Electro-tunable polymer stabilized cholesteric liquid crystal device and method of making same

Abstract

The application discloses an electrically adjustable polymer stabilized cholesteric liquid crystal device and a preparation method thereof, relates to the technical field of polymer stabilized cholesteric liquid crystal, and the preparation method of the liquid crystal device is as follows: negative nematic liquid crystal, reactive chiral monomer, chiral agent, ultraviolet radical polymerizable monomer, thiol monomer, a photoinitiator and an ultraviolet absorber are uniformly mixed by heating and stirring, and then filled into a liquid crystal cell composed of two layers of conductive transparent ITO glass substrates; the liquid crystal cell is irradiated by ultraviolet light under an alternating current electric field to perform a polymerization reaction, a pitch gradient is formed; and a direct current electric field is applied to the sample after the polymerization reaction, the pitch gradient is further increased, and a reflection band gap is wider. The application solves the technical problems of a very narrow initial bandwidth, high haze and high working voltage of a traditional electrically adjustable PSCLC.

Description

Technical Field

[0001] This invention relates to the field of polymer-stabilized cholesteric liquid crystal technology, and more particularly to electrically tunable polymer-stabilized cholesteric liquid crystal devices and their preparation methods. Background Technology

[0002] Cholesteric liquid crystals (CLCs) possess selective Bragg reflection properties due to their unique periodic helical structure, making them promising candidates for applications in reflective displays and smart dimming windows. The reflection center wavelength of CLCs is determined by the helical pitch (P), and the reflection bandgap (Δλ) can be expressed as Δλ = Δn·P, where Δn is the birefringence of the liquid crystal. However, the Δn value of common liquid crystal materials is limited (typically <0.3), resulting in a reflection bandgap of CLCs with a single uniform pitch that is usually narrower than 100 nm, making it difficult to cover the entire visible light band (approximately 400-800 nm). This severely restricts their application in full-color displays and broadband optics.

[0003] To broaden the reflection bandgap, the core idea is to create a gradient or non-uniform pitch distribution. Existing technologies mainly fall into three categories, but all have inherent limitations: 1. Photoinduced molecular diffusion: Devices prepared using this method have a fixed bandwidth and cannot be dynamically adjusted. For example, by introducing ultraviolet-absorbing dyes, a light intensity gradient is formed in the longitudinal direction during ultraviolet irradiation, causing different consumption rates of monomers on the upper and lower sides, inducing monomer diffusion, thereby preparing polymer-stabilized CLC films with a fixed gradient pitch. 2. Dynamic non-electro-modulation technology: Yang et al. used temperature-sensitive chiral agents to achieve reversible bandwidth changes with temperature; White et al. used photosensitive chiral agents to achieve photocontrolled bandwidth broadening. However, heat and light, as stimuli, have slow modulation speeds and are easily affected by environmental conditions (ambient temperature, stray light). 3. Dynamic electric field modulation technology: Yang Dengke's team significantly expanded the reflection bandgap of negatively dielectric anisotropic polymer-stabilized cholesteric liquid crystals (PSCLCs) by applying a DC voltage. Electric field modulation has outstanding advantages such as fast response, easy control, and good reversibility, making it an ideal solution for dynamically controlling the reflection bandgap of PSCLCs. However, traditional electric field-stretched PSCLC devices have extremely narrow initial band gaps, and their broadband reflection state is strongly dependent on the continuous application of an external electric field. In the power-off state, the device can usually only present a very narrow reflection band gap, at which point its optical function is basically lost. This greatly limits its application in scenarios with low power consumption or high reliability requirements. In addition, high haze (low transparency) and high operating voltage are also common problems that hinder its practical application.

[0004] In summary, existing PSCLC broadband reflection technologies either have inherent limitations such as non-adjustable bandwidth, or significant drawbacks such as narrow initial bandgap, high haze, and high operating voltage. Therefore, there is an urgent need in this field for a novel electrically adjustable PSCLC device and its fabrication method that can simultaneously achieve a preset and controllable initial bandgap, low driving voltage, and low haze. Summary of the Invention

[0005] Based on the technical problems existing in the background technology, the present invention proposes an electrically tunable polymer-stabilized cholesteric liquid crystal device and its preparation method, which solves the technical problems of narrow initial bandwidth, high haze and high operating voltage of traditional electrically tunable PSCLC.

[0006] The present invention proposes a method for preparing an electrically tunable polymer-stabilized cholesteric liquid crystal device, the method steps of which are as follows:

[0007] S1: The nematic liquid crystal, reactive chiral monomer, chiral agent, UV free radical polymerizable monomer, thiol monomer, photoinitiator and UV absorber are heated and stirred until uniformly mixed and then poured into the liquid crystal cell.

[0008] S2: The liquid crystal cell is subjected to an alternating electric field and ultraviolet light irradiation to carry out a polymerization reaction, thereby obtaining a liquid crystal device.

[0009] Preferably, the raw materials comprise the following percentages by mass: 0.1%-5% reactive chiral monomer, 0-5% chiral agent, 3%-10% UV-radical polymerizable monomer, 0-5% thiol monomer, 0.5%-3% photoinitiator, 0.5%-3% UV absorber, with the balance being nematic liquid crystal;

[0010] The amount of chiral agent and thiol monomer added is not zero.

[0011] Preferably, the nematic liquid crystal is a negative nematic liquid crystal with negative dielectric anisotropy, or a mixture thereof with a positive nematic liquid crystal, and the dielectric anisotropy of the mixture is still negative.

[0012] And / or, the negative nematic liquid crystal is one or more of HNG715600-100, HNG715500-000, HNG720600-000, HNG30500-100, CN118600-100, and CN2400-000; the positive nematic liquid crystal is E7 and / or GXP-6011.

[0013] Preferably, the reactive chiral monomer is one or more of the monomers whose chiral groups are chiral isoamyl alcohol, chiral phenyl ethylene glycol, and chiral isosorbide.

[0014] Preferably, the chiral agent is one or more of R6N, R811, R5011 and R1011.

[0015] Preferably, the UV-radical polymerizable monomer is one or more of acrylate, methacrylate, styrene, and diacetyl photopolymerizable monomers.

[0016] Preferably, the thiol monomer is a thiol monomer containing one or more benzene rings;

[0017] And / or, the photoinitiator is one or more of benzoin methyl ether, 2-isopropylthioxanthrone, photoinitiator 651, photoinitiator 184, photoinitiator 1173, photoinitiator 127, photoinitiator 2959, photoinitiator 784 and photoinitiator 2022;

[0018] And / or, the ultraviolet absorber is one or more of UV-9, UV-234, UV-327, UV-350, UV-1084 and UV-3030.

[0019] Preferably, the voltage of the alternating electric field in S2 is 70-200V and the frequency is 0.1-10KHz.

[0020] Preferably, the ultraviolet light irradiation conditions in S2 are: first, the light intensity is 0.05-5 mW / cm². 2 Irradiate with ultraviolet light for 20-40 minutes, then with light intensity of 20-120 mW / cm². 2 Expose to ultraviolet light for 20-40 minutes.

[0021] The present invention proposes an electrically tunable polymer-stabilized cholesteric liquid crystal device, which is prepared by the above-described method.

[0022] Beneficial technical effects of the present invention:

[0023] (1) This invention initiates free radical polymerization by ultraviolet light and regulates polymerization conditions such as ultraviolet light intensity and ultraviolet irradiation time to form a gradient polymer network structure to achieve precise pre-broadening of the reflection bandgap, so that the device is usable when there is no external electric field, and solves the problem of "failure when power is cut off" caused by the extremely narrow initial bandgap; then, a DC electric field is applied along the direction of the back light source of the device during ultraviolet light irradiation polymerization to induce the polymer network to move in an directional manner, making the short pitch shorter and the long pitch longer, thereby realizing the secondary dynamic broadening of the reflection bandgap of the device.

[0024] (2) The present invention significantly reduces light scattering by polymerizing under a high-frequency high-voltage electric field and adjusting the refractive index of liquid crystal and polymer to match, thereby greatly reducing the haze of the device.

[0025] (3) By introducing thiol compounds, the present invention reduces the crosslinking density of the polymer network and enhances its adsorption capacity for free ions, thereby effectively reducing the operating voltage of the device. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the liquid crystal device proposed in this invention;

[0027] Figure 2 These are the transmission spectrum curves of the liquid crystal device prepared in Example 1 of this invention before and after polymerization;

[0028] Figure 3 These are the transmission spectrum curves of the liquid crystal device prepared in Example 1 of this invention when different DC voltages are applied after polymerization;

[0029] Figure 4 It is the haze value of the liquid crystal device prepared by the present invention after polymerization and when a DC voltage of 60V is applied;

[0030] Figure 5 This is a physical image characterization of the liquid crystal device prepared by the present invention after polymerization and when a DC voltage of 60V is applied;

[0031] Figure 6 These are the transmission spectrum curves of the liquid crystal device prepared by Comparative Example 3 of the present invention when different DC voltages are applied after polymerization;

[0032] Figure 7 These are the transmission spectrum curves of the liquid crystal device prepared in Example 2 of this invention before and after polymerization;

[0033] Figure 8 These are the transmission spectrum curves of the liquid crystal device prepared in Example 2 of this invention when different DC voltages are applied after polymerization;

[0034] Figure 9 These are the transmission spectrum curves of the liquid crystal device prepared in Example 3 of this invention before and after polymerization;

[0035] Figure 10 These are the transmission spectrum curves of the liquid crystal device prepared in Example 3 of the present invention when different DC voltages are applied after polymerization. Detailed Implementation

[0036] The present invention will be further explained below with reference to specific embodiments.

[0037] The following materials were purchased in this invention: HNG715600-100 from Jiangsu Hecheng Display Technology Co., Ltd.; E7 from Yantai Xianhua Technology Group Co., Ltd.; GXP-6011 from Yantai Xianhua Technology Group Co., Ltd.; PALIOCOLOR LC 756 from Aladdin; R6N from Jiangsu Hecheng Display Technology Co., Ltd.; R5011 from Aladdin; RM257 from Beijing Bashikong LCD Technology Co., Ltd.; RM82 from Aladdin; BDMT from Aladdin; BMDT from Aladdin; 1,3-XDT from Aladdin; BPT from Aladdin; BME from Aladdin; photoinitiator 2959 from Aladdin; photoinitiator 651 from Shanghai Maclean Biochemical Technology Co., Ltd.; ITX from Aladdin; UV-234 from Aladdin; UV-327 from Aladdin; UV-9 from Aladdin; and BP-2 from Qingdao Emerald New Material Technology Co., Ltd.

[0038] Example 1

[0039] First, the nematic liquid crystal, reactive chiral monomer, chiral agent, UV-radical polymerizable monomer, thiol monomer, photoinitiator and UV absorber were mixed in a mass ratio of 90:1:3.5:7:0.15:0.8:0.8, heated and stirred until homogeneous, and then poured into a 30-micron parallel-oriented ITO liquid crystal cell to obtain sample A1.

[0040] Then, at 30°C, sample A1 was subjected to a high-frequency, high-voltage AC electric field of 150V and 1kHz with a light intensity of 0.7mW / cm². 2 Irradiate with 365nm ultraviolet light for 30 minutes, then use 50mW / cm 2 Irradiation with 365nm ultraviolet light for 30 minutes allows the monomers in the system to react completely, thus obtaining a liquid crystal device.

[0041] Among them, the nematic liquid crystal is a hybrid liquid crystal of HNG715600-100 and E7, with a mass ratio of 72:18.

[0042] The reactive chiral monomer is PALIOCOLOR LC 756 (4-[[(3AR,6S,6AR)-6-[4-[4-(3-prop-2-enoyloxypropoxy)benzoyl]oxybenzoyl]oxy-2,3,3A,5,6,6A-hexahydrofuran[3,2-B]furan-3-yl]oxycarbonyl]phenyl]4-(3-prop-2-enoyloxypropoxy)benzoate), with the following chemical structure:

[0043]

[0044] The chiral agent is R6N, and its chemical structural formula is as follows:

[0045]

[0046] The UV-radical polymerizable monomer is RM257 (1,4-bis-[4-(3-acryloyloxypropoxybenzoyloxy]-2-methylbenzene), with the following chemical structure:

[0047]

[0048] The thiol monomer is BDMT (1,4-phenylenedimethylthiol), with the following chemical structural formula:

[0049]

[0050] The photoinitiator is BME (benzoin methyl ether), with the following chemical structural formula:

[0051]

[0052] The ultraviolet absorber is UV-234 (2-(2H-benzotriazol-2-yl)-4,6-di(1-methyl-1-phenylethyl)phenol), with the following chemical structural formula:

[0053]

[0054] Reference Figure 2 The reflection bandgap of sample A1 is 200 nm; Figure 3 As shown, after applying a 60V DC electric field, the reflection bandgap of sample A1 reaches 425nm; Figure 4 As shown, the haze of sample A1 after polymerization and at 60V was 10.44 and 10.57, respectively.

[0055] Example 2

[0056] First, the nematic liquid crystal, reactive chiral monomer, chiral agent, UV-radical polymerizable monomer, thiol monomer, photoinitiator and UV absorber were mixed in a mass ratio of 90:1:4.2:7:0.32:1.0:1.0 and then poured into a 30-micron parallel-oriented ITO liquid crystal cell to obtain sample B1.

[0057] Then, at 30°C, sample B1 was subjected to a high-frequency, high-voltage AC electric field of 120V and 2kHz with a light intensity of 1.5mW / cm². 2 Irradiate with 365nm ultraviolet light for 30 minutes, then use light with an intensity of 60mW / cm². 2 The system was irradiated with ultraviolet light for 30 minutes to allow the monomers in the system to react completely, thus obtaining a liquid crystal device.

[0058] Among them, the nematic liquid crystal is a hybrid liquid crystal of HNG715600-100 and GXP-6011, with a mass ratio of 80:10.

[0059] The reactive chiral monomer is PALIOCOLOR LC 756.

[0060] The chiral agent is R5011, and its chemical structural formula is as follows:

[0061]

[0062] The UV-radical polymerizable monomer is RM82 (2-methyl-1,4-phenylene bis(4-((6-(acryloyloxy)hexyl)oxy)benzoate), with the following chemical structure:

[0063]

[0064] The thiol monomer is BMDT, and its chemical structure is as follows:

[0065]

[0066] The photoinitiator is photoinitiator 2959, and its chemical structure is as follows:

[0067]

[0068] The ultraviolet absorber is UV-327, and its chemical structure is as follows:

[0069]

[0070] like Figure 7 As shown, after UV-initiated polymerization, the reflection bandgap of the sample is 100 nm; Figure 8 As shown, the sample reflection bandgap reached 401 nm after applying a 60V DC electric field; the haze of the sample after polymerization and at 60V was 11.77 and 11.98, respectively.

[0071] Example 3

[0072] First, the nematic liquid crystal, reactive chiral monomer, chiral agent, UV-radical polymerizable monomer, thiol monomer, photoinitiator and UV absorber were mixed in a mass ratio of 90:1.2:3.5:7:0.18:0.8:0.8, heated and stirred until homogeneous, and then poured into a 30-micron parallel-oriented ITO liquid crystal cell to obtain sample C1.

[0073] Then, at 30°C, sample C1 was subjected to a high-frequency, high-voltage AC electric field of 100V and 3kHz with a light intensity of 1.2mW / cm². 2 Irradiate with 365nm ultraviolet light for 30 minutes, then use light with an intensity of 100mW / cm². 2 The system was irradiated with ultraviolet light for 30 minutes to allow the monomers in the system to react completely, thus obtaining a liquid crystal device.

[0074] The nematic liquid crystal is a mixture of HNG715600-100 and E7, with a mass ratio of 72:18.

[0075] The reactive chiral monomer is PALIOCOLOR LC 756; the chiral agent is R5011; and the UV-radical polymerizable monomer is RM257.

[0076] The thiol monomer is 1,3-XDT (1,3-phenylenedimethylthiol), with the following chemical structural formula:

[0077]

[0078] The photoinitiator is photoinitiator 651 (benzoin dimethyl ether), with the following chemical structure:

[0079]

[0080] The ultraviolet absorber is UV-9, and its chemical structure is as follows:

[0081]

[0082] like Figure 9 As shown, after UV-initiated polymerization, the reflection bandgap of the sample is 300 nm; Figure 10 As shown, the sample reflection bandgap reached 425 nm after applying a 60V DC electric field; the haze of the sample after polymerization and at 60V was 11.82 and 12.06, respectively.

[0083] Example 4

[0084] First, the nematic liquid crystal, reactive chiral monomer, chiral agent, UV-radical polymerizable monomer, thiol monomer, photoinitiator and UV absorber were mixed in a mass ratio of 90:0.9:4.1:6:0.3:1.0:0.8, heated and stirred until homogeneous, and then poured into a 30-micron parallel-oriented ITO liquid crystal cell to obtain sample D1.

[0085] Secondly, at 30℃, sample D1 was subjected to a high-frequency, high-voltage AC electric field of 100V and 3kHz with a light intensity of 0.8mW / cm². 2 Irradiate with 365nm ultraviolet light for 30 minutes, then use light with an intensity of 60mW / cm². 2 The system was irradiated with ultraviolet light for 30 minutes to allow the monomers in the system to react completely, thus obtaining a liquid crystal device.

[0086] The nematic liquid crystal is a mixture of HNG715600-100 and E7, with a mass ratio of 72:18.

[0087] The reactive chiral monomer is PALIOCOLOR LC 756; the chiral agent is R5011; and the UV-radical polymerizable monomer is RM257.

[0088] The thiol monomer is BPT (biphenyl-4-thiol), with the following chemical structural formula:

[0089]

[0090] The photoinitiator is ITX (2-isopropylthioxanthrone), with the following chemical structure:

[0091]

[0092] The ultraviolet absorber is UV-9.

[0093] After UV-initiated polymerization, the sample's reflectance bandgap was 160 nm; after applying a 60 V DC electric field, the sample's reflectance bandgap reached 417 nm; the haze of the sample after polymerization and at 60 V was 11.65 and 11.82, respectively.

[0094] Example 5

[0095] First, the nematic liquid crystal, reactive chiral monomer, chiral agent, UV-radical polymerizable monomer, thiol monomer, photoinitiator and UV absorber were mixed in a mass ratio of 90:1.1:3.4:6:0.3:0.8:0.8, heated and stirred until homogeneous, and then poured into a 30-micron parallel-oriented ITO liquid crystal cell to obtain sample E1.

[0096] Secondly, at 30℃, sample E1 was subjected to a high-frequency, high-voltage AC electric field of 160V and 1kHz with a light intensity of 1.5mW / cm². 2 Irradiate with 365nm ultraviolet light for 30 minutes, then use light with an intensity of 100mW / cm². 2 The system was irradiated with ultraviolet light for 30 minutes to allow the monomers in the system to react completely, thus obtaining a liquid crystal device.

[0097] Among them, the nematic liquid crystal is a hybrid liquid crystal of HNG715600-100 and GXP-6011, with a mass ratio of 80:10.

[0098] The reactive chiral monomer is PALIOCOLOR LC 756; the chiral agent is R6N; the UV-radical polymerizable monomer is RM82; the thiol monomer is BPT; and the photoinitiator is photoinitiator 651.

[0099] The UV absorber is BP-2 (2,2′,4,4′-tetrahydroxybenzene, with the following chemical structure):

[0100]

[0101] After UV-initiated polymerization, the sample's reflection bandgap was 240 nm, and after applying a 65 V DC electric field, the sample's reflection bandgap reached 419 nm; the haze of the sample after polymerization and at 65 V was 10.88 and 11.05, respectively.

[0102] Example 6

[0103] First, the nematic liquid crystal, reactive chiral monomer, chiral agent, UV-radical polymerizable monomer, thiol monomer, photoinitiator and UV absorber were mixed in a mass ratio of 90:1.1:4.0:6:0.18:0.8:0.8, heated and stirred until homogeneous, and then poured into a 30-micron parallel-oriented ITO liquid crystal cell to obtain sample F1.

[0104] Then, at 30°C, sample F1 was subjected to a high-frequency, high-voltage AC electric field of 160V and 3kHz with a light intensity of 1.3mW / cm². 2 Irradiate with 365nm ultraviolet light for 30 minutes, then use light with an intensity of 100mW / cm². 2 The system was irradiated with ultraviolet light for 30 minutes to allow the monomers in the system to react completely, thus obtaining a liquid crystal device.

[0105] Among them, the nematic liquid crystal is a hybrid liquid crystal of HNG715600-100 and GXP-6011, with a mass ratio of 80:10.

[0106] The reactive chiral monomer is PALIOCOLOR LC 756; the chiral agent is R5011; the UV-radical polymerizable monomer is RM82; the thiol monomer is BDMT; the photoinitiator is photoinitiator 651; and the UV absorber is BP-2.

[0107] After UV-initiated polymerization, the sample's reflectance bandgap was 220 nm, and after applying a 70 V DC electric field, the sample's reflectance bandgap reached 411 nm; the sample's haze was 11.05 after polymerization and 11.21 at 70 V.

[0108] Example 7

[0109] First, the nematic liquid crystal, reactive chiral monomer, chiral agent, UV-radical polymerizable monomer, thiol monomer, photoinitiator and UV absorber were mixed in a mass ratio of 90:1:3.5:7:0.25:0.8:0.8, heated and stirred until homogeneous, and then poured into a 30-micron parallel-oriented ITO liquid crystal cell to obtain sample G1.

[0110] Then, at 30°C, sample G1 was subjected to a high-frequency, high-voltage AC electric field of 180V and 2kHz with a light intensity of 1.0mW / cm². 2 Irradiate with 365nm ultraviolet light for 30 minutes, then use light with an intensity of 50mW / cm².2 The system was irradiated with ultraviolet light for 30 minutes to allow the monomers in the system to react completely, thus obtaining a liquid crystal device.

[0111] The nematic liquid crystal is a mixture of HNG715600-100 and E7, with a mass ratio of 72:18.

[0112] The reactive chiral monomer is PALIOCOLOR LC 756; the chiral agent is R6N; the UV-radical polymerizable monomer is RM257; the thiol monomer is BMDT; the photoinitiator is photoinitiator 2959; and the UV absorber is UV-234.

[0113] After UV-induced polymerization, the sample's reflectance bandgap was 180 nm; after applying a 60 V DC electric field, the sample's reflectance bandgap reached 406 nm; the haze of the sample after polymerization and at 60 V was 10.58 and 10.76, respectively.

[0114] Example 8

[0115] First, the nematic liquid crystal, reactive chiral monomer, chiral agent, UV-radical polymerizable monomer, thiol monomer, photoinitiator and UV absorber were mixed in a mass ratio of 90:1:3.5:7:0.25:0.8:0.8, heated and stirred until homogeneous, and then poured into a 30-micron parallel-oriented ITO liquid crystal cell to obtain sample H1.

[0116] Then, at 30°C, sample H1 was subjected to a high-frequency, high-voltage AC electric field of 150V and 2kHz with a light intensity of 1.0mW / cm². 2 Irradiate with 365nm ultraviolet light for 30 minutes, then use light with an intensity of 50mW / cm². 2 The system was irradiated with ultraviolet light for 30 minutes to allow the monomers in the system to react completely, thus obtaining a liquid crystal device.

[0117] The nematic liquid crystal is a mixture of HNG715600-100 and GXP-6011 with a mass ratio of 80:10.

[0118] The reactive chiral monomer is PALIOCOLOR LC 756; the chiral agent is R6N; the UV radical polymerizable monomer is RM82; the thiol monomer is BPT; the photoinitiator is BME; and the UV absorber is UV-234.

[0119] After UV-induced polymerization, the sample's reflectance bandgap was 225 nm; after applying a 60 V DC electric field, the sample's reflectance bandgap reached 427 nm; the haze of the sample after polymerization and at 60 V was 11.02 and 11.16, respectively.

[0120] Comparative Example 1

[0121] As a comparative example 1, the preparation process was basically the same as that of Example 1. The difference was that the sample of Example 1 was subjected to UV-initiated free radical polymerization under a high-frequency high-voltage AC electric field, while the sample of this example was subjected to polymerization reaction in an environment without an external electric field. All other conditions were the same as those of Example 1, and sample A2 was prepared.

[0122] like Figure 4 and Figure 5 As shown, after UV-initiated polymerization, the haze of the sample was 19.27 and 19.45 after polymerization and at 60V.

[0123] The reason why free radical polymerization can significantly reduce device haze under a high-frequency, high-voltage alternating electric field is that the electric field will keep the negative liquid crystal aligned perpendicular to the electric field, which can eliminate the interference of monomer diffusion and polymer network formation on the liquid crystal alignment.

[0124] Comparative Example 2

[0125] As a comparative example 2, the preparation process was basically the same as that of example 1, except that the type of liquid crystal in the formula was different, and sample A3 was prepared.

[0126] The formulation of sample A3 is HNG715600-100:LC756:R6N:RM257:BMDT:BME:UV234 = 90:1:3.5:7:0.15:0.8:0.8.

[0127] The liquid crystal used in sample A3 is pure HNG715600-100, while the liquid crystal used in A1 is a mixture of HNG715600-100 and E7 in a ratio of 72:18.

[0128] like Figure 4 and Figure 5 As shown, after UV-initiated polymerization, the haze of the sample was 19.09 and 19.28 after polymerization and at 60V.

[0129] Comparative Example 3

[0130] As a comparative example 3, the preparation process was basically the same as that of example 1, except that the sample formulation of example 1 contained 0.15% by mass of difunctional thiol BMDT, while the sample formulation of this example did not contain thiol components, and sample A4 was prepared.

[0131] The formulation of the sample is HNG715600-100:E7:LC756:UV234:RM257:BME:UV234 = 72:18:1:3.5:7:0.8:0.8.

[0132] like Figure 6As shown, after UV-initiated polymerization, the reflectance bandgap of the sample reached 405 nm when an 80V DC voltage was applied.

[0133] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application. The scope of this application is defined by the appended claims and their equivalents, all of which should be included within the protection scope of this application.

Claims

1. A method for preparing an electrically tunable polymer-stabilized cholesteric liquid crystal device, characterized in that, The steps are as follows: S1: The nematic liquid crystal, reactive chiral monomer, chiral agent, UV free radical polymerizable monomer, thiol monomer, photoinitiator and UV absorber are heated and stirred until uniformly mixed and then poured into the liquid crystal cell. S2: The liquid crystal cell is subjected to an alternating electric field and ultraviolet light irradiation to carry out a polymerization reaction, thereby obtaining a liquid crystal device; The electrically tunable polymer-stabilized cholesteric liquid crystal device comprises the following raw materials in the following mass percentages: 0.1%-5% reactive chiral monomer, 0-5% chiral agent, 3%-10% UV-radical polymerizable monomer, 0-5% thiol monomer, 0.5%-3% photoinitiator, 0.5%-3% UV absorber, with the balance being nematic liquid crystal. The amount of chiral agent and thiol monomer added is not zero; The nematic liquid crystal is a negative nematic liquid crystal with negative dielectric anisotropy, or a mixture of negative nematic liquid crystal and positive nematic liquid crystal, and the dielectric anisotropy of the mixture is still negative. The reactive chiral monomer is one or more of the following monomers whose chiral groups are chiral isoamyl alcohol, chiral phenyl ethylene glycol, and chiral isosorbide; The UV-radical polymerizable monomer is one or more of the following: acrylate, methacrylate, styrene, and diacetyl photopolymerizable monomers; The thiol monomer is a thiol monomer containing one or more benzene rings; The voltage of the alternating electric field in S2 is 70-200V, and the frequency is 0.1-10KHz.

2. The method for preparing an electrically tunable polymer-stabilized cholesteric liquid crystal device according to claim 1, characterized in that, The negative nematic liquid crystal is one or more of HNG715600-100, HNG715500-000, HNG720600-000, HNG30500-100, CN118600-100, and CN2400-000; And / or, the positive nematic liquid crystal is E7 and / or GXP-6011.

3. The method for preparing an electrically tunable polymer-stabilized cholesteric liquid crystal device according to claim 1, characterized in that, The chiral agent is one or more of R6N, R811, R5011 and R1011.

4. The method for preparing an electrically tunable polymer-stabilized cholesteric liquid crystal device according to claim 1, characterized in that, The photoinitiator is one or more of the following: benzoin methyl ether, 2-isopropylthioxanthrone, photoinitiator 651, photoinitiator 184, photoinitiator 1173, photoinitiator 127, photoinitiator 2959, photoinitiator 784, and photoinitiator 2022. And / or, the ultraviolet absorber is one or more of UV-9, UV-234, UV-327, UV-350, UV-1084 and UV-3030.

5. The method for preparing an electrically tunable polymer-stabilized cholesteric liquid crystal device according to claim 1, characterized in that, The conditions for ultraviolet irradiation in S2 are: first, the light intensity is 0.05-5 mW / cm². 2 Irradiate with ultraviolet light for 20-40 minutes, then with light intensity of 20-120 mW / cm². 2 Expose to ultraviolet light for 20-40 minutes.

6. An electrically tunable polymer-stabilized cholesteric liquid crystal device, characterized in that, It is prepared by the preparation method described in any one of claims 1-5.

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