing smart window according to claim 6, characterized in that, The activator is sodium hydride.

8. The preparation method of the low freezing point small molecule thermo-responsive color-changing smart window according to claim 6, characterized in that, The molar ratio of intermediate 1 to intermediate 2 is 1:1 to 1.5; The molar ratio of intermediate 1 to activator is 1:2.5~3.

5.

9. The preparation method of the low freezing point small molecule thermo-responsive color-changing smart window according to claim 6, characterized in that, The conditions for the first step reaction are: reaction temperature of 0-10℃ and reaction time of 0.5-2 hours; The conditions for the second step reaction are: reaction temperature of 20-30℃ and reaction time of 24-48 hours.

10. The application of the low freezing point small molecule thermo-responsive color-changing smart window according to claim 1 as a smart dynamic window for modulating light and heat transfer.

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