Optical-thermal responsive t-shaped liquid crystal molecules, preparation method thereof and smart window application

Abstract

The application provides a photothermal response T-shaped liquid crystal molecule, a preparation method thereof and smart window application, and a structure formula of the T-shaped liquid crystal molecule is shown as formula (1). The liquid crystal molecule of the technical scheme is T-shaped, the azobenzene structure in the liquid crystal molecule is reversibly converted from cis to trans under the switching of ultraviolet light and visible light, meanwhile, the molecular structure of 8CB and the structure of butylene glycol adipate are phase changed at room temperature, so that the molecule has the functions of light response and thermal response at room temperature; in addition to passive control by light and heat, after being electrified, the liquid crystal molecule is orderly arranged and has the function of electric response, so that the smart window can be actively restored to be transparent. In addition to the multiple responses, the molecule is also a low-carbon and environment-friendly material. The alkoxyl chain is connected to the side of the liquid crystal molecule of the technical scheme, the asymmetry is increased, the liquid crystal molecule has more abundant phase structures, and has great development prospect in the field of smart windows.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new materials, in particular to a photo-thermal responsive T-shaped liquid crystal molecule, a preparation method thereof and an intelligent window application. BACKGROUND

[0002] In recent years, global energy consumption continues to rise, with the industrial, transportation and building sectors being the main growth drivers. Although renewable energy applications continue to expand, fossil fuels still dominate the energy structure. Under the dual pressures of international carbon emission reduction commitments and climate governance, it is imperative to promote energy system reform and improve energy efficiency. Notably, building energy consumption accounts for 40% of total social energy consumption, and heating, cooling systems are the main energy consumption links, with higher energy consumption under extreme weather conditions, and lighting energy consumption is also a major problem in commercial buildings. Under this background, intelligent window technology has become a key breakthrough for improving building energy efficiency, optimizing indoor environment and promoting sustainable development.

[0003] Intelligent windows reduce energy consumption by automatically adjusting light transmittance and thermal conductivity. It can dynamically adjust transparency according to external light and temperature changes, maximize the use of natural light and maintain stable indoor temperature, thereby reducing the use of air conditioning and lighting equipment. Some intelligent windows also use low-emissivity coatings or electrochromic materials to further enhance thermal insulation, helping to achieve building energy saving, low-carbon emission reduction, while improving living comfort and promoting sustainable building development.

[0004] Currently, intelligent window technology research mainly focuses on electrochromic, thermochromic and photochromic systems. Electrochromic materials change color through reversible oxidation-reduction reactions under the action of external alternating voltage, common ones include inorganic transition metal oxides and organic conductive polymers; thermochromic relies on thermal response materials such as VO2, hydrogel, liquid crystal, ionic liquid and perovskite; photochromic intelligent windows are composed of optically active liquid crystal materials, specific wavelength light will cause liquid crystal molecules to reorient, thereby changing the optical state of the window.

[0005] Currently, intelligent window material research mainly focuses on electrical, optical and thermal responses. Although electrochromic intelligent windows have been successfully commercialized and widely used in electronic displays, intelligent windows and other fields, the preparation process is relatively mature, but there are problems such as high processing cost of metals and their oxides, high environmental pollution risk, and high energy consumption for active control. Therefore, research and development of thermochromic and photochromic materials has attracted much attention. Currently, most intelligent window materials only have single response function, and research on high-performance materials with both optical and thermal response is relatively rare. Such multifunctional response intelligent window materials have broad application prospects in the future. SUMMARY

[0006] In view of the above technical problems, the application discloses a light-thermal response T-shaped liquid crystal molecule, a preparation method thereof and intelligent window application.

[0007] To this end, the application adopts the technical scheme of:

[0008] A light-thermal response T-shaped liquid crystal molecule, a structure formula of which is shown as formula (1):

[0009]

[0010] In the molecule, the azobenzene group serves as a light response unit and can reversibly undergo cis-trans photoisomerization under alternating irradiation of ultraviolet light and visible light, thereby causing dynamic change of the molecular configuration; the molecule takes cyanophenyl as a rigid head and a flexible chain segment at the tail, so that the thermal response function is regulated; and the polybutylene adipate has biodegradable characteristics and conforms to the principle of green chemistry, so that it is more environmentally friendly.

[0011] The application discloses a preparation method of the light-thermal response T-shaped liquid crystal molecule, which comprises the following steps:

[0012] In step S1, 4'-amino-4-cyanophenyl and sodium nitrite are added to water, and then concentrated hydrochloric acid is added, and the mixture is stirred and uniformly mixed under ice bath conditions to obtain a diazonium salt solution;

[0013] Potassium carbonate, sodium hydroxide and 3-butoxyphenol are dissolved in water, and then the solution is added to the diazonium salt solution under ice bath conditions, and stirred for more than 6 hours; then the filter residue is collected, and the organic layer is collected after extraction and water washing; the collected organic layer is dried, n-hexane / ethyl acetate with a volume ratio of 6:1 is used as an eluent, and the red solid powder CNO is obtained by silica gel column chromatography; the structure formula of the CNO is shown as formula (2):

[0014]

[0015] In step S2, CNO, 4-(dimethylamino)pyridine, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and adipic acid are added to a reaction container, dichloromethane is added, and stirring is performed under a protective gas atmosphere overnight; after the reaction is completed, the crude product is washed with water, and the organic layer is collected; the collected organic layer is dried, n-hexane / ethyl acetate with a volume ratio of 2:1 is used as an eluent, and the light red powder CNCO is obtained by silica gel column chromatography; the structure formula of the CNCO is shown as formula (3):

[0016]

[0017] Step S3, the CNCO, 4-(dimethylamino)pyridine, N-(3-dimethylaminopropyl)-N'-ethyl carbodiimide hydrochloride, 1,4-butanediol are added into a reaction container, dichloromethane is added, and stirring is carried out under a protective gas atmosphere overnight. After the reaction is completed, the crude product is washed with water, the organic layer is collected, and after drying, the collected organic layer is purified by silica gel column chromatography with n-hexane / ethyl acetate as an eluent in a volume ratio of 8:1 to obtain a photothermal responsive T-shaped liquid crystal molecule with a structure as shown in formula (1).

[0018] As a further improvement of the present application, the protective gas is nitrogen or an inert gas. The inert gas is preferably argon.

[0019] As a further improvement of the present application, in step S1, the amount of sodium nitrite is 1.1-1.2 times the amount of 4-amino-4'-cyano biphenyl substance, the concentration of hydrochloric acid is 1.5-2M, the amount of sodium hydroxide is 1.2-1.3 times the amount of 4-amino-4'-cyano biphenyl substance, the amount of potassium carbonate is 1.2-1.3 times the amount of 4-amino-4'-cyano biphenyl substance, and the amount of 3-butoxyphenol is 1.1-1.2 times the amount of 4-amino-4'-cyano biphenyl substance.

[0020] As a further improvement of the present application, in step S2, the amount of adipic acid is 2.8-3.1 times the amount of CNO substance, the amount of 4-dimethylamino pyridine is 0.08-0.12 times the amount of CNO substance, and the amount of N-(3-dimethylaminopropyl)-N'-ethyl carbodiimide hydrochloride is 1.4-1.5 times the amount of CNO substance.

[0021] As a further improvement of the present application, in step S3, the amount of 4-dimethylamino pyridine is 0.1-0.13 times the amount of CNCO substance, the amount of N-(3-dimethylaminopropyl)-N'-ethyl carbodiimide hydrochloride is 2.8-3.1 times the amount of CNCO substance, and the amount of 1,4-butanediol is 4.8-5.2 times the amount of CNCO substance.

[0022] As a further improvement of the present application, in step S1, the residue is extracted with dichloromethane and dried with anhydrous magnesium sulfate.

[0023] As a further improvement of the present application, in steps S2 and S3, anhydrous magnesium sulfate is used for drying.

[0024] The present application also discloses an application of the photothermal responsive T-shaped liquid crystal molecule as described above to a smart window. The photothermal responsive T-shaped liquid crystal molecule is doped into a liquid crystal material to prepare a vertically aligned liquid crystal cell for a smart window.

[0025] As a further improvement of the present application, the composition of the liquid crystal material comprises a host liquid crystal and a chiral dopant; the doping mass percentage of the photo-thermal responsive T-shaped liquid crystal molecule is 1wt.%-5wt.%. Further preferably, the doping mass percentage of the photo-thermal responsive T-shaped liquid crystal molecule is 5wt.%.

[0026] As a further improvement of the present application, the chiral dopant is at least one of S5011, S811; the host liquid crystal is at least one of E7, SLC1717, 5CB, 8CB; the doping mass percentage of the chiral dopant is 5wt.%.

[0027] The present application also discloses a photo-thermal responsive liquid crystal material, which comprises a liquid crystal material and a photo-thermal responsive T-shaped liquid crystal molecule as described above; further, the doping mass percentage of the photo-thermal responsive T-shaped liquid crystal molecule is 1wt.%-5wt.%. Further preferably, the doping mass percentage of the photo-thermal responsive T-shaped liquid crystal molecule is 5wt.%.

[0028] As a further improvement of the present application, the composition of the liquid crystal material comprises a host liquid crystal and a chiral dopant.

[0029] As a further improvement of the present application, the chiral dopant is at least one of S5011, S811; the host liquid crystal is at least one of E7, SLC1717, 5CB, 8CB; the doping mass percentage of the chiral dopant is 5wt.%.

[0030] The present application discloses a kind of intelligent glass, it is filled into orientation liquid crystal box using photo-thermal responsive liquid crystal material as described above.

[0031] The present application discloses the preparation method of intelligent glass as described above, comprising the following steps:

[0032] Step S10, take two pieces of ITO conductive glass of same size, spin coating vertical alignment agent on surface;

[0033] Step S20, the ITO conductive glass of spin coating of step S10 is baked at 180-220 ℃ for 0.5-1.5 h;

[0034] Step S30, SiO2 Microspheres are dispersed in UV glue;

[0035] Step S40, the UV glue of step S30 is dropped in the four corners of ITO conductive glass, under ultraviolet light irradiation, vertical alignment liquid crystal box is made;

[0036] Step S50, the photo-thermal responsive liquid crystal material as described above is injected into vertical alignment liquid crystal box by capillary action, and intelligent glass is obtained.

[0037] The application further discloses a smart window prepared from the smart glass.

[0038] Compared with the prior art, the application has the following beneficial effects:

[0039] First, the liquid crystal molecules of the application are T-shaped, and the azobenzene structure in the liquid crystal molecules reversibly converts from cis to trans under the switching of ultraviolet light and visible light, and the molecular structure of 8CB and the structure of butylene glycol adipate change at room temperature, so that the molecules have light response function and also have thermal response function at room temperature; in addition to passive control by light and heat, after being powered on, the liquid crystal molecules are orderly arranged and have electric response function, so that the smart window can be actively restored to transparent state.

[0040] Second, the polybutylene adipate used in the application is a commonly used degradable plastic in daily life, and the molecule has multiple responses and is also a low-carbon and environmentally friendly material.

[0041] Third, the alkoxyl chain is linked to the side of the liquid crystal molecule in the application, which increases the asymmetry of the molecule and makes it have more abundant phase structures, so that it has great development prospects in the field of smart windows. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 It is a nuclear magnetic resonance hydrogen spectrum of the compound CNO in the embodiment of the application.

[0043] Figure 2 It is a nuclear magnetic resonance hydrogen spectrum of the compound CNCO in the embodiment of the application.

[0044] Figure 3 It is a nuclear magnetic resonance hydrogen spectrum of the compound CNOH in the embodiment of the application.

[0045] Figure 4 It is a POM picture of the compound CNOH in the embodiment of the application at room temperature.

[0046] Figure 5 It is a DSC curve of the compound CNOH in the embodiment of the application.

[0047] Figure 6 It is a 1D-WAXD spectrum of the compound CNOH in the embodiment of the application.

[0048] Figure 7 It is a POM picture of the compound CNOH in the embodiment of the application with temperature change, wherein, a-f are 120 DEG C, 62 DEG C, 40 DEG C, 80 DEG C, 85 DEG C and 98 DEG C respectively.

[0049] Figure 8 This is a POM image of the compound CNOH from an embodiment of the present invention after shearing.

[0050] Figure 9 The UV-Vis absorption spectrum of compound CNOH in chloroform is shown in the embodiment of the present invention.

[0051] Figure 10 This is a schematic diagram of the cis and trans conformations of compound CNOH according to an embodiment of the present invention.

[0052] Figure 11 This is a schematic diagram illustrating the fabrication of a vertically aligned liquid crystal cell according to an embodiment of the present invention.

[0053] Figure 12 The transparency change of the liquid crystal smart window in this embodiment of the invention after irradiation with 365nm ultraviolet light.

[0054] Figure 13 This is a schematic diagram illustrating the working principle of the liquid crystal smart window under ultraviolet light according to an embodiment of the present invention.

[0055] Figure 14 The images show the POM (Polymer Oxidation Model) images of the liquid crystal smart window before and after ultraviolet light irradiation, according to an embodiment of the present invention.

[0056] Figure 15 The figures show the DSC curves of liquid crystal mixtures doped with different proportions of CNOH according to embodiments of the present invention; wherein, (a) is the cooling curve and (b) is the heating curve.

[0057] Figure 16 This is the DSC curve of the liquid crystal mixture without CNOH doping in the control sample of this invention.

[0058] Figure 17 The DSC curve of the liquid crystal mixture after doping with 5% CNOH is shown in the embodiment of the present invention.

[0059] Figure 18 The transparency of the liquid crystal smart window in this embodiment of the invention varies at different temperatures.

[0060] Figure 19 This is a schematic diagram illustrating the working principle of the liquid crystal smart window in different temperatures according to an embodiment of the present invention.

[0061] Figure 20 The images are POM images of the liquid crystal smart window of this invention at different temperatures; where af represents 25℃, 30℃, 35℃, 34℃, 27℃, and 25℃, respectively.

[0062] Figure 21 The transparency change of the liquid crystal smart window in this embodiment of the invention before and after power-on.

[0063] Figure 22This is a schematic diagram illustrating the working principle of the liquid crystal smart window before and after power-on, according to an embodiment of the present invention.

[0064] Figure 23 The images are POM images of the LCD smart window before and after power-on, according to an embodiment of the present invention.

[0065] Figure 24 The light transmittance spectra of the liquid crystal smart window in different wavelength bands are shown in the embodiments of the present invention. Detailed Implementation

[0066] The preferred embodiments of the present invention will be described in further detail below.

[0067] A photothermal responsive T-type liquid crystal molecule, the structural formula of which is shown in formula (1):

[0068]

[0069] The liquid crystal molecule (CNOH) containing an azobenzene structure of the present invention is synthesized by a three-step reaction. In the first step, an aromatic primary amine reacts with nitrous acid under acidic conditions to generate a diazonium salt, which further undergoes an electrophilic substitution reaction with 3-butoxyphenol to obtain compound CNO. In the second step, CNO undergoes an esterification reaction with adipic acid under the action of condensing agent EDC and catalyst DMAP to obtain compound CNCO. In the third step, CNO undergoes an esterification reaction with 1,4-butanediol under the action of condensing agent EDC and catalyst DMAP to obtain compound CNOH. The overall synthetic route is as follows:

[0070]

[0071]

[0072] The synthesized compound CNOH was doped into the host liquid crystal 8CB, and a vertically oriented liquid crystal cell was prepared as smart glass for use in smart windows. The steps are as follows:

[0073] 1. Take two pieces of 1.5cm × 1.5cm ITO conductive glass and spin-coat a vertical alignment agent onto their surfaces;

[0074] 2. Bake the spin-coated ITO conductive glass at 200°C for one hour;

[0075] 3. Disperse 25μm SiO2 microspheres in a UV adhesive;

[0076] 4. Place the above UV adhesive droplets on the four corners of ITO conductive glass, and under ultraviolet light irradiation, fabricate vertically aligned liquid crystal cells with a spacing of 25μm.

[0077] 5. A liquid crystal mixture doped with CNOH is injected into a liquid crystal cell via capillary action to obtain a liquid crystal smart window;

[0078] The thermal, optical, and electrical responses of the prepared liquid crystal smart window were investigated. The results showed that after ultraviolet irradiation, the doped azobenzene molecules changed from the trans to the cis configuration, disrupting the ordered structure of the liquid crystal molecules and reducing the transparency of the smart window. When the temperature rose to 27℃-35℃, the mixed system transformed into a cholesteric phase liquid crystal, causing strong light scattering, blurring the smart window, and reducing its transmittance. After applying an electric current (30V AC), the liquid crystal mixed system became ordered under the influence of the electric field, and the smart window returned to a transparent state. However, after the voltage was removed, it became blurry again after 10 seconds.

[0079] The following description uses specific embodiments. It should be noted that the embodiments described below are merely exemplary manifestations of the present invention and do not represent all possible implementations.

[0080] Example 1

[0081] A photothermal responsive T-type liquid crystal molecule is prepared by the following steps:

[0082] Step S1, synthesis of compound CNO, the synthetic route is shown in equation (4) above, the specific steps include:

[0083] Take a 100ml three-necked flask, weigh 555mg (2.86mmol) of 4'-amino-4-cyanobiphenyl and 230mg (3.34mmol) of sodium nitrite into the flask, add 20ml of water, then add 0.89ml of concentrated hydrochloric acid, stir for 30 minutes in an ice bath at 0℃, dissolve 487mg (3.53mmol) of potassium carbonate, 143mg (3.57mmol) of sodium hydroxide and 555mg (3.34mmol) of 3-butoxyphenol in 10ml of water, add the solution to the above diazonium salt solution in an ice bath, stir for 6 hours, filter, collect the residue, extract with dichloromethane (3×20ml), wash with water, collect the organic layer, dry with anhydrous magnesium sulfate, and purify by silica gel column chromatography (eluent: hexane: ethyl acetate = 6:1) to obtain a red solid powder CNO 630mg (59.4%).

[0084] The obtained CNO 1H NMR spectrum is as follows Figure 1 As shown, the specific data is as follows:

[0085] 1H NMR (500MHz, DMSO-D6) δ10.41(s,1H),8.01–7.94(m,6H),7.90–7.86(m,2H),7.62(d,J=8.8Hz,1H),6.61(d,J=2.4Hz,1H), 6.47(dd,J=8.9,2.4Hz,1H), 4.14(t,J=6.5Hz,2H), 1.80(dq,J=8.3,6.5Hz,2H), 1.56–1.47(m,2H), 0.98(t,J=7.4Hz,3H).

[0086] Step S2, the synthesis of compound CNCO, the synthetic route is shown in equation (5) above, and the specific steps include:

[0087] Take a 100ml three-necked flask and weigh out 330mg (0.90mmol) CNO, 11mg (0.09mmol) 4-(dimethylamino)pyridine, 255mg (1.33mmol) N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride, and 390mg (2.67mmol) adipic acid. Protect the mixture with nitrogen atmosphere, add 15ml of dichloromethane, and stir overnight under nitrogen atmosphere. After the reaction is complete, pour the crude product into 50ml of water, wash three times, collect the organic layer, dry it with anhydrous magnesium sulfate, and purify it by silica gel column chromatography (eluent: hexane: ethyl acetate = 2:1) to obtain a pale red powder CNCO 280mg (62%).

[0088] The 1H NMR spectrum of the obtained product CNCO is as follows: Figure 2 As shown, the specific data is as follows:

[0089] 1H NMR (500MHz, DMSO-D6) δ12.10(s,1H),8.03–7.93(m,8H),7.65(d,J=8.7Hz,1H),7.12(d,J=2.4Hz,1H),6.83(dd,J=8.8,2.3Hz,1H),4.18(t, J=6.5Hz,2H),2.63(t,J=7.2Hz,2H),2.28(t,J=7.1Hz,2H),1.84–1.75(m,2H),1.71–1.58(m,4H),1.54–1.46(m,2H),0.97(t,J=7.4Hz,3H).

[0090] Step S2, the synthesis of compound CNOH, the synthetic route is shown in equation (6) above, and the specific steps include:

[0091] Take a 50 ml three-necked flask and weigh out 180 mg (0.36 mmol) CNCO, 5 mg (0.04 mmol) 4-(dimethylamino)pyridine, 208 mg (1.08 mmol) N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride, and 162 mg (1.8 mmol) 1,4-butanediol. Protect the mixture with nitrogen atmosphere, add 10 ml of dichloromethane, and stir overnight under nitrogen atmosphere. After the reaction is complete, pour the crude product into 50 ml of water, wash three times, collect the organic layer, dry it with anhydrous magnesium sulfate, and purify it by silica gel column chromatography (eluent: dichloromethane:ethyl acetate = 8:1) to obtain 80 mg (40%) of orange powder CNOH.

[0092] The 1H NMR spectrum of the product CNOH is as follows: Figure 3 As shown, the specific data is as follows:

[0093] 1H NMR (500MHz, DMSO-D6) δ7.99–7.89(m,8H),7.61(d,J=8.7Hz,1H),7.08(d,J=2.3Hz,1H) ,6.79(dd,J=8.8,2.3Hz,1H),4.40(t,J=5.1Hz,1H),4.15(t,J=6.5Hz,2H),3.99(t,J=6 .7Hz,2H),3.36(td,J=6.4,4.9Hz,2H),2.60(t,J=6.9Hz,2H),2.33(t,J=6.9Hz,2H),1. 76(dq,J=8.4,6.6Hz,2H),1.65–1.53(m,6H),1.51–1.38(m,4H),0.93(t,J=7.4Hz,3H):.

[0094] The structure of the obtained product CNOH was analyzed, such as... Figure 4 As shown, the spherulite morphology of this compound at room temperature can be observed under a polarizing microscope. The DSC curve of the product CNOH is shown below. Figure 5 As shown, CNOH exhibits a crystallization peak at 23℃ during the heating process, two endothermic peaks at 85℃ and 95℃, and an exothermic peak at 61℃ during the cooling process. Based on the DSC curve, variable-temperature wide-angle X-ray diffraction was performed on the sample near the phase transition temperature, and the results are as follows. Figure 6 As shown, phase transitions of the molecule were observed at different temperatures using one-dimensional wide-angle X-ray data. Simultaneously, POM images of the compound CNOH as a function of temperature are shown below. Figure 7 As shown, the molecules grow into crystals during the heating process, forming two crystalline phases, which melt at 85℃ and 98℃ respectively. During the cooling process, a liquid crystal phase structure was observed at 62℃.

[0095] To further observe the liquid crystal phase structure of the molecules, the sample was heated above its melting point and sheared, then isothermated at 0°C for 20 min. The nematic phase structure of the molecules was then observed under a polarizing microscope. Figure 8 As shown, when the sample is thicker, molecules tend to form a three-dimensional ordered structure (crystalline phase). As the sample becomes thinner (melt shear), the enhanced surface effect may constrain the three-dimensional order and promote the formation of a two-dimensional ordered liquid crystal phase.

[0096] Fabrication of vertically aligned liquid crystal cells:

[0097] Weigh 90 mg of 8CB, 5 mg of CNOH, and 5 mg of S811 into a sample vial, add 5 ml of dichloromethane, sonicate for 2 h, and dry the solvent at 60 °C to obtain a liquid crystal mixture.

[0098] After spin-coating vertically aligned polyimide onto two clean ITO glass plates, the plates were baked on a hot stage at 200°C for 1 hour and cured with UV adhesive to obtain vertically aligned liquid crystal cells with a spacing of 25 μm. Finally, a liquid crystal mixture was injected via capillary action to obtain a liquid crystal smart window, such as... Figure 11 As shown. The mixture ratio is: 90 wt.% 8CB, 5 wt.% CNOH, and 5 wt.% chiral dopant S811.

[0099] Based on Example 1 above, liquid crystal mixtures with CNOH added at mass percentages of 1%, 2%, 3% and 4% were also prepared, with the S811 ratio remaining unchanged and the 8CB mass percentages being 94%, 93%, 92% and 91%, respectively.

[0100] The multi-response function of the above-mentioned LCD smart window is studied, specifically including:

[0101] UV response: The UV-Vis absorption spectrum of compound CNOH in chloroform is as follows Figure 9 As shown, before ultraviolet irradiation, the maximum absorption peak is at 370 nm. After irradiation with 365 nm ultraviolet light, the maximum absorption peak is at 310 nm, showing a blue shift. After 10 minutes under visible light, the maximum absorption peak returns to 370 nm. This indicates that surface molecules can undergo reversible transformations between trans and cis conformations under both ultraviolet and visible light. Figure 10 As shown.

[0102] The transparency of the LCD smart window also changed significantly after being exposed to 365nm ultraviolet light, such as... Figure 12 As shown, this is attributed to the doped azobenzene molecules (CNOH) changing to a cis structure under ultraviolet light, causing the liquid crystal molecules in the mixed system to change from ordered to disordered, thus inducing light scattering and resulting in the blurring of the liquid crystal smart window, such as... Figure 13As shown in the image, polarized light microscope images of the liquid crystal smart window before and after ultraviolet light irradiation also show the same results. After 10 seconds of ultraviolet light irradiation, the liquid crystal molecules changed from a smectic phase to a spiral cholesteric phase structure, as shown in the image. Figure 14 As shown.

[0103] Thermal response: From Figure 15 The DSC curves show that as the proportion of CNOH increases, the nematic phase region of the mixed liquid crystal system gradually widens, such as... Figure 15 As shown. The temperature range of the nematic phase of the undoped CNOH liquid crystal mixture is 32℃-37℃, as... Figure 16 As shown, the nematic phase range of the 8CB liquid crystal mixture doped with 5% CNOH is 27℃-35℃. Figure 17 As shown, in contrast, CNOH doping can raise the temperature range of the nematic phase region in the mixed system.

[0104] When the temperature rises to 27℃-35℃, the LCD smart window changes from transparent to blurry, as... Figure 18 As shown, due to the doping of chiral molecules, the nematic liquid crystal molecules arrange themselves in a helical structure (cholesterol phase), which in turn causes light scattering, reducing the light transmittance of the liquid crystal smart window, such as... Figure 19 As shown in the image, polarized light microscopy images of the liquid crystal smart window at different temperatures also reveal its morphological variations between the smectic phase, cholesteric phase, and isotropic phase, such as... Figure 20 As shown.

[0105] Electrical response: After being powered by 30V AC, the LCD smart window can change from a blurred state to a transparent state, such as... Figure 21 As shown. After the voltage is removed, it will return to a blurred state within 10 seconds. Under the influence of the electric field, the originally disordered or helical liquid crystal molecules will become ordered again, and the light transmittance will increase, as shown. Figure 22 As shown in the polarizing microscope images before and after energization, it can be seen that after energization, the liquid crystal molecules change from an oily, cholesteric phase to an ordered phase. After the voltage is removed, they transform back into the cholesteric phase within 10 seconds. Figure 23 As shown.

[0106] When exposed to ultraviolet light or at a temperature of 32℃, the light transmittance of the smart window decreases significantly. After being powered on, the light transmittance increases again, corresponding to the phenomenon of the smart window switching between transparent and blurry states. Figure 24 As shown, the optical modulation capability of the developed tristimulus-responsive liquid crystal smart window was systematically evaluated. Visible light transmittance (Tlum, 360-830nm) and solar light modulation capability (ΔTsol) were calculated according to ISO 9050:2003 standard. The calculation formulas are defined as follows:

[0107]

[0108] This smart window can reversibly switch between transparent (Tlum>85%) and opaque (Tlum<20%) states under alternating ultraviolet (365nm) and visible light irradiation, with a solar modulation efficiency of ΔTsol = 69% (360-830nm). Within the temperature response range (27-35℃), Tlum<21%, and in the transparent state, Tlum>83%.

[0109] The low-energy-consumption T-type liquid crystal molecule with multiple stimulus-response characteristics in this embodiment is prepared by constructing an azophenyl group through an electrophilic addition reaction and then undergoing a two-step esterification reaction. Under ultraviolet light (365nm) irradiation or temperature (27℃-35℃) stimulation, the visible light transmittance of this material can be reduced from the initial 80% to below 20%, realizing a reversible transition from a transparent state to a fogged state. After applying a 30V AC voltage, the material recovers to the transparent state through electro-ordering (response time less than 3s), exhibiting excellent dynamic control capabilities of light, heat, and electricity, providing a novel material solution for the development of adaptive intelligent window systems.

[0110] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A photothermally responsive T-type liquid crystal molecule, characterized in that, Its structural formula is shown in equation (1): （1）。 2. The method for preparing photothermally responsive T-type liquid crystal molecules as described in claim 1, characterized in that, Includes the following steps: Step S1: Add 4'-amino-4-cyanobiphenyl and sodium nitrite to water, then add concentrated hydrochloric acid, and stir and mix evenly under ice bath conditions to obtain a diazonium salt solution; Potassium carbonate, sodium hydroxide, and 3-butoxyphenol were dissolved in water and added to the diazonium salt solution under ice bath conditions. The mixture was stirred for more than 6 hours, filtered, and the residue was collected. After extraction and washing with water, the organic layer was collected and dried. The organic layer was purified by silica gel column chromatography using a 6:1 (v / v) hexane / ethyl acetate mixture to obtain a red solid powder CNO. The structural formula of CNO is shown in formula (2). （2）； In step S2, CNO, 4-(dimethylamino)pyridine, N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride, and adipic acid were added to a reaction vessel, followed by dichloromethane. The mixture was stirred overnight under a protective atmosphere. After the reaction was complete, the crude product was washed with water, and the organic layer was collected. The collected organic layer was dried and purified by silica gel column chromatography using a 2:1 (v / v) hexane / ethyl acetate eluent to obtain a light red powder, CNCO. The structural formula of CNCO is shown in formula (3). （3）； In step S3, CNCO, 4-(dimethylamino)pyridine, N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride, and 1,4-butanediol were added to a reaction vessel, and dichloromethane was added. The mixture was stirred overnight under a protective atmosphere. After the reaction was completed, the crude product was washed with water, and the organic layer was collected. The collected organic layer was dried and purified by silica gel column chromatography using n-hexane / ethyl acetate at a volume ratio of 8:1 as the eluent to obtain a photothermal responsive T-type liquid crystal molecule with the structural formula shown in formula (1).

3. The method for preparing photothermally responsive T-type liquid crystal molecules according to claim 2, characterized in that: In step S1, the amount of sodium nitrite used is 1.1 to 1.2 times the amount of 4-amino-4'-cyanobiphenyl; the concentration of hydrochloric acid is 1.5 to 2 M; the amount of sodium hydroxide used is 1.2 to 1.3 times the amount of 4-amino-4'-cyanobiphenyl; the amount of potassium carbonate used is 1.2 to 1.3 times the amount of 4-amino-4'-cyanobiphenyl; and the amount of 3-butoxyphenol used is 1.1 to 1.2 times the amount of 4-amino-4'-cyanobiphenyl. In step S2, the amount of adipic acid used is 2.8-3.1 times the amount of CNO, the amount of 4-(dimethylamino)pyridine used is 0.08-0.12 times the amount of CNO, and the amount of N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride used is 1.4-1.5 times the amount of CNO. In step S3, the amount of 4-(dimethylamino)pyridine is 0.1-0.13 times the amount of CNCO; the amount of N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride is 2.8-3.1 times the amount of CNCO; and the amount of 1,4-butanediol is 4.8-5.2 times the amount of CNCO. The protective gas is nitrogen.

4. The method for preparing photothermally responsive T-type liquid crystal molecules according to claim 2, characterized in that: The protective gas is an inert gas.

5. The method for preparing photothermally responsive T-type liquid crystal molecules according to claim 2, characterized in that: In step S1, the filter residue is extracted with dichloromethane and dried with anhydrous magnesium sulfate; in steps S2 and S3, anhydrous magnesium sulfate is used for drying.

6. The application of the photothermally responsive T-shaped liquid crystal molecules as described in claim 1 in smart windows, characterized in that: The photothermally responsive T-type liquid crystal molecules are doped into a liquid crystal material to form a vertically oriented liquid crystal cell for use in smart windows. The liquid crystal material consists of a host liquid crystal and a chiral dopant. The doping mass percentage of the photothermally responsive T-type liquid crystal molecules is 1 wt.%-5 wt.%. The chiral dopant is at least one of S5011 and S811. The host liquid crystal is at least one of E7, SLC1717, 5CB, and 8CB. The doping mass percentage of the chiral dopant is 5 wt.%.

7. A photothermal responsive liquid crystal material, characterized in that: Its components are a main liquid crystal material and photothermal responsive T-type liquid crystal molecules as described in claim 1; the main liquid crystal material is composed of a host liquid crystal and a chiral dopant; the doping mass percentage of the photothermal responsive T-type liquid crystal molecules is 1 wt.%-5 wt.%; the chiral dopant is at least one of S5011 and S811; the host liquid crystal is at least one of E7, SLC1717, 5CB, and 8CB; the doping mass percentage of the chiral dopant is 5 wt.%.

8. A type of smart glass, characterized in that: It is obtained by filling an alignment liquid crystal cell with the photothermal responsive liquid crystal material as described in claim 7.

9. The method for preparing smart glass as described in claim 8, characterized in that: Includes the following steps: Step S10: Take two pieces of ITO conductive glass of the same size and spin-coat a vertical alignment agent onto their surfaces. Step S20: Bake the ITO conductive glass that has been spin-coated in step S10 at 180~220℃ for 0.5~1.5h; Step S30: Disperse SiO2 microspheres in UV adhesive; Step S40: Take the UV adhesive from step S30 and drop it onto the four corners of the ITO conductive glass. Under ultraviolet light irradiation, a vertically aligned liquid crystal cell is formed. Step S50: The photothermal responsive liquid crystal material as described in claim 7 is injected into a vertically aligned liquid crystal cell via capillary action to obtain smart glass.

10. A smart window, characterized in that: It is prepared using the smart glass as described in claim 8.

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