Thermophotovoltaic triple response liquid crystal dopant and its application in smart glass

Abstract

The application provides a thermo-opto-electric triple-response liquid crystal dopant and application thereof to smart glass, and the molecular formula of the liquid crystal dopant is shown as formula (1). The liquid crystal dopant is doped in a liquid crystal material, and by combining the unique optical and electrical characteristics of the liquid crystal material, the liquid crystal dopant can simultaneously respond to temperature, light and electric field, adapt to various environmental requirements, provide various optical states to meet the energy-saving requirements in different scenes, has high light modulation rate, high haze and strong privacy protection function, has simple preparation process, few synthesis steps, good stability, low raw material cost, and can be applied to fields of residential buildings, commercial buildings, automobile and aircraft windows and the like, and has wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new materials, in particular to a thermooptic photoelectric triple response liquid crystal dopant and its application in smart glass. BACKGROUND

[0002] Smart windows are a new type of building material that can adjust light transmittance, reflectance and absorptance. According to its working principle and technical characteristics, the smart windows currently widely studied can be roughly divided into electrochromic, thermochromic, photochromic and mechanical chromic smart windows. These smart windows change the chemical composition or structure to show different optical properties and states.

[0003] Most of the existing smart windows currently respond to only one or two stimuli, limiting their application scenarios. For example, electrochromic smart windows require external power supply and control system, increasing energy consumption and complexity; photochromic smart windows have slow response speed and single color change; thermochromic smart windows have high conversion temperature, limiting their application range. In addition, the existing smart windows have a single driving mode, which cannot meet the diversified needs in different environments. SUMMARY

[0004] To solve the above technical problems, the present application discloses a thermooptic photoelectric triple response liquid crystal dopant and its application in smart glass, which can be combined with liquid crystal materials to achieve rapid response to various environmental stimuli, provide multiple optical states, and be used in smart windows to meet the energy saving needs in different scenarios.

[0005] To this end, the technical solution adopted by the present application is as follows:

[0006] A thermooptic photoelectric triple response liquid crystal dopant, whose molecular formula is shown as formula (1):

[0007] (1)

[0008] This technical solution is based on cyano biphenyl, azobenzene and flexible ester chain structural units, has the characteristics of integrating light response, thermal response and electrical response, and can be coated on the surface of glass to controllably adjust the transparency change of the glass by changing the light, temperature and additional voltage.

[0009] The present application also discloses a preparation method of the thermooptic photoelectric triple response liquid crystal dopant (CBA) as described above, which adopts typical diazotization reaction and esterification reaction, including the following steps:

[0010] Step S1, under ice-bath condition at 0-5°C, sodium nitrite aqueous solution was added into 4-amino-4'-cyano biphenyl hydrochloride aqueous solution, and continuous stirring until the solution turned into clear light yellow solution, which was the reaction solution; another mixed solution was prepared by dissolving phenol, sodium hydroxide and potassium carbonate in distilled water, and the mixed solution was injected into the reaction solution, then the temperature was raised to room temperature and the reaction was stirred for at least 10 hours; after the reaction was completed, the crude product was collected by vacuum filtration, and dichloromethane / ethyl acetate (10:1 by volume) was used as eluent for silica gel column chromatography separation and purification, and finally the orange powder product A was obtained; the molecular formula of the product A is shown in formula (2):

[0011]

[0012] The reaction condition of this step S1 is deionized water, and the reaction equation is:

[0013]

[0014] Step S2, adipic acid, 4-dimethylaminopyridine and 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride were placed in a reaction vessel, and after adding a stirring magnet, vacuum was applied and nitrogen was filled to establish an inert atmosphere; then N,N-dimethylformamide was injected, and the reaction was stirred in an ice-water bath for 30 minutes; then product A was added, the cold bath was removed and the reaction system was raised to room temperature, and the reaction was continuously stirred for at least 40 hours; after the reaction was completed, vacuum filtration was performed, and the obtained orange filtrate was extracted with brine and ethyl acetate, and the combined organic phase was washed with saturated brine and dried, then rotary evaporation was performed for concentration, dichloromethane / methanol (20:1 by volume) was used as eluent for silica gel column chromatography purification, and finally the orange powder product B was obtained; the molecular formula of the product B is shown in formula (3):

[0015]

[0016] The reaction condition of this step S2 is N,N-dimethylformamide solvent and acid, and the reaction equation is:

[0017]

[0018] Step S3, the product B, 4-dimethylamino pyridine and 1-ethyl-(3-dimethylamino propyl) carbodiimide hydrochloride are placed in a reaction container, vacuumized, filled with nitrogen, and an inert atmosphere is established after a stirring magnet is added; N,N-dimethylformamide is injected, and stirring is activated in an ice water bath to keep the temperature at 0℃ to obtain a reaction solution; 1,4-butanediol is dissolved in N,N-dimethylformamide, and then injected into the reaction solution; the cold bath is removed, and the reaction solution is allowed to rise to room temperature; stirring is continued for at least 40 hours; after the reaction is completed, the filtrate is obtained by filtration under reduced pressure; the organic phase is obtained by extraction with brine and ethyl acetate, and then washed with saturated brine and dried; and then concentrated by rotary evaporation to obtain a crude product; the crude product is purified by silica gel column chromatography with dichloromethane / methanol (20:1 by volume) as an eluent to obtain an orange crystalline solid.

[0019] The reaction condition of step S3 is N,N-dimethylformamide solvent and acid, and the reaction equation is as follows:

[0020]

[0021] As a further improvement of the present application, in step S3, the obtained crude product is extracted, and then added to ethyl acetate solvent, and then rotary evaporated to remove the ethyl acetate solvent to obtain a CBA crude product; the CBA crude product is purified by silica gel column chromatography with dichloromethane / methanol (20:1 by volume) as an eluent to obtain a liquid crystal dopant with a thermophotovoltaic triple response.

[0022] As a further improvement of the present application, in step S1, the amount of sodium nitrite is 0.5-0.55 times the amount of 4-amino-4'-cyano biphenyl; the concentration of hydrochloric acid is 1.5-2M; the amount of phenol is 0.5-0.55 times the amount of 4-amino-4'-cyano biphenyl; the amount of sodium hydroxide is 0.55-0.58 times the amount of 4-amino-4'-cyano biphenyl; and the amount of potassium carbonate is 0.55-0.58 times the amount of 4-amino-4'-cyano biphenyl.

[0023] 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 the product A; the amount of 4-dimethylamino pyridine is 0.08-0.12 times the amount of the product A; and the amount of 1-ethyl-(3-dimethylamino propyl) carbodiimide hydrochloride is 2.8-3.1 times the amount of the product A.

[0024] As a further improvement of the present application, in step S3, the amount of 4-dimethylamino pyridine is 0.08-0.12 times the amount of product B, the amount of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride is 2.8-3.1 times the amount of product B, and the amount of 1,4-butanediol is 4.8-5.1 times the amount of product B.

[0025] The present application also discloses the application of the thermo-opto-electric triple response liquid crystal dopant as described above, which is used for doping into a liquid crystal material to prepare a thermo-opto-electric triple response liquid crystal device.

[0026] As a further improvement of the present application, the components of the liquid crystal material include a main liquid crystal and a chiral dopant.

[0027] As a further improvement of the present application, the doping mass ratio of the thermo-opto-electric triple response liquid crystal dopant is 1%-5%. Further, the doping mass ratio of the thermo-opto-electric triple response liquid crystal dopant is 1%-4%.

[0028] As a further improvement of the present application, the chiral dopant is at least one of S5011 and S811.

[0029] As a further improvement of the present application, the main liquid crystal is at least one of E7, SLC1717, 5CB and 8CB.

[0030] As a further improvement of the present application, the doping mass percentage of the chiral dopant is 5wt%.

[0031] The components of the liquid crystal material include that the chiral dopant is selected from one or both of S5011 and S811; preferably, the dopant concentration in the raw material is 5wt%; preferably, the liquid crystal main body is selected from one or more of E7, SLC1717, 5CB and 8CB.

[0032] As a further improvement of the present application, the doping mass ratio of the thermo-opto-electric triple response liquid crystal dopant is 1%-5%.

[0033] The present application also discloses a thermo-opto-electric triple response liquid crystal material, which includes a liquid crystal material and the thermo-opto-electric triple response liquid crystal dopant as claimed in claim 1.

[0034] As a further improvement of the present application, the components of the liquid crystal material include that the chiral dopant is selected from one or both of S5011 and S811; preferably, the dopant concentration in the raw material is 5wt%; preferably, the liquid crystal main body is selected from one or more of E7, SLC1717, 5CB and 8CB.

[0035] As a further improvement of the present application, the doping mass ratio of the thermooptic-electric triple response liquid crystal dopant is 1%-5%.

[0036] The present application also discloses a kind of intelligent glass, which is prepared from the thermooptic-electric triple response liquid crystal material described above.

[0037] The present application also discloses a kind of intelligent window, which is prepared from the intelligent glass described above.

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

[0039] By doping in the liquid crystal material, the present application can simultaneously respond to temperature, light and electric field by combining the unique optical and electrical properties of the liquid crystal material, and adapt to various environmental requirements. Specifically, thermochromic: as the temperature rises, the liquid crystal system changes from smectic phase to multi-domain cholesteric phase, realizing the switching of transparent and fuzzy state. Photochromic: under ultraviolet irradiation, azobenzene group undergoes reversible isomerization, inducing the system to change from smectic phase to cholesteric phase, realizing the switching of transparent and fuzzy state. Electrochromic: under the action of electric field, the helical superstructure of cholesteric liquid crystal is disordered, and the liquid crystal molecules are arranged along the electric field direction, realizing the switching of fuzzy state and transparent state.

[0040] Secondly, it can provide multiple optical states to meet the energy saving needs in different scenarios, and the light modulation rate is high, the haze is large, and the privacy protection function is strong. The intelligent window using the technical solution of the present application can provide four reversible adjustment modes, the transmittance of transparent state is more than 75%, the transmittance of fuzzy state is less than 25%, the light modulation rate is greater than 50%, the haze is greater than 65%, and it has privacy protection function. The four switching modes all have good cycle stability, and repeated switching will not significantly affect the optical properties.

[0041] Thirdly, the preparation process of the thermooptic-electric triple response liquid crystal dopant CBA molecule of the present application is simple, the synthesis steps are few, the separation and purification operation is simple, the stability is good, it has the characteristics of thermal / light / electric triple response, and it can still maintain good reversible performance in doped liquid crystal, the raw material cost is low, it can be applied to residential, commercial buildings, automobile and aircraft windows, etc. field, has broad application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 It is the nuclear magnetic resonance hydrogen spectrum of the reaction product of the step S1 of the embodiment of the present application.

[0043] Figure 2 It is the nuclear magnetic resonance hydrogen spectrum of the reaction product of the step S2 of the embodiment of the present application.

[0044] Figure 3The final product of step S3 of the embodiment of the present application but CBA nuclear magnetic resonance hydrogen spectrum.

[0045] Figure 4 The performance results of the CBA molecule of the embodiment of the present application; wherein, Fig. a is a schematic diagram of photoisomerization structure of the CBA molecule, Fig. b is the corresponding ultraviolet absorption spectrum (3×10 -5 M, DCM).

[0046] Figure 5 The spectrum of the CBA molecule of the embodiment of the present application, wherein Fig. a is an infrared absorption spectrum, and Fig. b is a Raman spectrum.

[0047] Figure 6 The thermal analysis results of the CBA molecule of the embodiment of the present application, wherein Fig. a is a TGA curve, and Fig. b is a DSC curve.

[0048] Figure 7 The polarized light microtexture maps of the CBA molecule of the embodiment of the present application in a parallel orientation liquid crystal cell at different temperature stages; wherein, a~f are 142℃, 140℃, 100℃, 90℃, 60℃, 50℃, respectively.

[0049] Figure 8 The one-dimensional X-ray diffraction maps of the CBA molecule in a capillary tube of the embodiment of the present application; wherein (a) is a cooling process; (b) is a heating process.

[0050] Figure 9 The two-dimensional wide-angle X-ray maps of the CBA molecule in a capillary tube at different temperatures of the embodiment of the present application.

[0051] Figure 10 The one-dimensional X-ray diffraction maps of the CBA molecule in a vertical alignment liquid crystal cell at different temperatures of the embodiment of the present application.

[0052] Figure 11 The schematic diagram of the CBA crystal structure of the embodiment of the present application.

[0053] Figure 12 The phase state evolution diagram of the CBA molecule with temperature decrease of the embodiment of the present application.

[0054] Figure 13 The preparation process of the CBA smart window model liquid crystal cell of the embodiment of the present application.

[0055] Figure 14 The DSC curves of the samples with different CBA molecule concentration doping ratios of the embodiment of the present application.

[0056] Figure 15Polarizing microtexture of CBA mixed LC system in a parallel alignment liquid crystal cell during the heating process of the embodiment of the present application; wherein a-f are 28℃, 31℃, 33℃, 37℃, 38℃, 39℃, respectively.

[0057] Figure 16 Polarizing microtexture of CBA mixed LC system in a parallel alignment liquid crystal cell during the cooling process of the embodiment of the present application; wherein a-f are 39℃, 37℃, 35℃, 33℃, 31℃, 28℃, respectively.

[0058] Figure 17 Polarizing microtexture of CBA mixed LC system in a vertical alignment liquid crystal cell during the heating process of the embodiment of the present application; wherein a-f are 28℃, 29℃, 33℃, 37℃, 40℃, 41℃, respectively.

[0059] Figure 18 Polarizing microtexture of CBA mixed LC system in a vertical alignment liquid crystal cell during the cooling process of the embodiment of the present application; wherein a-f are 41℃, 40℃, 37℃, 33℃, 29℃, 28℃, respectively.

[0060] Figure 19 Thermochromic schematic diagram of the embodiment of the present application.

[0061] Figure 20 Polarizing microtexture of LC mixed system without CBA doping in a vertical alignment liquid crystal cell at different temperatures of the embodiment of the present application; wherein a-h are 31℃, 32℃, 37℃, 38℃, 38℃, 37℃, 32℃, 31℃, respectively.

[0062] Figure 21 Polarizing microtexture of a vertical anchoring liquid crystal cell sample doped with CBA under ultraviolet-visible light response of the embodiment of the present application; wherein a is the initial state at 25℃, b is after 10s of ultraviolet light irradiation, c is after 150s of ultraviolet light irradiation, d is after 160s of ultraviolet light irradiation, e is after 170s of ultraviolet light irradiation, f is after 180s of ultraviolet light irradiation.

[0063] Figure 22 Photochromic schematic diagram of the embodiment of the present application.

[0064] Figure 23 Polarizing micrograph of a vertical anchoring liquid crystal cell sample doped with CBA under electric field response of the embodiment of the present application, wherein a-c are the photos of initial state at 35℃, applying electric field, and closing electric field, respectively; d-f are the photos of initial state of ultraviolet irradiation, applying electric field, and closing electric field, respectively.

[0065] Figure 24 Electrochromic schematic diagram of the embodiment of the present application, wherein (a) is the heating state; (b) is the ultraviolet irradiation state.

[0066] Figure 25 The thermal, photochromic and electrochromic mechanism and schematic diagram of the CBA smart window of the embodiment of the present application.

[0067] Figure 26 The standard light view luminous efficiency function curve of the embodiment (a) of the present application and the spectral distribution of solar irradiance under AM 1.5 conditions; (b) the transmittance spectrum of the synergistic response of temperature and electric field; (c) the transmittance spectrum of the synergistic response of UV and electric field.

[0068] Figure 27 The transmittance spectrum and scattering spectrum diagram of the CBA smart window in different states of the embodiment of the present application; a-d are the transmittance light flux (T1) and scattering light flux (T3) when the sample is not placed, the transmittance light flux (T2) and scattering light flux (T4) when the sample is placed at room temperature (25℃), the transmittance light flux (T2) and scattering light flux (T4) when the sample is placed after heating (35℃), and the transmittance light flux (T2) and scattering light flux (T4) when the sample is placed under ultraviolet irradiation.

[0069] Figure 28 The cycle test of different mode switching of the embodiment of the present application, wherein a is thermal chromism; b is electrochromism under high temperature; c is photochromism; d is electrochromism under ultraviolet irradiation. DETAILED DESCRIPTION

[0070] In order to have a more profound understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described in detail with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor belong to the scope of protection of the present application.

[0071] A thermophotovoltaic triple-response liquid crystal dopant (CBA), which is a liquid crystal dopant molecule based on cyano biphenyl, azobenzene and flexible ester chain structural units, and its structural formula is shown as formula (1):

[0072]

[0073] Embodiment 1

[0074] A thermophotovoltaic triple-response liquid crystal dopant molecule CBA, and its synthesis route is as follows:

[0075]

[0076]

[0077] Specifically includes the following steps:

[0078] Step S1, under ice-bath condition at 0-5 °C, sodium nitrite (NaNO2, 555 mg, 8 mmol) in water (10 mL) was added dropwise into 4-amino-4'-cyano biphenyl (1.3 g, 15.4 mmol) in hydrochloric acid aqueous solution (1.6 M, 20 mL) with continuous stirring for 1 h until the system turned into a clear light yellow solution. Separately, phenol (756 mg, 8 mmol), sodium hydroxide (NaOH, 348 mg, 8.7 mmol) and potassium carbonate (K2CO3, 1.2 g, 8.7 mmol) were dissolved in 30 mL distilled water, and the mixture solution was injected into the reaction system, which was then slowly warmed to room temperature and stirred for 12 h. After the reaction was completed, the crude product was collected by filtration under reduced pressure, and purified by silica gel column chromatography with dichloromethane / ethyl acetate (10:1 by volume) as eluent to obtain the target product as an orange powder 1.76 g in 88% yield.1H NMR (500 MHz, DMSO-d6) δ 10.36 (s), 7.98-7.87 (m), 7.83-7.78 (m), 6.95-6.90 (m), as shown in Figure 1 .

[0079] Step S2, adipic acid (2.58 g, 17.66 mmol), 4-dimethylaminopyridine (DMAP, 71.9 mg, 0.59 mmol) and 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC-HCl, 3.39 g, 17.66 mmol) were placed in a 250 mL two-necked round-bottom flask, which was subjected to three cycles of vacuum-nitrogen filling to establish an inert atmosphere after the addition of a stirring magnet. An appropriate amount of DMF was injected through a syringe, and the mixture was stirred in an ice-water bath at 0 °C for 30 min. Then, the starting material 1 (1.76 g, 5.9 mmol) was added, and the reaction system was slowly warmed to room temperature after the removal of the cold bath, and stirred for 48 h. After the reaction was terminated, the orange filtrate was filtered under reduced pressure, and extracted with brine and ethyl acetate. The combined organic phase was washed with saturated brine, dried over anhydrous magnesium sulfate, and concentrated by rotary evaporation. The crude product was purified by silica gel column chromatography (dichloromethane / methanol = 20:1) to obtain 1.27 g of an orange powder in 51% yield.1H NMR (500 MHz, DMSO-d6) δ 12.06, 8.08-7.84 (m), 7.45-7.22 (m), 2.62 (t, J = 7.2 Hz), 2.25 (t, J = 7.1 Hz), 1.72-1.49 (m), as shown in Figure 2 .

[0080] Step S3, raw material 2 (1.27 g, 2.97 mmol), 4-dimethylaminopyridine (DMAP, 36 mg, 0.30 mmol) and 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC-HCl, 1.71 g, 8.92 mmol) were placed in a 250 mL double-necked round-bottom flask, and an inert atmosphere was established by three cycles of vacuum-nitrogen filling after adding a stirring magnet. N,N-dimethylformamide (DMF, 50 mL) was injected by a syringe, and the stirring was activated for 30 minutes in an ice-water bath at 0°C. 1,4-Butanediol (1.34 g, 14.8 mmol) was dissolved in DMF (5 mL) and injected into the reaction system by a syringe. The cold bath was removed, and the reaction system was slowly warmed to room temperature. The stirring was continued for 48 hours. After the reaction was terminated, the filtrate was filtered under reduced pressure through a sand core funnel. The combined organic phase was washed with saturated brine and dried over anhydrous magnesium sulfate, and then concentrated by rotary evaporation. The crude product was purified by silica gel column chromatography (dichloromethane / methanol = 20:1), and finally 504.6 mg of orange crystalline solid was obtained with a yield of 34%. 1H NMR (500 MHz, DMSO-d6) δ 8.05-7.88 (m), 7.41-7.25 (m), 4.40 (t, J = 5.2 Hz), 4.00 (t, J = 6.7 Hz), 2.62 (t, J = 7.0 Hz), 2.33 (t, J = 6.9 Hz), 1.67-1.53 (m), 1.42 (ddd, J = 7.6, 6.0, 1.6 Hz), as shown in Figure 3 .

[0081] Example 2

[0082] The molecular CBA prepared in Example 1 was subjected to spectral analysis and thermal analysis, and the specific steps were as follows:

[0083] After extraction of the solution obtained by the three-step reaction of Example 1 into ethyl acetate solvent, the ethyl acetate solvent was removed by rotary evaporation to obtain CBA crude product. CBA powder was obtained by silica gel column chromatography, and it was proved by nuclear magnetic resonance hydrogen spectrum, as shown in Figure 3 .

[0084] CBA has good solubility in organic solvents such as dichloromethane and chloroform, and forms a transparent solution before and after ultraviolet light irradiation, and has a typical monomer-like absorption spectrum, and its photoisomerization structure diagram is shown in Figure 4 a, and the corresponding ultraviolet absorption spectrum is shown in Figure 4b. Before UV irradiation, the molecule is in trans state, there is a strong π-π* transition at 345 nm, a second order π-π* transition at 278 nm, and a weak n-π* transition at 442 nm. After 3 min UV irradiation at 365 nm, the liquid crystal molecules in solution are converted to cis state, the disappearance of the absorption peak at 345 nm is observed, a new strong absorption peak at 296 nm is generated, and the absorption peak at 442 nm is significantly enhanced. The significant change in UV spectrum confirms the photoisomerization process of CBA molecule.

[0085] To further characterize the functional groups and chemical structure of CBA, Fourier transform infrared spectroscopy and Raman spectroscopy were performed, and the results are shown in Figure 5 Figure 5 a. The main characteristic absorption peaks of CBA powder are as follows: the strong absorption peak at 3530 cm -1 is attributed to the stretching vibration of -OH in the molecule, indicating the presence of hydroxyl groups in the sample, the two groups of absorption peaks at 2850-3150 cm -1 can be attributed to the stretching vibration of C-H in alkyl chain and benzene ring, respectively, the narrow strong absorption peak at 3530 cm -1 is attributed to the stretching vibration of -C≡N, and the C=O and N=N stretching vibration peaks of ester bond and azo bond can be observed at 1749 cm -1 and 1719 cm -1 , respectively. The Raman shift of CBA molecule is shown in Figure 5 b. Among them, the Raman peak at 1185 cm-1 is attributed to the stretching vibration mode of C-C single bond, the Raman peaks at 1280 cm -1 and 1579 cm -1 are attributed to the breathing vibration of C-C aromatic ring and the stretching vibration mode of biphenyl, the Raman peak at 1453 cm -1 is attributed to the stretching vibration mode of N=N double bond, the Raman peak at 1410 cm -1 is attributed to the planar bending vibration mode of C-H single bond, and the Raman peak at 1145 cm -1 is attributed to the stretching vibration mode of C-N single bond. The vibration peaks of biphenyl structure and azobenzene structure further confirm the molecular structure.

[0086] TGA and DSC analysis of the CBA molecule were performed, and the results are shown in Figure 6 . The TGA data show that the initial decomposition temperature of CBA molecule is about 307.3°C, and it has good thermal stability Figure 6 a). The DSC curve of CBA molecule is shown in Figure 6 ​As shown in b, during the heating phase, the CBA molecule exhibits three endothermic peaks at 69.8℃, 96.5℃, and 132.9℃, respectively; during the cooling phase, the corresponding three exothermic peaks are at 47.5℃, 94.9℃, and 131.1℃, respectively. The three sets of transition peaks from high temperature to room temperature correspond to three phase transition processes: N-SmA, SmA–SmB, and SmB–Cr. The phase transition behavior of the CBA molecule below 200℃ demonstrates good thermal stability and reversibility.

[0087] Example 3:

[0088] The self-assembled structure design of the compound CBA prepared in Example 1 is as follows:

[0089] A parallel-aligned, frictionless liquid crystal cell encapsulated CBA molecular system was used. Its macroscopic molecular arrangement behavior and phase transition characteristics were characterized using polarized light microscopy. The polarized light microtexture images of CBA molecules in the parallel-aligned, frictionless liquid crystal cell at different temperature stages are shown below. Figure 7 As shown. Experimental data show that the substrate anchoring effect induced by the parallel alignment agent causes CBA molecules to exhibit in-plane ordered arrangement, and significant birefringence was observed under orthogonal polarization conditions. During the temperature-controlled process, the phase evolution of the system exhibits typical temperature dependence: when the temperature is maintained above 142℃, the sample shows a marble-like texture characteristic of the nematic phase; when the temperature is reduced to the 140-60℃ range, the system enters a broad-range smectic phase, and the edge of the layered texture shows a significant morphological transformation at 100℃—the edge of the layered structure in the high-temperature region (>100℃) is irregularly wrinkled, while in the low-temperature region (<100℃), it evolves into a smooth boundary structure. DSC analysis shows significant exothermic / endothermic peaks near 95℃, indicating the existence of reversible transitions between two smectic phase structures in the system. It is noteworthy that there is a systematic deviation of approximately 5°C between the phase transition temperature observed under microscopy and the results of DSC thermal analysis. This is presumably due to differences in experimental conditions: the DSC test was conducted in a closed, dark environment, while the continuous light source during polarized microscopy may have excited the photoresponse characteristics of the azophenyl groups, leading to a slight change in the molecular orientation order. When the system cools to below 60°C, the sample completes its transformation to the crystalline state, a process that corresponds well with the DSC curve.

[0090] To systematically study the phase transition behavior and microstructural order of CBA materials, two-dimensional wide-angle X-ray scattering (2D-WAXS) was used for temperature-dependent structural characterization. At temperatures above 100℃, CBA was injected into a 0.3 mm capillary tube via capillary force, and relatively good orientation was induced by shear flow within the capillary. The 2D-WAXS test results are as follows: Figure 9It can be observed that as the temperature decreases, the intensity of diffraction arcs in the small-angle region at the equator and the high-angle region along the meridian gradually increases, representing the transition from the nematic phase to the smectic phase. When the temperature decreases to room temperature, new diffraction arcs appear in both the small-angle and high-angle regions, representing a better-ordered crystal phase at room temperature. The diffraction peaks in the low-angle region are located at the equator, meaning that the X-rays are incident perpendicular to the long axis of the molecule, and CBA molecules tend to align perpendicular to the capillary wall in the capillary. By converting the above two-dimensional diagram into a one-dimensional spectrum (e.g., Figure 8 (As shown) A detailed analysis of the CBA self-assembled structure was conducted. At 160℃, the diffraction peaks in the low-angle region exhibited broad peak characteristics, corresponding to... The interplanar spacing, comparable to the length of a single molecule, indicates that the layered structure of the liquid crystal molecules is not yet complete, and the system is in the nematic phase. When the temperature drops to 120℃, the low-angle diffraction peaks transform into sharp, narrow peaks, and the interlayer spacing shrinks to a smaller value. This reflects the regular layered arrangement of molecules, but The broad peak at this point indicates a lack of long-range order between adjacent molecules, a characteristic consistent with the SmA phase. Upon further cooling to 80℃, the diffraction peaks characterizing intermolecular order sharpen into narrow peaks, and the interplanar spacing is finely adjusted to... This indicates the formation of a more ordered SmB phase. At room temperature, the newly appearing diffraction peaks confirm that the system has ultimately transformed into a higher-order crystalline phase.

[0091] To further verify the transition between the SmA and SmB phases, CBA molecules were injected into a vertically anchored liquid crystal cell. X-ray diffraction information parallel to the long axis of the liquid crystal molecules was obtained, as shown in the following results. Figure 10 As shown. At this point, the diffraction peaks in the low-angle region related to the interlayer spacing disappear, leaving only diffraction signals representing changes in the order of adjacent molecules. At temperatures above 100℃, no obvious diffraction peaks are observed, indicating that there is no significant positional order between adjacent molecules, and the CBA molecules are in the nematic and SmA phases. As the temperature decreases, the diffraction peak appearing at 20.7° at 95℃ indicates the formation of positional order between adjacent molecules, and the CBA molecules transform from the SmA phase to the SmB phase.

[0092] Understanding the crystal structure of CBA at room temperature is fundamental to resolving the entire phase transition process. At room temperature, CBA crystals exhibit four main diffraction peaks, corresponding to crystal plane distances of [missing information]. and Based on the distribution of crystal plane spacing and diffraction arc azimuth angle, the following unit cell parameters were determined. α=β=γ=90°, such as Figure 11 As shown. Crystalline plane distance at room temperature. and These can be represented by the 100, 020, and 002 crystal planes. The 020 and 002 crystal planes are mainly formed by the crystallization of ester chains at the ends of molecules. The interplanar spacing represents the weak π-π stacking between benzene ring segments. When X-rays are incident perpendicular to the long axis of the molecule, the 100 plane at the equator indicates that CBA molecules tend to align perpendicularly to the capillary wall in the capillary. The 020 and 002 planes appearing on the meridian indicate that the crystal orientation exists only in the a-axis direction. The resulting diffraction pattern is a mixture of

[010] and

[001] . Therefore, the self-assembly structure of CBA is mainly regulated by the ester chains at the molecular ends. As the temperature increases, the interaction forces between the ester chains gradually weaken, and the formed crystal structure gradually disappears. As the orderliness of the self-assembly structure decreases, the molecule transforms from a crystal to a smectic liquid crystal, and finally to a nematic liquid crystal, such as... Figure 12 As shown.

[0093] Example 4

[0094] The performance of the smart window doped with CBA molecules synthesized in Example 1 was studied, and the steps are as follows:

[0095] It is incorporated into the host liquid crystal 8CB and the chiral dopant S811, as shown in the flowchart below. Figure 13 As shown in Table 1, the doping ratios are as follows, where % is the mass percentage.

[0096] Table 1. Mixing ratio of the main liquid crystal 8CB, chiral dopant S811, and CBA molecules.

[0097] S0(％) S1(％) S2(％) S3(％) S4(％) S5(％) 8CB 95 94 93 92 91 90 S811 5 5 5 5 5 5 CBA 0 1 2 3 4 5

[0098] DSC curves of samples with different proportions were measured, such as... Figure 14 As shown, with a fixed mass fraction of chiral dopant S811, doping with CBA can broaden the cholesteric phase range of the LC system. Generally, increasing the dopant concentration decreases the cholesteric-isotropic phase transition temperature. Thanks to the slightly curved molecular structure of CBA, which is similar to the host liquid crystal molecules, the isotropic-cholesteric phase transition temperature gradually increases with increasing CBA concentration, reaching a maximum at a doping concentration of 4%. Above 4%, significant phase separation was observed in the smart glass prototype stored at room temperature for extended periods.

[0099] The following section explores the multi-response functionality of a smart window prototype with a CAB doping concentration of 4%.

[0100] First, the texture of the CBA hybrid LC system was observed using a parallel-aligned liquid crystal cell to determine its phase state. The polarized microtexture of the CBA hybrid LC system in the parallel-aligned liquid crystal cell during heating is shown below. Figure 15As shown, at room temperature, the mixture exhibits a typical smectic fan-shaped texture. With increasing temperature, it rapidly transforms into a cholesteric planar texture. At this temperature, the director of the liquid crystal molecules lies in a plane parallel to the substrate, and the helical axis is perpendicular to the substrate plane. As the temperature rises, the color gradually transitions from yellow to deep blue, indicating that the pitch of the cholesteric phase changes with temperature. At 39°C, the mixture transforms into an isotropic state, and the birefringence disappears.

[0101] The polarization microstructure of the CBA hybrid LC system in the parallel-aligned liquid crystal cell during the cooling process is as follows: Figure 16 As shown, during the cooling stage, numerous bundled oily streaks are generated when the mixed system transitions from the isotropic state to the cholesteric phase. These bundled oily streaks can be viewed as a network of defect lines dispersed in a uniform helical region. The structure of the bundled oily streaks is complex, mainly relying on the elastic constants of the liquid crystal molecules and the surface anchoring effect of the liquid crystal cell. At room temperature, even in the liquid crystal cell after unidirectional friction, this mixed system cannot form a uniform single-domain structure, which greatly affects its transmittance at room temperature, thus making it unsuitable for manufacturing smart glass.

[0102] In a vertically anchored liquid crystal cell, the polarization microtexture of the CBA hybrid LC system in the vertically oriented liquid crystal cell during the heating process is as follows: Figure 17 As shown, the CBA-mixed LC system can form a single-domain smectic structure at room temperature. In this state, the long axes of the liquid crystal molecules are arranged in an ordered manner perpendicular to the substrate plane. Because the molecular orientation vector is consistent with the direction of polarized light propagation, the system exhibits pseudo-isotropic optical properties. During heating, the mixed system undergoes a phase transition, and the smectic structure rapidly dissociates into a multi-domain cholesteric fingerprint texture, accompanied by the formation of numerous bundle-like oily streaks. Compared to the uniform planar state in the parallel orientation state, this multi-domain structure produces a significant light scattering effect at the oily streak interface.

[0103] The polarization microstructure of the CBA hybrid LC system in a vertically oriented liquid crystal cell during the cooling process is as follows: Figure 18 As shown in the diagram, during the cooling phase, the fingerprint texture gradually disappears, but the multi-domain characteristics further enhance with decreasing temperature. Based on the high transparency of the smectic single-domain structure and the light scattering properties of the cholesteric multi-domain structure, this system can achieve reversible switching between temperature-responsive transparent and blurred states. A schematic diagram of the thermochromic effect is shown below. Figure 19 As shown.

[0104] For comparison, undoped CBA liquid crystal cells were prepared, with 8CB and S811 ratios of 95% and 5%, respectively. The polarization microtextures of the CBA-free LC hybrid system in vertically oriented liquid crystal cells at different temperatures are shown below. Figure 20As shown. Under vertical orientation conditions, the system exhibits a single-domain smectic dark texture at room temperature. With increasing temperature, the system transforms from a smectic phase to a cholesteric phase at 32°C, displaying a uniform fingerprint texture under a polarizing microscope. At 38°C, the system transforms from a nematic phase to an isotropic phase, and birefringence disappears. During the cooling phase, the system exhibits a multi-domain focal conic texture, another typical texture of the cholesteric phase. The cholesteric phase region of the undoped CBA-containing mixed LC system is significantly reduced, consistent with the DSC curve results.

[0105] The structural changes during the reversible response to ultraviolet light can be observed using a polarizing microscope, and the results are as follows: Figure 21 As shown. The initial single-domain smectic phase appears as a dark state without birefringence under a polarizing microscope. After 10 seconds of irradiation with 365 nm ultraviolet light, the CBA molecule rapidly transforms from a relatively regular trans conformation to a distorted cis conformation. The distorted CBA molecule lowers the order parameter of the LC system, inducing the system to transform from a smectic phase to a multi-domain cholesteric phase. Under visible light irradiation with a polarizing microscope, the CBA molecule gradually returns to the trans conformation through thermal relaxation and visible light excitation. Figure 22 As shown, under visible light irradiation, the multi-domain cholesteric phase texture gradually transforms into a more uniform fingerprint texture, and finally gradually unwinds back into a single-domain smectic phase. Note that the transformation of the CBA molecule from the cis to the trans configuration is positively correlated with the intensity of visible light. When illuminated with a mobile phone flashlight, this visible light-induced isomerization process can be completed within seconds. Utilizing the conformational transition induced by ultraviolet light at room temperature, we can achieve passive switching of the ultraviolet response between the transparent and blurred states of a liquid crystal cell.

[0106] Polarized light micrographs of CBA-doped vertically anchored liquid crystal cell samples under electric field response, as shown in the image. Figure 23 As shown, under the influence of an electric field perpendicular to the substrate, the helical superstructure of the cholesteric liquid crystal unwinds, and the liquid crystal molecules rearrange their orientation along the direction of the electric field. This electro-orientation effect leads to the disappearance of optical anisotropy in the system, and the disappearance of birefringence can be observed under a crossed polarizing microscope. The high uniformity of molecular orientation significantly reduces the light scattering effect of the system, making the liquid crystal cell transparent. After the electric field is removed, the system can quickly return to the multi-domain cholesteric phase structure, basically consistent with the structure before the electric field was applied, exhibiting good reversibility. Whether the cholesteric phase structure is induced by ultraviolet light or by temperature rise, the liquid crystal molecules can be rearranged under the induction of an electric field, which can realize the rapid electrochromic function of CBA smart windows, such as... Figure 24 As shown.

[0107] The thermochromic, photochromic, and electrochromic mechanisms of smart windows incorporating CBA technology are as follows: Figure 25As shown, the CBA-doped smart window prototype exhibits a triple response to temperature, ultraviolet light, and electric field. At room temperature, the smart window is transparent, and the LC hybrid system exhibits a uniform smectic phase. On the one hand, as the temperature increases, the LC hybrid system enters a multi-domain cholesteric phase, exhibiting a blurred state at high temperatures. Applying a vertical electric field to the liquid crystal cell in the blurred state at high temperatures causes the chiral nematic phase of the LC hybrid system to orient itself under the influence of the electric field, returning to the transparent state at high temperatures. On the other hand, irradiating the room-temperature transparent smart window prototype with 365nm ultraviolet light causes the LC hybrid system to form a multi-domain cholesteric phase under the induction of azobenzene isomerization, exhibiting a blurred state under ultraviolet light. Similarly, applying a vertical electric field to the liquid crystal cell in the blurred state under ultraviolet light causes the chiral nematic phase of the LC hybrid system to orient itself under the influence of the electric field, returning to the transparent state under ultraviolet light. In summary, this liquid crystal smart window has multiple response functions, which helps to broaden the application scenarios of liquid crystal smart windows.

[0108] Transmission performance of the smart window prototype under different states, such as Figure 26 As shown in Table 2, the transmittance of the smart window prototype under different states was calculated. At room temperature (25℃), the smart window prototype had a Tlum of 82.74% and a Tsol of 75.64%, which were at a relatively high level. Under the blurred state at high temperature, Tlum and Tsol decreased to 18.73% and 17.08%, respectively, with ΔTlum and ΔTsol being 64.01% and 58.57%, respectively. Under the blurred state under ultraviolet radiation, Tlum and Tsol decreased to 16.38% and 15.41%, respectively, with ΔTlum and ΔTsol being 66.36% and 60.23%, respectively. Under the action of an electric field, the transmittance under both ultraviolet irradiation and high temperature conditions could return to the initial high transparency level, and the transmittance change ΔTon-off before and after applying voltage under different states ranged from 55% to 70%. This smart window prototype exhibits excellent light modulation performance.

[0109] Table 2 Calculated transmittance of CBA smart window under different conditions

[0110] 25℃(％) 35℃(％) 35℃-80V％) UV (%) UV-80V (%) [CAT lum ]]> 82.74 18.73 80.72 16.38 84.18 [CAT sol ]]> 75.64 17.08 73.03 15.41 74.91

[0111] According to GB / T2410-2008 "Determination of Light Transmittance and Haze of Transparent Plastics", an integrating sphere was used to measure the haze of the CBA smart window under different conditions. The calculation method for haze is shown in the formula:

[0112]

[0113] T=∫T(λ)dλ / ∫dλ

[0114] Where T1 and T3 represent the transmitted and scattered light fluxes without a sample, respectively, and T2 and T4 represent the transmitted and scattered light fluxes with the sample, respectively. The transmission and scattering spectra measured using an integrating sphere under different conditions are shown in the figure below. Figure 27 As shown in Table 3, the haze levels under different conditions were calculated using the formula. In the initial state, the smart glass in the smectic phase exhibited extremely low haze, only 3.17%. In the cholesteric phase haze state at higher temperatures, due to interface scattering of the multi-domain structure, the smart glass exhibited a haze as high as 70.71%. In the ultraviolet light-induced cholesteric phase haze state, the haze of the smart glass was 66.20%, still exhibiting good light scattering ability.

[0115] Table 3. Haze of CBA Smart Window under Different Conditions

[0116]

[0117] The stability of the CBA smart window prototype under four switching modes was measured using a spectrophotometer with a heating element, a UV lamp, and an adjustable regulated DC power supply. The light source wavelength was fixed at 550 nm. The transmittance in the transparent state was above 75% in all four switching modes, while it was below 25% in the blurred state. Figure 28 As shown in the figure. Cyclic test results indicate that all four reversible switching processes exhibit good stability, and repeated switching has almost no significant impact on their optical properties.

[0118] 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 liquid crystal dopant with thermo-photoelectric triple response, characterized in that: Its molecular formula is shown in formula (1): （1）。 2. The method for preparing the thermo-photoelectric triple-response liquid crystal dopant as described in claim 1, characterized in that: Includes the following steps: Step S1: Under ice bath conditions at 0-5℃, add sodium nitrite aqueous solution to hydrochloric acid aqueous solution of 4-amino-4'-cyanobiphenyl, and stir continuously until it turns into a clear pale yellow solution, which is the reaction solution; separately, dissolve phenol, sodium hydroxide and potassium carbonate in distilled water to obtain a mixed solution, inject the mixed solution into the reaction solution, heat to room temperature and stir the reaction for at least 10 hours; After the reaction was completed, the crude product was collected by vacuum filtration and purified by silica gel column chromatography using dichloromethane / ethyl acetate at a volume ratio of 10:1 as the eluent, finally obtaining an orange powder product A; the molecular formula of product A is shown in formula (2): （2）； Step S2: Adipic acid, 4-dimethylaminopyridine, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride were placed in a reaction vessel, and after adding a magnetic stir bar, the system was evacuated and purged with nitrogen to establish an inert atmosphere. Then N,N-dimethylformamide was injected, and the system was stirred and activated in an ice-water bath for 30 minutes. Subsequently, product A was added, the cold bath was removed, and the reaction system was brought to room temperature. The reaction was stirred continuously for at least 40 hours. After the reaction was completed, the system was filtered under reduced pressure, and the resulting orange filtrate was extracted with brine and ethyl acetate. The combined organic phases were washed with saturated brine and dried, and then concentrated by rotary evaporation. The product was purified by silica gel column chromatography using a 20:1 volume ratio of dichloromethane / methanol as the eluent to finally obtain orange powder product B. The molecular formula of product B is shown in formula (3): （3）； In step S3, product B, 4-dimethylaminopyridine, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride were placed in a reaction vessel. After adding a magnetic stir bar, a vacuum was drawn and nitrogen was applied to establish an inert atmosphere. N,N-dimethylformamide was injected and stirred at 0°C in an ice-water bath to activate the reaction solution. Separately, 1,4-butanediol was dissolved in N,N-dimethylformamide and then injected into the reaction solution. The cold bath was removed, and the reaction solution was allowed to rise to room temperature. The reaction was stirred continuously for at least 40 hours. After the reaction was completed, the solution was filtered under reduced pressure. The filtrate was extracted successively with brine and ethyl acetate. The combined organic phases were washed with saturated brine, dried, and concentrated by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography using a 20:1 (v / v) dichloromethane / methanol mixture as the eluent, and the final orange crystalline solid was obtained as a thermo-photoelectric triple-response liquid crystal dopant.

3. The method for preparing a thermo-photoelectric triple-response liquid crystal dopant according to claim 2, characterized in that: Step S3 further includes extracting the obtained crude product, then adding it to ethyl acetate solvent, followed by rotary evaporation to remove the ethyl acetate solvent and obtain the crude CBA product. The crude CBA product is then purified by silica gel column chromatography using dichloromethane / methanol at a volume ratio of 20:1 to obtain a thermo-photoelectric triple-response liquid crystal dopant.

4. The method for preparing a thermo-photoelectric triple-response liquid crystal dopant according to claim 2, characterized in that: In step S1, the amount of sodium nitrite used is 0.5-0.55 times the amount of 4-amino-4'-cyanobiphenyl; the concentration of hydrochloric acid is 1.5-2M; the amount of phenol used is 0.5-0.55 times the amount of 4-amino-4'-cyanobiphenyl; the amount of sodium hydroxide used is 0.55-0.58 times the amount of 4-amino-4'-cyanobiphenyl; and the amount of potassium carbonate used is 0.55-0.58 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 product A, the amount of 4-dimethylaminopyridine used is 0.08-0.12 times the amount of product A, and the amount of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride used is 2.8-3.1 times the amount of product A. In step S3, the amount of 4-dimethylaminopyridine used is 0.08-0.12 times the amount of product B, the amount of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride used is 2.8-3.1 times the amount of product B, and the amount of 1,4-butanediol used is 4.8-5.1 times the amount of product B.

5. The application of the thermo-photoelectric triple-response liquid crystal dopant as described in claim 1, characterized in that: The thermo-photoelectric triple-response liquid crystal dopant is used to dope into liquid crystal material and coated on a glass surface to prepare a thermo-photoelectric triple-response liquid crystal device; the liquid crystal material consists of a host liquid crystal and a chiral dopant; the doping mass percentage of the thermo-photoelectric triple-response liquid crystal dopant is 1wt%-5wt%; the chiral dopant is at least one of S5011 and S811; the host liquid crystal host is at least one of E7, SLC1717, 5CB, and 8CB; the doping mass percentage of the chiral dopant is 5wt%.

6. A liquid crystal material with thermo-photoelectric triple response, characterized in that: Its main components are liquid crystal materials and liquid crystal dopants with thermo-photoelectric triple response as described in claim 1.

7. The thermo-photoelectric triple-response liquid crystal material according to claim 6, characterized in that: The main liquid crystal material is composed of main liquid crystal 8CB and chiral dopant S811; the doping mass ratio of the thermo-photoelectric triple-response liquid crystal dopant is 1%-5%.

8. A type of smart glass, characterized in that: It is obtained by coating a glass surface with a liquid crystal material with a triple response of thermo-photoelectric properties as described in claim 6 or 7.

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

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