Polymer film and preparation method therefor and use thereof, and device based on polymer film

Abstract

The present application discloses a polymer film and a preparation method therefor and a use thereof, and a device based on the polymer film. The preparation method comprises: mixing an amphiphilic liquid crystal with a polar solvent to prepare a two-dimensional layered liquid crystal system having a polar solvent content of 1 wt%-80 wt%; mixing an additive comprising an initiator with the two-dimensional layered liquid crystal system to prepare a precursor slurry; coating the surface of a substrate with the precursor slurry, and carrying out orientation treatment to obtain a wet film, the orientation direction of the orientation treatment intersecting with the normal direction of the surface of the wet film; and carrying out in-situ polymerization curing treatment and drying treatment on the wet film. The polymer film prepared by the method internally has a plurality of two-dimensional layered channels which are transmembrane-oriented and arranged and have uniform size, and the method can adjust and control the size of the interlayer two-dimensional channels by controlling the content of the polar solvent in the two-dimensional layered liquid crystal system within a specific range, so that the size of channels between film layers can be uniform and controllable and the size can be continuously adjustable at a nanometer or sub-nanometer scale, and the obtained polymer film has both high selectivity and high permeability.

Description

Polymer membrane, preparation method, application and device based thereon

[0001] TECHNICAL FIELD

[0002] The present application relates to the field of membrane separation technology, in particular to a polymer membrane, a preparation method, application and device based thereon, and further relates to a preparation method of a polymer membrane with controllable interlayer channels, a polymer membrane and application. BACKGROUND

[0003] Membrane science and technology is a key basic technology affecting the development of chemical industry, environment, medical treatment, energy and other industries. Membrane separation is the most widely used field of membrane science, and separation membranes with nanometer pore size are the core technology in many fields such as seawater desalination, lithium-magnesium separation, carbon dioxide capture, osmotic pressure power generation and fuel cells. The essence of membrane separation technology is to control the selective mass transfer behavior in the membrane. "Selectivity" and "permeability" are two core indicators for measuring the performance of membrane separation technology. At present, the mass transfer channels constructed by traditional membrane preparation process have high tortuosity and low size uniformity, which leads to low permeability or / and low selectivity. The two-dimensional sub-nanometer channels with high size uniformity constructed by stacking two-dimensional material sheets realize high selectivity membrane separation. However, the Z-type sub-nanometer channels formed by the two-dimensional sub-nanometer channels significantly increase the travel distance of mass transfer path and the tortuosity of the channel, resulting in low permeability. An ideal selective mass transfer membrane should have high selectivity and high permeability. The existing design idea of separation membrane material cannot take into account the "high size uniformity" and "low tortuosity" of the mass transfer channel, so as to solve the bottleneck effect that "selectivity" and "permeability" cannot be obtained at the same time. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a preparation method of a polymer membrane, a polymer membrane and application.

[0005] In a first aspect of the present application, a preparation method of a polymer membrane is provided, comprising the following steps:

[0006] S1, a two-dimensional layered liquid crystal system is prepared by mixing an amphiphilic liquid crystal and a polar solvent; the content of the polar solvent in the two-dimensional layered liquid crystal system is 1 wt% to 80 wt%; the amphiphilic liquid crystal uses a long strip-shaped amphiphilic liquid crystal molecule with a hydrophilic segment and a hydrophobic segment, and the hydrophobic segment is longer than the hydrophilic segment; the long strip-shaped amphiphilic liquid crystal molecule is selected from any one of the amphiphilic liquid crystals of the following structural formula:

[0007]

[0008] In groups A and A', n>8, R1 involved in group D' is selected from alkylene;

[0009] S2, mixing and preparing a precursor slurry by mixing the two-dimensional layered liquid crystal system with an additive including an initiator;

[0010] S3, coating the precursor slurry on the surface of the substrate and performing orientation treatment to obtain a wet film; the orientation direction of the orientation treatment intersects with the surface normal direction of the wet film;

[0011] S4, performing in-situ polymerization curing treatment and drying treatment on the wet film; the surface of the substrate is a hydrophobic surface.

[0012] According to the preparation method of the polymer film, at least the following beneficial effects are achieved: the method prepares the polymer film through multi-step coupling, specifically, a two-dimensional layered liquid crystal system containing a specific amount of polar solvent is prepared by mixing amphiphilic liquid crystals and polar solvent, wherein under the condition of self interaction (van der Waals force, hydrogen bond, Π bond, etc.) and external polar solvent, the effective volume of the liquid crystal small molecule changes, and the molecular self-assembly behavior occurs, the layered microphase separation occurs to form a layered structure, that is, the bilayer structure of the solvated liquid crystal is formed, and a two-dimensional layered liquid crystal system with local domain structure is obtained, and the adjacent bilayers in the domain structure are filled with polar solvent to form a two-dimensional solvated layered channel, and within a specific range of polar solvent content, the thickness of the solvent layer between adjacent bilayers changes with the content of polar solvent, the greater the content of polar solvent, the thicker the solvent layer, and the larger the size of the two-dimensional solvated layered channel, and then the size of the two-dimensional solvated layered channel between layers can be controlled by controlling the content (or the amount of addition) of polar solvent, and the size of the channel is accurately and continuously controlled in nanometer or sub-nanometer scale; after introducing an additive including an initiator into the two-dimensional layered liquid crystal system, a precursor slurry in a polymerizable state is obtained; then the precursor slurry is coated on the surface of the substrate, and orientation treatment is performed with the orientation direction intersecting with the surface normal direction of the wet film to realize the alignment of the domains and the transmembrane orientation of the two-dimensional solvated layered channel; then the wet film is subjected to in-situ polymerization curing treatment and drying treatment to solidify the film structure. The polymer film prepared by the above method has a plurality of transmembrane two-dimensional layered channels, the channels are uniformly arranged and sized, and the size of the two-dimensional channel between layers can be controlled by controlling the amount of addition of polar solvent (or controlling the content of polar solvent in the two-dimensional layered liquid crystal system) within a specific range, the size of the channel between layers is uniformly controllable and continuously adjustable in nanometer or sub-nanometer scale, the prepared polymer film has high selectivity and high permeability, thereby breaking the bottleneck that ion selectivity and flux cannot be achieved simultaneously in traditional membrane preparation process, and having high application value in the field of membrane separation (such as ion nanofiltration, ion transport, water treatment, etc. in the field of energy and environment), and the size of the channel between layers of the polymer film can be accurately controlled by the above method to meet the size requirements of membrane separation according to the separation requirements.

[0013] In step S1, the amphiphilic liquid crystal has a hydrophilic end and a hydrophobic end, and the amphiphilic liquid crystal is generally a lyotropic liquid crystal. The amphiphilic liquid crystal can be a single-component liquid crystal or a mixed-component liquid crystal. Specifically, the amphiphilic liquid crystal material can include but is not limited to the amphiphilic liquid crystal shown in FIG. 1, and n in the groups A and A' shown in FIG. 1 is greater than 8; R1 involved in the group D' is selected from an alkylene group; and the shading on the groups A, A', B, C, and D' indicates the connection position between the groups.

[0014] The polar solvent can be a hydrogen bond donor solvent or a non-hydrogen bond donor solvent, and specifically includes but is not limited to water, methanol, ethanol, propanol, butanol, ethylene glycol, ethyl acetate, dichloromethane, trichloromethane, tetrahydrofuran, acetonitrile, acetic acid, acetone, hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, dimethylformamide, and dimethyl sulfoxide.

[0015] In some embodiments of the present application, the content of the polar solvent in the two-dimensional layered liquid crystal system is 1 wt% to 50 wt%, 20 wt% to 50 wt%, or 40 wt% to 50 wt%. Correspondingly, the use amount ratio of the amphiphilic liquid crystal and the polar solvent can be controlled to be 50 wt% to 99 wt% of the amphiphilic liquid crystal and 1 wt% to 50 wt% of the polar solvent, or 50 wt% to 80 wt% of the amphiphilic liquid crystal and 20 wt% to 50 wt% of the polar solvent, or 50 wt% to 60 wt% of the amphiphilic liquid crystal and 40 wt% to 50 wt% of the polar solvent.

[0016] In step S1, after mixing the amphiphilic liquid crystal and the polar solvent, the liquid crystal molecules form a two-dimensional layered liquid crystal system through self-assembly.

[0017] In some embodiments of the present application, in step S1, the mixing method of the amphiphilic liquid crystal and the polar solvent is at least one selected from stirring and ultrasonic method, freeze-thaw cycle method, and rotary evaporation method.

[0018] The ultrasonic stirring method specifically can include the following steps: after mixing the amphiphilic liquid crystal and the polar solvent, the solid-liquid two phases are initially mixed uniformly through stirring, and then ultrasonic oscillation is performed to fully dissolve the undissolved materials in the system; the above stirring and ultrasonic oscillation steps are repeated twice or more times in sequence. In addition, further centrifugation and standing treatment can be performed in sequence, wherein the bubbles in the system are removed through centrifugation; during the standing treatment, the mouth of the centrifuge tube can be sealed with a sealing film to avoid solvent evaporation and impurity mixing, and standing is performed to achieve full and uniform self-assembly of the liquid crystal molecules, and to eliminate the residual stress between the domains generated in the stirring and mixing process. The ultrasonic oscillation time in the ultrasonic stirring method can be controlled to be 10 min to 30 min; the centrifugal speed can be controlled to be 2000 r / min to 20000 r / min; and the centrifugal time can be controlled to be greater than or equal to 3 days.

[0019] The freeze-thaw method can specifically include: mixing the amphiphilic liquid crystal and the polar solvent, then freezing to solidification, and then thawing and stirring; and repeating the above freezing and thawing and stirring steps twice or more times in sequence. In addition, centrifugation and standing treatment can be further performed in sequence, wherein the bubbles generated in the system due to stirring are removed by centrifugation; during the standing treatment, the opening of the centrifuge tube can be sealed with a sealing film to avoid solvent evaporation and impurity mixing, and standing is performed to achieve full and uniform self-assembly of the liquid crystal molecules, and to eliminate the residual stress generated between domains in the system during stirring and mixing. During the above freeze-thaw treatment process, the freezing temperature can be controlled to be ≤-5°C; and the thawing temperature can be controlled to be 18°C to 25°C. The centrifugal speed can be controlled to be 2000 r / min to 20000 r / min; and the centrifugal time can be controlled to be ≥3 days.

[0020] The rotary evaporation method can specifically include: mixing the amphiphilic liquid crystal and the polar solvent and placing them in a rotary evaporator, rotating at a low speed and heating to a suitable temperature to evaporate part of the solvent; when the solution is concentrated to a certain degree, stop heating, cool to room temperature, and stir the mixture with a fine glass rod; and repeat the above two steps twice or more times in sequence. In addition, centrifugation and standing treatment can be further performed in sequence, wherein the bubbles generated in the system due to stirring are removed by centrifugation; during the standing treatment, the opening of the centrifuge tube can be sealed with a sealing film to avoid solvent evaporation and impurity mixing, and standing is performed to achieve full and uniform self-assembly of the liquid crystal molecules, and to eliminate the residual stress generated between domains in the sample during stirring and mixing.

[0021] During the rotary evaporation treatment process, the rotation speed of the rotary evaporator can be controlled to be ≤1500 r / min; and the heating temperature can be controlled to be ≥60°C. The centrifugal speed can be controlled to be 2000 r / min to 20000 r / min; and the centrifugal time can be controlled to be ≥3 days.

[0022] As described above, in step S1, the amount of the polar solvent added or the content of the polar solvent in the two-dimensional layered liquid crystal system can be adjusted within a certain range to regulate the size of the two-dimensional solvated layered channel in the two-dimensional layered liquid crystal system.

[0023] In some embodiments of the present application, in step S2, the mass ratio of the additive to the two-dimensional layered liquid crystal system is 1:(1-100000). Further, the mass ratio of the additive to the two-dimensional layered liquid crystal system can be 1:(2-10000), 1:(4-1000), 1:(5-100), 1:(8-50), 1:(10-30), or 1:(12-20).

[0024] In some embodiments of the present application, the viscosity of the precursor slurry is 1×10 3 mPa·s to 1×109 mPa s.

[0025] In some embodiments of the present application, the two-dimensional layered liquid crystal system and the precursor slurry are formed into a focal conic texture, that is, the polarized light microscopy texture of the two-dimensional layered liquid crystal system and the prepared precursor slurry is characterized by a uniform "focal conic texture" characteristic texture.

[0026] In some embodiments of the present application, the initiator is a photoinitiator or a thermal initiator. The photoinitiator can be one or more of a free radical type photoinitiator, a cationic type photoinitiator, and a dual type photoinitiator, which is a photoinitiator having both free radical and cationic characteristics.

[0027] In some embodiments of the present application, the additive includes 0-99 wt% functional monomer, 0-99 wt% crosslinking agent, 1-100 wt% photoinitiator, and 0-99 wt% thermal polymerization inhibitor; or, the additive includes 0-99 wt% crosslinking agent, 1-100 wt% photoinitiator, and 0-99 wt% thermal polymerization inhibitor; or, the additive includes 0-99 wt% crosslinking agent and 1-100 wt% thermal initiator. The crosslinking agent can be water-soluble, fat-soluble, or other; specifically, one or more of an epoxy type crosslinking agent, an amine type crosslinking agent, an isocyanate type crosslinking agent, and an olefin type crosslinking agent; and the functional monomer can be at least one of vinyl sulfonic acid, sodium vinyl sulfonate, and acrylamide.

[0028] In some embodiments of the present application, in step S2, the additive is first blended in an organic solvent, and then the organic solvent is removed before being mixed with the two-dimensional layered liquid crystal system to prepare the precursor slurry. The organic solvent can be one or more of alcohol, ketone, ester, ether, glycol derivative, halogenated hydrocarbon, and aliphatic hydrocarbon. The blending process can be assisted by stirring, and the stirring time can be controlled to be ≥1 h. The method for removing the organic solvent can be negative pressure rotary evaporation. The negative pressure rotary evaporation can be performed in a negative pressure vacuum environment (P≤0.1 bar) at a temperature ≥25°C. The treatment time can be controlled to be ≥48 h. The above method for blending the additive uniformly in the organic solvent, combined with the control of the amount of polar solvent in the two-dimensional layered liquid crystal system, ensures the low viscosity and polymerizability of the prepared precursor slurry.

[0029] In some embodiments of the present application, in step S2, the mixing of the additive with the two-dimensional layered liquid crystal system comprises: first stirring and mixing, and then ultrasonic oscillation; and then repeating the stirring and mixing and the ultrasonic oscillation for more than twice. In particular, the stirring and mixing can be performed by using a stirring rod, and the stirring rod can be an inert metal stirring rod. The ultrasonic oscillation time can be controlled to be greater than or equal to 45 minutes. In the mixing process, the original layered structure in the two-dimensional layered liquid crystal system moves with the stirring as a unit of domain, and gradually absorbs the additive into the layered structure.

[0030] After the last stirring and mixing and ultrasonic oscillation, the mixing process of the additive and the two-dimensional layered liquid crystal system can further sequentially perform centrifugation and standing treatment. In particular, the centrifugation is used to remove larger bubbles generated by stirring in the system; and the centrifuge tube opening can be sealed by using a sealing film during the standing treatment to eliminate residual stress. The centrifugation speed can be controlled to be greater than or equal to 3500 r / min to 6000 r / min, and the centrifugation time can be controlled to be greater than or equal to 5 minutes. The standing treatment time can be controlled to be greater than or equal to 3 days.

[0031] In some embodiments of the present application, in step S3, the angle between the orientation direction of the orientation treatment and the surface of the wet film is 0° to 45°; and / or, the orientation treatment is performed by the mechanical friction force in the coating process.

[0032] In particular, the angle between the orientation direction of the orientation treatment and the surface of the wet film is controlled to be 0° to 45°, which can shorten the path length of the interlayer channel and improve the permeability of the polymer film. Further, the angle between the orientation direction of the orientation treatment and the surface of the wet film can be controlled to be 0° to 20°, 0° to 15°, 0° to 10°, or 0° to 5°. Further, the angle between the orientation direction of the orientation treatment and the surface of the wet film can be directly controlled to be 0°, that is, the orientation direction of the orientation treatment is perpendicular to the surface normal direction of the wet film, and then the orientation treatment is parallel orientation, so that the interlayer channel is perpendicular to the surface of the polymer film, and the permeability of the polymer film is sufficiently improved.

[0033] In step S3, the precursor slurry is coated on the surface of the substrate and subjected to the orientation treatment. In particular, the precursor slurry can be coated on the surface of the substrate and subjected to the orientation treatment in a constant temperature, constant humidity, dust-free environment, and an inert gas protected environment. The precursor slurry can be fed into the liquid distribution cabin of the array coating die by using a feeding device, and then transferred to the surface of the substrate, and then uniformly coated by using a doctor blade or a roller. In particular, the inert gas can be nitrogen, helium, etc.; the feeding device can be a gravity type feeding device, a mechanical type feeding device, a pneumatic type feeding device, or a hydraulic type feeding device; the slurry coating method can be slot coating, flow coating, or curtain coating; and the coating speed can be controlled to be 3 mm / s to 20 mm / s.

[0034] In some embodiments of the present application, the surface of the substrate in step S3 is a hydrophobic surface; and / or, the substrate is a porous substrate.

[0035] Wherein, the surface of the substrate is a hydrophobic surface, the different components of the two-dimensional layered liquid crystal material in the precursor slurry can be induced to rearrange by interfacial interaction, and the transmembrane orientation of the interlayer channel is promoted. Specifically, long strip-shaped amphiphilic liquid crystal molecules can be used, and the hydrophobic segment is longer than the hydrophilic segment. For example, the amphiphilic liquid crystal shown in Figure 1, when the liquid crystal molecules are coated on the hydrophobic surface, the hydrophobic segment tends to adhere to the hydrophobic surface, causing the molecules to "lie down" on the hydrophobic surface. The solvent layer constructing the interlayer channel is a polar solvent, which is repelled by the hydrophobic surface, and then the solvent layer tends to arrange vertically to the hydrophobic surface of the substrate, which is beneficial to realize the transmembrane orientation arrangement of the interlayer channel. Therefore, the transmembrane oriented interlayer channel with uniform size and adjustable size is constructed by hydrophobic and hydrophilic interaction, molecular self-assembly behavior, and interfacial interaction.

[0036] The substrate can be a substrate composed of a hydrophobic material, or a substrate with a surface treated or modified by a hydrophobic material. The substrate can be a metal material, an inorganic non-metal material, an organic material, or an organic-inorganic composite material.

[0037] The substrate can be a porous substrate, wherein the pore structure can be a through hole penetrating through the substrate, or a blind hole not penetrating through the substrate. The pore size can range from 1 μm to 1000 μm.

[0038] The process of coating the precursor slurry on the surface of the substrate can be adjusted by adjusting the blade or roller pressure, feeding speed, and shear speed to adapt to different viscosities of the slurry, so as to generate a stress field suitable for the rotation, rolling and sliding of the two-dimensional liquid crystal, which is beneficial to induce the macroscopic orientation of the two-dimensional liquid crystal domain in the transmembrane direction of the two-dimensional plane.

[0039] Wherein, the coating thickness of the coating process can be controlled in the range of 5 μm to 300 μm, and the coating width can be controlled in the range of 0.01 m to 5 m.

[0040] In some embodiments of the present application, the relationship between the precursor slurry, the substrate characteristics and the coating process parameters can be controlled as shown in Table 1.

[0041] Table 1

[0042]

[0043] In some embodiments of the present application, in step S3, before the precursor slurry is coated on the surface of the substrate, the precursor slurry is subjected to defoaming treatment. The defoaming treatment can include microwave irradiation and ultrasonic oscillation in sequence. Specifically, the precursor slurry can be subjected to microwave irradiation and ultrasonic oscillation in sequence, and then the slurry is flowed into a container along a defoaming device having an inclined guide surface, and then sealed with a sealing film for standing to eliminate residual stress in the defoaming step. In this process, the precursor slurry can be subjected to intermittent microwave heating to reduce the viscosity of the precursor slurry; the frequency of the intermittent microwave heating can be controlled to be 1 time / min to 120 times / min; and the ratio of the heating time to the cooling time can be in the range of 1:9 to 9:1. Then, the precursor slurry is subjected to ultrasonic oscillation to make the small-diameter bubbles in the precursor slurry gather into large-diameter bubbles under the action of acoustic pressure; the ultrasonic oscillation time can be controlled to be ≥10 min. The defoaming device having an inclined guide surface is used to introduce the precursor slurry into the container, and the precursor slurry flows along the inclined guide surface, which can reduce the rising free distance and time of the bubbles in the slurry, so that the bubbles escape from the surface of the slurry under the action of buoyancy; wherein the inclination angle θ of the inclined guide surface or its tangent relative to the horizontal plane is 10°≤θ<90°, and the inclined guide surface can be hemispherical or conical. Specifically, the defoaming device can use a bell-shaped surface, i.e., bell-shaped surface defoaming. The standing time can be controlled to be ≥1 day. The above defoaming treatment can be carried out in a constant-temperature, constant-humidity, and dust-free environment.

[0044] In some embodiments of the present application, in step S3, the precursor slurry is coated on the surface of the substrate and subjected to orientation treatment to obtain a wet film, which specifically includes the following steps:

[0045] A first substrate having a first surface and a second substrate having a second surface are provided, and a liquid crystal containing space is defined between the first surface and the second surface, and a precursor slurry is placed in the liquid crystal containing space, and the first surface and the second surface are not completely hydrophilic interfaces;

[0046] A disturbance factor is applied to induce vertical alignment of the precursor slurry;

[0047] The disturbance factor includes at least one of a tangential force factor, a fluid flow factor, a temperature factor, an electric field factor, a magnetic field factor, a pressure factor, an additive factor, and a thermal radiation factor.

[0048] The beneficial effects of the embodiments of the present application are:

[0049] The wet film obtained by the above orientation treatment exhibits a unique vertical alignment structure in the finally obtained polymer film, the orientation effect is uniform, and the orientation requirements of large area, high precision, and controllability of the final polymer film can be met, the anisotropic arrangement is realized, the vertical alignment of the two-dimensional layer is realized, and the stability is high.

[0050] In some embodiments, the first surface and the second surface are solid surfaces.

[0051] In some embodiments, the first surface and the second surface are independently selected from any one of a flexible solid surface, a non-flexible solid surface.

[0052] In some embodiments, the contact angle of the first surface with water and the contact angle of the second surface with water are greater than 45°.

[0053] In some embodiments, the first surface and the second surface are independently selected from at least one of a metal, an inorganic non-metal, an organic material.

[0054] In some embodiments, the first surface and the second surface are independently selected from any one of a coating, a thin film.

[0055] In some embodiments, the first substrate or the second substrate is moved relative to the precursor slurry to induce anisotropic arrangement of liquid crystal domains of the precursor slurry.

[0056] In some embodiments, the direction of the relative movement of the first substrate or the second substrate includes at least one of tangential movement, normal movement along the first surface or the second surface.

[0057] In some embodiments, the type of the relative movement includes any one of unidirectional movement, circumferential movement, and reciprocating movement.

[0058] In some embodiments, the trajectory of the relative movement includes at least one of linear movement, arcuate movement.

[0059] In some embodiments, the speed of the relative movement is 0.1 mm / s to 50 mm / s.

[0060] In some embodiments, the relative movement of the precursor slurry includes at least one of relative movement driven by gravity, centrifugal force, shear stress, pressure difference, capillary force, temperature difference, and cross magnetic electric field.

[0061] In some embodiments, the relative movement of the first substrate or the second substrate relative to the precursor slurry includes: fixing the second substrate, and moving the first substrate relative to the precursor slurry.

[0062] In some embodiments, the first surface and the second surface are independently selected from any one of a plane, a curved surface.

[0063] In some embodiments, the approach angle of the first substrate relative to the precursor slurry is 5° to 90°, and the departure angle is 3° to 175°.

[0064] In some embodiments, the perturbation factor is applied by a tunable force field generator.

[0065] The rapid development of material science promotes the progress of liquid crystal science. Two-dimensional layered liquid crystals show great application value in the fields of optoelectronic devices, biomedicine, separation technology, etc. due to their unique physical and chemical properties and wide application potential. In high-performance applications such as optical devices and mass transfer membranes, the uniformity of orientation and anisotropy of two-dimensional layered liquid crystals directly affect the overall optical principal axis or channel orientation of the separation membrane, and further determine the final performance of the related devices, such as the key parameters of light transmittance, uniformity of optical principal axis, optical phase control ability, and mass transfer efficiency. Therefore, achieving uniform and directional arrangement structure is crucial to improve the performance of devices. Traditional liquid crystal alignment techniques mainly focus on the regulation of one-dimensional molecular arrangement, such as parallel or perpendicular alignment of nematic liquid crystals, mainly induced by single electric field or alignment layer. However, in the field of two-dimensional layered liquid crystals, especially for the precise control of microstructure and macroscopic performance, there are still many challenges. The above-mentioned electric field alignment is difficult to apply to large-area two-dimensional layered liquid crystal vertical alignment process, because too high electric field usually disperses the layered phase structure. At the same time, the method of alignment layer induction is difficult to meet the requirements of large area, high precision and controllable orientation. Moreover, these methods are difficult to achieve the vertical alignment of two-dimensional layers while realizing the anisotropic arrangement of two-dimensional layers, and the stability is insufficient in specific application environment.

[0066] In view of the above problems, the above orientation treatment method provided by the present application can induce the wet film to have a vertical liquid crystal orientation in the final polymer film, and provide a liquid crystal orientation scheme for molecular assembly structure regulation, optical signal modulation, and mass transfer process intensification under special working conditions. The final polymer film obtained by the present application is a two-dimensional layered liquid crystal. The present application realizes the vertical alignment and anisotropic arrangement of two-dimensional layers in the polymer film by precisely regulating the solid-liquid interface characteristics, introducing disturbance factors, and applying characteristic stress field and cross field. This innovative method not only greatly improves the accuracy and controllability of liquid crystal orientation, but also expands the range of liquid crystal types suitable for liquid crystal orientation technology, and endows the polymer film of the present application with potential in optical devices, mass transfer membranes and many high-tech applications.

[0067] The core of the above-mentioned alignment treatment method of the application is to propose and construct a new liquid crystal alignment treatment method, to realize the vertical alignment and macroscopic ordered arrangement of the two-dimensional layers in the two-dimensional layered liquid crystal (such as the polymer film of the application), and to comprehensively use the characteristic surface interface, the characteristic stress field, the magnetic-electric cross field, and the two-dimensional layered phase liquid crystal material. Through the optimized interaction between the interface and the liquid crystal material, combined with various disturbance factors, the arrangement and order degree of the two-dimensional layered liquid crystal are realized, and then the required vertical alignment and anisotropic structure are induced. This technical solution of the application is not only suitable for the two-dimensional layered liquid crystal of a single component, but also covers the complex mixed component system, which significantly enhances the universality and application range of the technology.

[0068] In some embodiments of the application, in step S4, the in-situ polymerization curing treatment is any one of light treatment and heating treatment. For example, under the environmental conditions of inert gas (such as nitrogen, argon, etc.), the wet film is irradiated with light or heated to induce the layered distribution of the polymer chain to form a two-dimensional solvent channel; wherein, if the wet film contains a crosslinking agent, the adjacent polymer chain segment layers can be crosslinked by the crosslinking agent to improve the mechanical strength.

[0069] For example, if the in-situ polymerization curing treatment adopts light treatment, the initiator generally corresponds to a photoinitiator, such as a photoinitiator containing a vinyl group. The light source of the light treatment can use a cold light source or a hot light source; the wavelength range can be controlled to be ≤450 nm; and the light irradiation time can be controlled to be 5 s-30 min.

[0070] For example, if the in-situ polymerization curing treatment adopts heating treatment, the initiator generally corresponds to a thermal initiator. The heating temperature can be controlled to be 30 °C-200 °C; and the heating time can be 30 s-60 min.

[0071] In some embodiments of the application, the drying treatment is selected from at least one of hot air drying, microwave drying, convection drying, and infrared drying. In some embodiments, the drying treatment can use hot air drying and microwave drying in sequence. Because it is considered that hot air drying will preferentially dry the surface, which will cause uneven drying, and the water in the internal part of the film layer may be damaged when it is discharged during the continuous drying process, microwave radiation can more uniformly dry, but its energy is relatively large, and long-time microwave radiation may also damage the alignment of the interlayer channel of the film material. Therefore, hot air drying and microwave drying are combined, the surface of the film layer is dried by hot air drying first, and then the microwave radiation with greater energy is used for drying, which is beneficial to the effective drying of the internal part of the film layer, and the combination of the two drying methods can effectively maintain the interlayer channel structure of the film material.

[0072] The hot air drying can be assisted by a baffle with a plurality of air vents. The air vents on the baffle are uniformly arranged, and the hot air blows to the film layer obtained by in-situ polymerization and solidification through the air vents on the baffle. The shape of the air vents on the baffle is not limited, which can be circular, rectangular, square, oval, etc. The temperature of the hot air can be controlled at 40 °C to 85 °C. The air supply speed can be controlled at 0.01 m / s to 50 m / s. The baffle with a plurality of air vents can further help to avoid damaging the orientation of the film during the drying process. After the hot air drying is completed, microwave radiation is further performed to reinforce the structure of the film layer. The processing frequency of the microwave radiation can be controlled at 1 time / min to 120 times / min.

[0073] In some embodiments of the present application, after the drying treatment is completed in step S4, a film peeling treatment is further included. Before the peeling treatment, the polymer film is loaded on the surface of the substrate. The peeling treatment can be performed by a peeling device to peel the polymer film from the substrate. The peeling device can use a wedge-shaped peeling piece. The peeling process can control the angle (or peeling entry angle) between the acting force direction of the wedge-shaped peeling piece and the surface of the substrate to be 0° to 45°. In addition, in combination with the structural characteristics of the polymer film, in order to facilitate the complete and continuous peeling of the polymer film, the hardness of the wedge-shaped peeling piece can be designed to be HRC>40, and the surface roughness can be less than 1 μm.

[0074] In some embodiments of the present application, after the drying treatment is completed in step S4, a film loading treatment is further included. The film loading treatment can enhance the bonding strength between the film layer and the substrate, ensure the close combination of the two, and form a stable film loading structure. The film loading treatment can be a hot pressing treatment, a chemical bonding treatment, a physical electrostatic adsorption treatment, etc.

[0075] In the second aspect of the present application, a polymer film is provided, which is prepared by the above-mentioned method for preparing a polymer film. The polymer film has a plurality of two-dimensional channels crossing the film, i.e., the extension direction of the two-dimensional channels intersects with the surface extension direction of the polymer film and penetrates through the polymer film. The two-dimensional channels in the polymer film have uniform sizes and have high selectivity and high permeability.

[0076] In some embodiments of the present application, the extension direction of the two-dimensional channels is perpendicular to the surface of the polymer film.

[0077] In some embodiments of the present application, the two-dimensional channels are generally two-dimensional layered channels.

[0078] In some embodiments of the present application, the size of the two-dimensional channels is distributed in the sub-nanometer and nanometer ranges. Specifically, the size of the two-dimensional channels can be controlled at 0.1 nm to 10 nm.

[0079] In some embodiments of the present application, the angle between the extension direction of the two-dimensional channel and the surface normal of the polymer film is 0°-45°, i.e. the angle between the two-dimensional channel and the surface of the polymer film is 45°-90°.

[0080] In a third aspect of the present application, a device is provided, which comprises the aforementioned polymer film.

[0081] In some embodiments, the device is any one of an optical filter, an optical phase modulator, a display, a sensor, an ion separation membrane, and an energy conversion device.

[0082] In a fourth aspect of the present application, a preparation method of the aforementioned polymer film or an application of the aforementioned polymer film in membrane separation is provided. The preparation method of the polymer film described above is a preparation method of a polymer film with controllable interlayer channels. In the application process of membrane separation, the size of the interlayer channels of the polymer film can be accurately controlled according to the separation requirements, so that the prepared polymer film can meet the separation requirements. BRIEF DESCRIPTION OF DRAWINGS

[0083] The present application will be further described below in conjunction with the drawings and examples, in which:

[0084] FIG. 1 is an amphiphilic liquid crystal that can be used in the preparation method of the polymer film of the present application;

[0085] FIG. 2 is a process flow diagram of the preparation method of the polymer film of Example 1;

[0086] FIG. 3 is a material conversion diagram of the polymer film preparation process of Example 1;

[0087] FIG. 4 is a photograph of the precursor slurry in Example 1;

[0088] FIG. 5 is a photograph comparison of the precursor slurry before and after defoaming in Example 1;

[0089] FIG. 6 is a polarized light microtexture diagram of the precursor slurry before and after defoaming in Example 1;

[0090] FIG. 7 is a polarized light microtexture diagram of the film layer before and after photocuring in Example 1;

[0091] FIG. 8 is a photograph of the polymer film obtained in Example 1;

[0092] FIG. 9 is a surface scanning electron micrograph of the polymer film obtained in Example 1;

[0093] FIG. 10 is a cross-sectional electron microscope and transmission electron microscope diagram of the polymer film obtained in Example 1;

[0094] FIG. 11 is a process flow diagram of the preparation method of the polymer film of Example 5;

[0095] Figure 12 is a polarized light microtexture image of the polymer film obtained in Comparative Example 1.

[0096] Figure 13 is a schematic diagram of an orientation device for achieving orientation treatment in one embodiment of the present application.

[0097] Figure 14 is a schematic diagram of the self-assembly structure of molecules in a monomolecular layer two-dimensional lamellar liquid crystal in one embodiment of the present application.

[0098] Figure 15 is a schematic diagram of the self-assembly structure of molecules in a bilayer two-dimensional lamellar liquid crystal in one embodiment of the present application.

[0099] Figure 16 is a bright field and dark field image of the polarized light microtexture of a two-dimensional liquid crystal domain after anisotropic vertical uniform orientation in different embodiments of the present application. Wherein, (A)-(H) are the polarized light microtexture under the influence of tangential force, fluid flow, temperature, electric field, magnetic field, pressure, additive, and thermal radiation, respectively; (I)-(N) are the polarized light microtexture of the orientation of lyotropic liquid crystal, thermotropic liquid crystal, smectic A-D, blue phase liquid crystal, single-component liquid crystal, and complex mixed-component liquid crystal, respectively. P and A in the figure represent the polarizing direction and the analyzing direction of the polarized light microscope, respectively.

[0100] Figure 17 is the stability test result of the orientation effect of a two-dimensional lamellar liquid crystal in one embodiment of the present application.

[0101] Figure 18 is a schematic diagram of the principle of the orientation of a two-dimensional lamellar liquid crystal in one embodiment of the present application.

[0102] Figure 19 is a comparison of the contact angles of different solid surfaces with deionized water in one embodiment of the present application. Wherein, (A) is hydrophilic glass, (B) is hydrophobic glass, (C) is stainless steel, and (D) is polytetrafluoroethylene.

[0103] Figure 20 is a type of different solid interface structure used in one embodiment of the present application. Wherein, (A) is a plane / plane structure, (B) is a plane / arc surface structure, (C) is a plane / inclined surface structure, and (D) is an arc surface / arc surface structure.

[0104] Figure 21 is a schematic diagram of the structure of a force field applying device used in one embodiment of the present application.

[0105] Figure 22 is the application of oriented two-dimensional lamellar liquid crystal to polarization light phase adjustment in one embodiment of the present application. Wherein, (A) is a schematic diagram of the principle of the test device, and (B) is a graph showing the variation of the polarization light phase difference with the rotation angle of the liquid crystal cell.

[0106] Reference signs: first substrate 110, electric field generating device 120, magnetic field generating device 130, second substrate 140, two-dimensional layered liquid crystal 150, injection port 160, liquid crystal molecule 210, hydrophilic segment 211, hydrophobic segment 212, two-dimensional layer 220. Embodiments of the present application

[0107] The concept and the technical effects of the present application will be described clearly and completely in combination with the embodiments below, so as to fully understand the purposes, features and effects of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0108] Embodiment 1

[0109] A preparation method of a polymer film, referring to FIG. 2 and FIG. 3, the preparation method comprises the following steps:

[0110] S1, a two-dimensional layered liquid crystal system with a polar solvent content of 1wt% is prepared by mixing 99wt% of amphiphilic liquid crystal and 1wt% of polar solvent; wherein the polar solvent is water, and the amphiphilic liquid crystal is tetradecyl vinyl imidazole bisulfate, and the structural formula is as follows:

[0111] 。

[0112] Specifically, the tetradecyl vinyl imidazole bisulfate solid powder is placed in a centrifuge tube, water is added drop by drop, and a two-dimensional liquid crystal solid-liquid mixture with a solvent content within the liquid crystal phase range is configured; the solid-liquid mixture is frozen in a refrigerator to completely solidify; then the mixture is taken out and thawed at room temperature 25°C, and a fine glass rod is used to stir gently; the above freezing and thawing and stirring steps are repeated for 10 times in sequence; a centrifuge is used to centrifuge at a speed of 500 r / min for 30 min at room temperature to remove the air bubbles generated in the system due to stirring; the centrifuge tube opening is sealed with a sealing film to avoid solvent evaporation and impurity mixing, and is placed for 1 day to realize the sufficient and uniform self-assembly of the tetradecyl vinyl imidazole bisulfate molecules in water, and at the same time, the residual stress generated between domains in the stirring and mixing process is eliminated, to obtain a two-dimensional layered liquid crystal system, and a polarized light microscopic imaging system is used to detect the texture characteristics, and a uniform “focal conic weave” characteristic texture is observed, proving the existence of the layered phase.

[0113] S2, a precursor slurry is prepared by mixing additives composed of a thermal initiator and a crosslinking agent with the two-dimensional layered liquid crystal system. Wherein ethylene glycol dimethacrylate is used as the crosslinking agent, and ammonium persulfate is used as the thermal initiator, and the mass ratio of the crosslinking agent to the thermal initiator is 1:1, and the mass ratio of the additives to the two-dimensional layered liquid crystal system is 6:94.

[0114] Specifically, ethylene glycol dimethacrylate was used as a crosslinking agent, and ammonium persulfate was used as a thermal initiator. The crosslinking agent and the thermal initiator were taken in a mass ratio of 1:1, dissolved in dichloromethane, and stirred with a glass rod for 10 min. Then, the solvent was removed by rotary evaporation under reduced pressure and placed in a negative pressure environment for not less than 8 h to obtain a fully mixed additive. Then, the additive was taken in a mass ratio of 6:94 to the two-dimensional layered liquid crystal system, and added to the two-dimensional liquid crystal system prepared in step S1. An inert metal rod was used for stirring to preliminarily mix the solid-liquid two phases uniformly. Ultrasonic oscillation was used to oscillate at room temperature for 60 min to fully dissolve the undissolved solids in the system. Then, the above stirring and ultrasonic oscillation steps were repeated 4 times in sequence. A centrifuge was used at a speed of 2000 r / min at room temperature for 5 min to remove the upper slurry with a high content of air bubbles. The above steps were repeated 3 times to remove the larger air bubbles generated in the system due to stirring. The film-sealed centrifuge tube was left to stand for 1 week to eliminate residual stress, and a precursor slurry was obtained, which had a viscosity of 6 x 10 8 mPa·s; the texture characteristics were detected using a polarized light microscopic imaging system, and uniform "focal conic texture" characteristic texture was observed, proving the existence of a layered phase.

[0115] S3, defoaming treatment was performed on the precursor slurry.

[0116] Specifically, in a dust-free operation room with a humidity of 95 RH% and a temperature of 25°C, the precursor slurry was intermittently heated by a microwave chemical reactor, 5 times per minute, each time for 5 s, and then cooled for 7 s; the heating temperature was set to 55°C-60°C. Then, the precursor slurry was treated by an ultrasonic cell disruptor at a power of 1 W / cm 2 The precursor slurry was subjected to ultrasonic oscillation. The treated precursor slurry flowed along the interface of a 30 cm diameter hemispherical bell surface, wherein the inclination angle of the tangent of the hemispherical bell surface relative to the plane was 45°; the treated slurry was placed in a beaker and film-sealed for 1 week to obtain a precursor slurry without air bubbles, as shown in FIG. 4, and the actual comparison of the precursor slurry before and after defoaming treatment in step S3 and the polarized light microstructure diagram are shown in FIGS. 5 and 6, respectively, where P and A represent the polarizing direction and the analyzing direction of the polarized light microscope, respectively.

[0117] S4, the precursor slurry was coated on the surface of a substrate and subjected to parallel alignment treatment to obtain a wet film.

[0118] Specifically, in a dust-free operating room with humidity of 95 RH% and temperature of 25°C, the precursor slurry is injected into the liquid distribution cabin of the array coating die through a gear pump under the condition of nitrogen protection, and is uniformly transferred to the PMMA substrate conveyed on the conveying belt by slot coating at a coating speed of 3 cm / s. The conveying belt speed is 3 cm / s, the coating width is 10 cm, and the thickness is 10 μm. A metal scraper is used to apply a horizontal shear force to the coated slurry. The contact surface of the scraper is a plane, the cutting angle is 30°, the leaving angle is 200°, the shear force is 100 N, and the parallel orientation is achieved through the mechanical friction force during the coating process. After the coating is completed, a wet film is formed on the surface of the substrate.

[0119] S5, in-situ polymerization and curing treatment and drying treatment are performed on the wet film.

[0120] In a dust-free operating room with humidity of 95 RH% and temperature of 25°C, the solution film with uniform thickness is heated to 90°C and maintained for 15 min to 45 min to form a layered distribution of polymer chains by thermal polymerization of the vinyl groups; ethylene glycol dimethacrylate crosslinks adjacent polyethylene layers to provide mechanical strength, and the solution film with uniform thickness is converted into a solid wet film. The film layer polarized light micro-texture map before and after the in-situ polymerization and curing treatment is shown in FIG. 7, where P and A represent the polarizing direction and the analyzing direction of the polarized light microscope, respectively.

[0121] After the above in-situ polymerization and curing treatment is completed, hot air at a temperature of 60°C and a wind speed of 0.5 m / s is blown vertically to the solid wet film after in-situ curing through a rectangular slot with a size of 5 cm x 10 cm and a spacing of 5 cm. The solid wet film is intermittently heated by a microwave chemical reactor, each heating for 5 min and then cooling for 2 min, and the radiation intensity is 700 mW / cm 2 to complete the drying of the solid wet film.

[0122] S6, film peeling, i.e., peeling the film material from the surface of the substrate. Specifically, a metal wedge-shaped peeling piece is used to apply a horizontal shear force to the polymer film to achieve peeling of the film from the substrate. The wedge-shaped peeling piece has a cutting angle of 3°, and the shear force is 25 N. After peeling is completed, the finished polymer film is obtained through a winding process, as shown in FIG. 8.

[0123] Example 2

[0124] The difference between this embodiment and Example 1 is that the raw material ratio of the two-dimensional layered liquid crystal system in step S1 is 80 wt% amphiphilic liquid crystal and 20 wt% polar solvent, and the polar solvent content in the two-dimensional layered liquid crystal system is 20 wt%; the precursor slurry prepared in step S2 is 4 x 10 6mPa-s; other operations are the same as in Example 1, and a polymer film is prepared.

[0125] Example 3

[0126] The difference between this example and Example 1 is that the raw material ratio of the two-dimensional layered liquid crystal system in step S1 is 60 wt% of the amphiphilic liquid crystal and 40 wt% of the polar solvent, and the content of the polar solvent in the two-dimensional layered liquid crystal system is 40 wt%; the precursor slurry prepared in step S2 is 5 x 10 5 mPa-s; other operations are the same as in Example 1, and a polymer film is prepared.

[0127] The thickness of the polymer film prepared in this example is about 10 μm. The surface scanning electron microscope image of the polymer film is shown in Figure 9, in which the left side is the surface electron microscope image of the polymer film, and the right side is the local simulation image of the polymer film. As can be seen from Figure 9, the above prepared polymer film retains the two-dimensional channels which are vertically oriented along the transmembrane direction, uniform in size and distribution, and the channels are anisotropically oriented in the membrane plane direction and vertically arranged perpendicular to the membrane plane in the transmembrane direction. The cross-section electron microscope image and the projection electron microscope image of the polymer film are shown in Figure 10, in which (a) is the electron microscope image; (b) is the projection electron microscope image. As can be seen from Figure 10, the cross-section of the polymer film has a two-dimensional layered structure which is vertically oriented, uniform in size and has distinct morphological characteristics, and the two-dimensional vertical channels which are uniform in size and have a size of sub-nanometer or nanometer are periodically distributed therein, and the channel width is 0.9 nm according to theoretical calculation.

[0128] Example 4

[0129] The difference between this example and Example 1 is that the raw material ratio of the two-dimensional layered liquid crystal system in step S1 is 50 wt% of the amphiphilic liquid crystal and 50 wt% of the polar solvent, and the content of the polar solvent in the two-dimensional layered liquid crystal system is 50 wt%; the precursor slurry prepared in step S2 is 4 x 10 4 mPa-s; other operations are the same as in Example 1, and a polymer film is prepared.

[0130] Example 5

[0131] The preparation method of the polymer film in this example is shown in Figure 11, which is different from Example 1 in that the film peeling operation in step S6 is cancelled, and the finished polymer film is prepared by winding process after step S5, and other operations are the same as in Example 1.

[0132] The above polymer film is composed of a substrate and a film layer loaded on the surface of the substrate. In order to improve the bonding strength of the substrate and the film layer, the film loading treatment such as hot pressing treatment, chemical bonding treatment, physical electrostatic adsorption treatment, etc. can be carried out before winding.

[0133] Polymer membrane performance test

[0134] Water flux: The water flux of the polymer membrane was tested by using a pressure-driven dead-end filtration cup. Deionized water was used as the test solvent, and the polymer membrane was first immersed in deionized water for pre-wetting treatment for 1 h. The test pressure was set to 5 bar, and the effective membrane area of the test device was 100 cm 2 ; The water flux calculation formula is as follows:

[0135] ;

[0136] Wherein, J is the water flux, unit is Lm -2 h -1 ; Q is the volume of permeated deionized water, unit is L; A is the effective membrane area, unit is m 2 ; Δt is the test time, unit is h.

[0137] Li + / Mg 2+ Ion separation ratio: 1000 ppm MgCl2 solution and LiCl solution were prepared respectively, and the ion separation performance of the polymer membrane was evaluated by using an ultrafiltration cup with a stirring tank in a dead-end filtration mode. A nitrogen cylinder was connected to the upstream of the ultrafiltration cup to provide a constant pressure, and the effective area of the membrane for testing was 4 cm 2 . The 1000 ppm MgCl2 solution was used as the stock solution, and the filtrate downstream of the membrane was collected under the condition of 5 bar. The conductivity of the stock solution and the filtrate was tested by using a conductivity meter, and the MgCl2 concentration in the filtrate was calculated by referring to the standard curve. The ion rejection rate was calculated as 1-(filtrate concentration / stock solution concentration). The LiCl rejection rate was measured by the same method. The above test was repeated for not less than 3 times and the average value was taken. + / Mg 2+ The ion separation ratio was calculated as Mg rejection rate / Li rejection rate, and the ion separation performance of the membrane was obtained.

[0138] By using the above method, the performance of the polymer membranes prepared in Examples 1-4 was tested, and the results are shown in Table 2.

[0139] Table 2

[0140]

[0141] The hydrated kinetic diameters of Li ion and Mg ion are about 0.7 nm and 0.8 nm, respectively, with a difference of 0.1 nm. The difference in channel size leads to different resistance to the two ions crossing the channel. The larger Mg ion is subjected to greater resistance and is therefore more difficult to cross the channel. Therefore, the key to realizing lithium-magnesium separation is to control the channel size. According to Table 2, the channel size in the membrane can be specifically controlled to 0.6 nm to 1 nm. In order to effectively realize lithium-magnesium separation, high water flux and lithium-magnesium ion separation ratio (or selectivity) are preferred, and the polymer membrane prepared by the preparation method of Example 3 or 4 is preferably used. Specifically, the polymer membrane can be selected according to the requirements of the separation process parameters. For example, if the Li + / Mg 2+ ion separation ratio is required to be no less than 12 or 13, the polymer membrane prepared by the preparation method of Example 3 or 4 can be selected; if the Li + / Mg 2+ ion separation ratio is required to be no less than 14, the polymer membrane prepared by the preparation method of Example 3 can be selected.

[0142] In addition, the inventors further studied the influence of further increasing the amount of polar solvent on the structure of the polymer membrane during the research process. It was found that when the content of polar solvent in the two-dimensional layered liquid crystal system exceeds 80 wt%, no two-dimensional layered channel is formed in the polymer membrane.

[0143] For example, based on Example 1, the raw material ratio of the two-dimensional layered liquid crystal system in step S1 is 15 wt% of amphiphilic liquid crystal and 85 wt% of polar solvent, and the other operations are the same as those of Example 1. The polymer membrane prepared by the method is obtained. The polarized light microscope image of the polymer membrane is shown in FIG. 12. In FIG. 12, P and A represent the polarizing direction and the analyzing direction of the polarized light microscope, respectively. The polarized light texture image shown in FIG. 12 is completely dark, and no two-dimensional layer channel appears in the polymer membrane.

[0144] From the above, the polymer membranes prepared in the above examples have a plurality of two-dimensional layered channels with uniform transmembrane orientation, size and distribution. The preparation method of the above polymer membranes can control the size of the two-dimensional layered channels between the polymer membrane layers by controlling the addition amount of polar solvent or the content of polar solvent in the two-dimensional layered liquid crystal system within a specific range, so as to realize uniform and controllable channel size between the membrane layers and continuous adjustment of the size in nanometer or sub-nanometer scale. The polymer membranes prepared have high selectivity and high permeability. The above polymer membranes and the preparation method thereof can be applied to the field of membrane separation. Specifically, the size of the channels between the polymer membrane layers can be accurately controlled by controlling the addition amount of polar solvent according to the separation requirements, so that the obtained polymer membrane meets the requirements of membrane separation.

[0145] Example 6

[0146] Referring to FIG. 13, an alignment device for realizing the above-mentioned alignment process is shown, which includes a first substrate 110 having a first surface and a second substrate 140 having a second surface, the first surface and the second surface being oppositely arranged and defining a liquid crystal accommodating space. In the alignment process, a two-dimensional layered liquid crystal 150 is placed in the liquid crystal accommodating space. The first surface and the second surface are not completely hydrophilic interfaces. A perturbation factor is applied to induce the two-dimensional layered liquid crystal to be vertically aligned. Thus, the two-dimensional liquid crystal domains are vertically and anisotropically aligned. The perturbation factor can be at least one of a tangential force factor, a fluid flow factor, a temperature factor, an electric field factor, a magnetic field factor, a pressure factor, an additive factor, and a thermal radiation factor.

[0147] The term "two-dimensional layered liquid crystal" refers to a liquid crystal that exhibits a two-dimensional layered structure at a microscopic scale. In some embodiments, the two-dimensional layered liquid crystal is formed of a single component that independently forms a two-dimensional layered structure. In other embodiments, the two-dimensional layered liquid crystal is formed of a plurality of components that are mixed to form a two-dimensional layered structure. Thus, the two-dimensional layered liquid crystal includes any one of a single-component liquid crystal and a mixed-component liquid crystal. In some embodiments, the two-dimensional layered structure includes, but is not limited to, a layered monomolecular layer structure and a layered bilayer structure. In some embodiments, the liquid crystal molecules 210 in the two-dimensional layered liquid crystal of the layered monomolecular layer structure and the layered bilayer structure include a hydrophilic segment 211 and a hydrophobic segment 212, the liquid crystal molecules being surfactant-type, the hydrophilic segment 211 being mutually attracted to the two-dimensional layer 220, and the hydrophobic segment 212 being repelled from the two-dimensional layer 220. It can be understood that, in this case, the two-dimensional layer 220 is composed of a hydrophilic component, such as at least one polar solvent, including but not limited to water, butyl acetate, ethyl acetate, n-butanol, phenol, methyl ethyl alcohol, tert-butyl alcohol, tetrahydrofuran, dioxane, acetone, ethanol, methanol, and the like.

[0148] The "precursor slurry" in the above-mentioned embodiment 1 of the present application is also a form of the above-mentioned "two-dimensional layered liquid crystal".

[0149] In some embodiments, the single-component two-dimensional layered liquid crystal includes surfactant-type molecules of a hydrophilic segment-hydrophobic segment structure or molecules of a rigid structure (e.g., rigid rod-like, disc-like, ring-like); in the mixed-component two-dimensional layered liquid crystal, the liquid crystal molecules include a hydrophilic segment and a hydrophobic segment, and are mixed with at least one of a salt, water, a liquid organic substance, and a liquid acid. Thus, the liquid crystal molecules themselves or the liquid substances added in the liquid crystal molecule material can induce the layered microphase separation of the liquid crystal molecular layers and self-assemble to form a layered structure.

[0150] In some embodiments, the liquid crystal molecules are synthesized by introducing hydrophilic fragments (such as at least one functional group of amino, hydroxyl, imidazolyl, pyridyl, quaternary ammonium group, etc.) and hydrophobic fragments (such as at least one functional group of alkyl chain, etc.) into the liquid crystal molecules, so as to prepare the liquid crystal molecules meeting the preparation of two-dimensional layered liquid crystals, and to prepare two-dimensional layered liquid crystals with bilayer structure. In some embodiments, the molecular fragments containing typical rigid liquid crystal units (such as rigid rod-like, disc-like, ring-like molecular fragments) are used as the liquid crystal phase inducing source (i.e. the hydrophobic fragments), and the liquid crystal small molecules are synthesized by connecting the hydrophilic fragments to one end of the liquid crystal units, so as to induce the formation of two-dimensional layered liquid crystals with bilayer characteristics. The liquid crystal small molecules are synthesized by connecting the hydrophilic fragments to both ends of the liquid crystal units, so as to induce the formation of two-dimensional layered liquid crystals with monolayer characteristics. In some embodiments, the uniform mixing can be achieved by at least one of centrifugation, heating, stirring, shaking, etc. In some embodiments, further adding components such as organic small molecules, solvents, soluble salts, etc. to the system can further regulate the structure and orientability of the two-dimensional layered liquid crystals.

[0151] Referring to FIG. 14, the liquid crystal molecules in the two-dimensional layered liquid crystals with layered monolayer structure include a hydrophobic fragment 212 in the middle and hydrophilic fragments 211 on both sides, and the hydrophilic fragments 211 on both sides are respectively affinitive to the adjacent two-dimensional layers 220 so that the hydrophobic fragment 212 is located therebetween. Referring to FIG. 15, the liquid crystal molecules 210 in the two-dimensional layered liquid crystals with layered bilayer structure include a hydrophobic fragment 212 on one side and a hydrophilic fragment 211 on the other side. The hydrophilic fragment 211 of one of the two liquid crystal molecules 210 is affinitive to one two-dimensional layer 220, and the hydrophilic fragment 211 of the other liquid crystal molecule is affinitive to the adjacent other two-dimensional layer 220, so as to form the layered structure of the two-dimensional layers 220 by the two liquid crystal molecules. It can be understood that the above two liquid crystal molecules can be the same liquid crystal molecule, or can be different liquid crystal molecules, and the latter specifically includes but is not limited to at least one of different hydrophilic fragments, different hydrophobic fragments.

[0152] In some embodiments, the liquid crystal molecules in the two-dimensional layered liquid crystals are any one of thermotropic liquid crystals and lyotropic liquid crystals, so that the two-dimensional layered liquid crystals can also be divided into thermotropic liquid crystals and lyotropic liquid crystals. For thermotropic liquid crystals, it includes the above-mentioned surfactant type thermotropic two-dimensional layered liquid crystals containing hydrophilic fragments and hydrophobic fragments, and also includes thermotropic two-dimensional layered liquid crystals containing ring-like rigid structures. Among them, the ring-like rigid structures include but are not limited to aromatic ring structures such as benzene ring, naphthalene ring, triphenylene ring, etc.

[0153] In some embodiments, the two-dimensional layered liquid crystal is a two-dimensional layered liquid crystal mixed by A1 and A2, wherein A1 is at least one of a smectic A phase liquid crystal, a smectic B phase liquid crystal, a smectic C phase liquid crystal, a smectic D phase liquid crystal, a blue phase liquid crystal, and a lamellar phase liquid crystal; and A2 is at least one of a salt, water, a liquid organic substance, and a liquid acid. The liquid organic substance includes, but is not limited to, a liquid organic small molecule and a liquid polymer. The salt includes, but is not limited to, an inorganic salt and an organic salt.

[0154] In some embodiments, the two-dimensional layered liquid crystal exhibits a temperature range of a liquid crystal phase of -10 ℃ to 300 ℃, for example, -10 ℃, 0 ℃, 10 ℃, 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 120 ℃, 140 ℃, 160 ℃, 180 ℃, 200 ℃, 220 ℃, 240 ℃, 260 ℃, 280 ℃, or 300 ℃.

[0155] In some embodiments, the two-dimensional layered liquid crystal has a viscosity in a range of 10 3 mPa·s to 10 10 mPa·s, for example, 10 3 mPa·s, 10 4 mPa·s, 10 5 mPa·s, 10 6 mPa·s, 10 7 mPa·s, 10 8 mPa·s, 10 9 mPa·s, 10 10 mPa·s.

[0156] Referring to FIG. 13, the first substrate 110 has a first surface, and the second substrate 140 has a second surface. The first surface and the second surface are oppositely arranged and define a liquid crystal accommodating space, and the two-dimensional layered liquid crystal is arranged in the liquid crystal accommodating space. It can be understood that the liquid crystal accommodating space defined by the first surface and the second surface is usually an open accommodating space, but in some embodiments, it can also be a closed one. Open or closed refers to the openness or closeness in the direction of the first surface and the second surface.

[0157] In some embodiments, the first surface and the second surface are solid surfaces, including but not limited to flexible solid surfaces and non-flexible (rigid) solid surfaces. For example, the first surface and the second surface can be independently selected from any of the flexible solid surfaces and the non-flexible solid surfaces, so that different materials and processes can be adapted for different first surfaces and second surfaces.

[0158] In some embodiments, the first surface and the second surface are not completely hydrophilic. It is understood that the hydrophilic or hydrophobic property of the surface can be obtained by the intrinsic property of the material, or by physical, chemical, or coating treatment. In some embodiments, the contact angle of the first surface with water and the contact angle of the second surface with water are each independently greater than 45°, for example, the contact angle can be 50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, etc. The design of such a specific hydrophilic or hydrophobic surface is beneficial for controlling the hydrophobic segment or liquid crystal mesogen segment of the liquid crystal molecules near the first surface of the first substrate or the second surface of the second substrate to fully contact and adhere to the hydrophobic surface, and to induce the rearrangement and order of the non-surface-adjacent liquid crystal molecules by means of the weak interaction force between the same segments or segments of adjacent liquid crystal molecules, to control the arrangement of the molecules near the interface, and to enhance the vertical alignment effect.

[0159] In some embodiments, to achieve the above-mentioned contact angle requirements, the material of the first surface and the second surface is independently selected from at least one of metal, inorganic non-metal, and organic matter. In some embodiments, the material of the first surface of the first substrate and the second surface of the second substrate includes but is not limited to platinum, titanium and titanium alloy, gold, titanium oxide, and resin, wherein the materials of the first surface and the second surface can be the same or different. In some embodiments, the first surface and the second surface are independently selected from any one of a coating and a film.

[0160] In some embodiments, when the tangential force factor is applied for disturbance, the shear stress of the tangential force acting on the liquid crystal surface is ≥1.5 N / cm 2 , the normal stress is ≥0.7 N / cm 2 , for example, the shear stress is 1.5 N / cm 2 , 2 N / cm 2 , 2.5 N / cm 2 , 3 N / cm 2 , 3.5 N / cm 2 , 4 N / cm 2 , 4.5 N / cm 2 , 5 N / cm 2 , the normal stress is 0.7 N / cm 2 , 0.8 N / cm 2 , 0.9 N / cm 2 , 1 N / cm 2 , 2 N / cm 2 , 3 N / cm 2 , 4 N / cm 2 , 5 N / cm 2 .

[0161] In some embodiments, the flow rate of the two-dimensional layered liquid crystal is ≥ 1 mm / s, for example, it can be 1 mm / s, 2 mm / s, 3 mm / s, 4 mm / s, 5 mm / s, 6 mm / s, 8 mm / s, 10 mm / s, when the fluid flow factor is applied to disturb.

[0162] In some embodiments, the temperature acting condition is 60-200 ℃, for example, it can be 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 120 ℃, 140 ℃, 160 ℃, 180 ℃, 200 ℃, when the temperature factor is applied to disturb. In some of the embodiments, the temperature acting time is ≥ 1 min, for example, it can be 2 min, 3 min, 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 80 min, 100 min.

[0163] In some embodiments, the electric field strength is ≥ 500 V / cm, for example, it can be 500 V / cm, 600 V / cm, 800 V / cm, 1000 V / cm, when the electric field factor is applied to disturb. In some of the embodiments, the electric field acting time is ≥ 5 s, for example, it can be 5 s, 10 s, 20 s, 30 s, 40 s, 45 s, 50 s, 60 s, 2 min, 3 min, 5 min.

[0164] In some embodiments, the magnetic field strength is ≥ 0.5 T, for example, it can be 0.5 T, 1 T, 2 T, 3 T, 4 T, 5 T, when the magnetic field factor is applied to disturb. In some of the embodiments, the magnetic field acting time is ≥ 5 s, for example, it can be 5 s, 10 s, 20 s, 30 s, 40 s, 45 s, 50 s, 60 s, 2 min, 3 min, 5 min.

[0165] In some embodiments, the pressure is ≥ 100 Pa, for example, it can be 100 Pa, 200 Pa, 300 Pa, 400 Pa, 500 Pa, 600 Pa, 800 Pa, 1000 Pa, when the pressure factor is applied to disturb. In some of the embodiments, the frequency of the pressure is ≥ 0.5 Hz, for example, it can be 0.5 Hz, 1 Hz, 2 Hz, 3 Hz, 4 Hz, 5 Hz. In some of the embodiments, the frequency of the pressure is ≥ 3 times, for example, it can be 3 times, 4 times, 5 times, 6 times, 8 times, 10 times.

[0166] In some embodiments, the additive includes few-layer two-dimensional inorganic magnetic nanosheets when the additive factor is applied to perturb. In some of these embodiments, the number of layers of the two-dimensional inorganic magnetic nanosheets includes, but is not limited to, 1-10 layers, such as 10 layers, 9 layers, 8 layers, 7 layers, 6 layers, 5 layers, 4 layers, 3 layers, 2 layers, 1 layer. In some of these embodiments, the two-dimensional inorganic magnetic nanosheets include, but are not limited to, defective graphene (such as point defects, nitrogen doping, sulfur doping, fluorination, hydroxylation, boundary states), defective boron nitride (such as point defects, carbon doping), transition metal halides (such as CrX3, X = I, Br, Cl; VI3), transition metal phosphosulfide (such as TMPX3, TM = Fe, Mn, Ni, Co, Cr, X = S, Se), transition metal telluride CrXTe3 (CrSiTe3, CrGeTe3), Fe x GeTe2(x = 3-5), Fe3O4, Ti2O3, etc. In some of these embodiments, the lateral size of the two-dimensional inorganic magnetic nanosheets is ≥ 10 μm, such as 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 100 μm. In some of these embodiments, the amount of the two-dimensional inorganic magnetic nanosheets added to the two-dimensional layered liquid crystal is 0.01 wt% to 30 wt%, such as 0.01 wt%, 0.02 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 1 wt%, 2 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%. In some of these embodiments, the two-dimensional layered liquid crystal is allowed to stand for ≥ 1 h after the addition of the additive, such as 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 8 h, 10 h.

[0167] In some embodiments, the radiation power is ≥ 100 W, such as 100 W, 200 W, 300 W, 400 W, 500 W, 600 W, 800 W, 1000 W, when the heat radiation factor is applied to perturb. In some of these embodiments, the radiation time is ≥ 5 min, such as 5 min, 10 min, 15 min, 20 min, 30 min, 45 min, 60 min. In some of these embodiments, the wavelength of the radiation light source is 850 nm to 940 nm. In some of these embodiments, the distance between the radiation light source and the two-dimensional layered liquid crystal is ≤ 10 cm, such as 10 cm, 9 cm, 8 cm, 7 cm, 6 cm, 5 cm, 4 cm, 3 cm, 2 cm, 1 cm.

[0168] It can be understood that the above-mentioned perturbation factors can be added individually or in combination, simultaneously or in a certain order.

[0169] In some embodiments, the applied perturbation factors generally include, but are not limited to, at least one of applying an alternating tangential force to the two-dimensional layered liquid crystal, raising the temperature, applying a multi-directional cross magnetic electric field, applying an alternating pressure, applying infrared heat radiation, adding a thickening agent, and the like. Among them, the alternating tangential force refers to the shear stress generated by reciprocating shear, and the direction of the shear stress is parallel to the substrate; it can be understood that when the substrate is a curved surface, the shear stress is parallel to the tangent direction of the curved surface. The alternating pressure refers to the pressure or normal stress caused by reciprocating extrusion, and the direction of the pressure stress is perpendicular to the substrate; it can be understood that when the substrate is a curved surface, the pressure stress is perpendicular to the tangent direction of the curved surface. For example, referring to FIG. 13, an alternating electric field is applied by the electric field generating device 120, and an alternating magnetic field is applied by the magnetic field generating device 130.

[0170] By this method, the materials and hydrophilic / hydrophobic properties of the first surface and the second surface are designed, the interfacial interaction between the two-dimensional layered liquid crystal and the first surface and the second surface is controlled, and the hydrophilic segments / components, hydrophobic segments / components in the two-dimensional layered liquid crystal are induced to orderly microphase separate and arrange into a vertical orientation structure.

[0171] The interaction of the solid-liquid interface is the driving force for the vertical arrangement of the two-dimensional layered liquid crystal, and the application of the perturbation factor is the energy source for intensifying the thermal motion of the molecules in the two-dimensional layered liquid crystal domain and inducing the rearrangement of the two-dimensional layered liquid crystal domain, so as to break through the high-energy barrier of the movement of the liquid crystal small molecules and the liquid crystal domain in the high-viscosity system. By controlling the type and perturbation strength of the perturbation factor, the speed of molecular assembly, the speed of vertical orientation, and the effect of vertical orientation can be quantitatively controlled, so as to meet the needs of different liquid crystal orientation process conditions and different liquid crystal orientation effects. It can also optimize its macroscopic performance to meet the needs of different application scenarios for liquid crystal optical, structural, and mass transfer functions. The flexible use of the above-mentioned perturbation factors ensures the accurate control of the micro-assembly behavior, process, and result of the liquid crystal.

[0172] In some embodiments, the orientation treatment further includes inducing the normal direction of the liquid crystal domain to be further anisotropically oriented. Specifically, in the state that the two-dimensional layered liquid crystal domain has been vertically oriented or tends to be vertically oriented, a tangential stress is applied to induce the two-dimensional liquid crystal domains with different normal directions to rotate and exhibit macroscopic ordered arrangement of the liquid crystal domains in the plane under the action of the tangential stress.

[0173] In some embodiments, the first substrate 110 or the second substrate 140 is relatively moved relative to the two-dimensional layered liquid crystal 150 to induce anisotropic arrangement of the two-dimensional layered liquid crystal domains.

[0174] In some embodiments, the direction of the relative movement of the first substrate or the second substrate comprises at least one of tangential movement, normal movement along the first face or the second face. The normal movement refers to a pressing movement perpendicular to the substrate. In some embodiments, the type of the relative movement comprises any one of unidirectional movement, circumferential movement, and reciprocating movement. In some embodiments, the trajectory of the relative movement comprises at least one of straight line movement, arc line movement. In some embodiments, the speed of the relative movement is 0.1 mm / s-50 mm / s.

[0175] In some embodiments, the anisotropic arrangement of the two-dimensional layered liquid crystal is dependent on a force applying device composed of the first substrate and the second substrate, so that the first substrate or the second substrate has a relative movement with respect to the two-dimensional layered liquid crystal. In some embodiments, the second substrate is fixed, and the first substrate has a relative movement with respect to the two-dimensional layered liquid crystal. In some embodiments, referring to FIG. 18, the first face of the first substrate 110 and the second face of the second substrate 140 are independently selected from any one of a plane and an arc face, i.e., a plane / plane, a plane / arc face, an arc face / plane, and an arc face / arc face, etc. In some embodiments, referring to FIG. 21, the approach angle of the first substrate 110 with respect to the two-dimensional layered liquid crystal 150 is 5°-90°, and the departure angle is 3°-175°. In some embodiments, the relative movement of the two-dimensional layered liquid crystal induced by the tangential stress comprises at least one of a relative movement driven by gravity, centrifugal force, shear stress, pressure difference, capillary force, temperature difference, and cross magnetic electric field. In some embodiments, the disturbance factor is applied by a tunable force field generator. Thus, in these embodiments, the cross magnetic electric field and mechanical shear force, etc. are provided by the geometric shape (plane / arc face combination) of the first face and the second face, the approach and departure angles of the first face, and the integrated tunable force field generator, to assist in achieving more precise liquid crystal domain orientation.

[0176] In some embodiments, the two-dimensional layered liquid crystal is subjected to a relative movement by the first substrate and the second substrate to set the shear rate and the shear duration for orientation. In some embodiments, the shear rate is ≥0.1 mm / s, for example, 0.1 mm / s, 0.2 mm / s, 0.3 mm / s, 0.4 mm / s, 0.5 mm / s, 0.6 mm / s, 0.7 mm / s, 0.8 mm / s, 0.9 mm / s, 1 mm / s. In some embodiments, the shear duration is ≥1 s, for example, 1 s, 2 s, 3 s, 4 s, 5 s, 6 s, 7 s, 8 s, 9 s, 10 s. In some embodiments, the environmental temperature of the shear is 20 ℃ or higher, for example, 20 ℃, 25 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃.

[0177] The application also provides a device comprising the aforementioned two-dimensional layered liquid crystal.

[0178] In some embodiments, the device is any one of an optical filter, an optical phase modulator, a display, a sensor, an ion separation membrane, and an energy conversion device.

[0179] The orientation treatment provided in the embodiments of the application has the following advantages and effects over the prior art:

[0180] (1) Unique technology: The two-dimensional layered liquid crystal material obtained through the above orientation treatment exhibits a unique vertical orientation structure, and the orientation effect is uniform, which is suitable for large-area and precise orientation processes.

[0181] (2) Mild and efficient preparation process: The proposed preparation process is implemented under mild conditions, which not only ensures energy efficiency, but also is suitable for large-scale production, ensuring uniform orientation structure of the two-dimensional layered liquid crystal material, and the orientation effect is stable and reliable.

[0182] (3) Wide application field: The two-dimensional lyotropic liquid crystal material of the application is very suitable for use in optical filters, optical phase retarders, display technology, sensors, special vertical channel high-efficiency separation membranes, and energy conversion devices, and other high-tech fields due to its unique vertical orientation structure and excellent performance, showing a broad application prospect.

[0183] (4) Flexibility and customizability: Whether it is the specific implementation of the method, device, or material, it can be flexibly adjusted according to specific application requirements to ensure optimal performance in different scenarios, further highlighting the practical value and technical innovation of the application.

[0184] Example 7

[0185] Preparation of two-dimensional layered liquid crystal

[0186] Select tetradecane vinyl imidazole hydrogen sulfate (abbreviated as VImHS) molecules as liquid crystal molecules and deionized water as a polar solvent to induce the preparation of two-dimensional layered liquid crystal with a monomer hydration degree of 15 (VImHS-15) having a bilayer structure, and the specific steps are as follows:

[0187] (1) Take an appropriate amount of VImHS powder into a centrifuge tube, and add deionized water according to a molar ratio of VImHS:H2O of 1:15;

[0188] (2) Stir thoroughly with a glass rod;

[0189] (3) Ultrasonic oscillation under room temperature conditions;

[0190] (4) Repeat steps (2) and (3) multiple times in sequence;

[0191] (5) Centrifugal treatment at room temperature at 60000 rpm for 5 minutes;

[0192] (6) The centrifugal tube opening is sealed with a sealing film, and is left to stand for 24 hours to realize sufficient and uniform self-assembly of VImHS molecules.

[0193] The above steps make the raw materials fully mixed and uniform, eliminate the air bubbles inside the system, prevent solvent evaporation, prevent external impurities from entering, and prevent the formation of small stresses between two-dimensional liquid crystal domains in the relaxation stirring and mixing links.

[0194] Example 8

[0195] The two-dimensional layered liquid crystal prepared in Example 7 is subjected to morphological observation under a polarizing microscope, and the polarized microscopic structure characteristics of the functional paste thereof are recorded under various temperature conditions; X-ray diffraction (XRD) technology is used to accurately measure the key structure parameters of the system, covering the single-period interlayer distance of the two-dimensional layered liquid crystal, the VImHS layer thickness, and the water layer thickness information.

[0196] An EMPYREAN X-ray diffractometer of the Netherlands Panalytical Company is used, a Cu-Kα target (λ = 0.154 nm), a loading voltage of 40 kV, a loading current of 40 mA, and a scanning range of θ = 0.5~30°. The interlayer spacing of the bilayer is calculated by using the Bragg formula:

[0197] d = nλ / 2sinθ

[0198] Wherein, d is the interplanar spacing (nm); θ is the diffraction half angle (rad); n is the diffraction order, n = 1, 2,···; λ is the target wavelength, nm;

[0199] The average thickness of the water layer and the VImHS layer can be determined by the interlayer spacing of the molecules, the solvent / solute ratio, and the physical property parameters.

[0200] The volume fraction (φs) of VImHS can be calculated by the following formula:

[0201] φ s =(W s / ρ s ) / (W s / ρ s )+(W w / ρ w )

[0202] W s is the mass percentage of VImHS; W w is the mass percentage of deionized water; ρ s is the mass density of VImHS; ρ wis the density of VImHS;

[0203] wherein ρ is measured by the method of casting molten VImHS with a constant volume crucible s is 0.586 g / cm 3 , and the water density is taken as 1 g / cm 3 . The average thickness of the hydrophobic layer d L and the average thickness of the water layer d w can be calculated by the following formula.

[0204] d L= = φ·d

[0205] d w = d - d L

[0206] The molecular layer spacing, the thickness of the VImHS layer and the water layer are calculated as shown in Table 3.

[0207] Table 3

[0208]

[0209] Example 9

[0210] The interface properties of the solid base material are important factors in determining the affinity of the VImHS-15 two-dimensional layered liquid crystal slurry to the solid surface, and directly affect the feasibility and effect of the vertical orientation of the two-dimensional layers in the VImHS-15 two-dimensional layered liquid crystal slurry. In this example, the method of contact angle analysis is used to realize the design and optimization of the solid-liquid interface properties. By measuring the contact angle (CA) of a drop of deionized water on the surface of the solid base, the compatibility is analyzed, and the smaller the CA, the better the solid-liquid compatibility.

[0211] The test process is carried out at a temperature > 5°C and a humidity of 40% to 90%. The surface contact angles of hydrophilic glass, hydrophobic glass, stainless steel and polytetrafluoroethylene are tested using the above method, and the contact angles are measured to be 40°, 79°, 70° and 120°, respectively, as shown in FIG. 19.

[0212] The solid interface structure type used in this embodiment includes plane / plane structure, plane / inclined plane structure, plane / arc surface structure, arc surface / arc surface structure, and the structure is shown in FIG. 20. The thickness of the two-dimensional layered liquid crystal 150 is 5 μm to 500 μm, and the thickness can be uniform or non-uniform. In (A) of FIG. 20, α1≤90°; in (B), 0°<α2≤360°; in (C), α3≤90°; in (D), 0°<α4≤360°, and l1can be any length. The structure in the figure can be a combination of any n similar units, where 0°<αn≤360°, and ln can be any length. The first substrate 110 and the second substrate 140 in FIG. 20 can be any material and any size; outside the amorphous transition region of the edge, it can be any structure.

[0213] Embodiment 10

[0214] The VImHS-15 two-dimensional layered liquid crystal slurry prepared in Embodiment 7 has good reversible shear deformation characteristics. Therefore, referring to FIG. 13, the first substrate 110 and the second substrate 140 are both selected to be hydrophobic glass plates with a water contact angle of 79°, the distance between the first substrate 110 and the second substrate 140 is 100 μm, the system temperature is 25°C, the second substrate 140 is fixed, and the VImHS-15 two-dimensional layered liquid crystal prepared in Embodiment 7 is injected from the injection port 160. The first substrate 110 is moved at a shear rate of 1.3 mm / s to shear the two-dimensional layered liquid crystal 150 placed between the first substrate 110 and the second substrate 140 in one direction for 10 s.

[0215] The polarized light texture of the VImHS-15 two-dimensional layered liquid crystal slurry after shearing is shown in (A) of FIG. 16, which is full bright in the field of view, and becomes full dark after a deflection of 45°, and shows periodic changes, indicating that the shear action causes the two-dimensional layer anisotropy in the VImHS-15 two-dimensional layered liquid crystal slurry to be uniformly oriented vertically. The possible molecular arrangement mode transition process is shown in FIG. 16, and the normal vector of the bilayer shows consistent arrangement. The key to successful shear orientation is the viscosity of the VImHS-15 two-dimensional layered liquid crystal (under the test conditions of 100 rad / s, the elastic modulus of VImHS-15 is 20,000 Pa, the viscous modulus is 4,000 Pa, and the viscosity is 10,000 mPa·s), and the shear stress can be transmitted from the surface of the VImHS-15 two-dimensional layered liquid crystal slurry to the inside, so as to realize the uniform orientation of the VImHS-15 two-dimensional layered liquid crystal slurry along the thickness direction.

[0216] In addition, as a comparison with the polytetrafluoroethylene material, the contact angle with water is gradually reduced to hydrophilic by plasma treatment, so as to set up different gradient contact angle experimental groups, and as a replacement of the above-mentioned 79° hydrophobic glass flat plate for orientation. It is found that when the contact angle of the substrate material with water is less than 45°, the two-dimensional layered liquid crystal appears the phenomenon of incomplete, uneven or failure orientation. Therefore, it is determined that the critical point of the contact angle of the substrate material with water is 45°, and the substrate with a contact angle with water not less than 45° can obtain good orientation effect by the orientation method of the embodiment.

[0217] Examples 11~27

[0218] Referring to Example 10, the orientation is carried out according to the components or orientation conditions shown in Table 4 (different orientation conditions) and Table 5 (different liquid crystals and orientation conditions), and the polarized texture is shown in (B)~(N) of FIG. 16, respectively.

[0219] Table 4

[0220]

[0221] In which, the preparation method of VImHS-13 two-dimensional layered liquid crystal refers to Example 7, and the difference is that the hydration degree is reduced to 13.

[0222] Table 3

[0223]

[0224] In which, the preparation method of VImHS-11 two-dimensional layered liquid crystal refers to Example 7, and the difference is that the hydration degree is reduced to 11; VImHS is pure tetradecane vinyl imidazole bisulfite without any additive; MImBr is tetradecane methyl imidazole bromide, which is prepared by quaternary ammonium reaction of 1-methyl imidazole and bromotetradecane at 60°C, and then recrystallized several times with ethyl acetate; MImCl is tetradecane methyl imidazole chloride, which is prepared by quaternary ammonium reaction of 1-methyl imidazole and chlorotetradecane at 60°C, and then recrystallized several times with ethyl acetate.

[0225] Example 28

[0226] Stability experiment

[0227] The POM optical anisotropy of the VImHS-15 two-dimensional layered liquid crystal slurry in the interval of 0~1000 h after orientation showed a consistent and stable rule. After 250 h of shearing, the optical anisotropy was enhanced, and under high magnification, uniform stripe texture perpendicular to the shearing direction was observed, indicating that after the shearing stress was unloaded, the oriented liquid crystal domains slowly relaxed and further assembled into an oriented structure with higher order. After 1000 h of standing, referring to FIG. 17, the POM texture of the sheared and oriented VImHS-15 two-dimensional layered liquid crystal slurry still showed significant light and dark changes after deflection of 45°, indicating that the macroscopic orientation of the liquid crystal domains in the VImHS-15 two-dimensional layered liquid crystal slurry could be stable for more than 1000 h under constant temperature and sealed conditions, which was attributed to the stability of the vertically oriented structure of the VImHS-15 two-dimensional layered liquid crystal domains due to the hydrophobic properties of the upper and lower substrate interfaces.

[0228] The oriented VImHS-15 two-dimensional layered liquid crystal constructed anisotropic vertically uniform oriented long-range ordered layered channels along the transmembrane direction, which was expected to realize application and performance enhancement in the fields of optics and mass transfer.

[0229] The oriented two-dimensional layered liquid crystals in Examples 11~27 were tested by the above method, and the macroscopic orientation of the liquid crystal domains in the two-dimensional layered liquid crystals could also be stable for more than 1000 h under constant temperature and sealed conditions.

[0230] Example 29

[0231] Application of polarized light phase adjustment

[0232] Polarized light is light whose vibration direction is limited in a certain plane. Polaroid can screen light of a specific vibration direction to realize polarization of light. The transparent dimming sheet produces phase delay to the passing polarized light through its internal structure, and the delay amount changes with the rotation angle of the dimming sheet, which can be used to modulate the interference, diffraction and other properties of light. In this embodiment, the anisotropic vertically uniform oriented two-dimensional layered liquid crystal after orientation in Example 10 was placed in a liquid crystal cell made of transparent quartz glass, which was used as a dimming sheet with phase adjustment function to adjust the phase of polarized light.

[0233] Referring to (A) in FIG. 22, the light signal transmitter in this embodiment is a monochromatic laser, and the wavelength is set to 520 nm. Polaroid is selected as the starting polarizer, and the light beam of the tube transmitter is polarized light, which ensures that the incident light is in a single polarization state. The center of the anisotropic vertically uniform oriented two-dimensional layered liquid crystal cell is coincided with and perpendicular to the light path. A photodetector is selected as the light signal receiver to detect the light intensity or phase information after passing through the dimming sheet. A rotary table clamping the anisotropic vertically uniform oriented two-dimensional layered liquid crystal cell is set to accurately control the rotation angle of the dimming sheet. A data acquisition system is set to record the relationship between the output signal of the photodetector and the rotation angle.

[0234] Initial calibration, adjust the system to ensure the light path is correct, photodetector in the best receiving position. Angle rotation and data recording: light modulation film with small angle step (such as every 15 °) rotation, record the output signal of photodetector after each rotation (here the signal is the indirect reflection of phase difference, or directly using phase measurement equipment). Repeat the measurement, in order to improve the accuracy of data, each angle at least three times and take the average value.

[0235] The results are shown in Figure 22, the observation found that with the rotation of the liquid crystal cell along the center point, the phase difference of 520 nm polarized light through the light modulation film showed a sinusoidal change trend, indicating that the phase delay effect of light modulation film on light and rotation angle showed a periodic relationship.

[0236] The sinusoidal change of phase difference shows that this phenomenon is consistent with the modulation principle in optics, the internal structure of liquid crystal cell (liquid crystal molecule arrangement) changes with the rotation angle, which leads to the different phase delay when light passes through, and then forms the sinusoidal change of phase difference, reference (B) in Figure 22. The calculation of phase delay shows that the fitting experimental data can be sinusoidal function, and the specific function expression of phase difference with rotation angle is obtained, and the phase delay of light modulation film at different angles is further calculated. This application not only verifies the phase modulation ability of anisotropic vertical uniform alignment two-dimensional layered liquid crystal, but also provides experimental basis for using light modulation film for optical information processing and optical computing.

[0237] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of variations and improvements can be made, which are within the scope of protection of the present application.

Claims

1. A method for producing a polymer film, characterized by, The method comprises the following steps: S1, preparing a two-dimensional layered liquid crystal system by mixing an amphiphilic liquid crystal and a polar solvent; the content of the polar solvent in the two-dimensional layered liquid crystal system is 1wt%-80wt%; the amphiphilic liquid crystal adopts a long strip-shaped amphiphilic liquid crystal molecule with a hydrophilic segment and a hydrophobic segment, and the hydrophobic segment is longer than the hydrophilic segment; the long strip-shaped amphiphilic liquid crystal molecule is selected from any one of the amphiphilic liquid crystals with the following structural formula: In the group A, A', n>8, and R1 in the group D' is selected from an alkylene group; S2, mixing an additive including an initiator with the two-dimensional layered liquid crystal system to prepare a precursor slurry; S3, coating the precursor slurry on the surface of a substrate and performing orientation treatment to obtain a wet film; The orientation direction of the orientation treatment intersects with the surface normal direction of the wet film; the surface of the substrate is a hydrophobic surface; S4, performing in-situ polymerization curing treatment and drying treatment on the wet film.

2. The method of claim 1, wherein the polymer film is prepared by a method comprising: The mass ratio of the additive to the two-dimensional layered liquid crystal system in step S2 is 1: (1-100000); and / or, the viscosity of the precursor slurry is 1x10 3 mPa·s-1x10 9 mPa·s.

3. The method of claim 2, wherein the polymer film is prepared by a method comprising: The two-dimensional layered liquid crystal system and the amphiphilic liquid crystal in the precursor slurry form a focal conic texture; And / or, the additive includes 0-99wt% functional monomers, 0-99wt% cross-linking agents, 1-100wt% initiators, and 0-99wt% thermal polymerization inhibitors.

4. The method of claim 1, wherein the polymer film is prepared by a process comprising: In step S2, the additive is first blended in an organic solvent, and then the organic solvent is removed before being mixed with the two-dimensional layered liquid crystal system to prepare the precursor slurry; And / or, the mixing of the additive with the two-dimensional layered liquid crystal system includes: first stirring and mixing, and then ultrasonic oscillation; and then repeating stirring and mixing and ultrasonic oscillation for more than twice.

5. The method of claim 1, wherein the polymer film is prepared by a process comprising: In step S1, the mixing method of the amphiphilic liquid crystal and the polar solvent is selected from at least one of stirring and ultrasonic method, freeze-thaw method, and rotary evaporation method.

6. The method of claim 1, wherein the polymer film is prepared by a process comprising: In step S3, the angle between the orientation direction of the orientation treatment and the surface of the wet film is 0°-45°; and / or, the orientation treatment is performed by mechanical friction force in the coating process.

7. The method for preparing the polymer film according to claim 1 or 6, characterized in that, In step S3, the precursor slurry is coated on the surface of a substrate and subjected to orientation treatment to obtain a wet film, which specifically comprises the following steps: A first substrate having a first surface and a second substrate having a second surface are provided, and a liquid crystal containing space is defined between the first surface and the second surface, and a precursor slurry is placed in the liquid crystal containing space, and the first surface and the second surface are not completely hydrophilic interfaces; A disturbance factor is applied to induce vertical alignment of the precursor slurry; The disturbance factor includes at least one of tangential force factor, fluid flow factor, temperature factor, electric field factor, magnetic field factor, pressure factor, additive factor, and thermal radiation factor.

8. The method of claim 7, wherein the polymer film is prepared by a method comprising: The contact angle of the first surface with water and the contact angle of the second surface with water are greater than 45°.

9. The method of claim 7, wherein the polymer film is prepared by a process comprising: Relative movement of the first substrate or the second substrate relative to the precursor slurry is induced to arrange the liquid crystal domains of the precursor slurry in anisotropy.

10. The method for preparing the polymer film according to claim 9, characterized in that, The relative movement of the precursor slurry includes at least one of gravity, centrifugal force, shear stress, pressure difference, capillary force, temperature difference, and crossed magnetic and electric fields.

11. The method of claim 9, wherein the polymer film is prepared by a process comprising: The relative movement of the first substrate or the second substrate relative to the precursor slurry comprises: fixing the second substrate, and moving the first substrate relative to the two-dimensional layered liquid crystal.

12. The method for preparing the polymer film according to claim 9, characterized in that, The perturbation factor is applied by a tunable force field generator.

13. The method for preparing the polymer film according to claim 1, characterized in that, In step S3, the substrate is a porous substrate.

14. The method of claim 1 to 13, wherein the polymer film is prepared by a method comprising the steps of: In step S4, the in-situ polymerization curing treatment is any one of light treatment, heating treatment; and / or, the drying treatment is at least one selected from hot air drying, microwave drying, infrared drying.

15. A polymer film, characterized by, The polymer film is prepared by the method of any one of claims 1 to 14.

16. A device, characterized by The polymer film comprises the polymer film of claim 15.

17. The device of claim 16, wherein, The device is any one of an optical filter, an optical phase modulator, a display, a sensor, an ion separation membrane, an energy conversion device.

18. The polymer film prepared by the method of any one of claims 1 to 14 or the polymer film of claim 15 is used in membrane separation.

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