Ferroelectric nematic liquid crystal molecule and preparation method and application thereof
By designing ferroelectric nematic liquid crystal molecules with strong second harmonic response characteristics, the problem of instability of traditional liquid crystal materials at room temperature was solved, stable spontaneous polarization switching at room temperature was achieved, and its application in optical and flexible storage fields was expanded.
Patent Information
- Application Number
- CN202510768580.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-10
- Publication Date
- 2025-09-12
AI Technical Summary
Traditional nematic liquid crystal materials lack ferroelectric properties and are difficult to exist stably at room temperature, which limits their application range. In addition, the phase transition process is complex, making it difficult to study polar topology and spin topology structures.
A ferroelectric nematic liquid crystal molecule was designed. Its unique molecular structure gives it strong second harmonic response characteristics, and spontaneous polarization is achieved on the layered structure, simplifying it into a ferroelectric nematic phase that is stable at room temperature. It can achieve spontaneous polarization structure switching and maintain stability under a small electric field.
The realization of room-temperature stable ferroelectric nematic liquid crystal materials has enhanced the controllability and stability of the material's electric field response, expanded its application in optics and flexible storage, and provided a material basis for new optical devices.
Smart Images
Figure CN120624031A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of optoelectronic materials, and in particular relates to a ferroelectric nematic liquid crystal molecule and a preparation method and application thereof. Background Art
[0002] Liquid crystals, as a key optoelectronic material, play a vital role in fields such as optoelectronic displays and spatial light modulation. Traditional nematic liquid crystals possess only orientational order, lacking positional order. While individual molecules possess a permanent dipole moment, the director has an equal probability of being distributed upward and downward, causing the polarities of the entire liquid crystal system to cancel each other out. This lack of ferroelectric properties poses certain limitations for improving core technical indicators such as dielectric constant and electric field response speed, as well as for developing new optoelectronic functions.
[0003] In 2017, Richard Mandle and John Goodby at the University of York in the UK successfully synthesized a wedge-shaped molecule, RM734, with a large electric dipole. Their research revealed that while the molecule exhibits a normal nematic phase at high temperatures, at low temperatures (below 133°C), it exhibits a novel nematic structure with ferroelectric characteristics. This structure involves the molecular arrangement generating spontaneous polarization, and the spatial distribution of the nematic molecular dipole moments becomes ordered, forming domains with specific orientations. That same year, Hiroya Nishikawa of the RIKEN Institute in Japan discovered a polar nematic liquid crystal, DIO, with an extremely high dielectric constant and exhibiting properties such as a strong second harmonic response. This novel ferroelectric nematic liquid crystal, upon entering this phase, undergoes spontaneous polarization, generating microscopic polarization domains and macroscopic electric polarization. The resulting structure exhibits transformative physical properties, including high dielectric constant, strong ferroelectricity, nonlinear optical response, low electric field response, and ultra-strong external field shielding. This opens new possibilities for the development of advanced optical and electrical liquid crystal devices and is attracting widespread attention in the field of soft matter.
[0004] However, fundamental research on this new nematic phase is still in its infancy. Most ferroelectric nematic liquid crystal materials undergo a phase transition from liquid phase (Iso) to non-polar nematic phase (N) and then to ferroelectric nematic phase (NF), which to some extent limits the study of their polar and spin topological structures. Moreover, such ferroelectric nematic liquid crystals are generally difficult to exist stably at room temperature, which greatly restricts the practical application of such liquid crystal materials. In addition, traditional liquid crystal molecules are restricted by symmetry, making it difficult to achieve ferroelectricity, which limits the research and application scope of ferroelectric liquid crystal materials. The development of ferroelectric liquid crystal materials with good room temperature stability and a wide phase transition temperature has become an important research direction in the field of optoelectronic materials. Summary of the Invention
[0005] The purpose of the present invention is to provide a ferroelectric nematic liquid crystal molecule and its preparation method and application, which overcomes the shortcomings of the existing technology. Through unique molecular design, it is given a strong second harmonic response characteristic, fills the shortcomings of traditional liquid crystal materials in nonlinear optical performance, and provides a new molecular basis for the development of new optical devices.
[0006] In order to solve the above problems, the technical solutions adopted by the present invention are as follows:
[0007] A ferroelectric nematic liquid crystal molecule, wherein the structural formula of the ferroelectric nematic liquid crystal molecule is:
[0008]
[0009] The present invention also provides a method for preparing the above-mentioned ferroelectric nematic liquid crystal molecules. The reaction process of the ferroelectric nematic liquid crystal molecules is as follows:
[0010]
[0011] Finally, the present invention protects a liquid crystal medium comprising the above-mentioned ferroelectric nematic liquid crystal molecules.
[0012] Furthermore, the liquid crystal medium is used for electro-optical purposes.
[0013] Furthermore, the electro-optical purpose refers to a nonlinear perfect vector light beam generating element, a preparation method and an application.
[0014] Furthermore, the electro-optical purpose is to be used to manufacture supercapacitors and electromechanical devices including generators and actuators.
[0015] Furthermore, the electro-optical purpose refers to the use for manufacturing nonlinear optical components, sensors or storage devices.
[0016] Furthermore, the electro-optical purpose refers to the manufacture of electro-optical liquid crystal displays and wearable smart devices.
[0017] Compared with the prior art, the present invention has the following beneficial effects:
[0018] The ferroelectric nematic liquid crystal molecules of the present invention can spontaneously polarize on the basis of a layered structure and exhibit macroscopic polarity; through a unique molecular design, they are endowed with strong second harmonic response characteristics, filling the deficiencies of traditional liquid crystal materials in nonlinear optical performance and providing a new molecular basis for the development of new optical devices.
[0019] This invention pioneers a room-temperature stable ferroelectric nematic liquid crystal material. Unlike similar materials that require complex phase transitions, this material can directly enter the ferroelectric nematic phase. It exhibits ultrahigh sensitivity to minute electric fields, enabling spontaneous polarization structure switching through in-plane electric fields. This polarization structure remains stable even after the electric field is removed, significantly enhancing the controllability and stability of the material's electric field response.
[0020] The ferroelectric nematic liquid crystal of the present invention has both ferroelectric properties and good fluidity, and can achieve morphological adjustability and efficient data storage in the field of flexible storage; in the field of optics, it provides a new material option for the preparation of nonlinear perfect vector light beam generating elements, expanding the application boundaries and scenarios of ferroelectric materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 Schematic diagram of the molecular structure of a ferroelectric nematic liquid crystal molecule.
[0022] Figure 2 A ferroelectric nematic liquid crystal molecule 1 H NMR spectrum.
[0023] Figure 3 This is a line graph of the DSC results of a ferroelectric nematic liquid crystal molecule.
[0024] Figure 4 Schematic diagram of the liquid crystal molecular orientation of the nonlinear perfect vector light beam generating element prepared by the present invention.
[0025] Figure 5 This is the texture image of the nonlinear perfect vector beam generating element prepared by the present invention under a polarizing microscope. DETAILED DESCRIPTION
[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0027] Example 1
[0028] This embodiment discloses a method for preparing ferroelectric nematic liquid crystal molecules:
[0029] The reaction process is:
[0030]
[0031] 2-Propoxybenzoic acid 20g, 2-fluoro-4-hydroxybenzaldehyde 15.5g, DMAP 0.5g, and dichloromethane 200ml were added to a 500ml three-necked flask, and the temperature was lowered to 0°C while stirring. A dichloromethane solution of DCC (30g DCC dissolved in 100ml dichloromethane) was added dropwise. The temperature was controlled at 0-10°C during the addition. After the addition was completed, the temperature was kept at 10°C for 12h, then filtered, and the filtrate was added with 30% hydrogen peroxide, tempo, and sodium dihydrogen phosphate. Then, an aqueous sodium chlorite solution was added dropwise. After the addition was completed, the temperature was kept for 2h. The mixture was allowed to stand and stratify. The organic layer was concentrated to dryness, recrystallized from ethyl acetate, and dried to obtain 28.2g of the intermediate with a yield of 79.8%.
[0032] 16 g of the intermediate acid, 7.8 g of 3,5-difluoro-4-cyanophenol, 0.5 g of DMAP, and 200 ml of dichloromethane were added to a 500 ml three-necked flask, stirred, and cooled to 0°C. A dichloromethane solution of DCC (15 g of DCC dissolved in 50 ml of dichloromethane) was added dropwise. The temperature was controlled at 0-10°C during the addition. After the addition was completed, the mixture was kept at 10°C for 12 hours, then filtered, and the filtrate was washed with water and concentrated to dryness to obtain an oily substance. The oily substance was passed through a 1 / 4 EA / PE column and recrystallized to obtain 17.4 g of the ferroelectric nematic liquid crystal molecule with a yield of 76%. Its structural formula is shown in FIG. Figure 1 , Figure 2 For this compound 1 H NMR spectrum, Figure 3 Figure 1 DSC of the medium structure.
[0033] Example 2
[0034] This embodiment discloses an application of ferroelectric nematic liquid crystal molecules for electro-optical purposes, which refers to a nonlinear perfect vector light beam generating element, a preparation method, and an application.
[0035] The nonlinear perfect vector beam generating element includes a first glass substrate, a first optical alignment layer, a ferroelectric nematic liquid crystal layer, a second optical alignment layer, and a second glass substrate. The first and second optical alignment layers are applied to the first and second glass substrates by spin coating, and the first and second optical alignment layers are provided with nonlinear perfect vector beam control patterns. Spacer particles are placed between the first and second optical alignment layers to control the distance between the first and second optical alignment layers.
[0036] Ultrasonic cleaning of the first and second glass substrates was performed using an ethanol-alcohol solution for 20 minutes. Ultrasonic cleaning was then repeated twice using ultrapure water, each time for 10 minutes. The cleaned substrates were placed in a drying oven set to 140°C for 40 minutes. Finally, the first and second glass substrates were cleaned using UV-ozone for 30 minutes.
[0037] Subsequently, the photo-alignment agent SD1 is spin-coated on the first glass substrate and the second glass substrate. The spin coating method is as follows: the first step of the spin coating has a rotation speed of 3000 rpm and a spin coating time of 40 seconds. The second step of the spin coating has a rotation speed of 300 rpm and a spin coating time of 10 seconds. After the photo-alignment layer prepared by the selected SD1 material is spin-coated on the first glass substrate and the second glass substrate, the first glass substrate and the second glass substrate are placed on a hot plate at a temperature of 100°C to cure the photo-alignment layer for 10 minutes. After curing, the first photo-alignment layer is formed on the side of the first glass substrate, and the second photo-alignment layer is formed on the side of the second glass substrate.
[0038] Silica microspheres mixed with frame sealant were used as spacers. After a uniform mixture, they were applied to both sides of the first optical alignment layer. A second glass substrate, with the second optical alignment layer formed on the side facing the spacer particles, was then placed for encapsulation. The first and second glass substrates were bonded together in a staggered manner and exposed to UV light until the frame sealant cured, forming a liquid crystal cell. The cell thickness was controlled by varying the diameter of the silica microspheres, and the cell thickness of the liquid crystal cell in this example was measured using interferometry.
[0039] Figure 4 This is a schematic diagram of the liquid crystal molecule orientation of the nonlinear perfect vector beam generating element prepared by the present invention. The diagram illustrates the liquid crystal molecule orientation distribution within the first period of the nonlinear perfect vector beam control pattern. Each period consists of two concentric circular rings of equal width, with the orientation angle difference between adjacent circular rings being 90 degrees. The first and second photo-controlled orientation layers are oriented using polarized UV exposure. Azo-based photo-controlled orientation material SD1 is selected as the orientation agent for the first and second photo-controlled orientation layers. Under irradiation with linearly polarized light, the photo-controlled orientation material molecules align perpendicularly to the direction of the linearly polarized light and interact with the liquid crystal molecules to form a specifically designed, ordered arrangement. The liquid crystal material is poured between the first and second glass substrates. The new ferroelectric nematic liquid crystal material NJU001 is heated to 150°C and poured into the liquid crystal cell through a capillary glass tube. Figure 5 This is the texture image of the nonlinear perfect vector beam generating element prepared by the present invention under a polarizing microscope.
[0040] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.
Claims
1. A ferroelectric nematic liquid crystal molecule, characterized in that: The structural formula of the ferroelectric nematic liquid crystal molecule is:
2. A method for preparing ferroelectric nematic liquid crystal molecules according to claim 1, characterized in that: The reaction process of the ferroelectric nematic liquid crystal molecules is as follows:
3. A liquid crystal medium, characterized in that: Contains the ferroelectric nematic liquid crystal molecules according to claim 1 or 2.
4. Use of the liquid crystal medium according to claim 3 for electro-optical purposes.
5. The use according to claim 4, characterized in that: The electro-optical purpose refers to nonlinear perfect vector light beam generating elements, preparation methods and applications.
6. The use according to claim 5, characterized in that: The electro-optical purpose is to use it in the manufacture of supercapacitors and electromechanical devices including generators and actuators.
7. The use according to claim 5, characterized in that: The electro-optical purpose refers to the use in manufacturing nonlinear optical components, sensors or storage devices.
8. The use according to claim 5, characterized in that: The electro-optical purpose is to be used for manufacturing electro-optical liquid crystal displays and wearable smart devices.