Preparation method of thermochromic self-healing gel and its application in smart windows

Abstract

A preparation method of a thermochromic self-repairing gel and its application in a smart window, the steps are as follows: trimethylammonium salt modified olefin compound and bistrifluoromethanesulfonyl imide salt are stirred, washed and dried in water to obtain ionic liquid A; acrylic acid-2-phenoxyethyl ester is mixed with ionic liquid A and hydrophobic ionic liquid, a crosslinker and a photoinitiator are added, and a precursor B is obtained by ultrasonic dispersion; a phenylboronic acid olefin compound is dissolved in a tertiary amine methacrylate aqueous solution, a crosslinker and a photoinitiator are added, and a precursor C is obtained by ultrasonic dispersion; bubbles are removed by vacuum, and the gel is cured layer by layer under the action of an initiator to obtain a thermochromic self-repairing gel. The preparation process is simple, and the obtained hydrogel is applied to a smart window to obtain a smart window with high durability, fast thermal response, and self-repairability after external force damage; the smart window has thermochromic performance, and can automatically adjust the light transmittance according to the change of ambient temperature, so as to realize intelligent control of indoor temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogels, and in particular to a method for preparing a thermochromic self-repairing gel and an application of the same in smart windows. Background Art

[0002] As global warming and energy crisis become increasingly severe, the energy conservation and emission reduction issues of the construction industry, as one of the main areas of energy consumption, have attracted more and more attention. According to statistics, the energy used by buildings exceeds that of the industrial and transportation sectors, and windows are the main channel for internal and external exchange of energy in buildings. Improving their energy-saving performance is of great significance to reducing building energy consumption.

[0003] Traditional windows have limitations in terms of heat preservation, heat insulation, and light transmittance regulation. In particular, strong direct sunlight in summer can cause indoor temperatures to rise rapidly, increasing the energy consumption of refrigeration equipment. In addition, when traditional windows are damaged by external forces, the entire window usually needs to be replaced, which not only increases maintenance costs but also affects the aesthetics of the building.

[0004] To solve the limitations of traditional windows, smart windows came into being. They can achieve intelligent control of indoor temperature by adjusting the transmittance or absorption characteristics of incident light, thereby reducing building energy consumption. At present, smart windows are mainly divided into three forms: photochromic, electrochromic and thermochromic. Among them, although electrochromic smart windows and photochromic smart windows have efficient control capabilities, electrochromic requires power supply, electrical equipment and additional operating systems, and the manufacturing cost is high. Photochromic cannot be adaptively adjusted and the installation and maintenance costs are expensive, which limits its large-scale application. Thermochromic materials are the key to thermochromic smart windows. Thermochromic materials are a series of materials that can change color under temperature changes and do not require additional energy supply. The performance of this material directly affects the application of thermochromic smart windows. Therefore, choosing a thermochromic material with excellent performance is the key. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a thermochromic self-repairing gel and its application in smart windows. The method has a simple preparation process. The prepared hydrogel is applied to the smart window to obtain a smart window with high durability, fast thermal response, and the ability to self-repair after external force damage. At the same time, the smart window has thermochromic properties and can automatically adjust the light transmittance according to changes in ambient temperature, thereby realizing intelligent control of indoor temperature.

[0006] To achieve the above object, the present invention provides a method for preparing a thermochromic self-repairing gel, comprising the following steps:

[0007] S1, adding a trimethylammonium salt-modified olefin compound and a bistrifluoromethanesulfonyl imide salt to water and stirring, standing and stratifying, taking out the lower oil phase, washing it several times, and drying it to obtain an ionic liquid A;

[0008] S2, mixing 2-phenoxyethyl acrylate with ionic liquid A and hydrophobic ionic liquid, adding a crosslinking agent and a photoinitiator, and ultrasonically dispersing to obtain a precursor B;

[0009] S3, adding a phenylboronic acid olefin compound, a crosslinking agent, and a photoinitiator to the aqueous solution of tertiary amine methacrylate, and ultrasonically dispersing to obtain a precursor C;

[0010] S4. Vacuum remove the bubbles in precursor B and precursor C, and cure them layer by layer into glue under ultraviolet light in the order of a layer of precursor B, a layer of precursor C, and a layer of precursor B. That is, a layer of precursor B is cured by ultraviolet irradiation, and then a layer of precursor solution C is poured on the cured precursor B and cured by ultraviolet, and then a layer of precursor solution B is poured on the cured precursor C and cured by ultraviolet to obtain a three-layer structure of thermochromic self-healing gel.

[0011] Preferably, in step S1, the trimethylammonium salt modified olefin compound is methacryloyloxyethyl trimethylammonium chloride or vinyl trimethylammonium chloride; and the bistrifluoromethanesulfonyl imide salt is lithium bistrifluoromethanesulfonyl imide or silver bistrifluoromethanesulfonyl imide.

[0012] Preferably, in step S1, the mass ratio between the trimethylammonium salt modified olefin compound and the bistrifluoromethanesulfonyl imide salt is 1:(1-2), and the mass ratio between the trimethylammonium salt modified olefin compound and water is 1:(3-5).

[0013] Preferably, in step S2, the hydrophobic ionic liquid is one of 1-butyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide, bis(trifluoromethylsulfonyl)imide, and N-butylpyridine bis(trifluoromethylsulfonyl)imide.

[0014] Preferably, in step S2, the mass ratio between the 2-phenoxyethyl acrylate and the ionic liquid A is 1:(10-13); the molar ratio between the 2-phenoxyethyl acrylate and the hydrophobic ionic liquid is 1:(3-7); and the molar ratio between the 2-phenoxyethyl acrylate and the cross-linking agent is (45-50):1.

[0015] Preferably, in step S3, the phenylboronic acid olefin compound is styrylphenylboronic acid or 3-methacrylamidephenylboronic acid; and the tertiary amine methacrylate is one of dimethylaminoethyl methacrylate and N,N-diethylaminoethyl methacrylate.

[0016] Preferably, in step S3, the molar ratio of the tertiary amine methacrylate to the phenylboronic acid olefin compound is (9-11):1; the concentration of the tertiary amine methacrylate aqueous solution is 7-9 mol / L; and the molar ratio of the tertiary amine methacrylate to the cross-linking agent is (450-500):1.

[0017] Preferably, in steps S2 and S3, the crosslinking agent is one of glyoxal, diphenylmethane diisocyanate, methylenebisacrylamide, and acyl chloride; the photoinitiator is one of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone; the molar ratio between the photoinitiator and the crosslinking agent is (3-5):1; and the ultrasonic power is 10-100W.

[0018] Preferably, in step S4, the volume ratio of the precursor B, precursor C, and precursor B to be cured layer by layer is 1:(0.5-2):1; the power of the ultraviolet lamp is 60-70W, and the curing time for each layer is 2-5min; in step S1, the drying temperature is 50-70°C, and the drying time is 8-12h.

[0019] In order to achieve the above-mentioned purpose of the invention, the present invention also provides a smart window assembled with the thermochromic self-repairing gel prepared by the above-mentioned preparation method.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The preparation process of the present invention is simple. The prepared hydrogel is applied to a smart window to obtain a smart window with fast thermal response and capable of self-repair after external force damage. At the same time, the smart window has thermochromic properties and can automatically adjust light transmittance according to changes in ambient temperature to achieve intelligent control of indoor temperature. In addition, the smart window has the advantages of adjustable transparency, high toughness, strong impact resistance, good durability, etc., and can achieve the purpose of energy saving, emission reduction, and energy efficiency reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a comparison chart of the contact angle test results of different gel surfaces to water. In the figure, DA is the gel prepared in Comparative Example 2, DEE is the gel prepared in Comparative Example 1, and DEE-DA is the gel prepared in Example 1;

[0023] Figure 2 This is the mass change curve of the gel prepared in Example 1 swelling at room temperature within 7 days, and the inset is an enlarged view of the first 12 hours;

[0024] Figure 3It is a comparison chart of water loss test results of different gels at different temperatures within 20 days. In the figure, DA is the gel prepared in Comparative Example 2, DEE is the gel prepared in Comparative Example 1, and DEE-DA is the gel prepared in Example 1;

[0025] Figure 4 This is a schematic diagram of the transparency test results of the gel prepared in Example 1 at different temperatures;

[0026] Figure 5 The self-healing test results of the gel prepared in Example 1 at room temperature, i.e., the stress-strain curves at different healing times;

[0027] Figure 6 The self-healing test of the gel prepared in Example 1 at different temperatures, i.e., the change curve of stress and strain with time;

[0028] Figure 7 The self-healing efficiency of the gel prepared in Example 1 at 30° C., that is, a schematic diagram showing the relationship between the healing time and the efficiency;

[0029] Figure 8 Figure 2 is the stress-strain curve of gels with different ratios; in the figure, DEE2-DA (DEE-DA) is the gel prepared in Example 1; DEE 1。5 -DA represents the gel prepared in Example 2; DEE1-DA represents the gel prepared in Example 3;

[0030] Fig. 9 : are stress-strain curves of gels of different thicknesses; in the figure, DEE-DA-1 (DEE-DA) is the gel prepared in Example 1; DEE-DA-0.5 represents the gel prepared in Example 4, and DEE-DA-2 represents the gel prepared in Example 5;

[0031] Fig.10 Schematic diagram comparing the temperature barrier test results of a smart window assembled by using the gel prepared in Example 1 and a common window assembled by using traditional glass. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] The raw materials and reagents used in the following examples, unless otherwise specified, are all commercially available.

[0034] Example 1

[0035] A method for preparing a thermochromic self-repairing gel comprises the following steps:

[0036] S1. At 30°C, 5 g of methacryloyloxyethyl trimethylammonium chloride and 5.74 g of lithium bis(trifluoromethanesulfonyl imide) were added to 20 mL of water. After stirring, standing and stratification, the lower oil phase was taken out and washed several times, and dried at 70°C for 8 h to remove moisture to obtain ionic liquid A.

[0037] S2, 0.814 g of 2-phenoxyethyl acrylate, 10 g of ionic liquid A, and 5 g of 1-butyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide were mixed, 13.3 mg of methylenebisacrylamide and 66.7 μL of 2-hydroxy-2-methyl-1-phenyl-1-propanone were added, and ultrasonic dispersion was performed at 100 W power for 3 min to obtain precursor B;

[0038] S3, after adding 3.75 g of dimethylaminoethyl methacrylate into 3 mL of water to form a solution, 0.4931 g of 3-methacrylamidophenylboronic acid, 7.5 mg of methylenebisacrylamide, and 37.5 μL of 2-hydroxy-2-methyl-1-phenyl-1-propanone were added, and ultrasonic dispersion was performed at a power of 100 W for 3 min to obtain a precursor C;

[0039] S4. After removing the bubbles in precursor B and precursor C by vacuum, 1 mL of precursor B, 1 mL of precursor C, and 1 mL of precursor B were cured layer by layer using a 60 W ultraviolet lamp for 2 min to obtain a three-layer thermochromic self-healing gel DEE-DA.

[0040] from Figure 1 It can be seen that the contact angle of the gel surface prepared in this example to water is the largest compared with other gels, which is 112°.

[0041] from Figure 2 It can be seen that during the swelling process, the change in gel mass is always maintained at around 100%, indicating that the gel mass has no obvious change and has good anti-swelling ability.

[0042] from Figure 3 It can be seen that the gel mass ratio of the gel prepared in this embodiment is always maintained above 95% at different temperatures.

[0043] from Figure 4 It can be seen that the transparency of the gel prepared in this example is above 70% at 30°C; at 60°C, the gel phase separation caused by the breaking of some hydrogen bonds in the gel reduces its transparency to below 10%.

[0044] from Figure 5 It can be seen that the stress-strain curves of the gel prepared in this example are roughly the same after healing for 12 hours.

[0045] from Figure 6 It can be seen that with the increase of temperature, the stress and strain of the gel increase.

[0046] from Figure 7 It can be seen that as the healing time increases, the healing performance of the gel increases and is consistent with the strength of the uncut gel after 12 hours.

[0047] from Fig.10 It can be seen that the temperature difference between the inside and outside of the smart window is 18.7℃, and the temperature difference between the inside and outside of the ordinary window is 8.3℃. The temperature difference between the inside and outside of the smart window is much higher than that of the ordinary window, and its internal temperature is much lower than the internal temperature of the ordinary window under the same conditions. This shows that the smart window has good heat barrier ability.

[0048] Example 2

[0049] In this embodiment, only the amount of "1-butyl-3-methylimidazole di(trifluoromethylsulfonyl)imide" in step S2 is changed to 6.67 g, and the other steps are kept consistent with Example 1. The obtained thermochromic self-healing gel DEE 1.5 -DA.

[0050] The stress-strain curve of the gel prepared in this example corresponds to Figure 8 DEE 1.5 -DA, it can be seen that its stress is less than that of Example 1.

[0051] Example 3

[0052] In this embodiment, only 10 g of "1-butyl-3-methylimidazole di(trifluoromethylsulfonyl)imide" in step S2 is changed, and the other steps are kept consistent with Example 1 to obtain the thermochromic self-healing gel DEE1-DA.

[0053] The stress-strain curve of the comparative gel corresponds to Figure 8 It can be seen from the DEE1-DA in Example 1 that its stress is much smaller than that of Example 1 and Example 2.

[0054] from Figure 8 It can be seen that with the increase of monomer ratio, the stress gradually increases and the elongation gradually decreases.

[0055] Example 4

[0056] This embodiment only changes the step S4 of "curing 2 mL of precursor B, 1 mL of precursor C, and 2 mL of precursor B layer by layer under ultraviolet light to form a gel", and the other steps remain consistent with Example 1 to obtain the thermochromic self-healing gel DEE-DA-0.5.

[0057] The stress-strain curve of the gel in this example corresponds to Fig. 9 It can be seen that the breaking strength of DEE-DA-0.5 is less than that of Example 1.

[0058] Example 5

[0059] This embodiment only changes the step S4 of "curing 0.5 mL of precursor B, 1 mL of precursor C, and 0.5 mL of precursor B layer by layer under ultraviolet light to form a gel", and the other steps remain consistent with Example 1 to obtain the thermochromic self-healing gel DEE-DA-2.

[0060] The stress-strain curve of the comparative gel corresponds to Fig. 9 It can be seen that the elongation of DEE-DA-2 is less than that of Example 1.

[0061] from Fig. 9 It can be seen that the relative thickness of the middle layer gradually increases and the stress gradually increases.

[0062] Example 6

[0063] In this embodiment, only the "methacryloyloxyethyltrimethylammonium chloride" in step S1 is replaced by "vinyltrimethylammonium chloride", the "1-butyl-3-methylimidazole di(trifluoromethylsulfonyl)imide" in step S2 is replaced by "bis(trifluoromethylsulfonyl)imide", and the "13.3 mg methylenebisacrylamide" is replaced by "5.0 mg glyoxal", and the "7.5 mg methylenebisacrylamide" in step S3 is replaced by "2.8 mg glyoxal". The other steps remain consistent with Example 1, and the thermochromic self-healing gel DEE-DA is obtained.

[0064] The performance of the polymer and polymer epidermal patch electrode prepared in this embodiment was examined with reference to embodiment 1, and similar performance to that of embodiment 1 was obtained.

[0065] Example 7

[0066] In this embodiment, only the "lithium bis(trifluoromethanesulfonyl imide)" in step S1 is replaced by "silver bis(trifluoromethanesulfonyl imide), and the "0.4931 g 3-methylacrylamide phenylboronic acid" in step S3 is replaced by "0.3551 g phenylvinyl boronic acid", and the other steps are kept consistent with Example 1 to obtain the thermochromic self-healing gel DEE-DA.

[0067] The performance of the polymer and polymer epidermal patch electrode prepared in this embodiment was examined with reference to embodiment 1, and similar performance to that of embodiment 1 was obtained.

[0068] Example 8

[0069] In this embodiment, only "1-butyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide" in step S2 is replaced by "N-butylpyridine bis(trifluoromethylsulfonyl)imide", and "dimethylaminoethyl methacrylate" in step S3 is replaced by "N,N-diethylaminoethyl methacrylate". The other steps remain consistent with Example 1, and the obtained thermochromic self-healing gel DEE-DA is obtained.

[0070] The performance of the polymer and polymer epidermal patch electrode prepared in this embodiment was examined with reference to embodiment 1, and similar performance to that of embodiment 1 was obtained.

[0071] Comparative Example 1

[0072] In this comparative example, step S1 and step S2 are consistent with those in Example 1. Compared with Example 1, step S3 is deleted. Step S4 is to remove the bubbles in the precursor B by vacuum and solidify it into a gel by ultraviolet light to obtain ion gel DEE.

[0073] The water contact angle of the gel surface prepared in this comparative example corresponds to Figure 1 From the DEE in the gel, it can be seen that the hydrophobicity of the gel surface is the key to improving the surface contact angle of Example 1.

[0074] The water loss test of the comparative gel at different temperatures within 20 days corresponds to Figure 3 From the DEE in the figure, it can be seen that the gel mass ratio at different temperatures is always maintained above 95%.

[0075] Comparative Example 2

[0076] Compared with Example 1, this comparative example deletes step S1 and step S2, and step S3 is consistent with Example 1. Step S4 is to remove the bubbles in the precursor C by vacuum, and cure it into a gel by ultraviolet light to obtain hydrogel DA.

[0077] The surface water contact angle of the gel in this comparative example corresponds to Figure 1 DA, it can be seen that the contact angle of the gel surface to water is the smallest compared with other gels.

[0078] The water loss test of the comparative gel at different temperatures within 20 days corresponds to Figure 3 DA, it can be seen that the gel mass ratio of this comparative example at different temperatures is much lower than that of Example 1 and Comparative Example 1.

Claims

1. A method for preparing a thermochromic self-repairing gel, characterized in that: The following steps are involved: S1, adding a trimethylammonium salt-modified olefin compound and a bistrifluoromethanesulfonyl imide salt to water and stirring, standing and stratifying, taking out the lower oil phase, washing it several times, and drying it to obtain an ionic liquid A; S2, mixing 2-phenoxyethyl acrylate with ionic liquid A and hydrophobic ionic liquid, adding a crosslinking agent and a photoinitiator, and ultrasonically dispersing to obtain a precursor B; S3, adding a phenylboronic acid olefin compound, a crosslinking agent, and a photoinitiator to the aqueous solution of tertiary amine methacrylate, and ultrasonically dispersing to obtain a precursor C; S4. The bubbles in the precursor B and the precursor C are removed by vacuum, and the precursors are cured layer by layer under ultraviolet light in the order of a layer of precursor B, a layer of precursor C, and a layer of precursor B to obtain a three-layer structure of thermochromic self-healing gel.

2. The method for preparing a thermochromic self-repairing gel according to claim 1, characterized in that: In step S1, the trimethylammonium salt modified olefin compound is methacryloyloxyethyl trimethylammonium chloride or vinyl trimethylammonium chloride; the bistrifluoromethanesulfonyl imide salt is lithium bistrifluoromethanesulfonyl imide or silver bistrifluoromethanesulfonyl imide.

3. A method for preparing a thermochromic self-repairing gel according to claim 1 or 2, characterized in that: In step S1, the mass ratio between the trimethylammonium salt modified olefin compound and the bistrifluoromethanesulfonyl imide salt is 1:(1-2), and the mass ratio between the trimethylammonium salt modified olefin compound and water is 1:(3-5).

4. A method for preparing a thermochromic self-repairing gel according to claim 1 or 2, characterized in that: In step S2, the hydrophobic ionic liquid is one of 1-butyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide, bis(trifluoromethylsulfonyl)imide, and N-butylpyridine bis(trifluoromethylsulfonyl)imide.

5. The method for preparing a thermochromic self-repairing gel according to claim 1 or 2, characterized in that: In step S2, the mass ratio of the 2-phenoxyethyl acrylate to the ionic liquid A is 1:(10-13); the molar ratio of the 2-phenoxyethyl acrylate to the hydrophobic ionic liquid is 1:(3-7); and the molar ratio of the 2-phenoxyethyl acrylate to the crosslinking agent is (45-50):

1.

6. A method for preparing a thermochromic self-repairing gel according to claim 1 or 2, characterized in that: In step S3, the phenylboronic acid olefin compound is styrylphenylboronic acid or 3-methacrylamidephenylboronic acid; and the tertiary amine methacrylate is one of dimethylaminoethyl methacrylate and N,N-diethylaminoethyl methacrylate.

7. A method for preparing a thermochromic self-repairing gel according to claim 1 or 2, characterized in that: In step S3, the molar ratio of the tertiary amine methacrylate to the phenylboronic acid olefin compound is (9-11):1; the concentration of the tertiary amine methacrylate aqueous solution is 7-9 mol / L; and the molar ratio of the tertiary amine methacrylate to the cross-linking agent is (450-500):

1.

8. The method for preparing a thermochromic self-repairing gel according to claim 1 or 2, characterized in that: In steps S2 and S3, the crosslinking agent is one of glyoxal, diphenylmethane diisocyanate, methylenebisacrylamide, and acyl chloride; the photoinitiator is one of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone; the molar ratio between the photoinitiator and the crosslinking agent is (3-5):1; and the ultrasonic power is 10-100W.

9. The method for preparing a thermochromic self-repairing gel according to claim 1 or 2, characterized in that: In step S4, the volume ratio of the precursor B, precursor C, and precursor B to be cured layer by layer is 1:(0.5-2):1; the power of the ultraviolet lamp is 60-70W, and the curing time for each layer is 2-5min; in step S1, the drying temperature is 50-70°C, and the drying time is 8-12h.

10. A smart window assembled with a thermochromic self-repairing gel prepared by the preparation method according to any one of claims 1 to 9.

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