Liquid crystal material for ultraviolet band as well as preparation method and application of liquid crystal material

Abstract

The invention relates to a liquid crystal material for an ultraviolet band as well as a preparation method and application thereof, and belongs to the technical field of preparation of liquid crystal materials. According to the liquid crystal material for the ultraviolet band, the liquid crystal material is designed by selecting groups which do not generate light absorption and light reaction in the band of 300-400 nm, the liquid crystal material is an ultraviolet-resistant liquid crystal material which does not generate light absorption and light reaction in the ultraviolet band, and a general formula and application suitable for forming the liquid crystal material are provided. The liquid crystal material has very high stability in the wave band of 300-400 nm. The liquid crystal material disclosed by the invention is mainly applicable to the fields of fast spatial light modulators and the like, such as light polymerization type 3D printing of liquid crystal spatial light modulators and the like.

Description

Technical Field

[0001] This invention belongs to the field of liquid crystal material preparation technology, specifically relating to a liquid crystal material for the ultraviolet band, its preparation method, and its application. Background Technology

[0002] Liquid crystal spatial light modulators (LC-SLMs) are devices that use birefringent liquid crystal materials as the dimming medium, possessing computational capabilities and enabling rapid input and output. They hold an important position in the field of optical information processing. LC-SLMs primarily utilize the electro-optic properties of liquid crystals. Their working surface consists of an array of many independent units, each representing a pixel. These units can receive external optical and electrical control signals. By applying independently controllable driving voltages to corresponding pixels, the long axes of the liquid crystal molecules align parallel to the electric field, changing the molecule pointing vector and forming a stepped phase surface on the exiting surface. This modulates the phase of the incident light, resulting in enhanced interference in the far field and achieving random beam pointing control.

[0003] Currently, liquid crystal modulators (LC-SLMs) for visible and near-infrared wavelength modulation are relatively mature. However, with the development of deep ultraviolet (DEW) communication, high-precision lithography, photopolymerization 3D printing, and high-density information storage, the demand for DEW modulation is gradually increasing. However, common liquid crystal materials exhibit strong absorption in the DEW band (300-400 nm). Under DEW irradiation, liquid crystal molecules undergo photodegradation or photopolymerization, causing the material to gradually lose its liquid crystal properties and leading to device degradation and failure. These factors limit the application of liquid crystal materials in the DEW band; currently, common commercial LC-SLMs cannot modulate DEW light below 400 nm.

[0004] Although researchers at home and abroad have made some progress in the study of the ultraviolet stability of liquid crystal materials, the research wavelengths on the ultraviolet stability of liquid crystal materials are mainly concentrated in the range of 380-450 nm, and rarely involve wavelengths of 350 nm or shorter. In the actual application of LC-SLM, liquid crystal materials need to have good stability in the 300-400 nm band. Summary of the Invention

[0005] This invention addresses the technical problem of stability of liquid crystal materials in the ultraviolet (UV) band in existing technologies, providing a liquid crystal material for the UV band, its preparation method, and its applications. This invention designs liquid crystal materials by selecting functional groups that do not undergo light absorption or photoreaction in the 300-400 nm wavelength range, and provides general formulations and applications suitable for forming such liquid crystal materials. These liquid crystal materials exhibit high stability in the 300-400 nm wavelength range.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A liquid crystal material for the ultraviolet band, comprising: One or more of the general structural formulas I, one or more of the general structural formulas II, one or more of the general structural formulas III, one or more of the general structural formulas IV, and one or more of the general structural formulas V; Or include: One or more of the general structural formula I, one or more of the general structural formula II, one or more of the general structural formula III, one or more of the general structural formula IV, one or more of the general structural formula V, and one or more of the general structural formula VI; Ⅰ; II; III; IV; V; VI; In structural formulas I-VI: L1 to L3 are independently -H atoms, -F atoms, or -CF3, respectively; The values ​​of m1 to m4 are 0 or 1 respectively, and m1 and m2 are not both 0 at the same time, and m3 and m4 are both 0 at the same time; R1 to R6 are alkane chains or alkoxy chains with 2 to 7 carbon atoms, respectively; X is ―CH2CH2―, ―CF2CF2―, ―CH2O―, or ―CF2O―; Y can be a single bond, cyclohexyl group, -CH2CH2-, -CF2CF2-, -CH2O-, or -CF2O-; Z is an alkane chain or alkoxy chain with 2 to 7 C atoms, or a -H atom, -F atom, or -CF3.

[0007] In the above technical solution, it is preferred that R1 to R6 are alkane chains with 3 to 5 C atoms.

[0008] In the above technical solution, Z is preferably -C2H5O or -CF3.

[0009] In the above technical solution, it is preferred that X is ―CH2CH2― or ―CF2O―.

[0010] In the above technical solution, it is preferred that Y is a single bond, -CH2CH2- or -CF2O-.

[0011] In the above technical solution, preferably, the liquid crystal material comprises the following mass percentages of liquid crystal compound; 20%; 6%; 5%; 6%; 5%; 10%; 15%; 7%; 15%; 11%.

[0012] In the above technical solution, preferably, the liquid crystal material comprises the following mass percentages of liquid crystal compound; 16%; 4%; 3%; 6%; 5%; 4%; 8%; 6%; 8%; 5%; 6%; 10%; 6%; 6%; 7%.

[0013] A method for preparing a liquid crystal material for the ultraviolet band includes the following steps: Weigh one or more of the general structural formula I, one or more of the general structural formula II, one or more of the general structural formula III, one or more of the general structural formula IV, and one or more of the general structural formula V; Alternatively, it may be referred to as one or more of the general structural formulas I, II, III, IV, V, and VI. The above-weighed compounds are mixed and placed in a water bath heating tank with electromagnetic stirring. The mixture is stirred at 50°C to 70°C for 1 to 1.5 hours until all solid components are completely dissolved, forming a homogeneous liquid crystal mixture, which is the liquid crystal material for the ultraviolet band.

[0014] The present invention relates to the application of a liquid crystal material for the ultraviolet band in a fast spatial light modulator.

[0015] The beneficial effects of this invention are: This invention relates to a liquid crystal material for the ultraviolet (UV) band, which is a UV-resistant liquid crystal material that does not undergo light absorption or photoreaction in the UV band. A general formulation and application suitable for forming this type of liquid crystal material are provided. This liquid crystal material exhibits high stability in the 300-400 nm wavelength range. The liquid crystal material of this invention is primarily applicable to fields such as fast spatial light modulators, and can be used in applications such as photopolymerization 3D printing of liquid crystal spatial light modulators. Attached Figure Description

[0016] Figure 1 This is the ultraviolet absorption spectrum of a dicyclohexyl liquid crystal compound. Wherein: 3CCV stands for: ; 5CCV represents: .

[0017] Figure 2 This is the ultraviolet absorption spectrum of a dicyclohexylbenzene liquid crystal compound. Wherein: VCCP1 represents: ; C3-CYLCYL-BEN-F3 represents: ; C5-CYL-CYL-BEN-F3 represents: ; C3-CYL-CYL-BEN-OCF3 represents: .

[0018] Figure 3 The images show the UV absorption spectra of dicyclohexylbiphenyl and cyclohexylbiphenyl compounds. Wherein: The structural formula of dicyclohexylbiphenyl is as follows: ; The structural formula of cyclohexylbiphenyl is as follows: .

[0019] Figure 4 The image shows the ultraviolet absorption spectrum of the mixed liquid crystal material (i.e., liquid crystal mixture) prepared in Example 2. Detailed Implementation

[0020] The present invention provides a liquid crystal material for the ultraviolet band, comprising: one or more of general structural formula I, one or more of general structural formula II, one or more of general structural formula III, one or more of general structural formula IV, and one or more of general structural formula V; Or it may include: one or more of the general structural formula I, one or more of the general structural formula II, one or more of the general structural formula III, one or more of the general structural formula IV, one or more of the general structural formula V, and one or more of the general structural formula VI; Ⅰ; II; III; IV; V; VI; In structural formulas I-VI: L1 to L3 are independently -H atoms, -F atoms, or -CF3, respectively; The values ​​of m1 to m4 are 0 or 1 respectively, and m1 and m2 are not both 0 at the same time, and m3 and m4 are both 0 at the same time; R1 to R6 are alkane chains or alkoxy chains with 2 to 7 carbon atoms, respectively; preferably, R1 to R6 are alkane chains with 3 to 5 carbon atoms, respectively. X is ―CH2CH2―, ―CF2CF2―, ―CH2O―, or ―CF2O―; preferably, X is ―CH2CH2― or ―CF2O―.

[0021] Y is a single bond, cyclohexyl, -CH2CH2-, -CF2CF2-, -CH2O-, or -CF2O-; preferably, Y is a single bond, -CH2CH2-, or -CF2O-; Z is an alkane chain or alkoxy chain with 2 to 7 C atoms, or a -H atom, -F atom, or -CF3; preferably, Z is -C2H5O or -CF3.

[0022] In this invention, preferably, the liquid crystal material comprises the following mass percentages of liquid crystal compound; 20%; 6%; 5%; 6%; 5%; 10%; 15%; 7%; 15%; 11%.

[0023] In this invention, preferably, the liquid crystal material comprises the following mass percentages of liquid crystal compound; 16%; 4%; 3%; 6%; 5%; 4%; 8%; 6%; 8%; 5%; 6%; 10%; 6%; 6%; 7%.

[0024] This invention also provides a method for preparing a liquid crystal material for the ultraviolet band, comprising the following steps: Weigh one or more of the general structural formula I, one or more of the general structural formula II, one or more of the general structural formula III, one or more of the general structural formula IV, and one or more of the general structural formula V; Alternatively, it may be referred to as one or more of the general structural formulas I, II, III, IV, V, and VI. The above-weighed compounds are mixed and placed in a borosilicate glass bottle. A magnetic stir bar is placed inside, and the bottle is sealed with a polytetrafluoroethylene film. The sealed borosilicate glass bottle is then placed in a water bath heating tank with electromagnetic stirring and stirred at 50°C to 70°C for 1 to 1.5 hours until all solid components are completely dissolved, forming a homogeneous liquid crystal mixture.

[0025] In the above preparation method, the corresponding compounds of each general formula can be weighed according to the following weight percentages: 5-30% for general formula I liquid crystal compounds, 3-26% for general formula II liquid crystal compounds, 3-21% for general formula III liquid crystal compounds, 3-15% for general formula IV liquid crystal compounds, 3-26% for general formula V liquid crystal compounds, and 0-40% for general formula VI liquid crystal compounds.

[0026] The present invention also provides an application of the liquid crystal material of the present invention for the ultraviolet band in a fast spatial light modulator, such as its use in light-dependent polymerization 3D printing of liquid crystal spatial light modulators.

[0027] The present invention will be described more clearly and completely below through examples. In the following examples, the performance tests of the liquid crystal mixtures (i.e., the liquid crystal materials of the present invention for the ultraviolet band) were all performed in accordance with the industry standards for liquid crystal materials. In the process of determining the birefringence of the liquid crystal mixtures, the test results of the samples were obtained by extrapolation. The purity of all the various liquid crystal compounds used in the present invention is greater than 99.5%, and they can all be prepared with reference to the prior art or commercially available.

[0028] Example 1 The components and their mass percentages in the liquid crystal material (liquid crystal mixture) for the ultraviolet band of the present invention are shown in Table 1: Table 1. Composition and proportions of the liquid crystal mixture in Example 1

[0029] Weigh each liquid crystal compound according to the mass percentage in Table 1, mix them, put them into a borosilicate glass bottle, place a magnetic stir bar inside, seal the bottle with a polytetrafluoroethylene film, place the sealed borosilicate glass bottle in an electromagnetically stirred water bath heating tank, stir at 50°C for 1 hour until all solid components are completely dissolved to form a homogeneous liquid crystal mixture, which is the liquid crystal material for the ultraviolet band of the present invention.

[0030] The above liquid crystal mixture was subjected to performance testing, and the test data are shown in Table 2.

[0031] Table 2 Performance parameters of the liquid crystal mixture in Example 1

[0032] Example 2 The components and their mass percentages in the liquid crystal material (liquid crystal mixture) for the ultraviolet band of the present invention are shown in Table 3: Table 3. Composition and proportions of the liquid crystal mixture in Example 2

[0033]

[0034] Weigh each liquid crystal compound according to the mass percentage in Table 3, mix them, put them into a borosilicate glass bottle, place a magnetic stir bar inside, seal the bottle with a polytetrafluoroethylene film, place the sealed borosilicate glass bottle in an electromagnetically stirred water bath heating tank, stir at 70°C for 1.5 hours until all solid components are completely dissolved to form a homogeneous liquid crystal mixture, which is the liquid crystal material for the ultraviolet band of the present invention.

[0035] The above liquid crystal mixture was subjected to performance tests, and the test data are shown in Table 4.

[0036] Table 4 Performance parameters of the liquid crystal mixture in Example 2

[0037] The liquid crystal mixtures described in the above examples have Δn values ​​of 0.072-0.113, Δε values ​​of 7.69-9.41, and a temperature range of -29.3℃ to 108.8℃. Most importantly, the liquid crystal mixtures of the present invention are stable liquid crystal materials in the ultraviolet band of 300nm-400nm.

[0038] This invention measured the ultraviolet absorption spectra of the dicyclohexyl liquid crystal compounds, dicyclohexylbenzene liquid crystal compounds, and dicyclohexylbiphenyl and cyclohexylbiphenyl compounds used, respectively, as detailed below. Figure 1-3 The present invention also performed ultraviolet absorption spectroscopy measurements on the mixed liquid crystal material prepared in Example 2, i.e., the liquid crystal mixture, see [link to relevant documentation]. Figure 4 .Depend on Figure 1-4 It can be seen that neither the liquid crystal compound used in this invention nor the liquid crystal mixture finally prepared exhibits high stability in the ultraviolet band of 300nm-400nm, indicating that there is no absorption.

[0039] The liquid crystal mixtures described in the above embodiments only illustrate some of the liquid crystal molecule structures and proportions of the present invention, and are not exhaustive, nor are they limited to the disclosed embodiments. Based on the above embodiments, further preferred combinations using the liquid crystal compounds represented by the general formulas listed in the present invention can achieve the objectives of the present invention. Therefore, the above embodiments are only for illustrating the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A liquid crystal material for the ultraviolet band, characterized in that, Include: One or more of the general structural formulas I, one or more of the general structural formulas II, one or more of the general structural formulas III, one or more of the general structural formulas IV, and one or more of the general structural formulas V; Or include: One or more of the general structural formula I, one or more of the general structural formula II, one or more of the general structural formula III, one or more of the general structural formula IV, one or more of the general structural formula V, and one or more of the general structural formula VI; Ⅰ； Ⅱ； Ⅲ； Ⅳ； Ⅴ； Ⅵ； In structural formulas I-VI: L1 to L3 are independently -H atoms, -F atoms, or -CF3, respectively; The values ​​of m1 to m4 are 0 or 1 respectively, and m1 and m2 are not both 0 at the same time, and m3 and m4 are both 0 at the same time; R1 to R6 are alkane chains or alkoxy chains with 2 to 7 carbon atoms, respectively; X is ―CH2CH2―, ―CF2CF2―, ―CH2O―, or ―CF2O―; Y can be a single bond, cyclohexyl group, -CH2CH2-, -CF2CF2-, -CH2O-, or -CF2O-; Z is an alkane chain or alkoxy chain with 2 to 7 C atoms, or a -H atom, -F atom, or -CF3.

2. The liquid crystal material for the ultraviolet band according to claim 1, characterized in that, R1 to R6 are alkane chains with 3 to 5 carbon atoms, respectively.

3. The liquid crystal material for the ultraviolet band according to claim 1, characterized in that, Z is either -C2H5O or -CF3.

4. The liquid crystal material for the ultraviolet band according to claim 1, characterized in that, X is either ―CH2CH2― or ―CF2O―.

5. The liquid crystal material for the ultraviolet band according to claim 1, characterized in that, Y represents a single bond, ―CH2CH2―, or ―CF2O―.

6. The liquid crystal material for the ultraviolet band according to claim 1, characterized in that, The liquid crystal material comprises the following liquid crystal compounds in the indicated mass percentages; 20%； 6%； 5%； 6%； 5%； 10%； 15%； 7%； 15%； 11%。 7. The liquid crystal material for the ultraviolet band according to claim 1, characterized in that, The liquid crystal material comprises the following liquid crystal compounds in the indicated mass percentages; 16%； 4%； 3%； 6%； 5%； 4%； 8%； 6%； 8%； 5%； 6%； 10%； 6%； 6%； 7%。 8. A method for preparing a liquid crystal material for the ultraviolet band according to any one of claims 1-7, characterized in that, Includes the following steps: Weigh one or more of the general structural formula I, one or more of the general structural formula II, one or more of the general structural formula III, one or more of the general structural formula IV, and one or more of the general structural formula V; Alternatively, it may be referred to as one or more of the general structural formulas I, II, III, IV, V, and VI. The above-weighed compounds are mixed and placed in a water bath heating tank with electromagnetic stirring. The mixture is stirred at 50°C to 70°C for 1 to 1.5 hours until all solid components are completely dissolved, forming a homogeneous liquid crystal mixture, which is the liquid crystal material for the ultraviolet band.

9. The application of a liquid crystal material for the ultraviolet band as described in any one of claims 1-7 in a fast spatial light modulator.

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