A liquid crystal material, a composite material, and a preparation method and application thereof

Abstract

The present invention discloses a liquid crystal material, a composite material, and their preparation methods and applications. The liquid crystal material in the present invention includes liquid crystal molecules oriented along the logarithmic spiral direction. The liquid crystal material in the present invention can be applied to a lens: when stimulated, the response protrusion becomes an approximate spherical surface, resulting in a good imaging effect. The liquid crystal material can be used in cooperation with a flexible substrate. During response, a uniform spherical-like convex deformation will be formed, and the protrusion is an approximate spherical surface, thereby a flexible microlens with adjustable focal length can be formed, and it has good application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid crystal lenses, and particularly relates to a liquid crystal material, a composite material, and their preparation methods and applications. Background Art

[0002] Lenses and microlenses are inseparable from people's daily lives and play an important role in many aspects such as focusing and light regulation. Traditional lenses mostly have fixed values and cannot achieve dynamic regulation. However, the use of liquid crystal thin film technology can generate the rotation of liquid crystal molecules through external stimuli to regulate the focal length. Usually, photolithography technology is used to achieve the orientation regulation of liquid crystal molecules. By controlling the rotation direction of liquid crystal molecules, the transmittance and reflectivity of light in the liquid crystal thin film can be controlled, and then a lens can be formed. Most existing liquid crystal thin film lenses have a relatively complex circuit between two substrates to regulate the phase of liquid crystal molecules in each region. This regulation method requires more precise processing of the regulating device. Currently, with the use of photoalignment technology, there has been a designed orientation in a circular ring shape. However, it will form a defective structure, making the liquid crystal thin film form a topological structure of +1 or -1. When the liquid crystal thin film responds to external stimuli and changes from a two-dimensional film to a three-dimensional object, due to the radial expansion of each defect center, a cone appears and cannot form a smooth lens surface, affecting the use effect of the lens. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. For this purpose, the present invention provides a liquid crystal material, which is used in a lens: when stimulated, the response protrusion becomes an approximate spherical surface, obtaining a lens with good imaging effect.

[0004] The present invention also provides a composite material.

[0005] The present invention also provides a preparation method of the composite material.

[0006] The present invention also provides a microlens.

[0007] The present invention also provides an electronic device.

[0008] The present invention also provides an application of the above composite material.

[0009] In the first aspect of the present invention, a liquid crystal material is provided, and the distribution of liquid crystal molecules in the material includes an orientation along the direction of a logarithmic spiral.

[0010] The liquid crystal material according to the embodiments of the present invention has at least the following beneficial effects:

[0011] When the liquid crystal material is used in a lens in the present invention, by distributing liquid crystal molecules along the direction of a logarithmic spiral, based on this special orientation distribution of liquid crystal molecules, the intermolecular forces of liquid crystal molecules can be better exerted during stimulus response (such as heat, electricity, light, etc.) to form protrusions. That is, on the basis of the turning of liquid crystal molecules, the shape deformation is increased, and the adjustment range of the lens is enlarged. And because the liquid crystal molecules are distributed along the logarithmic spiral, there is a special existence at the center, that is, the origin of the curve, and there is no absolute center point. Therefore, when the liquid crystal material is stimulated and responds, a uniform deformation will be formed, rather than a topological structure of +1 or -1. This makes it difficult for the liquid crystal material to form a cone shape and enables it to respond and protrude into an approximate spherical surface, that is, to form a smooth lens surface, and the imaging effect of the lens is good. Specifically, when the liquid crystal material is stimulated, the existing oriented material will expand radially. Since the liquid crystal molecules are distributed along the direction of the logarithmic spiral, and the points on the spiral are getting farther and farther away from the origin, the farther the point is from the origin, the greater the distance from the center of the sphere will be, resulting in an increasing radial radius, so a quasi-spherical surface will be formed.

[0012] Meanwhile, in the present invention, according to actual needs, the orientation distribution of liquid crystal molecules can be designed as any suitable logarithmic spiral, so that the obtained liquid crystal material has designability. In the present invention, the liquid crystal material can be compounded with a flexible substrate to obtain a composite material. The obtained composite material has a deformation response to heat, electricity, and light, forms a microlens and can realize focal length adjustment. The focal length can be adjusted according to the intensity of the stimulus, and the two show a positive correlation.

[0013] In some embodiments of the present invention, the preparation raw materials of the liquid crystal material include liquid crystal monomers, chain extenders, and photoinitiators.

[0014] In some embodiments of the present invention, the liquid crystal monomers include at least one of RM82, LC242, RM257, RM105, or RM23.

[0015] RM82: 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene;

[0016] LC242: 2-methyl-1,4-diphenol ester of 4-(((4-(acryloyloxy)butoxy)carbonyl)oxy)benzoic acid;

[0017] RM257: 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene;

[0018] RM105: 4-methoxyphenyl 4-[[6-[(1-oxo-2-propenyl)oxy]hexyl]oxy]benzoate;

[0019] RM23: 4-cyanophenyl 4'-(6-acryloyloxyhexyloxy)benzoate.

[0020] In some embodiments of the present invention, the liquid crystal monomer includes at least one of liquid crystal monomer I or liquid crystal monomer II.

[0021] In some embodiments of the present invention, the liquid crystal monomer I includes at least one of RM82 or LC242.

[0022] In some embodiments of the present invention, the liquid crystal monomer II includes at least one of RM257, RM105 or RM23.

[0023] In some embodiments of the present invention, in the preparation raw materials, the mass fraction of the liquid crystal monomer is 70-95%, and optionally 80-95%.

[0024] In some embodiments of the present invention, in the preparation raw materials, the mass fraction of the liquid crystal monomer I is 60-78%; the mass fraction of the liquid crystal monomer II is 12-25%.

[0025] In some embodiments of the present invention, in the preparation raw materials, the mass fraction of the liquid crystal monomer I is 66-72%; the mass fraction of the liquid crystal monomer II is 17-25%. Optionally, in the preparation raw materials, the mass fraction of the liquid crystal monomer II is 17-21%.

[0026] In some embodiments of the present invention, the chain extender includes at least one of pentaerythritol tetra(3-mercaptopropionate) or xylylene dimercaptan.

[0027] In some embodiments of the present invention, in the preparation raw materials, the mass fraction of the chain extender is 5-20%, optionally 5-15%, and further optionally 9-13%.

[0028] In some embodiments of the present invention, the photoinitiator is a photoinitiator for Michael addition reaction.

[0029] In some embodiments of the present invention, the photoinitiator includes at least one of Irg651, Irg819 or bis(1-(2,4-difluorophenyl)-3-pyrrolyl)titanocene dichloride.

[0030] In some embodiments of the present invention, in the preparation raw materials, the mass fraction of the photoinitiator is 0.5-3%, and optionally 1-2%.

[0031] In some embodiments of the present invention, the preparation raw materials of the liquid crystal material further include a polymerization inhibitor.

[0032] Through the above embodiments, the addition of the polymerization inhibitor can be beneficial to controlling the progress of the polymerization reaction, such as the polymerization rate and the degree of polymerization, etc., and is more beneficial to the preparation of the liquid crystal material.

[0033] In some embodiments of the present invention, the inhibitor includes butylated hydroxytoluene.

[0034] In some embodiments of the present invention, in the preparation raw materials, the mass fraction of the inhibitor is 0.5-3%, and may be optionally 1-2%.

[0035] In some embodiments of the present invention, the preparation raw materials further include a photo-reactive molecule.

[0036] In some embodiments of the present invention, the photo-reactive molecule includes at least one of N-ethyl-N-(2-hydroxyethyl)-4-(4-nitrophenylazo)aniline or 2-methyl-1,1'-[(1E)-1,2-diazenediylbis(4,1-phenyleneoxy-3,1-propanediyl)] bis(2-propionate).

[0037] Through the above embodiments, the preparation raw materials contain photo-reactive molecules, which can respond to ultraviolet light. The composite material obtained by compounding the liquid crystal material and the flexible substrate can be used as a photo-responsive microlens, which can realize the autonomous response ability of the composite material to ultraviolet light. And in the direction where the liquid crystal molecules are oriented in a logarithmic spiral, the response protrusion can form a lens surface and is sensitive to ultraviolet light. The deformation of the microlens and the phase of the liquid crystal molecules can be regulated by adjusting the light intensity and irradiation area of the ultraviolet light, that is, the focal length of the microlens can be autonomously adjusted by ultraviolet light. Therefore, the composite material can be applied to microscopes or optical magnification systems in a normal light environment (such as a sunlight irradiation environment, etc.), and the deformation degree of the microlens and the phase of the liquid crystal molecules in the lens can be autonomously regulated according to the brightness of the surrounding environment of the instrument, and the light energy received by the microlens can be adjusted to meet the requirements of the instrument; it can also be used as an autonomously adjustable photo-responsive homogenizer device, and has good application prospects.

[0038] In some embodiments of the present invention, in the preparation raw materials, the mass fraction of the photo-reactive molecule is 1-8%, and may be optionally 4-5%.

[0039] In some embodiments of the present invention, in the liquid crystal material, the polar coordinate equation of the logarithmic spiral of the liquid crystal molecule orientation is:

[0040] r = ae bθ ;

[0041] where r is the polar radius, a and b are constants, θ is the polar angle, and e is the base of the natural logarithm.

[0042] The polar angle refers to the angle between any point in the plane to the pole and the polar axis, and the range of θ can be 0-2Π°.

[0043] In some embodiments of the present invention, a is 0.5-0.8; b is 0.3-0.5.

[0044] Starting from the origin, the points on the spiral are getting farther and farther away from the origin. The farther away from the origin, the greater the distance of the point deviating from the center of the sphere, resulting in an increasingly larger radial radius. When a is 0.5 - 0.8 and b is 0.3 - 0.5, the points on the spiral can better maintain a more appropriate distance from the origin, and when the liquid crystal material is stimulated, a relatively smooth spherical-like surface can be formed, and the protruding area is more appropriate, which is conducive to producing a better lens effect when it is used in a lens.

[0045] In some embodiments of the present invention, a is taken as 0.618 and b is taken as 0.306.

[0046] In some embodiments of the present invention, in the liquid crystal material, the rectangular coordinate equation of the logarithmic spiral of the liquid crystal molecule orientation is:

[0047] f(x) = e x ;

[0048] e is the natural constant. The logarithmic spiral has the characteristic of equal angles. Due to the self-similarity of the logarithmic spiral, that is, it can be exactly the same as the original figure after magnification, and the perpendicular line of the logarithmic spiral is also a special property of the equiangular spiral. From its rectangular coordinate formula, the value range is from negative infinity to positive infinity, so the polar radius r is never zero.

[0049] When the liquid crystal molecules are distributed along the logarithmic spiral, there is a special existence at the center, that is, the origin of the curve. There is no absolute center point. Therefore, when the liquid crystal material is stimulated and responds, a uniform deformation will be formed, making it not easy to form a cone shape and forming a spherical-like surface.

[0050] In the second aspect of the present invention, a composite material is proposed, which includes a flexible substrate and a liquid crystal material layer arranged in a laminated manner, and the liquid crystal material layer includes the above-mentioned liquid crystal material.

[0051] The composite material according to the embodiment of the present invention has at least the following beneficial effects:

[0052] The composite material in the present invention can be used as or applied to a lens, that is, a responsive microlens based on a logarithmic spiral-oriented liquid crystal film. By distributing liquid crystal molecules along the direction of the logarithmic spiral, the liquid crystal molecules in the liquid crystal material layer are in this special distribution, so that the intermolecular forces of the liquid crystal molecules can be better exerted during the stimulus response to form a protrusion. That is, on the basis of the turning of liquid crystal molecules, the shape deformation is increased, and the adjustable range of the microlens is enlarged. By designing the liquid crystal to be oriented along the logarithmic spiral direction, the liquid crystal molecules can generate uniform deformation, and the elastic material makes its adjustable range larger. When the liquid crystal material layer is stimulated, it responds to protrude into an approximate spherical surface, and can form a lens in cooperation with the flexible substrate. At the same time, the cooperation of the liquid crystal material layer and the flexible substrate makes its deformation more uniform, and a uniform spherical-like protrusion deformation will be formed. In addition, due to the special property of the equal angle of the logarithmic spiral, the equal-sized and uniform deformation can be achieved by controlling the stimulus variable, so as to better realize the smooth change of the focal length of the responsive liquid crystal film microlens, solve the problem that the protrusion of the conventional liquid crystal film is conical and not smooth, and the imaging effect of the lens is good.

[0053] In some embodiments of the present invention, the flexible substrate includes at least one of polydimethylsiloxane (PDMS), polyimide (PI), or polyethylene naphthalate (PEN).

[0054] When a rigid substrate is bonded to the liquid crystal material, it is difficult to get rid of the restraint of the rigid substrate and generate a deformation response when stimulated. However, the flexible substrate used in the present invention is soft and elastic, and as the substrate of the composite material, it can deform together with the liquid crystal material layer. Specifically, when stimulated, it helps the liquid crystal material layer to act on the side away from the flexible substrate, forming a more uniform spherical-like protrusion. Therefore, when stimulated, both the phase of the liquid crystal molecules and the deformation of the liquid crystal material layer are changed. Under the dual effects, a lens with a wider response range can be achieved, and the liquid crystal material used enables the composite material to respond autonomously when stimulated.

[0055] In some embodiments of the present invention, the flexible substrate includes polydimethylsiloxane (PDMS).

[0056] In some embodiments of the present invention, the preparation raw materials of the flexible substrate include a precursor of PDMS and a crosslinking agent.

[0057] In some embodiments of the present invention, the precursor of PDMS and the crosslinking agent can be selected from DC184 of Dow Corning Corporation.

[0058] In some embodiments of the present invention, the mass ratio of the crosslinking agent to the precursor of PDMS is between 1:(9 - 30).

[0059] In some embodiments of the present invention, the thickness of the flexible substrate is 1-5 mm, and optionally 2-3 mm.

[0060] In some embodiments of the present invention, the thickness of the liquid crystal material layer is 1-20 μm, and optionally 5-12 μm.

[0061] In some embodiments of the present invention, a conductive material layer is provided on the side of the liquid crystal material layer facing away from the substrate.

[0062] In some embodiments of the present invention, the conductive material layer includes at least one of silver, gold, indium tin oxide, indium zinc oxide, polycarbazole, polyaniline, or polythiophene.

[0063] In some embodiments of the present invention, the thickness of the conductive material layer is 80-120 nm.

[0064] In some embodiments of the present invention, the composite material includes a conductive material layer, a liquid crystal material layer, and a flexible substrate that are sequentially stacked.

[0065] In some embodiments of the present invention, the composite material is at least one of a thermoresponsive composite material, an electroresponsive composite material, or a photoreactive composite material.

[0066] In some embodiments of the present invention, the response temperature of the thermoresponsive composite material includes 40-70 °C.

[0067] In some embodiments of the present invention, the preparation raw materials of the liquid crystal material layer in the composite material include the photoreactive molecules, and the composite material is a photoreactive composite material.

[0068] In some embodiments of the present invention, the response light wavelength of the photoreactive composite material includes 350-400 nm.

[0069] In some embodiments of the present invention, the composite material includes a conductive material layer, and the composite material is an electroresponsive composite material.

[0070] In some embodiments of the present invention, the response electric field of the electroresponsive composite material includes 35-40 V.

[0071] In some embodiments of the present invention, the response electric field frequency of the electroresponsive composite material includes 500-1000 kHz.

[0072] In some embodiments of the present invention, both the flexible substrate and the liquid crystal material layer can be easily bent manually to touch at both ends, and will rebound into a flat shape when released.

[0073] In some embodiments of the present invention, the sum of the thicknesses of the flexible substrate, the liquid crystal material layer, and the conductive material layer is 1000 - 5025 μm, and may be 2005 - 3015 μm.

[0074] In some embodiments of the present invention, the composite material includes a rigid substrate, a flexible substrate, and a liquid crystal material layer that are sequentially stacked.

[0075] Through the above embodiments, when the composite material undergoes a deformation response under stimulation, the flexible substrate deforms along with the deformation of the liquid crystal material layer, and the side in contact with the rigid substrate can remain in contact with the rigid substrate.

[0076] In some embodiments of the present invention, the rigid substrate includes glass.

[0077] In a third aspect of the present invention, a method for preparing a composite material is provided, including the following steps: preparing a liquid crystal material layer, and laminating and compounding the liquid crystal material layer with a flexible substrate.

[0078] In some embodiments of the present invention, the preparation method includes the following steps: preparing a liquid crystal material layer, disposing a conductive material layer on one surface of the liquid crystal material layer, and disposing a flexible substrate on the other surface.

[0079] In some embodiments of the present invention, the preparation method includes the following steps: preparing a liquid crystal material layer, and disposing a flexible substrate on the surface of the liquid crystal material layer.

[0080] In some embodiments of the present invention, the preparation method includes the following steps:

[0081] S1, designing a logarithmic spiral, and preparing a photo-alignment material layer oriented in the direction of the logarithmic spiral;

[0082] S2, injecting a raw material for preparing a liquid crystal material layer into a cell with a photo-alignment material layer inside, and polymerizing to form a liquid crystal material layer with a logarithmic spiral orientation;

[0083] S3, preparing a substrate on the surface of the liquid crystal material layer.

[0084] Through the above embodiments, by designing the logarithmic spiral of the liquid crystal molecule orientation in the liquid crystal material and cooperating with the photo-alignment material layer, a liquid crystal material layer with a logarithmic spiral orientation is prepared; specifically, the raw material for preparing the liquid crystal material layer contains liquid crystal molecules, and the liquid crystal molecules form a designed regular arrangement under the anchoring action of the photo-alignment material in the photo-alignment material layer, and the regular arrangement is along the direction of the logarithmic spiral, that is, the liquid crystal molecules are arranged along the direction in which the logarithmic spiral extends.

[0085] In some embodiments of the present invention, in step S1, a logarithmic spiral is designed, and a mask plate for forming the liquid crystal alignment of the logarithmic spiral is prepared; the photo-alignment material on the substrate surface is photo-induced aligned by using the mask plate, and a photo-alignment material layer is formed on the substrate surface.

[0086] In some embodiments of the present invention, the photo-alignment material includes SD1.

[0087] In some embodiments of the present invention, in step S1, the photo-alignment material is photo-aligned by using linearly polarized ultraviolet light.

[0088] Through the above embodiments, after the photo-alignment material layer is photo-induced, due to the absorption of linearly polarized ultraviolet light, a photo-induced cis-trans isomerization reaction occurs, and the SD1 molecules are arranged in a direction perpendicular to the polarization direction, that is, after photo-induction, the SD1 molecules exhibit the designed pattern (logarithmic spiral), and the liquid crystal molecules will be induced and anchored by the SD1 molecules with the existing direction to form the designed pattern after entering the cell.

[0089] In some embodiments of the present invention, in step S1, the photo-alignment material is coated on the substrate surface, the cell is made with the substrate as the bottom surface, and then the photo-alignment material in the cell is photo-induced aligned to obtain the photo-alignment material layer.

[0090] In some embodiments of the present invention, in step S1, a logarithmic spiral is designed, and a mask plate for forming the liquid crystal molecule alignment of the logarithmic spiral is prepared; the photo-alignment material is coated on the substrate surface, the cell is made with the substrate as the bottom surface, and then the photo-alignment material in the cell is photo-induced aligned by using the mask plate to obtain the photo-alignment material layer.

[0091] In some embodiments of the present invention, the photo-alignment material coated on the substrate surface is located inside the cell.

[0092] In some embodiments of the present invention, the cell is a glass cell, and the substrate is a glass substrate.

[0093] In some embodiments of the present invention, in step S2, at a temperature higher than the clearing point of the liquid crystal material in the preparation raw material, the preparation raw material of the liquid crystal material layer is filled into the cell, and is irradiated with light and polymerized under a protective atmosphere to obtain the liquid crystal material layer. Optionally, the wavelength of the light irradiation includes 300 - 560 nm. Optionally, the time of the light irradiation includes 10 - 30 min.

[0094] Among them, the capillary suction of the cell can be selected to fill the preparation raw material of the liquid crystal material layer into the cell.

[0095] Due to the effect of the photo-alignment material layer, the liquid crystal molecules in the preparation raw materials are arranged in the direction of logarithmic spiral extension. After illumination, the liquid crystal molecules in the logarithmic spiral direction are polymerized into a film under the anchoring effect of the photo-alignment material molecules, and a liquid crystal material layer is obtained.

[0096] In some embodiments of the present invention, in step S2, after polymerization, the substrate is removed to obtain the liquid crystal material layer.

[0097] In some embodiments of the present invention, step S1 specifically includes the following operations:

[0098] S1-1, design a logarithmic spiral. The polar coordinate equation of the logarithmic spiral is: r = ae bθ ; where r is the polar radius, a and b are constants, θ is the polar angle, and e is the base of the natural logarithm. Furthermore, the rectangular coordinate equation of the logarithmic spiral is obtained as: f(x) = e x ;

[0099] S1-2, through the logarithmic spiral, fit to obtain the phase diagram of the liquid crystal molecules. Use matlab software to calculate the phase of the liquid crystal molecules in each pixel grid in the phase diagram, divide it into multiple pictures with different exposure angles, and make a mask template in a unified format;

[0100] S1-3, match the angle of the mask template with the linearly polarized ultraviolet light, program an exposure program, and use the program to control the linearly polarized light to be exposed at different angles, so that the photo-alignment material presents a direction perpendicular to the linearly polarized light, and a photo-alignment material layer is obtained.

[0101] Through the above embodiments, a responsive microlens based on a logarithmically spiral-aligned liquid crystal thin film can be prepared, including a liquid crystal material layer and a flexible substrate. The liquid crystal material layer is placed above the flexible substrate and can be deformed. Analyze the phase of the liquid crystal molecules in each pixel, design the orientation direction of the liquid crystal molecules. The liquid crystal material layer is formed by polymerizing liquid crystal molecules oriented along the logarithmic spiral direction. The flexible substrate can be a flexible material such as PDMS, etc., to form a liquid crystal thin film microlens responsive to stimuli.

[0102] In some embodiments of the present invention, in step S1-1, a is 0.5-0.8; b is 0.3-0.5.

[0103] In some embodiments of the present invention, in step S1-1, take a as 0.618 and b as 0.306. At this time, the ratio of adjacent polar radii on the same radius line in the spiral is 0.618, having a golden ratio relationship.

[0104] In some embodiments of the present invention, in step S1-3, the photo-alignment material is induced to align using linearly polarized ultraviolet light with a wavelength of 405 nm, causing a cis-trans isomerization reaction in the photo-alignment material. The linearly polarized ultraviolet light exposes the photo-alignment material layer in the designed logarithmic spiral direction, which then becomes the liquid crystal alignment layer.

[0105] In some embodiments of the present invention, in step S1-3, through the exposure process using the mask, the cell is photo-aligned using linearly polarized ultraviolet light in a photo-alignment machine to obtain the photo-alignment material layer.

[0106] Through the above embodiments, the mask is programmed at the required exposure angle, and the cell is photo-aligned using linearly polarized ultraviolet light in a photo-alignment machine DMD in a dry environment. After the photo-alignment material (such as azobenzene molecules) in the cell absorbs polarized ultraviolet light, a cis-trans isomerization reaction occurs, that is, the azobenzene molecules tend to align in a direction perpendicular to the linearly polarized ultraviolet light.

[0107] In some embodiments of the present invention, in step S3, the surface of the liquid crystal material layer is coated with the raw material of the flexible substrate, and after curing, a flexible substrate is formed on the surface of the liquid crystal material layer.

[0108] In some embodiments of the present invention, in step S3, a conductive material layer is provided on the side of the liquid crystal material layer facing away from the substrate.

[0109] Through the above embodiments, with the provision of the conductive material layer, the composite material can be used as an electro-responsive microlens. In an electric field, the composite material can respond to electricity and transform from a two-dimensional thin film into a three-dimensional spherical shape, forming a lens surface. By adjusting the voltage of the electrode, liquid crystal molecules with different phases, i.e., different transmittances, and different lens deformation amounts of the liquid crystal material layer can be obtained, thus becoming lenses with different focal lengths.

[0110] In some embodiments of the present invention, the conductive material layer is prepared on the surface of the liquid crystal material layer by evaporation.

[0111] In some embodiments of the present invention, in step S3, the conductive material layer and the flexible substrate are respectively provided on both sides of the liquid crystal material layer.

[0112] In the fourth aspect of the present invention, a microlens is proposed, which includes the above composite material.

[0113] In some embodiments of the present invention, the microlens is a responsive microlens.

[0114] In some embodiments of the present invention, the microlens includes at least one of a thermo-responsive microlens, an electro-responsive microlens, or a photo-responsive microlens.

[0115] In some embodiments of the present invention, the thermoresponsive microlens comprises the thermoresponsive composite material.

[0116] In some embodiments of the present invention, the electroresponsive microlens comprises the electroresponsive composite material.

[0117] In some embodiments of the present invention, the photoreactive microlens comprises the photoreactive composite material.

[0118] In some embodiments of the present invention, the composite material in the microlens comprises a circular film layer.

[0119] In some embodiments of the present invention, the diameter of the composite material in the microlens is 3 - 6 mm, and may be optionally 4 - 5 mm.

[0120] In some embodiments of the present invention, the area of the composite material in the microlens is 0.07 - 0.3 cm 2 , and may be optionally 0.12 - 0.2 cm 2 .

[0121] In some embodiments of the present invention, the adjustable focal length range of the microlens is 0 - 3 mm.

[0122] In a fifth aspect of the present invention, an electronic device is proposed, which comprises the above microlens.

[0123] In a sixth aspect of the present invention, an application of the above composite material in preparing a near-eye display device, a virtual reality device or a human eye diopter detection device is proposed. BRIEF DESCRIPTION OF THE DRAWINGS

[0124] The present invention will be further described below with reference to the drawings and embodiments, where:

[0125] Figure 1 is a schematic structural diagram and a deformation diagram of the composite material in Embodiment 1 of the present invention;

[0126] Figure 2 is a logarithmic spiral diagram of the liquid crystal molecules designed in Embodiment 1 of the present invention;

[0127] Figure 3 is a phase diagram of the liquid crystal molecules designed in Embodiment 1 of the present invention;

[0128] Figure 4 is a deformation diagram of the composite material at different temperatures in Embodiment 1 of the present invention;

[0129] Figure 5 is a test result diagram of the composite material under a polarized light microscope in Embodiment 1 of the present invention;

[0130] Figure 6 This is the deformation result diagram of the composite material during thermal response in Embodiment 1 of the present invention. Detailed implementation manners

[0131] The concept of the present invention and the resulting technical effects will be clearly and completely described below in conjunction with embodiments to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0132] For the experimental methods without specific conditions indicated in the following embodiments, they are usually carried out according to the conventional conditions in the art or according to the conditions recommended by the manufacturer; the raw materials, reagents, etc. used, unless otherwise specified, are all raw materials and reagents that can be obtained from commercial channels such as the conventional market.

[0133] SD1: Purchased from Guangzhou Baijun Technology Co., Ltd., product number: D119450;

[0134] Crosslinking agent and precursor of PDMS: Purchased from DOW CORNING / Dow Corning Corporation, product number: DC184;

[0135] Embodiment 1

[0136] This embodiment discloses a composite material, the structural schematic diagram of which is as Figure 1 shown, including a liquid crystal material layer and a flexible substrate arranged in a stacked manner. The thickness of the liquid crystal material layer is 7 - 8 μm, and the thickness of the flexible substrate is 4 mm (2 - 4 mm is acceptable). The preparation process of the composite material includes:

[0137] (Ⅰ) Prepare a total of 0.1 g of raw materials according to the following dosage ratio, including: 69 wt% liquid crystal monomer RM82, 18 wt% liquid crystal monomer RM257, 11 wt% chain extender benzenedimethanethiol, 1 wt% photoinitiator Irg651, and 1 wt% inhibitor butylated hydroxytoluene; place the above materials in a sample bottle, add dichloromethane, an organic solvent that covers all the materials, put in a magnetic stirrer, stir evenly on a yellow light and 45 °C hot stage, and then stir until all the organic solvents are evaporated to obtain a well-mixed liquid crystal material.

[0138] (Ⅱ) In an environment with a humidity below 35 degrees and no ultraviolet light, spin-coat the photo-alignment material SD1 on a glass substrate and place it on a 100 °C hot stage for ten minutes to evaporate the solvent in SD1. Dot UV glue doped with 10 μm spacers at the four corners of the glass substrate, cover it with another clean untreated glass, gently press it flat, and under the irradiation of an ultraviolet lamp, the UV glue cures to form a liquid crystal cell with a fixed cell thickness and a uniform cell thickness.

[0139] (Ⅲ) Design a logarithmic spiral, as shown in Figure 2 , which can be specifically obtained from the formula r = ae bθ ; Take a as 0.618 and b as 0.306. At this time, the ratio of adjacent polar radii on the same radius line in the spiral is 0.618, having the golden ratio relationship;

[0140] Fit the designed logarithmic spiral to obtain the phase diagram of liquid crystal molecules, as shown in Figure 3 ;

[0141] Use matlab software to calculate the phase of liquid crystal molecules in each pixel grid in Figure 3 . Divide the schematic diagram of Figure 3 into small units every ten degrees according to the exposure angle. Make every four small units into a mask plate, that is, each small unit will appear four times, making the rotation of the logarithmic spiral smoother. Combine them into 18 pictures with different exposure angles and make them into mask plates in a unified format; Make the ones with the same polarization angle on the same mask plate to save the subsequent exposure procedure and duration.

[0142] (Ⅳ) Combine the mask plate with the angle of linearly polarized ultraviolet light to compile an exposure program. The direction of the linearly polarized ultraviolet light needs to be perpendicular to the molecules of the photo-alignment material. Expose the liquid crystal cell in step (Ⅱ) for 2 seconds at different angles using program control of the linearly polarized ultraviolet light in an environment with a humidity below 30 degrees, so that the azobenzene molecules in the photo-alignment material SD1 show a direction perpendicular to the linearly polarized ultraviolet light.

[0143] (Ⅴ) After the exposed liquid crystal cell is at a temperature higher than the clearing point of the liquid crystal material, use a pipette to move the mixed liquid crystal material in step (Ⅰ) near the liquid crystal cell and use the capillary suction of the liquid crystal cell to fill the liquid crystal material into the liquid crystal cell (the area of the liquid crystal material liquid layer formed by the liquid crystal material placed in the liquid crystal cell is about 2 cm * 2 cm). At this time, the distribution of liquid crystal molecules is along the direction of the logarithmic spiral; Wait until it cools to 55 °C (any temperature between 50 - 60 °C is acceptable) in an environment filled with nitrogen (that is, an oxygen-free environment to prevent oxygen from affecting the polymerization reaction of free radicals in the liquid crystal material), and irradiate it with 365 nm ultraviolet light for ten minutes, so that the liquid crystal molecules in the direction of the logarithmic spiral are polymerized into a film under the anchoring action of the photo-alignment material molecules to obtain a liquid crystal material layer.

[0144] (Ⅵ) Mix the cross-linking agent and precursor of PDMS in a mass ratio of 1:15, then put them into a square glass mold groove (including a glass bottom plate), place it in a vacuum pump and evacuate for ten minutes, then close the valve and balance for five minutes, and repeat the operation twice to remove the bubbles in the mixture to obtain PDMS material. Place it on a 60 °C hot stage for 2 hours to cure into an elastomer, and remove the glass mold groove to obtain a PDMS material layer (that is, a flexible substrate) connected to the glass bottom plate.

[0145] (Ⅶ) Immerse the liquid crystal cell from step (Ⅴ) in deionized water, remove one glass plate. At this time, the photo-aligned layer SD1 will dissolve in water. Remove the liquid crystal cell housing, and cut the obtained liquid crystal material layer into a circular film layer with a radius of 0.25 cm centered on the spiral origin of the liquid crystal molecule orientation. Adhere the circular film layer to the side of the PDMS material layer facing away from the glass substrate with a small amount of non-oriented RM82 (the thickness of the RM82 used for adhesion is less than 0.05 μm. Specifically, it can include quickly coating RM82 above the clearing point temperature of RM82 on the surface of the circular film layer and making it fit with the PDMS material layer, or quickly coating it on the surface of the PDMS material layer and making it fit with the circular film layer), to obtain a composite material with a glass bottom plate.

[0146] This embodiment also discloses a thermo-responsive microlens, including the composite material prepared in this embodiment. The area of the liquid crystal material layer in the composite material is about 0.19625 cm 2 . (In some other embodiments of the present invention, the area of the liquid crystal material layer of other sizes can be selected)

[0147] This embodiment also discloses an electronic device, including the microlens of this embodiment.

[0148] In some other embodiments of the present invention, the thickness of the liquid crystal material layer is 10 μm.

[0149] Example 2

[0150] This embodiment discloses a composite material, the difference from the composite material of Example 1 is only that: this embodiment further includes an evaporation operation to prepare a conductive material layer, and a conductive material layer is provided on the side of the liquid crystal material layer facing away from the PDMS substrate. Specifically, step (Ⅶ) of this embodiment is as follows:

[0151] Remove one glass substrate from the liquid crystal cell in step (Ⅴ), evaporate a layer of transparent conductive material indium tin oxide on the surface of the liquid crystal material layer in the liquid crystal cell, evaporate for 30 minutes at room temperature, then spin-coat the PDMS material prepared in step (Ⅵ) on the side of the liquid crystal material layer facing away from the conductive material layer, place it on a 60 °C hot stage for 2 hours to cure into an elastomer, and remove the liquid crystal lens film to obtain a composite material. The thickness of the evaporated silver layer can be 80 - 120 nm.

[0152] This embodiment also discloses an electro-responsive microlens, including the composite material prepared in this embodiment.

[0153] This embodiment also discloses an electronic device, including the microlens of this embodiment.

[0154] In some other embodiments of the present invention, the conductive material may be selected from at least one of silver, gold, indium zinc oxide, polycarbazole, polyaniline, or polythiophene.

[0155] Example 3

[0156] This example discloses a composite material, and its preparation process includes:

[0157] (Ⅰ) Prepare raw materials according to the following dosage ratios: 75 wt% liquid crystal monomer RM82, 20 wt% crosslinking agent pentaerythritol tetra(3-mercaptopropionate), 4 wt% photo-reactive molecule N-ethyl-N-(2-hydroxyethyl)-4-(4-nitrophenylazo)aniline, 1 wt% photoinitiator bis(1-(2,4-difluorophenyl)-3-pyrrolyl)titanocene dichloride, and 1 wt% inhibitor butylated hydroxytoluene; place the above materials in a sample bottle, add dichloromethane, an organic solvent that covers all the materials, put in a magnetic stir bar, stir evenly on a yellow light and 45 °C hot stage, and then stir until all the organic solvents are evaporated to obtain a well-mixed liquid crystal material.

[0158] (Ⅱ)-(Ⅳ): The same operation procedures as in Example 1.

[0159] (Ⅴ) Following the above step (Ⅳ), at a temperature higher than the clearing point of the liquid crystal material, use the capillary suction of the liquid crystal cell to fill the liquid crystal material mixed in step (Ⅰ) into the liquid crystal cell; after cooling to 55 °C, in an environment filled with nitrogen, that is, an oxygen-free environment, irradiate with green light with a wavelength of 530 nm for ten minutes, so that liquid crystal molecules in the logarithmic spiral direction are polymerized into a film under the anchoring action of the photo-alignment material molecules to obtain a liquid crystal thin film.

[0160] (Ⅵ)-(Ⅶ): The same operation procedures as in steps (Ⅵ)-(Ⅶ) of Example 1.

[0161] This example also discloses a light-responsive microlens, including the composite material prepared in this example.

[0162] This example also discloses an electronic device, including the microlens of this example.

[0163] Example 4

[0164] This example discloses a composite material, and the difference from the composite material of Example 1 is only that: steps (Ⅵ)-(Ⅵ) are different. In this example:

[0165] (Ⅵ) Mix the crosslinking agent and precursor of PDMS in a mass ratio of 1:15, then put it into a square mold groove, place it in a vacuum pump to evacuate for ten minutes, then close the valve and balance for five minutes, and repeat the operation twice to remove the bubbles in the mixture to obtain PDMS material.

[0166] (VII) Soak the liquid crystal box of step (V) in deionized water and remove a piece of glass. At this time, the photo-alignment layer SD1 will dissolve in the water. Then, spin-coat the PDMS material prepared in step (VI) on the liquid crystal material layer and place it on a hot stage at 60°C for 2 hours to cure it into an elastomer. Remove the liquid crystal box shell to obtain a composite material.

[0167] The obtained composite material can be cut to obtain a circular film layer with a preset radius (such as a radius of 0.25 cm) for use in a microlens.

[0168] This embodiment also discloses a light-responsive microlens, including the composite material prepared in this embodiment.

[0169] This embodiment also discloses an electronic device, including the microlens of this embodiment.

[0170] The performance of the composite material of Example 4 is comparable to that of the composite material of Example 1.

[0171] Test example

[0172] This test example tests the performance of the composite materials, microlenses, etc. in the embodiments and comparative examples, specifically including:

[0173] (1) The composite material with a glass substrate prepared in Example 1 can be used as a thermally responsive microlens and placed on a hot plate (the temperature of the hot plate can be 45°C, 55°C, 65°C, 70°C, etc.), so that the liquid crystal material layer (LCE film) and the flexible substrate (PDMS film) in the composite material can respond to heat and transform from a two-dimensional film into a three-dimensional spherical shape. Figure 4 As shown, a lens surface can be formed (the side of the PDMS film facing away from the LCE film is not separated from the rigid substrate-glass bottom plate). By adjusting the temperature, liquid crystal molecules of different phases (i.e. different transmittances) and different lens deformation amounts of the liquid crystal material layer can be obtained, thus forming lenses with different focal lengths. The two reactions are formed under one stimulus, which increases the adjustable range of the response, and the adjustable focal length range is about 0-3mm. Since the plane area of ​​the lens is only 0.2cm 2 The volume of the protrusion is small, and the phase and deformation of the response can be adjusted autonomously according to dynamic stimulation, that is, the focal length of the responsive microlens can be changed. It can be applied to virtual reality equipment or equipment that requires image capture to adjust the focal length to capture portraits or objects, and a larger response adjustment range can be achieved during capture. Specifically, the image of the composite material prepared in Example 1 under a polarizing microscope is as follows: Figure 5 As shown, the composite material produces a spherical deformation in thermal response (70°C), making it a responsive microlens, such as Figure 6 As shown: Figure 6The left figure in the middle shows the state of the composite material before thermal response, and the right figure shows the state of the composite material during thermal response.

[0174] (2) The composite material prepared in Example 2 can be used as an electro-responsive microlens (a circular microlens can be obtained by cutting). Connect the film of the composite material prepared in Example 2 in an alternating current electric field of 800 kHz and 38 V. Under the action of the alternating current electric field, the liquid crystal molecules are stimulated to expand radially, which can make the composite material respond to electricity and transform from a two-dimensional thin film to a three-dimensional spherical shape. The response bulge is an experimental effect equivalent to that of Example 1, and a lens surface can be formed. By adjusting the voltage of the electrode, liquid crystal molecules with different phases, that is, different transmittances, and different lens deformations of the liquid crystal material layer can be obtained, so lenses with different focal lengths are formed. The two reactions are formed under one stimulus, increasing the adjustable range of the response. Since the lens and the volume are small, it is also possible to autonomously adjust the phase and deformation amount of the response according to the dynamic stimulus, that is, change the focal length of the response-type microlens, and it can be applied to a near-eye display system or a virtual reality device, and used in a human eye diopter detection device, so that the focal length in the near-eye display system or the virtual reality device corresponds to the diopter of the user's human eye.

[0175] (3) The composite material prepared in Example 3 can be used as a light-responsive microlens (a circular microlens can be obtained by cutting). In Example 3, since a photo-reactive molecule is added to the liquid crystal monomer mixture material, and this photo-reactive molecule responds to ultraviolet light, in order not to affect the subsequent experimental effect, the ultraviolet initiator is replaced with a green initiator; the liquid crystal thin film microlens can be made to have the ability to autonomously respond to ultraviolet light, and under the condition that the liquid crystal molecule orientation is in the direction of a logarithmic spiral, the response bulge is an experimental effect equivalent to that of Example 1, and it is sensitive to ultraviolet light. The deformation of this liquid crystal thin film microlens and the phase of the liquid crystal molecules can be regulated by adjusting the light intensity and irradiation area of the ultraviolet light, that is, the focal length of the microlens will be autonomously adjusted by ultraviolet light. Specifically, the added photo-reactive molecule is a cis-trans isomer. Under the stimulation of ultraviolet light, the trans isomer absorbs energy and transforms into the cis isomer. The reaction in the liquid crystal material layer caused by the instability of the cis isomer. After the ultraviolet light is removed, the cis isomer will slowly transform back into the trans isomer, and the liquid crystal material layer returns to the initial state. Therefore, the light-responsive composite material in the present invention can be applied to a microscope or an optical magnification system in an environment of normal light (such as sunlight irradiation), autonomously regulate the deformation degree of the microlens and the phase of the liquid crystal molecules in the lens according to the brightness of the surrounding of the instrument, and adjust the light energy received by the microlens to cooperate with the requirements of the instrument; it can also be used as an autonomously adjustable light-responsive homogenizer device.

[0176] In summary, the present invention discloses a responsive microlens based on a logarithm spiral-oriented liquid crystal film, which includes a liquid crystal material layer and a flexible substrate. The liquid crystal material layer is placed above the flexible substrate and can be deformed. The phase of the liquid crystal molecules in each pixel is analyzed, and the orientation direction of the liquid crystal molecules is designed. The liquid crystal material layer is composed of liquid crystal molecules oriented along the logarithm spiral direction. The flexible substrate can be made of PDMS material, forming a liquid crystal film microlens that responds to stimuli (such as heat, electricity, and light). The arrangement of the liquid crystal molecules in the liquid crystal material layer is arranged along the logarithm spiral direction. The microlens responds to external stimuli, and the response is a designed aspherical surface: for example, the focal length can be adjusted according to the intensity of the stimulus, and the two show a positive correlation. Further, the smoothness of the deformation can be further optimized by adjusting the degree of the stimulus.

[0177] Through steps such as spin-coating a photo-alignment material on a glass substrate, fabricating a liquid crystal cell from the substrate, performing photo-alignment treatment on the liquid crystal cell, filling and polymerizing the liquid crystal in the liquid crystal cell, and placing the liquid crystal film on the flexible substrate, the present invention realizes a responsive microlens based on a logarithm spiral-oriented liquid crystal film. Since the liquid crystal molecules are evenly distributed at equal angles along the logarithm spiral, when the liquid crystal film is subjected to external stimuli, it protrudes into an approximate spherical surface, and thus a flexible microlens with adjustable focal length can be formed.

[0178] It should be noted that in this article, "room temperature" and "normal temperature" are approximately 25°C unless otherwise specified; the meanings of "about" and "around" related to numerical values in this article are an error of ±2%.

[0179] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A liquid crystal material, characterized in that, The liquid crystal material includes liquid crystal molecules oriented along a logarithmic spiral direction; The raw materials for preparing the liquid crystal material include liquid crystal monomers, chain extenders, and photoinitiators. The liquid crystal monomers include at least one of RM82, LC242, RM257, RM105, or RM23; The liquid crystal material is prepared by the following method: Design a logarithmic spiral, and prepare a photo-alignment material layer oriented in the logarithmic spiral direction. The photo-alignment material includes SD1; Inject the raw materials for preparing the liquid crystal material into a cell with a photo-alignment material layer inside, and polymerize to form a liquid crystal material with a logarithmic spiral orientation.

2. The liquid crystal material according to claim 1, characterized in that, The chain extender includes at least one of pentaerythritol tetrakis(3-mercaptopropionate) or xylylene dimercaptan.

3. The liquid crystal material according to claim 1, wherein The raw materials for preparation further include photo-reactive molecules.

4. The liquid crystal material according to claim 3, characterized in that, The photo-reactive molecules include at least one of N-ethyl-N-(2-hydroxyethyl)-4-(4-nitrophenylazo)aniline or 2-methyl-1,1'-[(1E)-1,2-diazenediylbis(4,1-phenyleneoxy-3,1-propanediyl)] bis(2-propionate).

5. The liquid crystal material according to claim 1, wherein In the liquid crystal material, the polar coordinate equation of the logarithmic spiral of the liquid crystal molecule orientation is: ； where r is the radial distance, a and b is a constant, θ is the polar angle, e is the base of the natural logarithm; a is 0.5 - 0.8; b is 0.3 - 0.

5.

6. A composite material, characterized in that, It includes a flexible substrate and a liquid crystal material layer stacked. The liquid crystal material layer includes the liquid crystal material according to any one of claims 1-5.

7. The composite material according to claim 6, characterized in that, The flexible substrate includes at least one of polydimethylsiloxane, polyimide, or polyethylene naphthalate.

8. The composite material according to claim 6, characterized in that, A conductive material layer is provided on one side of the liquid crystal material layer facing away from the substrate.

9. The composite material according to claim 8, wherein The conductive material layer includes at least one of silver, gold, indium tin oxide, indium zinc oxide, polycarbazole, polyaniline, or polythiophene.

10. The composite material according to claim 8, wherein, The thickness of the conductive material layer is 80-120 nm.

11. A method for preparing a composite material as described in claim 6, characterized in that, It includes the following steps: prepare a liquid crystal material layer, and stack and compound the liquid crystal material layer with a flexible substrate layer.

12. The preparation method according to claim 11, characterized in that, The preparation method includes the following steps: prepare a liquid crystal material layer, and provide a flexible substrate on the surface of the liquid crystal material layer.

13. The preparation method according to claim 11, characterized in that, The preparation method includes the following steps: S1, design a logarithmic spiral, and prepare a photo-alignment material layer oriented in the logarithmic spiral direction; S2, inject the raw materials for preparing the liquid crystal material layer into a cell with a photo-alignment material layer inside, and polymerize to form a liquid crystal material layer with a logarithmic spiral orientation; S3, prepare a substrate on the surface of the liquid crystal material layer.

14. A microlens, characterized in that, It includes the composite material according to any one of claims 6-10.

15. An electronic device, characterized in that, It includes the microlens according to claim 14.

16. The application of the composite material according to any one of claims 6-10 or the composite material prepared by the preparation method according to any one of claims 11-13 in the preparation of near-eye display devices, virtual reality devices, or human eye diopter detection devices.

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