An azobenzene liquid crystal and a synthesis method and application thereof

Abstract

This invention discloses an azobenzene liquid crystal, its synthesis method, and its applications. The chemical structure of the synthesized azobenzene liquid crystal is characterized by: azobenzene as the central structure, with urethane or urea functional groups capable of forming hydrogen bonds on the molecular chain, as well as specific terminal functional groups. Furthermore, this azobenzene liquid crystal monomer possesses the anisotropic properties of liquid crystals. The specific synthesis process consists of two steps: (1) the terminal hydroxyl azobenzene substance undergoes a nucleophilic substitution reaction with a haloalcohol or haloamine to generate an intermediate product. (2) the intermediate product undergoes a nucleophilic addition reaction with a monoisocyanate to generate an azobenzene liquid crystal monomer. The azobenzene liquid crystal monomer described in this invention is a liquid crystal molecule with functionalized terminal groups. If the terminal group is an active group, the liquid crystal molecule has the ability to further polymerize or react with other reactive functional groups.

Description

Technical Field

[0001] This invention belongs to the field of liquid crystals and liquid crystal polymers, specifically relating to an azobenzene liquid crystal, its synthesis method, and its applications. Background Technology

[0002] Liquid crystals (LCs) are substances whose phase changes under specific conditions, resulting in ordered orientation of liquid crystal molecules. This characteristic gives liquid crystals and their polymers anisotropy. Due to their excellent optical anisotropy, liquid crystals are widely used in anti-counterfeiting materials, optical display devices, and other fields. Furthermore, liquid crystal polymers retain the ordered orientation of their molecular units, exhibiting macroscopically reversible driven deformation behavior under external stimuli, thus holding important applications in artificial muscles, soft robots, and actuators.

[0003] Existing technologies for preparing azobenzene liquid crystal monomers and their derivatives involve single-step synthesis, with few commercially available methods, and the synthesized products often lack specific functional groups, significantly limiting their applications. Therefore, developing novel azobenzene liquid crystals with functional groups is of paramount importance to expand the types and applications of azobenzene liquid crystals. Summary of the Invention

[0004] To address the shortcomings and deficiencies of existing technologies for preparing azobenzene liquid crystals, this invention proposes an azobenzene liquid crystal, its synthesis method, and its applications. The two-step method in synthesizing azobenzene liquid crystals overcomes the limitations of single-step methods in introducing functional groups and the limited variety of synthesized monomers. The synthesized liquid crystal exhibits significant optical anisotropy, playing a crucial role in advancing the technology of anti-counterfeiting materials, optical display devices, and actuators.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] A method for synthesizing azobenzene liquid crystal, characterized by comprising the following steps:

[0007] (1) A mixture of a good solvent, a terminal hydroxyazobenzene substance, a haloalcohol or haloamine, and a catalyst is added to a reaction vessel to carry out a nucleophilic substitution reaction. Nitrogen gas is introduced for protection during the reaction process, and an intermediate product is obtained after the reaction is completed.

[0008] (2) Add a good solvent, the intermediate product of step (1), monoisocyanate and catalyst into a reactor to undergo a nucleophilic addition reaction to generate an azobenzene liquid crystal monomer with a specific functional group at the end.

[0009] Preferably, in step (1), the mass ratio of the benign solvent, terminal hydroxyazobenzene substance, haloalcohol or haloamine, and catalyst is (80~90):(2~5):(3~5):(5~10); the nucleophilic substitution reaction is carried out at a temperature of 70~100℃ for 10~16h under a nitrogen atmosphere; after the reaction is completed, the mixed solution of the intermediate crude product is filtered, separated and purified, and recrystallized with dichloromethane to obtain the intermediate product.

[0010] In step (2), the mass ratio of the benign solvent: intermediate product: monoisocyanate: catalyst is (85~95):(2~5):(2~5):(0.2~0.5); the nucleophilic addition reaction is carried out at a temperature of 30~40℃ for 70~80h under nitrogen atmosphere; after the reaction is completed, crystals are precipitated at room temperature, filtered, and the crystals are recrystallized with N,N-dimethylformamide to obtain the azobenzene liquid crystal monomer.

[0011] Preferably, the benign solvent mentioned in steps (1) and (2) is one or more of toluene, dichloromethane, chloroform, petroleum ether, N-methylpyrrolidone, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0012] Preferably, the terminal hydroxyazobenzene substance in step (1) is one or more of 4-hydroxyazobenzene, 4-dimethylamino-4'-hydroxyazobenzene, 4,4'-dihydroxyazobenzene, 4-n-butyl-4'-hydroxyazobenzene, 2,2'-dihydroxyazobenzene, and 2,4,2'-trihydroxyazobenzene.

[0013] Preferably, the haloalcohol mentioned in step (1) is a monohydric alcohol or polyhydric alcohol with halogen atom substitution and its derivatives, specifically 2-fluoroethanol, 3-fluoro-1-propanol, 3-fluoro-1,2-propanediol, 4-fluoro-1-butanol, 5-fluoro-1-pentanol, 6-fluoro-1-hexanol, 7-fluoro-1-heptanol, 8-fluoro-1-octanol, 9-fluoro-1-nonanol, 10-fluoro-1-decanol, 2-(2-fluoroethoxy)ethanol, 2-chloroethanol, 2-chloro-1,1-ethylenediol, 3-chloro-1-propanol, and 3-chloro-1,2-propanediol. 4-Chloro-1-butanol, 4-Chloro-1,3-butanediol, 5-Chloro-1-pentanol, 6-Chloro-1-hexanol, 7-Chloro-1-heptanol, 8-Chloro-1-octanol, 9-Chloro-1-nonanol, 10-Chloro-1-decanol, 11-Chloro-1-undecanol, 12-Chloro-1-dodecanol, 13-Chloro-1-tridecanol, 14-Chloro-1-tetradecanol, 15-Chloro-1-pentadecanol, 16-Chloro-1-hexadecanol, 2-(2-chloroethoxy)ethanol, 2-bromoethanol, 3-bromo-1-propanol, 3-bromo-1 2-Propanediol, 4-Bromo-1-Butanol, 4-Bromo-1,2-Butanediol, 2-Bromo-1,3,4-Butanetriol, 5-Bromo-1-Pentanol, 6-Bromo-1-Hexanol, 6-Bromo-1,2-Hexanediol, 7-Bromo-1-Heptanol, 8-Bromo-1-Octanol, 9-Bromo-1-Nonanol, 10-Bromo-1-Decanol, 11-Bromo-1-Undecanol, 12-Bromo-1-Dodecanol, 13-Bromo-1-Trigechalcone, 14-Bromo-1-Tetradecanol, 15-Bromo-1-Pentadecanol, 16-Bromo-1-Hexadecanol, 2 1-(2-bromoethoxy)ethanol, 17-bromo-3,6,9,12,15-pentaheptadecane-1-ol, 2-iodoethanol, 3-iodo-1-propanol, 1-iodo-2,3-propanediol, 4-iodo-1-butanol, 5-iodo-1-pentanol, 6-iodo-1-hexanol, 7-iodo-1-heptanol, 8-iodo-1-octanol, 9-iodo-1-nonanol, 10-iodo-1-decanol, 11-iodo-1-undecanol, 12-iodo-1-dodecanol, 2-(2-iodoethoxy)ethanol and one or more of their isomers;

[0014] The haloamine mentioned in step (1) is a monoamine, diamine, or polyamine or its derivatives with halogen atom substitution, specifically 2-fluoroethylamine, 3-fluoroprop-1-amine, 5-fluoropentylamine, 8-fluoro-1-naphthylamine, 2-(2-fluorophenoxy)ethylamine, N-(3-fluorobenzyl)-1-propylamine, 3-(5-fluoro-3-indolyl)-1-propylamine, 2-chloroethylamine, 3-chloropropylamine, and 3-chloro-2-methylpropane-1-amine. One or more of the following: 4-chloro-1-butylamine, 5-chloro-1-pentylamine, 6-chlorohexane-1-amine, 2-(2-chloroethoxy)acetamide, 2-bromoethylamine, 3-bromopropylamine, 4-bromo-1-butylamine, 5-bromo-1-pentylamine, 6-bromohexane-1-amine, 6-bromohexaneamide, 11-bromoundecanamide, 2-(2-bromoethoxy)ethylamine, 2-iodoethane-1-amine, 2-iodoacetamide, and their isomers.

[0015] Preferably, the catalyst mixture in step (1) is a mixture of at least one of sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, ammonium bicarbonate, potassium bicarbonate, sodium hydroxide, and potassium hydroxide with at least one of potassium iodide and sodium iodide, in a mass ratio of 100:1.

[0016] Preferably, the monoisocyanate mentioned in step (2) is one or more of the following: isopropyl isocyanate, cyclohexyl isocyanate, methyl isocyanate, ethyl isocyanate, propyl isocyanate, butyl isocyanate, pentyl isocyanate, hexyl isocyanate, heptyl isocyanate, octyl isocyanate, nonyl isocyanate, decyl isocyanate, dodecyl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate, octadecyl isocyanate, 2-methoxyphenyl isocyanate, 2,6-diisopropylphenyl isocyanate, 4-ethylphenyl isocyanate, m-tolyl isocyanate, p-isopropylphenyl isocyanate, 1,1-di(acryloyloxymethyl)ethyl isocyanate, ethyl isocyanate acrylate, ethyl isocyanate methacrylate, allyl isocyanate, trimethylsilyl isocyanate, and methoxymethyl isocyanate.

[0017] The catalyst mentioned in step (2) is one or more of the following: dibutyltin dilaurate, stannous octoate, bismuth isooctanoate, potassium octoate, bismuth neodecanoate, triethylenediamine, bis-(dimethylaminoethyl) ether, and dimethylcyclohexylamine.

[0018] The azobenzene liquid crystal prepared by the method of the present invention is characterized in that the azobenzene liquid crystal has an azobenzene as the central structure, and the molecular chain has urethane or urea functional groups capable of forming hydrogen bonds, as well as specific end functional groups.

[0019] The terminal functional group is at least one selected from the following: carbon-carbon double bond, carbon-nitrogen triple bond, methoxy, isopropyl, cyclohexyl, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, 2-methoxyphenyl, 2,6-diisopropylphenyl, 4-ethylphenyl, m-tolyl, p-isopropylphenyl, 1,1-di(acryloyloxymethyl)ethyl, ethyl acrylate, ethyl methacrylate, and trimethylsilyl.

[0020] Preferably, the structural formula of the azobenzene liquid crystal is:

[0021] .

[0022] The application of the azobenzene liquid crystal of the present invention is characterized in that the azobenzene liquid crystal has polarization properties and is applied to at least one of optical drive devices, soft robots, anti-counterfeiting materials, and optical display devices; specifically, the azobenzene liquid crystal is prepared with liquid crystal RM257, a dimercapto substance, and a tetramercapto substance to form a prepolymer spinning solution, which is reacted at room temperature and in an alkaline environment for 1 to 5 hours, and then spun to obtain azobenzene liquid crystal elastomer fibers.

[0023] Compared with the prior art, the present invention has the following features and benefits:

[0024] The synthetic route for azobenzene liquid crystals described in this invention employs a two-step method. By controlling the monoisocyanate used in the reaction steps, it overcomes the limitations of single-step methods in introducing functional groups and the insufficient designability of liquid crystal molecular structures compared to existing techniques (CN 119192023 A). The azobenzene liquid crystal synthesized in this invention possesses more hydrogen bonding sites than the azobenzene liquid crystal molecule reported in CN 108191711 A, and its end groups can be designed as reactive functional groups to participate in the reaction and form polymers. The azobenzene liquid crystal described in this invention can be applied in multiple fields. Its polarization properties have important applications in information anti-counterfeiting, and the ultraviolet light stimulation response characteristics of the azobenzene structure have wide applications in the actuator field. If the designed end groups are specific reactive functional groups, it can be further applied in the polymer field. Attached Figure Description

[0025] Figure 1 The image shows the proton NMR spectrum of the azobenzene liquid crystal in Example 1 of this invention. The peak values ​​of different chemical shifts correspond to the hydrogen sites in the molecular structure, indicating that the azobenzene liquid crystal was successfully synthesized, proving that the technical route is scientifically feasible.

[0026] Figure 2 The image shown is an electron microscope image of the azobenzene liquid crystal in Example 1 of this invention, showing a cuboid shape.

[0027] Figure 3The image shown is a polarizing microscope image of the azobenzene liquid crystal in Embodiment 2 of the present invention. It exhibits the optical anisotropy characteristics of liquid crystal and displays colored polarized light on its surface.

[0028] Figure 4 These are electron microscope and polarizing microscope images of the liquid crystal elastomer fibers prepared by the reaction of azobenzene liquid crystal in Example 3 of the present invention.

[0029] Figure 5 This is the synthetic route for the azobenzene liquid crystal of the present invention. Detailed Implementation

[0030] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. The specific embodiments described below can be further understood in conjunction with the accompanying drawings. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention, and any technical modifications made in accordance with the spirit of this invention are within the scope of protection of this invention.

[0031] Example 1

[0032] This embodiment illustrates a method for synthesizing azobenzene liquid crystals, and the synthesis route is as follows: Figure 5 As shown, the specific steps are as follows:

[0033] (1) A mixture of N,N-dimethylformamide, 4,4'-dihydroxyazobenzene, 6-chloro-1-hexanol, potassium carbonate and potassium iodide in a mass ratio of 80:5:5:10 and a total mass of 20g was added to a nitrogen-protected reactor. The mass ratio of potassium carbonate and potassium iodide in the mixture was 100:1. The mixture was stirred at 80℃ for 12h. After the reaction was completed, a mixed solution of crude intermediate product was obtained. The solution was filtered and purified by chromatography. The purified intermediate product was obtained by recrystallization with dichloromethane three times.

[0034] (2) N,N-dimethylformamide, the intermediate product from step (1), allyl isocyanate, and dibutyltin dilaurate were added to a nitrogen-protected reactor in a mass ratio of 90.5:5:4:0.5, with a total mass of 10 g. The mixture was stirred at 35 °C for 72 h. After the reaction was completed, the reactor was placed at room temperature to precipitate crystals. The crystals were collected after filtration and recrystallized three times with N,N-dimethylformamide as a solvent to obtain an azobenzene liquid crystal product with a specific reactive functional group (carbon-carbon double bond) at the end group.

[0035] Example 2

[0036] This embodiment provides an optical anti-counterfeiting application, in which the azobenzene liquid crystal product of Example 1 is directly printed and coated onto a substrate. The synthesized azobenzene liquid crystal possesses the optical anisotropy characteristics of liquid crystals and exhibits unique polarization properties under a polarizing microscope.

[0037] Example 3

[0038] This embodiment provides a method for preparing azobenzene liquid crystal elastomer fibers. A prepolymer spinning solution is prepared by combining the azobenzene liquid crystal product of Example 1 with liquid crystal RM257, a dithioyl substance (chain extender), and a tetrathioyl substance (crosslinking agent). The reaction conditions are room temperature and alkaline environment, and the fiber is obtained after spinning.

[0039] The azobenzene liquid crystal in Example 1 possesses reactive functional groups (carbon-carbon double bonds) and can undergo an Aza-Michael addition reaction with thiol groups at room temperature. The resulting azobenzene liquid crystal elastomer fiber has a complete structure and exhibits polarization properties.

[0040] Azobenzene liquid crystal elastomer fibers also possess the ability to drive under ultraviolet light stimulation, and have a wide range of applications in photoelectric devices, soft robots, and other fields.

[0041] Test Results

[0042] The 1H NMR spectrum of the azobenzene liquid crystal synthesized in Example 1 of this invention is shown in the appendix. Figure 1 As shown, the product eluted at chemical shifts of 7.86, 6.98, 5.84, 5.20, 5.12, 4.09, 4.03, 3.81, 1.83, 1.62, 1.52, and 1.44, with integral ratios of a:b:c:d:e:f:g:h:i:j:k:l of 5.68:4.08:2.00:2.10:2.05:4.02:4.21:4.05:3.98:4.28:4.04:4.01. The results are consistent with the predictions, proving the successful synthesis of azobenzene liquid crystals, with the following structure:

[0043] .

[0044] The azobenzene liquid crystal synthesized in Example 1 of this invention was characterized by electron microscopy, and the test results are attached. Figure 2 As shown. The recrystallized azobenzene liquid crystal has a cuboid shape and a thickness of approximately 0.5-1 μm.

[0045] Embodiment 2 of the present invention provides an optical anti-counterfeiting application as shown in the appendix. Figure 3 As shown, azobenzene liquid crystal is coated onto a paper substrate. The coated area is designated as the marked area, and the uncoated area is designated as the unmarked area. When the anti-counterfeiting effect is tested under a polarizing microscope, the azobenzene liquid crystal in the marked area exhibits colored polarized light characteristics, while the unmarked area displays a black visual effect.

[0046] Example 3 of this invention provides a method for preparing azobenzene liquid crystal elastomer fibers. After preparing the spinning solution, azobenzene liquid crystal elastomer fibers were successfully spun. Electron microscope images and polarizing microscope test results of the fibers are attached. Figure 4 As shown, the fiber structure is regular and defect-free, and it possesses polarizing properties. The reaction mechanism is as follows: the two ends of the azobenzene liquid crystal molecule have reactive functional groups (carbon-carbon double bonds), which can undergo addition reactions with liquid crystal RM257 and mercapto substances.

[0047] Based on the above test results, it is clear that the synthesis route of the azobenzene liquid crystal described in this embodiment of the invention is scientifically feasible, and the two-step method expands the diversity of azobenzene liquid crystal synthesis. The synthesized azobenzene liquid crystal has a characteristic structure with azobenzene as the center and specific functional groups with urea groups as hydrogen bonding sites and carbon-carbon double bonds as end groups, and can be applied to fields such as optical anti-counterfeiting, polymers, and actuators.

[0048] It should be further noted that this invention, by selecting monoisocyanates with different structures as reactants, can control the terminal groups of the resulting azobenzene liquid crystal compounds. For example, the terminal group is isopropyl when using isopropyl isocyanate, cyclohexyl when using cyclohexyl isocyanate, methyl when using methyl isocyanate, ethyl when using ethyl isocyanate, trimethylsilyl when using trimethylsilyl isocyanate, and methoxy when using methoxymethyl isocyanate. In general, the terminal functional group of the target compound is directly determined by the structure of the selected monoisocyanate. This synthetic strategy provides a simple and efficient way to achieve diversification and customization of the properties of azobenzene liquid crystal materials.

[0049] However, this application is not limited to the above embodiments. Various changes made in the relevant technical field without departing from the spirit of this application, as well as technical solutions that are the same as or similar to this application, should be within the protection scope of this invention.

Claims

1. A method for synthesizing azobenzene liquid crystal, characterized in that, Includes the following steps: (1) A mixture of a good solvent, a terminal hydroxyazobenzene substance, a haloalcohol or haloamine, and a catalyst is added to a reaction vessel to carry out a nucleophilic substitution reaction. Nitrogen gas is introduced for protection during the reaction process, and an intermediate product is obtained after the reaction is completed. (2) Add a good solvent, the intermediate product of step (1), monoisocyanate and catalyst into a reactor to undergo a nucleophilic addition reaction to generate an azobenzene liquid crystal monomer with a specific functional group at the end.

2. The method for synthesizing azobenzene liquid crystal according to claim 1, characterized in that, In step (1), the mass ratio of the benign solvent, terminal hydroxyazobenzene substance, haloalcohol or haloamine, and catalyst is (80~90):(2~5):(3~5):(5~10); the nucleophilic substitution reaction is carried out at a temperature of 70~100℃ for 10~16h under a nitrogen atmosphere; after the reaction is completed, the mixed solution of the intermediate crude product is filtered, separated and purified, and recrystallized with dichloromethane to obtain the intermediate product. In step (2), the mass ratio of the benign solvent: intermediate product: monoisocyanate: catalyst is (85~95):(2~5):(2~5):(0.2~0.5); the nucleophilic addition reaction is carried out at a temperature of 30~40℃ for 70~80h under nitrogen atmosphere; after the reaction is completed, crystals are precipitated at room temperature, filtered, and the crystals are recrystallized with N,N-dimethylformamide to obtain the azobenzene liquid crystal monomer.

3. The method for synthesizing azobenzene liquid crystal according to claim 1, characterized in that, The benign solvent mentioned in steps (1) and (2) is one or more of toluene, dichloromethane, chloroform, petroleum ether, N-methylpyrrolidone, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide.

4. The method for synthesizing azobenzene liquid crystal according to claim 1, characterized in that, The terminal hydroxyazobenzene substance mentioned in step (1) is one or more of 4-hydroxyazobenzene, 4-dimethylamino-4'-hydroxyazobenzene, 4,4'-dihydroxyazobenzene, 4-n-butyl-4'-hydroxyazobenzene, 2,2'-dihydroxyazobenzene, and 2,4,2'-trihydroxyazobenzene.

5. The method for synthesizing azobenzene liquid crystal according to claim 1, characterized in that, The haloalcohol mentioned in step (1) is a monohydric alcohol or polyhydric alcohol and its derivatives with halogen atom substitution, specifically 2-fluoroethanol, 3-fluoro-1-propanol, 3-fluoro-1,2-propanediol, 4-fluoro-1-butanol, 5-fluoro-1-pentanol, 6-fluoro-1-hexanol, 7-fluoro-1-heptanol, 8-fluoro-1-octanol, 9-fluoro-1-nonanol, 10-fluoro-1-decanol, 2-(2-fluoroethoxy)ethanol, 2-chloroethanol, 2-chloro-1,1-ethylenediol, 3-chloro-1-propanol, 3-chloro-1,2-propanediol, 4- 1-Chloro-butanol, 4-chloro-1,3-butanediol, 5-chloro-1-pentanol, 6-chloro-1-hexanol, 7-chloro-1-heptanol, 8-chloro-1-octanol, 9-chloro-1-nonanol, 10-chloro-1-decanol, 11-chloro-1-undecanol, 12-chloro-1-dodecanol, 13-chloro-1-tridecanol, 14-chloro-1-tetradecanol, 15-chloro-1-pentadecanol, 16-chloro-1-hexadecanol, 2-(2-chloroethoxy)ethanol, 2-bromoethanol, 3-bromo-1-propanol, 3-bromo-1,2-propanol -Propylene glycol, 4-bromo-1-butanol, 4-bromo-1,2-butanediol, 2-bromo-1,3,4-butanetriol, 5-bromo-1-pentanol, 6-bromo-1-hexanol, 6-bromo-1,2-hexanediol, 7-bromo-1-heptanol, 8-bromo-1-octanol, 9-bromo-1-nonanol, 10-bromo-1-decanol, 11-bromo-1-undecanol, 12-bromo-1-dodecanol, 13-bromo-1-tridecanol, 14-bromo-1-tetradecanol, 15-bromo-1-pentadecanol, 16-bromo-1-hexadecanol, 2- One or more of the following: (2-bromoethoxy)ethanol, 17-bromo-3,6,9,12,15-pentaheptadecane-1-ol, 2-iodoethanol, 3-iodo-1-propanol, 1-iodo-2,3-propanediol, 4-iodo-1-butanol, 5-iodo-1-pentanol, 6-iodo-1-hexanol, 7-iodo-1-heptanol, 8-iodo-1-octanol, 9-iodo-1-nonanol, 10-iodo-1-decanol, 11-iodo-1-undecanol, 12-iodo-1-dodecanol, 2-(2-iodoethoxy)ethanol and their isomers; The haloamine mentioned in step (1) is a monoamine, diamine, or polyamine or its derivatives with halogen atom substitution, specifically 2-fluoroethylamine, 3-fluoroprop-1-amine, 5-fluoropentylamine, 8-fluoro-1-naphthylamine, 2-(2-fluorophenoxy)ethylamine, N-(3-fluorobenzyl)-1-propylamine, 3-(5-fluoro-3-indolyl)-1-propylamine, 2-chloroethylamine, 3-chloropropylamine, and 3-chloro-2-methylpropane-1-amine. One or more of the following: 4-chloro-1-butylamine, 5-chloro-1-pentylamine, 6-chlorohexane-1-amine, 2-(2-chloroethoxy)acetamide, 2-bromoethylamine, 3-bromopropylamine, 4-bromo-1-butylamine, 5-bromo-1-pentylamine, 6-bromohexane-1-amine, 6-bromohexaneamide, 11-bromoundecanamide, 2-(2-bromoethoxy)ethylamine, 2-iodoethane-1-amine, 2-iodoacetamide, and their isomers.

6. The method for synthesizing an azobenzene liquid crystal according to claim 1, characterized in that, The catalyst mixture in step (1) is a mixture of at least one of sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, ammonium bicarbonate, potassium bicarbonate, sodium hydroxide, and potassium hydroxide with at least one of potassium iodide and sodium iodide, in a mass ratio of 100:

1.

7. The method for synthesizing azobenzene liquid crystal according to claim 1, characterized in that, The monoisocyanate mentioned in step (2) is one or more of the following: isopropyl isocyanate, cyclohexyl isocyanate, methyl isocyanate, ethyl isocyanate, propyl isocyanate, butyl isocyanate, pentyl isocyanate, hexyl isocyanate, heptyl isocyanate, octyl isocyanate, nonyl isocyanate, decyl isocyanate, dodecyl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate, octadecyl isocyanate, 2-methoxyphenyl isocyanate, 2,6-diisopropylphenyl isocyanate, 4-ethylphenyl isocyanate, m-tolyl isocyanate, p-isopropylphenyl isocyanate, 1,1-di(acryloyloxymethyl)ethyl isocyanate, ethyl isocyanate acrylate, ethyl isocyanate methacrylate, allyl isocyanate, trimethylsilyl isocyanate, and methoxymethyl isocyanate. The catalyst mentioned in step (2) is one or more of the following: dibutyltin dilaurate, stannous octoate, bismuth isooctanoate, potassium octoate, bismuth neodecanoate, triethylenediamine, bis-(dimethylaminoethyl) ether, and dimethylcyclohexylamine.

8. An azobenzene liquid crystal prepared by the method according to any one of claims 1 to 7, characterized in that, The azobenzene liquid crystal has an azobenzene-centered structure, with urethane or urea functional groups capable of forming hydrogen bonds on the molecular chain, as well as specific end functional groups. The terminal functional group is at least one selected from the following: carbon-carbon double bond, carbon-nitrogen triple bond, methoxy, isopropyl, cyclohexyl, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, 2-methoxyphenyl, 2,6-diisopropylphenyl, 4-ethylphenyl, m-tolyl, p-isopropylphenyl, 1,1-di(acryloyloxymethyl)ethyl, ethyl acrylate, ethyl methacrylate, and trimethylsilyl.

9. The azobenzene liquid crystal according to claim 8, characterized in that, The structural formula of the azobenzene liquid crystal is: 。 10. The application of the azobenzene liquid crystal according to claim 8 or 9, characterized in that, The azobenzene liquid crystal has polarization properties and can be used in at least one of optical drive devices, soft robots, anti-counterfeiting materials, and optical display devices. Specifically, the azobenzene liquid crystal is prepared with liquid crystal RM257, a dithiolated substance, and a tetrathiolated substance to form a prepolymer spinning solution, which is reacted at room temperature and in an alkaline environment for 1 to 5 hours. After spinning, azobenzene liquid crystal elastomer fibers are obtained.

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