Polymer liquid crystal material with nano Bi2S3 wrapped by polyacrylonitrile and preparation method of polymer liquid crystal material

Abstract

The invention discloses a preparation method of a polymer liquid crystal material with nano Bi2S3 wrapped by polyacrylonitrile. The preparation method comprises the following steps: preparation of nano Bi2S3 powder, preparation of a PAN solution, preparation of Bi2S3 and PAN composite spheres, and compounding of nematic liquid crystals and the nano Bi2S3 and PAN composite spheres. The polyacrylonitrile-coated nano Bi2S3 polymer liquid crystal material disclosed by the invention shows excellent optical performance, and the average light transmittance of the polyacrylonitrile-coated nano Bi2S3 polymer liquid crystal material in a visible light range is gt; moreover, the material has high contrast and short response time, and meets the high-dynamic display requirement; in addition, the material also shows excellent thermal stability and thermal decomposition temperature gt; the stable performance can be kept at the high temperature, and the high-temperature-resistant coating is suitable for various harsh application scenes.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid crystal materials, and particularly relates to polyacrylonitrile-encapsulated nano Bi 2 S 3 A polymer liquid crystal material and a preparation method thereof. Background Art

[0002] The liquid crystal material industry is a highly technology-intensive field. In terms of high-performance hybrid liquid crystal materials, core technologies and patents have long been firmly controlled by foreign companies. With the continuous iteration and upgrading of liquid crystal display technology, the market demand for high-performance liquid crystal materials is increasing day by day. Liquid crystal materials have been widely used in the display field due to their unique physical properties. From common mobile phone screens to large TV displays, they are indispensable. However, current liquid crystal materials have also exposed some limitations in practical applications, such as color performance shortcomings and limited contrast. These problems have limited the further development of liquid crystal display technology to a certain extent.

[0003] Bismuth sulfide is a direct bandgap semiconductor material with a bandgap width of Eg = 1.30 eV at room temperature. It has good light absorption and excellent optoelectronic properties, which helps to improve the contrast and color performance of liquid crystals. However, the doping of nanoparticles may cause defects in the liquid crystal structure and affect the stability of the liquid crystal system. Summary of the invention

[0004] In order to solve the above technical problems, the present invention intends to introduce polyacrylonitrile microspheres with good compatibility as carriers to solve the problem that nanoparticles are easy to agglomerate and difficult to disperse, thereby further improving the application properties of liquid crystal materials.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: polyacrylonitrile encapsulates nano Bi 2 S 3 The method for preparing a polymer liquid crystal material comprises the following steps:

[0006] Step 1: Nano Bi 2 S 3 Preparation of powder: a certain amount of Bi(NO 3 ) 3 ·5H 2 O was added to a certain amount of ethylene glycol and ultrasonically treated at room temperature until it was completely dissolved, then a certain amount of thioacetamide was added and stirred, and then the solution was sealed and heated for a period of time, and then naturally cooled to room temperature, and the precipitate was collected by centrifugation, washed with deionized water and ethanol for multiple times, and dried to obtain nano Bi 2 S 3 powder;

[0007] Step 2: Preparation of PAN solution. Weigh a certain amount of polyacrylonitrile powder, add an appropriate amount of N,N-dimethylformamide, and dissolve it fully under magnetic stirring to prepare a PAN solution with a mass fraction of 10 - 20%;

[0008] Step 3: Preparation of Bi 2 S 3 @PAN composite spheres. Add an appropriate amount of emulsifier sodium dodecyl sulfate to a certain amount of the prepared PAN solution above, stir, then slowly add an appropriate amount of deionized water, and continue stirring to form a stable oil-in-water emulsion system;

[0009] Disperse the nano Bi 2 S 3 powder in a small amount of N,N-dimethylformamide, and after ultrasonic treatment, form a uniform Bi 2 S 3 dispersion. Then slowly drip the Bi 2 S 3 dispersion into the above oil-in-water emulsion system, and continuously stir during the dripping process until it is uniformly dispersed. Then add a certain amount of azobisisobutyronitrile, stir until it is uniformly mixed, introduce nitrogen to remove the oxygen in the reaction system, and heat and react in an environment of 70 - 80 °C to promote the polymerization reaction of polyacrylonitrile, gradually wrapping the Bi 2 S 3 nano-particles to form composite spheres; after the reaction is completed, cool the reaction product to room temperature, wash it repeatedly with a large amount of deionized water and absolute ethanol, and perform centrifugal separation. Finally, put the washed nano Bi 2 S 3 @PAN composite spheres into vacuum drying to obtain pure nano Bi 2 S 3 @PAN composite spheres;

[0010] Step 4: Select a certain amount of nematic liquid crystal, and slowly add a certain amount of nano Bi 2 S 3 @PAN composite spheres into the nematic liquid crystal, and stir magnetically to make the nano Bi 2 S 3 @PAN composite spheres uniformly dispersed in the liquid crystal, and finally obtain a polymer liquid crystal material with polyacrylonitrile wrapping nano Bi 2 S 3 .

[0011] As the preference of the above technical solution, in the step 1, 2.29 g of Bi(NO 3 ) 3 ·5H 2O was added to 50 mL of ethylene glycol and sonicated at room temperature until completely dissolved. Then, 0.71 g of thioacetamide was added and stirred for 10 min. Subsequently, the solution was transferred to a Teflon-lined stainless-steel autoclave with an internal volume of 70 mL. The stainless-steel autoclave was sealed and maintained at 160 °C for 18 h, then naturally cooled to room temperature. The precipitate was collected by centrifugation, washed repeatedly with deionized water and ethanol, and dried at 80 °C for 5 h to finally obtain black nano-Bi 2 S 3 powder.

[0012] As a preference of the above technical solution, the addition amount of sodium dodecyl sulfate in the third step is 2-5% of the mass of polyacrylonitrile, and the addition amount of azobisisobutyronitrile is 1-3% of the mass of polyacrylonitrile.

[0013] As a preference of the above technical solution, the nematic liquid crystal in the fourth step is E7 nematic liquid crystal.

[0014] As a preference of the above technical solution, 10 mL of E7 nematic liquid crystal and 0.5 g of nano-Bi 2 S 3 @PAN composite spheres were weighed and stirred and mixed.

[0015] The polymer liquid crystal material with polyacrylonitrile-coated nano-Bi 2 S 3 was prepared by the above preparation method.

[0016] The beneficial effects of the present invention are as follows: The polymer liquid crystal material with polyacrylonitrile-coated nano-Bi 2 S 3 exhibits excellent optical properties. Its average transmittance in the visible light range is >85%, and the material has a high contrast ratio (>1000:1) and a fast response time (turn-on time <10 ms, turn-off time <20 ms), meeting the requirements of high dynamic display; in addition, the material also shows excellent thermal stability, with a thermal decomposition temperature >300 °C, and can maintain stable performance at high temperatures, being suitable for a variety of harsh application scenarios. Description of the Drawings

[0017] Figure 1 is the SEM photograph of the nano-Bi 2 S 3 @PAN composite microspheres. Detailed Embodiments

[0018] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] Reagents used in the examples

[0020] Bi(NO 3 ) 3 ·5H 2 O: Shanghai Macklin Biochemical Co., Ltd.;

[0021] Ethylene glycol (EG), Jinan Kehuida Chemical Co., Ltd.;

[0022] Thioacetamide (TAA), Jiangsu Bost Chemical Technology Co., Ltd.;

[0023] Polyacrylonitrile (PAN): Mw = 1.5×105, Shanghai Macklin Biochemical Co., Ltd.;

[0024] 2,2'-Azobis(2-methylpropionitrile) (AIBN): Jinan Weizhen Chemical Co., Ltd.

[0025] Example 1

[0026] 2.29 g of Bi(NO 3 ) 3 ·5H 2 O was added to 50 mL of ethylene glycol (EG), and ultrasonically treated at room temperature until completely dissolved. Then, 0.71 g of thioacetamide (TAA) was added and stirred for 10 min. Subsequently, the solution was transferred to a 70 mL stainless steel autoclave lined with Teflon. The autoclave was sealed and maintained at 160 °C for 18 h, then naturally cooled to room temperature. The precipitate was collected by centrifugation, washed repeatedly with deionized water and ethanol, and dried at 80 °C for 5 h to finally obtain black Bi 2 S 3 powder.

[0027] In addition, by using an equimolar amount of thiourea (TU) or L-cysteine to replace TAA and using water-ethylene glycol (EG) as the solvent, Bi 2 S 3 nanostructures with different morphologies can be prepared.

[0028] A certain amount of PAN powder was weighed, an appropriate amount of N,N-dimethylformamide (DMF) was added, and it was fully dissolved under magnetic stirring to prepare a 10% (by mass) PAN solution for facilitating the subsequent construction of composite spheres.

[0029] Take a certain amount of the above-prepared PAN solution and pour it into a three-necked flask. Add an appropriate amount of the emulsifier sodium dodecyl sulfate (SDS), and the dosage of SDS is 2% of the mass of PAN. Start magnetic stirring, and control the rotation speed at 800 r / min. Then slowly add an appropriate amount of deionized water while continuing to stir to form a stable oil-in-water (O / W) emulsion system. The appearance of the emulsion should be milky white, uniform, and stable, without obvious stratification or precipitation.

[0030] Disperse the dried nano-Bi 2 S 3 powder in a small amount of DMF, and ultrasonically treat it for 30 min to form a uniform Bi 2 S 3 dispersion. Then use a dropper to slowly drip the Bi 2 S 3 dispersion into the above emulsion system. Keep stirring during the dripping process to make the Bi 2 S 3 nano-particles evenly disperse in the oil phase of the emulsion. After the dripping is completed, continue to stir until evenly dispersed.

[0031] Subsequently, add the initiator azobisisobutyronitrile (AIBN) to the above emulsion. Its dosage is approximately 1% of the mass of PAN. Stir until evenly mixed, and introduce nitrogen for 20 min to remove the oxygen in the reaction system. Then, place the three-necked flask in an oil bath at 70 °C and heat it for 4 h to cause the polymerization reaction of PAN, gradually wrapping the Bi 2 S 3 nano-particles to form composite spheres. After the reaction is completed, cool the reaction product to room temperature, wash it repeatedly with a large amount of deionized water and absolute ethanol, and remove impurities such as unreacted substances and emulsifiers by centrifugal separation (centrifugal speed 8000 r / min, centrifugal time 10 min). Finally, put the washed nano-Bi 2 S 3 @PAN composite spheres into a vacuum drying oven and dry them at 70 °C for 12 h to obtain pure nano-Bi 2 S 3 @PAN composite microspheres.

[0032] Accurately measure 10 mL of E7 nematic liquid crystal and place it in a clean and dry container. The performance indicators such as the purity and phase state of the liquid crystal material should be checked in advance to ensure compliance with the experimental requirements. Then, slowly add 0.5 g of nano-Bi2S3@PAN composite microspheres to the container containing the liquid crystal, and use magnetic stirring with a rotation speed controlled at 200 r / min for 30 min to make it evenly disperse in the liquid crystal, finally obtaining a polymer liquid crystal material with polyacrylonitrile wrapping nano-Bi 2 S 3 .

[0033] Example 2

[0034] 2.29 g of Bi(NO 3 ) 3 ·5H 2 O was added to 50 mL of ethylene glycol (EG), and ultrasonically treated at room temperature until completely dissolved. Then, 0.71 g of thioacetamide (TAA) was added and stirred for 10 min. Subsequently, the solution was transferred to a 70 mL Teflon-lined stainless steel autoclave. The autoclave was sealed and maintained at 160 °C for 18 h, then naturally cooled to room temperature. The precipitate was collected by centrifugation, washed repeatedly with deionized water and ethanol, and dried at 80 °C for 5 h to finally obtain black nano Bi 2 S 3 powder.

[0035] A certain amount of PAN powder was weighed, an appropriate amount of N,N-dimethylformamide (DMF) was added, and it was fully dissolved under magnetic stirring to prepare a PAN solution with a mass fraction of 15% for facilitating the subsequent construction of composite spheres.

[0036] A certain amount of the above-prepared PAN solution was poured into a three-necked flask, and an appropriate amount of emulsifier sodium dodecyl sulfate (SDS) was added. The dosage of SDS was generally 3% of the mass of PAN. The magnetic stirring was started, and the rotation speed was controlled at 1000 r / min. Then, an appropriate amount of deionized water was slowly added while continuing to stir to form a stable oil-in-water (O / W) emulsion system. The appearance of the emulsion should be milky white, uniform and stable, without obvious stratification or precipitation.

[0037] The dried nano Bi 2 S 3 powder was dispersed in a small amount of DMF and ultrasonically treated for 50 min to form a uniform Bi 2 S 3 dispersion. Then, the Bi 2 S 3 dispersion was slowly added dropwise to the above emulsion system with a dropper while maintaining stirring to make the Bi 2 S 3 nano-particles evenly disperse in the oil phase of the emulsion. After the dropwise addition was completed, stirring was continued until evenly dispersed.

[0038] Subsequently, initiator azobisisobutyronitrile (AIBN) was added to the above emulsion. Its dosage was approximately 2% of the mass of PAN. Stir until evenly mixed, and introduce nitrogen for 20 min to remove the oxygen in the reaction system. Then, the three-necked flask was placed in an oil bath at 70 °C and heated for 4 h to cause the polymerization of PAN to gradually wrap Bi 2 S 3The nanoparticles form composite spheres. After the reaction is completed, the reaction product is cooled to room temperature and washed repeatedly with a large amount of deionized water and absolute ethanol. Unreacted substances and impurities such as emulsifiers are removed by centrifugal separation (centrifugal speed: 8000 r / min, centrifugal time: 10 min). Finally, the washed nano-Bi 2 S 3 @PAN composite spheres are placed in a vacuum drying oven and dried at 70 °C for 12 h to obtain pure nano-Bi 2 S 3 @PAN composite microspheres.

[0039] Accurately measure 10 mL of E7 nematic liquid crystal and place it in a clean and dry container. The performance indicators such as purity and phase state of the liquid crystal material should be checked in advance to ensure compliance with the experimental requirements. Then, 0.5 g of nano-Bi 2 S 3 @PAN composite microspheres are slowly added to the container containing the liquid crystal. Magnetic stirring is used, and the rotation speed is controlled at 200 r / min, and the stirring time is 30 min to make it uniformly dispersed in the liquid crystal. Finally, a polymer liquid crystal material with nano-Bi 2 S 3 wrapped by polyacrylonitrile is obtained.

[0040] Example 3

[0041] 2.29 g of Bi(NO 3 ) 3 ·5H 2 O is added to 50 mL of ethylene glycol (EG), and ultrasonic treatment is carried out at room temperature until it is completely dissolved. Then, 0.71 g of thioacetamide (TAA) is added and stirred for 10 min. Subsequently, the solution is transferred to a 70 mL stainless steel autoclave lined with Teflon. The autoclave is sealed and maintained at 160 °C for 18 h, then naturally cooled to room temperature. The precipitate is collected by centrifugation, washed repeatedly with deionized water and ethanol, and dried at 80 °C for 5 h. Finally, black nano-Bi 2 S 3 powder is obtained.

[0042] Weigh a certain amount of PAN powder, add an appropriate amount of N,N-dimethylformamide (DMF), and fully dissolve it under magnetic stirring to prepare a PAN solution with a mass fraction of 20% for the subsequent construction of composite spheres.

[0043] Take a certain amount of the above-prepared PAN solution and pour it into a three-necked flask. Add an appropriate amount of the emulsifier sodium dodecyl sulfate (SDS). The dosage of SDS is 5% of the mass of PAN. Start magnetic stirring and control the rotation speed at 1200 r / min. Then slowly add an appropriate amount of deionized water while continuing to stir to form a stable oil-in-water (O / W) emulsion system. The appearance of the emulsion should be milky white, uniform, and stable, without obvious stratification or precipitation.

[0044] Disperse the dried nano-Bi 2 S 3 powder in a small amount of DMF and ultrasonically treat it for 30 min to form a uniform Bi 2 S 3 dispersion. Then use a dropper to slowly add the Bi 2 S 3 dispersion to the above emulsion system. Keep stirring during the dropping process to make the Bi 2 S 3 nano-particles uniformly disperse in the oil phase of the emulsion. After the dropping is completed, continue stirring until evenly dispersed.

[0045] Subsequently, add the initiator azobisisobutyronitrile (AIBN) to the above emulsion. Its dosage is approximately 3% of the mass of PAN. Stir until evenly mixed, and then introduce nitrogen for 20 min to remove the oxygen in the reaction system. Then, place the three-necked flask in an oil bath at 80 °C and heat it for 5 h to cause the polymerization of PAN, gradually wrapping the Bi 2 S 3 nano-particles to form composite spheres. After the reaction is completed, cool the reaction product to room temperature, wash it repeatedly with a large amount of deionized water and absolute ethanol, and remove impurities such as unreacted substances and emulsifiers by centrifugal separation (centrifugal speed 8000 r / min, centrifugal time 15 min). Finally, put the washed nano-Bi 2 S 3 @PAN composite spheres into a vacuum drying oven and dry them at 70 °C for 20 h to obtain pure nano-Bi 2 S 3 @PAN composite microspheres.

[0046] Accurately measure 10 mL of E7 nematic liquid crystal and place it in a clean and dry container. The performance indicators such as the purity and phase state of the liquid crystal material should be checked in advance to ensure compliance with the experimental requirements. Then, slowly add 0.5 g of nano-Bi 2 S 3 @PAN composite microspheres to the container containing the liquid crystal. Use magnetic stirring, control the rotation speed at 300 r / min, and stir for 60 min to make it evenly disperse in the liquid crystal. Finally, obtain polyacrylonitrile-coated nano-Bi 2 S 3Polymer liquid crystal materials.

[0047] Comparative Example 1

[0048] An undoped E7 nematic liquid crystal was used as the liquid crystal material for Comparative Example 1.

[0049] Comparative Example 2

[0050] 0.5 g of nano-Bi 2 S 3 powder was added to 10 mL of E7 nematic liquid crystal, and magnetic stirring was used with the rotation speed controlled at 200 r / min for 30 min to uniformly disperse it in the liquid crystal, and finally a liquid crystal material containing nano-Bi 2 S 3 was obtained as Comparative Example 2.

[0051] Comparative Example 3

[0052] 0.5 g of nano-Bi 2 S 3 powder was dispersed in DMF, ultrasonicated for 30 min and then mixed with PAN solution, stirred for 1 h, and then added to 10 mL of E7 nematic liquid crystal, and magnetic stirring was used with the rotation speed controlled at 200 r / min for 30 min to obtain a physically mixed Bi 2 S 3 / PAN / E7.

[0053] Performance Test

[0054] I. Optical Performance Test

[0055] Test method: Use a UV-Vis spectrophotometer to measure the transmittance of the material in the visible light range (380 - 780 nm).

[0056] Test conditions: The sample thickness is 50 μm, the test wavelength range is 380 - 780 nm, and the light source is a xenon lamp.

[0057] Results:

[0058]

[0059] It can be seen that the average transmittance of the material prepared by the preparation method of the present invention in the visible light range > 85%, and the transmittance at 550 nm reaches 90%.

[0060] II. Contrast Test

[0061] Test method: Use a photodetector to measure the transmittance of the material in the on and off states.

[0062] Test conditions: The applied voltage is 20 V / μm and the test temperature is 25 °C.

[0063] Results:

[0064]

[0065]

[0066] The contrast ratio of the material > 1000:1.

[0067] III. Response time test

[0068] Test method: Use an oscilloscope and a photodetector to measure the change in light transmittance of the material after applying an electric field.

[0069] Test conditions: The applied voltage is 20 V / μm and the test temperature is 25 °C.

[0070] Results:

[0071]

[0072] The turn-on time (ton) of the material < 10 ms and the turn-off time (toff) < 20 ms.

[0073] IV. Thermal stability test

[0074] Test method: Use a thermogravimetric analyzer (TGA) to measure the thermal decomposition temperature of the material.

[0075] Test conditions: The heating rate is 10 °C / min and the nitrogen atmosphere.

[0076] Results:

[0077] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Thermal decomposition temperature 315℃ 325℃ 335℃ 280℃ 305℃ 270℃

[0078] The thermal decomposition temperature of the material > 300 °C, indicating its excellent thermal stability.

[0079] It is worth mentioning that the technical features such as the thermogravimetric analyzer, oscilloscope, and photodetector involved in this invention patent application should be regarded as prior art. The specific structures, working principles, and possible control methods and spatial arrangement methods of these technical features can be selected conventionally in the art and should not be regarded as the inventive points of this invention patent. This invention patent will not be further elaborated specifically.

[0080] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art in this technical field based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should fall within the protection scope determined by the claims.

Claims

1. A method for preparing a polymer liquid crystal material of polyacrylonitrile-coated nano-Bi2S3, characterized in that: The following steps are included: Step 1, preparation of nano Bi2S3 powder, adding a certain amount of Bi(NO3)3·5H2O to a certain amount of ethylene glycol, and ultrasonically treating at room temperature until completely dissolved, then adding a certain amount of thioacetamide and stirring, then sealing the solution and heating to react for a period of time, and then naturally cooling to room temperature, collecting the precipitate by centrifugation, washing with deionized water and ethanol for multiple times, and drying to obtain nano Bi2S3 powder; Step 2: Preparation of PAN solution: weigh a certain amount of polyacrylonitrile powder, add an appropriate amount of N,N-dimethylformamide, and fully dissolve it under magnetic stirring to prepare a PAN solution with a mass fraction of 10-20%; Step 3: Preparation of Bi2S3@PAN composite spheres: Add an appropriate amount of emulsifier sodium dodecyl sulfate to a certain amount of the prepared PAN solution, stir, then slowly add an appropriate amount of deionized water, continue stirring, and form a stable water-in-oil emulsion system; The nano-Bi2S3 powder is dispersed in a small amount of N,N-dimethylformamide, and a uniform Bi2S3 dispersion is formed after ultrasonic treatment. The Bi2S3 dispersion is then slowly dripped into the above-mentioned water-in-oil emulsion system, and stirring is continued during the dripping process until it is uniformly dispersed. Then a certain amount of azobisisobutyronitrile is added and stirred until the mixture is uniformly mixed. Nitrogen is introduced to remove oxygen in the reaction system, and the reaction is heated at 70-80°C to promote the polymerization of polyacrylonitrile, which gradually wraps the Bi2S3 nanoparticles to form composite spheres. After the reaction is completed, the reaction product is cooled to room temperature, and repeatedly washed with a large amount of deionized water and anhydrous ethanol, and centrifuged. Finally, the washed nano-Bi2S3@PAN composite spheres are placed in a vacuum dryer to obtain pure nano-Bi2S3@PAN composite spheres. Step 4: Select a certain amount of nematic liquid crystal, slowly add a certain amount of nano-Bi2S3@PAN composite balls into the nematic liquid crystal, and stir magnetically to evenly disperse the nano-Bi2S3@PAN composite balls in the liquid crystal, and finally obtain a polymer liquid crystal material of nano-Bi2S3 wrapped in polyacrylonitrile.

2. The method for preparing the polymer liquid crystal material of polyacrylonitrile-coated nano-Bi2S3 according to claim 1, characterized in that: In the step 1, 2.29 g of Bi(NO3)3·5H2O is added to 50 mL of ethylene glycol and ultrasonically treated at room temperature until completely dissolved, then 0.71 g of thioacetamide is added and stirred for 10 min, and then the solution is transferred to a stainless steel autoclave lined with Teflon and having an internal volume of 70 mL, the stainless steel autoclave is sealed and maintained at 160° C. for 18 h, and then naturally cooled to room temperature, the precipitate is collected by centrifugation, washed with deionized water and ethanol multiple times, and dried at 80° C. for 5 h, and finally a black nano-Bi2S3 powder is obtained.

3. The method for preparing the polymer liquid crystal material of polyacrylonitrile-coated nano-Bi2S3 according to claim 1, characterized in that: In the step 3, the amount of sodium dodecyl sulfate added is 2-5% of the mass of polyacrylonitrile, and the amount of azobisisobutyronitrile added is 1-3% of the mass of polyacrylonitrile.

4. The method for preparing the polymer liquid crystal material of polyacrylonitrile-coated nano-Bi2S3 according to claim 1, characterized in that: The nematic liquid crystal in step 4 is E7 nematic liquid crystal.

5. The method for preparing the polymer liquid crystal material of polyacrylonitrile-coated nano-Bi2S3 according to claim 4, characterized in that: In the step 4, 10 mL of E7 nematic liquid crystal and 0.5 g of nano-Bi2S3@PAN composite spheres were weighed and stirred and mixed.

6. Polymer liquid crystal material of polyacrylonitrile encapsulating nano Bi2S3, characterized in that: Prepared by the preparation method according to any one of claims 1 to 5.

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