A polymer dispersed liquid crystal composition, a polymer dispersed liquid crystal film and a method for preparing the same

Abstract

The application discloses a polymer dispersed liquid crystal composition, a polymer dispersed liquid crystal film and a preparation method thereof. The polymer dispersed liquid crystal composition is prepared from the following components in a mass ratio: a polymerizable monomer composition, a nematic liquid crystal, and a photoinitiator; the polymerizable monomer composition comprises at least one (meth)acrylic monomer with a terminal quaternary ammonium salt structure, and the mass percentage of the (meth)acrylic monomer is 20-50%; the mass percentage of the nematic liquid crystal is 50-80%; and the photoinitiator accounts for 0.5-2.5% of the total mass of the acrylic monomer and the liquid crystal. By introducing the acrylic monomer with a strong polar terminal, an ordered anchoring layer is formed at the polymer liquid crystal interface during the curing process, the driving voltage is significantly reduced to about 20 V, the response time is shortened to less than 100 ms, and the polymer dispersed liquid crystal composition is suitable for low-power consumption applications such as smart light-adjusting glass.

Description

Technical Field

[0001] This invention relates to the field of polymer-dispersed liquid crystal materials technology, specifically to a polymer-dispersed liquid crystal composition, a polymer-dispersed liquid crystal film, and a method for preparing the same. Background Technology

[0002] Polymer-dispersed liquid crystal (PDLC) is a composite material formed by dispersing liquid crystal droplets within a continuous polymer matrix. It is widely used in smart dimming glass, display devices, and other fields. When no electric field is applied, the liquid crystal droplets are randomly oriented, and their effective refractive index does not match the polymer matrix, leading to light scattering and a milky white, opaque film. When a sufficiently strong electric field is applied, the liquid crystal molecules align along the direction of the electric field, matching the effective refractive index of the liquid crystal droplets with the polymer matrix, thus allowing light to pass through and the film becoming transparent. Based on this electrically controlled light scattering characteristic, PDLC materials are widely used in smart dimming glass, privacy windows, display devices, and optical switches.

[0003] However, the overall performance of existing conventional PDLC materials, especially their electro-optic properties, remains significantly insufficient, limiting their wider application. Currently, mainstream PDLC systems typically use conventional alkyl methacrylate monomers (such as methyl methacrylate and butyl acrylate) as precursors for the polymer matrix. The interfacial interaction between these monomers and the liquid crystal is weak, resulting in low anchoring energy within the liquid crystal microdroplets. This directly leads to the following problem:

[0004] 1. High driving voltage: To overcome the random orientation of liquid crystal molecules and achieve sufficient reorientation, a high electric field is usually required, with driving voltages generally above 50 V, and even as high as 100 V. This not only increases energy consumption but also places higher demands on the driving circuit.

[0005] 2. Slow response speed: Due to weak initial anchoring, the liquid crystal molecules lack coordination in the transition process from the scattering state to the transparent state, resulting in a long response time (especially the turn-off time), usually on the order of hundreds of milliseconds, which makes it difficult to meet the needs of dynamic dimming or fast display.

[0006] 3. Contrast needs improvement: Weak interfacial interactions may result in insufficient disorder in the arrangement of liquid crystal molecules in the power-off state, or insufficient consistency in the arrangement in the power-on state, thereby affecting the opacity of the scattering state and the transmittance of the transparent state, i.e., low contrast.

[0007] In the prior art, although some studies have been conducted to adjust interfacial properties by adding surfactants or modifying the polymer backbone, these methods are often complex, or the introduced components may affect the long-term stability of the material. Summary of the Invention

[0008] To address the shortcomings of conventional PDLC materials in the prior art, such as high driving voltage and slow response speed, this invention aims to provide a novel polymer-dispersed liquid crystal material and its preparation method.

[0009] The objective of this invention is achieved through the following technical solution.

[0010] In a first aspect, the present invention provides a polymer-dispersed liquid crystal composition prepared from the following components in a mass ratio:

[0011] A polymerizable monomer composition comprising at least one (meth)acrylic acid monomer having a terminal quaternary ammonium salt structure, wherein the monomer comprises 20% to 50% by mass.

[0012] Nematic liquid crystals, with a mass percentage of 50% to 80%;

[0013] The photoinitiator accounts for 0.5% to 2.5% of the total mass of the acrylic monomer and the liquid crystal.

[0014] Furthermore, the (meth)acrylic acid monomer has the structure shown in general formula (I) or (II):

[0015] General formula (I):

[0016] CH2=C(R 1 )-COO-(CH2) n -N + (R 2 (R) 3 (R) 4 ) X - ,

[0017] General Formula (II):

[0018] CH2=C(R 1 )-COO-(CH2-CH2-O) m -(CH2) p -N + (R 2 (R) 3 (R) 4 ) X - ,

[0019] in,

[0020] R 1 Selected from H or CH3;

[0021] n and p are independent integers from 1 to 6;

[0022] m is an integer from 1 to 3;

[0023] R 2 R 3 R 4 Alkyl groups independently selected from C1-C4.

[0024] Furthermore, the X - The counterion is selected from halide ions, BF4 ions, etc. - PF6 - CF3SO3 - One or more of them.

[0025] Furthermore, the acrylic monomer is selected from at least one of acryloyloxyethyltrimethylammonium chloride and 2-(2-(methacryloyloxy)ethoxy)-N,N,N-trimethylethane-1-aminochloride.

[0026] Furthermore, the mass ratio of the acrylic monomer to the liquid crystal is 2:8 to 5:5.

[0027] In a second aspect, the present invention provides a polymer-dispersed liquid crystal film comprising the polymer-dispersed liquid crystal composition as described above.

[0028] Thirdly, the present invention provides a method for preparing a polymer-dispersed liquid crystal film, comprising the following steps: mixing the acrylic monomer with a nematic liquid crystal and stirring until homogeneous; adding a photoinitiator and continuing to stir until homogeneous; injecting the mixture into a liquid crystal cell; and curing under ultraviolet light to obtain a PDLC film.

[0029] Furthermore, the method for preparing the polymer-dispersed liquid crystal composition includes the following steps:

[0030] S1. Premixing: Under light-protected or dark conditions, the (meth)acrylic acid monomer with the terminal quaternary ammonium salt structure is mixed with the nematic liquid crystal and mechanically stirred or ultrasonically treated at 20°C to 40°C for 0.5 to 2 hours to form a uniform, transparent isotropic prepolymer mixture.

[0031] S2. Adding the photoinitiator: Add the photoinitiator to the prepolymer mixture obtained in step S1, and continue stirring for 10 to 30 minutes to ensure that the photoinitiator is completely dissolved and evenly dispersed;

[0032] S3, Filling the cell: Fill the homogeneous mixture obtained in step S2 into the pre-assembled liquid crystal cell;

[0033] S4. UV Curing: The liquid crystal cell filled with the mixture is placed under a UV curing device and irradiated with UV light in a nitrogen atmosphere or an air atmosphere. The curing temperature is controlled between 15°C and 40°C. During the curing process, phase separation occurs, forming a composite thin film structure in which liquid crystal microdroplets are dispersed in the polymer matrix.

[0034] Furthermore, in step S2, the photoinitiator is selected from trimethylbenzoyl diphenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 1-hydroxycyclohexylphenyl ketone.

[0035] Furthermore, in step S4, the wavelength of the ultraviolet light is 300-400 nm; the irradiation intensity is 2-20 mW / cm²; and the irradiation time is 2-15 minutes.

[0036] Compared with the prior art, the present invention has the following beneficial effects.

[0037] Compared with the prior art, the present invention has the following significant advantages:

[0038] 1. Significantly Reduced Driving Voltage: During phase separation, quaternary ammonium salt monomers spontaneously accumulate at the polymer-liquid crystal interface, where their cationic head groups generate strong ion-dipole interactions with the liquid crystal molecules, forming a strong anchoring layer. This allows the liquid crystal molecules to orient more cooperatively and efficiently under an electric field, achieving a high-transmittance state at a significantly lower voltage. Examples show that the driving voltage can be reduced to 15-25 V (@25 μm cell thickness), far lower than the 50-70 V of the comparative example.

[0039] 2. Significantly faster response speed: Strong interface anchoring provides a more consistent initial alignment of liquid crystals (power-off state) and also promotes the effective transfer of electric field within the droplets. Therefore, the orientation process (on state) and relaxation process (off state) of liquid crystal molecules are accelerated, and the total response time can be shortened to less than 100 ms, which is much faster than the hundreds of milliseconds of the comparative model.

[0040] 3. Improved contrast: Strong anchoring makes the liquid crystal arrangement more disordered and the scattering stronger when the power is off; when the power is on, the arrangement is more uniform and the transmittance is higher, thereby improving the electro-optical contrast of the material.

[0041] 4. Simple process and good compatibility: This invention only requires replacing the conventional monomers with the quaternary ammonium salt monomers in the conventional PDLC formulation. No complicated post-processing or additional interface modifiers are required. The preparation process is fully compatible with the traditional UV-cured PDLC process and is easy to industrialize.

[0042] 5. Adjustable performance: By selecting different counterions (X... - By adjusting the content of quaternary ammonium salt monomers and copolymerizing with other conventional monomers, the strength of the interfacial anchoring energy can be easily adjusted, thereby allowing for fine control of performance such as driving voltage and response time to meet the needs of different application scenarios.

[0043] This invention introduces terminal quaternary ammonium salt structure monomers to form a strong anchoring layer at the polymer liquid crystal interface, significantly reducing the driving voltage to about 20V and shortening the response time to less than 100ms, making it suitable for low-power intelligent dimming devices. Detailed Implementation

[0044] To make the technical problems solved, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the embodiments described herein are only some, not all, of the embodiments of this invention, and are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the protection scope of this invention.

[0045] This invention provides a polymer-dispersed liquid crystal composition, a polymer-dispersed liquid crystal film, and a method for preparing the same, which have low driving voltage and fast response characteristics. The PDLC system optimizes the interface anchoring characteristics by introducing acrylic monomers with quaternary ammonium salt structures at the ends.

[0046] In a first aspect, the polymer-dispersed liquid crystal composition provided by the present invention is prepared from the following components in the following mass ratio:

[0047] A polymerizable monomer composition comprising at least one (meth)acrylic acid monomer having a terminal quaternary ammonium salt structure, wherein the monomer comprises 20% to 50% by mass.

[0048] Nematic liquid crystals, with a mass percentage of 50% to 80%;

[0049] The photoinitiator accounts for 0.5% to 2.5% of the total mass of the acrylic monomer and the liquid crystal.

[0050] The core of this invention lies in introducing acrylic acid (or methacrylic acid) monomers with quaternary ammonium salt groups at the ends of specific structures into copolymerization. By utilizing the strong polarity and interfacial enrichment characteristics of the quaternary ammonium salt groups, a strong and ordered anchoring layer is formed at the interface between the polymer and liquid crystal microdroplets, thereby significantly reducing the driving voltage of the material, shortening the response time, and improving the contrast.

[0051] Specifically, this invention introduces an acrylic monomer with a terminal quaternary ammonium salt structure. During film curing, these terminal quaternary ammonium salt groups spontaneously migrate and accumulate at the interface between the polymer and the liquid crystal microdroplets, as the interface is the highest energy level. The cationic head groups of the quaternary ammonium salt exert strong interactions (such as ion-dipole interactions) on the liquid crystal molecules (which typically have weak dipole moments or polar groups), thereby forming a strong and ordered oriented anchoring layer at the interface. In the off-state, this strong anchoring results in a more uniform initial alignment of the liquid crystal molecules within the microdroplets. When an electric field is applied (ON), the liquid crystal molecules need to align from the strongly anchored state towards the electric field direction. Although aligning requires overcoming the anchoring energy, the more ordered initial state and the polar interface of the quaternary ammonium salt itself facilitate electric field transmission and distribution, allowing the liquid crystal molecules to be driven more cooperatively and efficiently by the electric field, resulting in a shorter response time and sufficient reorientation at lower voltages, thus achieving a low transmittance state (or a high scattering state). Ultimately, this significantly reduces the driving voltage.

[0052] In some specific embodiments, the polymer-dispersed liquid crystal composition of the present invention is prepared by UV-induced phase separation polymerization and curing of the following components. The (meth)acrylic acid monomer has the structure shown in general formula (I) or (II):

[0053] General formula (I):

[0054] CH2=C(R 1 )-COO-(CH2) n -N + (R 2 (R) 3 (R) 4 ) X - ,

[0055] General Formula (II):

[0056] CH2=C(R 1 )-COO-(CH2-CH2-O) m -(CH2) p -N + (R 2 (R) 3 (R) 4 ) X - ,

[0057] in,

[0058] R 1 Selected from H or CH3;

[0059] n and p are independent integers from 1 to 6;

[0060] m is an integer from 1 to 3;

[0061] R 2 R 3 R 4 Alkyl groups independently selected from C1-C4, preferably all of which are methyl;

[0062] Specifically, X - It is a counterion, selected from halide ions (Cl... - , Br - , I - ), BF4 - PF6 - CF3SO3 - One of them. The smaller the ion, the higher the mobility, but it is affected by solvation effects and ion-polymer interactions.

[0063] In some specific embodiments, the acrylic monomer with a quaternary ammonium salt structure may include, but is not limited to: acryloyloxyethyltrimethylammonium chloride (DAC), methacryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium bromide, 2-(2-(methacryloyloxy)ethoxy)-N,N,N-trimethylethane-1-aminochloride, etc.

[0064] Specifically, the nematic liquid crystal is selected from commercially available nematic liquid crystal mixtures with positive dielectric anisotropy, such as E7, E8, E44, SLC1717, MLC-series, etc.

[0065] Specifically, the photoinitiator is a free radical photoinitiator that is cured by ultraviolet light, such as trimethylbenzoyl diphenylphosphine oxide (TPO), 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), 1-hydroxycyclohexylphenyl methyl ketone (184), etc.

[0066] In some specific embodiments, the mass ratio of the acrylic monomer to the liquid crystal is 2:8 to 5:5.

[0067] In a second aspect, the present invention provides a polymer-dispersed liquid crystal film comprising the polymer-dispersed liquid crystal composition as described above.

[0068] Thirdly, the present invention provides a method for preparing a polymer-dispersed liquid crystal film, characterized by comprising the following steps: mixing the acrylic monomer with a nematic liquid crystal and stirring until homogeneous; adding a photoinitiator and continuing to stir until homogeneous; injecting the mixture into a liquid crystal cell; and curing under ultraviolet light to obtain a PDLC film.

[0069] More specifically, the method for preparing the polymer-dispersed liquid crystal film includes the following steps:

[0070] S1. Premixing: Under light-protected or dark conditions, the (meth)acrylic acid monomer with terminal quaternary ammonium salt structure is mixed with the nematic liquid crystal in the above proportion, and mechanically stirred or ultrasonically treated at 20°C to 40°C for 0.5 to 2 hours to form a uniform and transparent isotropic prepolymer mixture.

[0071] S2. Adding the photoinitiator: Add the photoinitiator to the prepolymer mixture obtained in step S1, and continue stirring for 10 to 30 minutes to ensure that the photoinitiator is completely dissolved and evenly dispersed;

[0072] S3. Filling: The homogeneous mixture obtained in step S2 is filled into the pre-assembled liquid crystal cell. The liquid crystal cell consists of two glass substrates with a transparent conductive layer (such as ITO). The cell thickness is controlled by spacers (such as spherical or fibrous gaskets) between the substrates, with a typical cell thickness of 5 to 25 μm.

[0073] S4. UV Curing: The liquid crystal cell filled with the mixture is placed under a UV curing device and irradiated with UV light of a wavelength of 300-400 nm (preferably 365 nm) in a nitrogen or air atmosphere. The irradiation intensity is 2-20 mW / cm², and the irradiation time is 2-15 minutes. The curing temperature is controlled between 15°C and 40°C. During the curing process, phase separation occurs, forming a composite thin film structure in which liquid crystal microdroplets are dispersed in the polymer matrix.

[0074] In some specific embodiments, in step S2, the photoinitiator is selected from trimethylbenzoyl diphenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 1-hydroxycyclohexylphenyl ketone.

[0075] In some specific embodiments, in step S4, the wavelength of the ultraviolet light is 300-400 nm; the irradiation intensity is 2-20 mW / cm²; and the irradiation time is 2-15 minutes.

[0076] The specific embodiments of the present invention will be further explained and described below through examples and comparative examples.

[0077] Unless otherwise specified, all reagents, materials, and instruments used in the following description are conventional reagents, materials, and instruments, all of which are commercially available. The reagents involved can also be synthesized using conventional synthetic methods. Unless otherwise specified, the methods in the examples are conventional methods in the art. Monomers conforming to this invention are commercially available.

[0078] Description of the raw materials and equipment used in the exemplary embodiments and comparative examples of this invention:

[0079] 1. Quaternary ammonium salt monomers:

[0080] A: Acryloyloxyethyltrimethylammonium chloride (DAC, 80% aqueous solution, purified by vacuum distillation to remove moisture and polymerization inhibitor before use), its structural formula is: ;

[0081] B: 2-(2-(methacryloyloxy)ethoxy)-N,N,N-trimethylethane-1-aminochloride (homemade or commercially available), its structural formula is: ;

[0082] C: Methacryloxyethyltrimethylammonium bromide.

[0083] 2. Comparison of monomers:

[0084] D: n-Butyl acrylate (BA);

[0085] E: Methyl methacrylate (MMA);

[0086] 3. Liquid crystal: Nematic liquid crystal mixture E7, SLC1717.

[0087] 4. Photoinitiator: Trimethylbenzoyl diphenylphosphine oxide (TPO).

[0088] 5. Liquid crystal cell: ITO glass substrate, cell thickness 20 ± 2 μm (controlled by spherical pads).

[0089] 6. Equipment: Ultraviolet point light source (365 nm), photometer, oscilloscope, signal generator.

[0090] Example 1

[0091] 1. Weigh 1.5 g of DAC monomer and 3.5 g of E7 liquid crystal and place them in a brown sample vial.

[0092] 2. Place the sample vial on a magnetic stirrer at 35°C and stir for 1.5 hours in the dark to obtain a homogeneous and transparent mixture.

[0093] 3. Add 0.05 g of TPO photoinitiator (1% of the total mass) to the mixture and continue stirring in the dark for 20 minutes.

[0094] 4. Add the mixture droplets to the injection port of the liquid crystal cell, and use capillary action to fill the entire space inside the cell.

[0095] 5. Place the filled liquid crystal cell horizontally under a UV lamp and irradiate it vertically with 365 nm UV light at an intensity of 10 mW / cm² for 5 minutes in an air atmosphere at 25°C to complete the curing process and obtain the PDLC thin film sample.

[0096] The above embodiments and comparative examples are detailed in Table 1.

[0097] Performance testing:

[0098] The liquid crystal materials prepared in the above embodiments and comparative examples were subjected to performance tests, and the results are shown in Table 2.

[0099] 1. Transmittance-Voltage Curve: Place the sample in the optical path of the photometer and apply an AC square wave voltage with a frequency of 1 kHz. Gradually increase the voltage from 0 V to the saturation voltage (where transmittance no longer increases significantly), and record the transmittance T at each voltage. The maximum transmittance T is then recorded. max The voltages corresponding to 10% and 90% are denoted as V10 and V90 (threshold voltage and saturation voltage), respectively. The driving voltage is characterized by V90.

[0100] 2. Contrast Ratio: CR = T max / T min T min Transmittance at 0V.

[0101] 3. Response Time: Apply a step voltage (from 0V to V90), and record the transmittance change over time using an oscilloscope and photodetector. The transmittance changes from the applied voltage to T... min Rise to T max The time required for 90% of the process is the startup time t. on From voltage removal to transmittance from T max Descending to T max The time required for 10% is the shutdown time t. off The total response time is t. on + t off .

[0102] Table 1

[0103] serial number Monomer composition Monomer weight LCD type LCD quality The mass ratio of monomers to liquid crystals Photoinitiator mass percentage (wt%) Irradiation intensity (mW / cm²) under 365nm ultraviolet light. Irradiation time (min) Example 1 DAC 1.5 E7 3.5 3:7 1.0 10 5 Example 2 DAC 2.0 E7 3.0 4:6 1.0 10 5 Example 3 DAC 2.5 E7 2.5 5:5 1.0 10 5 Example 4 B 2.0 SLC1717 3.0 4:6 1.2 10 6 Example 5 C 1.8 E7 3.2 3.6:6.4 1.0 10 5 Example 6 DAC+ BA DAC: 1.0 BA: 1.0 E7 3.0 4:6 1.0 10 5 Comparative Example 1 BA 2.0 E7 3.0 4:6 1.0 10 5 Comparative Example 2 MMA 2.0 E7 3.0 4:6 1.0 10 5 Comparative Example 3 DAC+ BA DAC: 0.2 + BA: 1.8 E7 3.0 4:6 1.0 10 5 Comparative Example 4 DAC (Aqueous Phase) 0.5 E7 3.5 - 1.0 10 5

[0104] Table 2 serial number Drive voltage Contrast Response time Example 1 20 V 63.0% 90 ms Example 2 21 V 62.1% 100 ms Example 3 23 V 60.6% 110 ms Example 4 22 V 62.9% 105 ms Example 5 20 V 63.2% 120 ms Example 6 32 V 52.6% 230 ms Comparative Example 1 60 V 36.1% 650 ms Comparative Example 2 55 V 37% 700 ms Comparative Example 3 48 V 42.1% 560 ms Comparative Example 4 - - -

[0105] As can be clearly seen from Examples 1-3 and Comparative Examples 1-2, under the same formulation ratio and process conditions, the PDLC film prepared using quaternary ammonium salt monomers (DAC) has a significantly lower driving voltage than the film prepared using conventional acrylic monomers (BA, MMA), while also exhibiting a significantly faster response speed and higher contrast. This directly proves that the introduction of the terminal quaternary ammonium salt structure is the key inventive point that brings about performance improvement.

[0106] Examples 1-3 demonstrate the effect of quaternary ammonium salt monomer content on performance. With increasing content, the driving voltage slightly increases, the response speed remains relatively unchanged but the turn-off time slightly increases, and the contrast decreases slightly. This may be because excessively high quaternary ammonium salt content enhances interfacial anchoring, but it may also alter the droplet morphology or the properties of the polymer matrix. The results indicate that a content range of 30%-40% achieves the optimal balance between low voltage and good overall performance.

[0107] Examples 4 and 5 used other quaternary ammonium salt monomers (B and C), and both achieved excellent performance similar to DAC, demonstrating the universality of the technical solution of the present invention and its independence from any specific compound.

[0108] Example 6 shows that copolymerization of quaternary ammonium salt monomers with conventional monomers (DAC:BA=1:1) can still significantly improve performance. Although it is not as good as pure quaternary ammonium salt monomers, it is better than pure conventional monomers. This provides a flexible means for cost control and performance fine-tuning.

[0109] Comparative Example 3 shows that when the content of quaternary ammonium salt monomer is very low (only 10% of the total monomer content), the performance improvement is limited, indicating that sufficient quaternary ammonium salt monomer is required to effectively form a strong interfacial anchoring layer, verifying the rationality of the lower limit of the content range in the claims.

[0110] Comparative Example 4 attempted to use an aqueous solution of DAC that had not been adequately dehydrated, resulting in extremely poor compatibility with the liquid crystal, uncontrolled phase separation process, and inability to form a uniform PDLC film, thus emphasizing the importance of raw material processing in this invention.

[0111] In summary, this invention successfully prepared PDLC materials with low driving voltage, fast response, and high contrast by introducing acrylic monomers with terminal quaternary ammonium salt structures within a specific content range. This solves the prominent problems of existing technologies and has significant industrial application value.

[0112] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the nature and scope of the present invention. Various modifications made to the above embodiments by those skilled in the art after reading this specification are all within the scope of protection of the present invention.

Claims

1. A polymer-dispersed liquid crystal composition, characterized in that, It is prepared from the following components in the following mass ratio: A polymerizable monomer composition comprising at least one (meth)acrylic acid monomer having a terminal quaternary ammonium salt structure, wherein the monomer comprises 20% to 50% by mass. Nematic liquid crystals, with a mass percentage of 50% to 80%; The photoinitiator accounts for 0.5% to 2.5% of the total mass of the acrylic monomer and the liquid crystal.

2. The polymer-dispersed liquid crystal composition according to claim 1, characterized in that, The (meth)acrylic acid monomer has the structure shown in general formula (I) or (II): General formula (I): CH2=C(R 1 )-COO-(CH2) n -N + (R 2 )(R 3 )(R 4 ) X - , General Formula (II): CH2=C(R 1 )-COO-(CH2-CH2-O) m -(CH2) p -N + (R 2 )(R 3 )(R 4 ) X - , in, R 1 Selected from H or CH3; n and p are independent integers from 1 to 6; m is an integer from 1 to 3; R 2 R 3 R 4 Alkyl groups independently selected from C1-C4.

3. The polymer-dispersed liquid crystal composition according to claim 2, characterized in that, X⁻ is a counterion, selected from halide ions, BF4 ions, etc. - PF6 - CF3SO3 - One or more of them.

4. The polymer-dispersed liquid crystal composition according to claim 1, characterized in that, The acrylic monomer is selected from at least one of acryloyloxyethyltrimethylammonium chloride and 2-(2-(methacryloyloxy)ethoxy)-N,N,N-trimethylethane-1-aminochloride.

5. The polymer-dispersed liquid crystal composition according to claim 1, characterized in that, The mass ratio of the acrylic monomer to the liquid crystal is 2:8 to 5:

5.

6. A polymer-dispersed liquid crystal film comprising the polymer-dispersed liquid crystal composition as described in any one of claims 1-5.

7. A method for preparing a polymer-dispersed liquid crystal film as described in claim 6, characterized in that, Includes the following steps: The acrylic monomer is mixed with the nematic liquid crystal and stirred until homogeneous; Add the photoinitiator and continue stirring until homogeneous; pour the mixture into the liquid crystal cell; The PDLC film was obtained by curing under ultraviolet light.

8. The method for preparing a polymer-dispersed liquid crystal composition according to claim 7, characterized in that, Includes the following steps: S1. Premixing: Under light-protected or dark conditions, the (meth)acrylic acid monomer with the terminal quaternary ammonium salt structure is mixed with the nematic liquid crystal and mechanically stirred or ultrasonically treated at 20°C to 40°C for 0.5 to 2 hours to form a uniform, transparent isotropic prepolymer mixture. S2. Adding the photoinitiator: Add the photoinitiator to the prepolymer mixture obtained in step S1, and continue stirring for 10 to 30 minutes to ensure that the photoinitiator is completely dissolved and evenly dispersed; S3, Filling the cell: Fill the homogeneous mixture obtained in step S2 into the pre-assembled liquid crystal cell; S4. UV Curing: The liquid crystal cell filled with the mixture is placed under a UV curing device and irradiated with UV light in a nitrogen atmosphere or an air atmosphere. The curing temperature is controlled between 15°C and 40°C. During the curing process, phase separation occurs, forming a composite thin film structure in which liquid crystal microdroplets are dispersed in the polymer matrix.

9. A method for preparing a polymer-dispersed liquid crystal composition according to claim 7 or 8, characterized in that, In step S2, the photoinitiator is selected from trimethylbenzoyl diphenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 1-hydroxycyclohexylphenyl ketone.

10. The method for preparing a polymer-dispersed liquid crystal composition according to claim 8, characterized in that, In step S4, the wavelength of the ultraviolet light is 300 ~ 400 nm; the irradiation intensity is 2-20 mW / cm²; and the irradiation time is 2-15 minutes.