Liquid crystal elastomer flexible device and preparation method and application thereof

Abstract

The present invention provides a liquid crystal elastomer flexible device and its preparation method and application, the preparation method comprises the following steps: step S1, preparing a self-repairing liquid crystal elastomer by introducing one or more of dynamic covalent bonds, supramolecular effects or pre-embedded reactive groups into liquid crystal molecules; step S2, overlapping at least two self-repairing liquid crystal elastomer parts, and ultrasonic welding the overlapping parts by applying pressure at room temperature; the self-repairing liquid crystal elastomer is one or more of liquid crystal systems that respond to different stimuli such as heat, light, electricity, magnetism and humidity. The technical solution of the present invention is to design and prepare a self-repairing, weldable liquid crystal elastomer, and to achieve low-temperature, rapid and efficient construction of a complex three-dimensional structure actuator by room temperature and rapid ultrasonic welding, and ultrasonic welding can improve the efficiency of solid phase bonding, effectively maintain the orientation of liquid crystal molecules, and improve the driving stability of the liquid crystal elastomer.

Description

Technical Field

[0001] The present invention belongs to the technical field of intelligent polymer materials, and in particular to a liquid crystal elastomer flexible device and a preparation method and application thereof. Background Art

[0002] In recent years, liquid crystal elastomers (LCEs) have the advantages of high specific strength and fatigue resistance, as well as the synergistic effect of their liquid crystal orientation and cross-linking network, which has extremely sensitive response deformation ability to the environment. They are widely used in flexible actuators, soft robots and other fields, and have attracted great attention from scientific researchers. The function of flexible actuators depends largely on their shape changes, and the complexity of their shapes is crucial to related application fields. However, due to the insoluble and infusible characteristics of the liquid crystal cross-linking network after molding, the traditional preparation process of liquid crystal elastomers is limited to the preparation of two-dimensional film samples, which can only produce simple telescopic and bending actuation, and it is difficult to construct complex three-dimensional structure actuators. Recently, domestic and foreign scholars have achieved the welding assembly of self-healing liquid crystal elastomers by introducing dynamic covalent bonds and pre-embedded reactive groups in the liquid crystal cross-linking system. This is an effective strategy for constructing liquid crystal elastomer complex structure actuators. Up to now, the welding assembly process of liquid crystal elastomers still has problems such as high processing temperature and long processing time. The welding process may lead to a decrease in liquid crystal orientation and a decrease in driving stability. Related research only focuses on the chemical modification of the dynamic cross-linking network and the regulation of material composition, which makes it difficult to achieve a balance between processability and driving stability. How to improve the reaction rate of the solid-phase interface of liquid crystal elastomers and efficiently prepare complex three-dimensional structure actuators is the key to promoting the application of soft robots in related fields, and it is also a difficult point in research. Summary of the invention

[0003] In response to the above technical problems, the present invention discloses a liquid crystal elastomer flexible device and its preparation method and application. By introducing an external ultrasonic energy field to promote the solid-phase bonding of the liquid crystal dynamic cross-linking network, a complex three-dimensional structure actuator can be constructed at low temperature, quickly and efficiently. On this basis, the welding assembly of complex structure liquid crystal elastomers is studied to realize the composite drive of the actuator in multiple modes (stretching, bending, twisting, etc.) and multiple stimuli (heat, light, etc.), and promote the application and development of key technologies in the fields of micro-electromechanical systems, soft robots, etc.

[0004] To this end, the technical solution adopted by the present invention is:

[0005] A method for preparing a liquid crystal elastomer flexible device comprises the following steps:

[0006] Step S1, preparing a self-healing liquid crystal elastomer by introducing one or more of dynamic covalent bonds, supramolecular interactions or pre-embedded reactive groups into liquid crystal molecules;

[0007] Step S2, after overlapping at least two self-repairing liquid crystal elastomer parts, applying pressure to the overlapping parts at room temperature for ultrasonic welding; wherein the self-repairing liquid crystal elastomer is one or more liquid crystal systems that respond to different stimuli such as heat, light, electricity, magnetism, and humidity.

[0008] This technical solution is adopted to design and prepare self-repairing and weldable liquid crystal elastomers with excellent mechanical properties and responsiveness, and to realize the low-temperature, fast and efficient construction of complex three-dimensional structure actuators through room temperature and fast ultrasonic welding technology. The ultrasonic welding technology used utilizes the high-frequency vibration of ultrasound to convert the ultrasonic energy field into friction work and deformation energy between liquid crystal elastomers under positive load, and makes the welding interface infinitely close through limited temperature rise and plastic deformation, so that diffusion and bonding occur, and a reliable solid-phase connection is formed after cooling. Among them, the ultrasonic welding technology is selected from spot welding and roll welding. Moreover, compared with traditional solid-phase connection methods (hot plate welding, etc.), ultrasonic welding has the advantages of low welding temperature (room temperature), short welding time (<1s), and high production efficiency. In addition, the ultrasonic vibration during the welding process and the relative friction of the test piece can improve the solid-phase bonding efficiency, effectively maintain the orientation of liquid crystal molecules, and improve the driving stability of liquid crystal elastomers.

[0009] Furthermore, on this basis, heterogeneous liquid crystal elastomers with different liquid crystal compositions or orientations can be welded and assembled to achieve composite driving of flexible devices in multi-state modes (stretching, bending, twisting, etc.) and multi-field stimulation (heat, light, electricity, etc.), which has great application prospects in wearable devices, micro-electromechanical systems, soft robots and other fields.

[0010] As a further improvement of the present invention, in step S2, the thickness of the self-healing liquid crystal elastomer is 0.01-0.5 mm.

[0011] As a further improvement of the present invention, in step S2, the vibration frequency of ultrasonic welding is 20-40kHz, the amplitude is 1-50μm, the ultrasonic power is not more than 4000W, the ultrasonic time is not more than 10s, and the welding head pressure is 0.5-5MPa. Further, the ultrasonic time is less than 1s, and the shorter the welding time, the better, and the higher the efficiency. Further preferably, the ultrasonic time is less than 0.68s. The specific ultrasonic time is adjusted according to the ultrasonic power, etc.

[0012] As a further improvement of the present invention, step S1 includes: dissolving liquid crystal monomers, self-repairing monomers, fillers, chain extenders, cross-linking agents, and initiators in a solvent, mixing and stirring, and reacting to form a film to obtain a self-repairing liquid crystal elastomer film. The self-repairing monomers include monomers that introduce one or more of dynamic covalent bonds, supramolecular effects, and pre-buried reactive groups.

[0013] As a further improvement of the present invention, the dynamic covalent bond includes at least one of a disulfide bond, a diselenide bond, an ester exchange dynamic bond, and a Diels-Alder dynamic bond; the supramolecular action includes introducing substances containing multiple hydrogen bonds, ionic bonds, and metal coordination bonds or introducing high molecular weight polymers for physical entanglement; the pre-embedded reactive group includes introducing excess acrylate double bonds and photo / thermal initiators or introducing active lipid groups.

[0014] As a further improvement of the present invention, the added amount of the self-healing monomer is 5% to 50% of the molar weight of the liquid crystal monomer, the added amount of the filler is 0.01 to 5wt.% of the total mass of the liquid crystal elastomer, the added amount of the chain extender is 50% to 200% of the molar weight of the liquid crystal monomer; the added amount of the cross-linking agent is 0.5% to 10% of the molar weight of the liquid crystal monomer.

[0015] As a further improvement of the present invention, in step S1, the liquid crystal monomer, self-repairing monomer, filler, chain extender, cross-linking agent and initiator are mixed and dissolved in a solvent, stirred at 30-90°C for 0.5-6h using a magnetic stirrer, fully mixed and dissolved, and then cast in a polytetrafluoroethylene mold; after drying, preliminary polymerization is carried out by thermal initiation or photoinitiation, stretched to 200%-500% of the original length for liquid crystal mechanical orientation, and then completely cured by thermal initiation or photoinitiation to obtain a self-repairing liquid crystal elastomer film.

[0016] As a further improvement of the present invention, the solvent is preferably one or more of N,N-dimethylformamide, tetrahydrofuran, ethanol, acetone, chloroform, and dichloromethane.

[0017] As a further improvement of the present invention, the liquid crystal monomer may be selected to have a molecular structure that responds to stimuli such as heat, light, electricity, magnetism, and humidity.

[0018] The order of the thermotropic liquid crystal elastomer is dependent on the change of temperature. Further, the liquid crystal monomer may include a biphenyl liquid crystal unit, a stilbene liquid crystal unit or a benzoate liquid crystal unit. Further preferably, the benzoate liquid crystal unit includes at least one of 1,4-bis-[4-(3-acryloxypropoxy)benzoyloxy]-2-methylbenzene (RM257) and 1,4-bis-[4-(6-acryloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82).

[0019] The photoresponsive liquid crystal elastomer is a liquid crystal unit (such as azobenzene) whose molecular configuration changes when light is absorbed, causing the orientation of the liquid crystal network to be disordered, thereby causing deformation. It is also possible to compound the photothermal conversion particles (graphene, carbon nanotubes, etc.) with the thermal responsive liquid crystal elastomer, so that light is absorbed by the conversion particles and heated in situ to the phase transition temperature, causing deformation.

[0020] Electromagnetic response liquid crystal elastomer is a liquid crystal elastomer that contains carbon black conductive particles, ferroferric oxide magnetic particles, etc., which indirectly generates heat under the action of external electric and magnetic fields, and in situ heats the liquid crystal elastomer to the phase transition temperature, causing it to undergo macroscopic deformation. Humidity response liquid crystal elastomer: The film surface expands through the hydration of hydrophilic C=O and COC groups in the liquid crystal, and the liquid crystal orientation changes, causing the entire film to undergo macroscopic deformation.

[0021] As a further improvement of the present invention, the filler includes one or a mixture of micro-nano silicon dioxide, titanium dioxide, carbon black, graphene, carbon nanotubes, MXene, silver nanomaterials, gold nanomaterials, and ferroferric oxide magnetic particles. In the technical solution of the present invention, the essence of ultrasound is a mechanical wave, which must be transmitted through a medium to couple energy to the interface and interior of the material to be formed. In order to ensure that the ultrasonic effect is maximized, the composite filler can further optimize the mechanical properties, thermal conductivity and acoustic conductivity of the liquid crystal elastomer, and adapt to the ultrasonic welding process.

[0022] As a further improvement of the present invention, the chain extender includes a low molecular weight bifunctional compound containing hydroxyl, amino, and thiol. Further, the chain extender includes butanediol, ethylenediamine, 2,2'-(1,2-ethylenedioxy)diethylmercaptan (EDDET), and the like.

[0023] As a further improvement of the present invention, the crosslinking agent includes a multifunctional compound containing a hydroxyl group, an amino group, a thiol group, a carbon-carbon double bond, etc. Further, the crosslinking agent includes triallyl isocyanurate (TATATO), pentaerythritol tetrakis (3-mercaptopropionate) (PETMP), etc.

[0024] The present invention also discloses a flexible device based on liquid crystal elastomer, which is prepared by using any of the above methods for preparing a liquid crystal elastomer flexible device.

[0025] The present invention also discloses the application of the above-mentioned flexible device based on liquid crystal elastomer, which is used in the fields of wearable devices, micro-electromechanical systems, and soft robots. Furthermore, it is preferably used in the preparation of actuators, smart switches, sensors, bionic materials, and electronic skin.

[0026] The present invention further adopts the above-mentioned technical features, which has the advantage that by introducing an ultrasonic energy field to increase the rate of solid-phase interface bonding, the welding temperature and welding time can be greatly reduced, and complex structure liquid crystal elastomer flexible devices can be efficiently prepared.

[0027] Furthermore, the liquid crystal elastomer flexible device of the technical solution of the present invention is welded and assembled by heterogeneous liquid crystal elastomers with different orientation directions, different driving modes, and different driving temperatures, so as to realize the multiple compound driving of the actuator in multi-state modes (stretching, bending, twisting, etc.) and multi-field stimulation (heat, light, electricity, etc.), such as intelligent mechanical arms with dual control of light and heat, etc. It can also be combined with the structural design of flexible electronic devices to convert the actuation function into electrical signals, and expand the intelligent application of liquid crystal elastomers in the fields of micro-electromechanical systems, soft robots, etc.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] First, the technical solution of the present invention designs and prepares self-repairing and weldable liquid crystal elastomers, and realizes low-temperature, rapid and efficient construction of complex three-dimensional structure actuators through room temperature and rapid ultrasonic welding. In addition, the use of ultrasonic welding can improve the solid-phase bonding efficiency, effectively maintain the orientation of liquid crystal molecules, and improve the driving stability of liquid crystal elastomers.

[0030] Second, the technical solution of the present invention, aimed at the design and development of complex structure devices of liquid crystal elastomers, first proposes to introduce ultrasonic energy fields to improve the efficiency of welding and assembly of liquid crystal elastomers, greatly reduce welding temperature and welding time, and optimize the quality of welded assembly joints by combining material modification, process parameter improvement and other means. At the same time, the ultrasonic vibration and relative friction of the test piece are cleverly used to effectively maintain the orientation of liquid crystal molecules and improve the driving stability of liquid crystal elastomers, which is of great significance to the expansion of liquid crystal elastomer orientation processing technology. In addition, the present invention can flexibly replace the liquid crystal group as needed, and expand the above working mechanism to flexible devices that respond to different stimuli such as heat, light, electricity, magnetism, and humidity. For liquid crystal elastomers, assembling single-domain samples with different orientation directions, different driving modes, and different driving temperatures together has the advantages of simple operation, flexible and complex driving modes, and customizable deformation methods, laying a solid experimental theoretical foundation for practical applications in the fields of wearable devices, micro-electromechanical systems, and soft robots. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 These are actual photographs of the self-healing liquid crystal elastomer molecules in Example 1 of the present invention being driven to deform under heating, infrared light or ultraviolet light, wherein (a) is heating or infrared light, and (b) is ultraviolet light.

[0032] Figure 2 Graph showing the stress-strain curve of the liquid crystal elastomer before and after welding in Example 2 of the present invention.

[0033] Figure 3 This is a scanning electron microscope photograph (SEM image) of the cross section of the liquid crystal elastomer before and after welding in Example 2 of the present invention.

[0034] Figure 4 This is a relationship diagram between the shear failure load and welding time of the joint of the liquid crystal elastomer in Example 2 of the present invention.

[0035] Figure 5 This is a two-dimensional wide-angle X-ray diffraction pattern (2DXRD pattern) of the liquid crystal elastomer before and after welding in Example 2 of the present invention.

[0036] Figure 6 Schematic diagram of the application of complex structure liquid crystal elastomer in Example 3 of the present invention in a multi-degree-of-freedom intelligent soft robot. DETAILED DESCRIPTION

[0037] The preferred embodiments of the present invention are described in further detail below.

[0038] Example 1

[0039] Preparation of self-healing liquid crystal elastomer based on disulfide-silver nanowire coordination bonds.

[0040] A self-repairing, weldable liquid crystal elastomer based on disulfide-silver nanowire coordination bonds, the system contains both disulfide dynamic covalent bonds (SS) and silver-sulfur coordination supramolecular effects (Ag-S), and the preparation method specifically includes the following steps:

[0041] Weigh 734.6 mg of liquid crystal monomer 1,4-bis-[4-(3-acryloxypropoxy)benzoyloxy]-2-methylbenzene (RM257), 36.1 mg of self-healing monomer N,N'-bis(acryl)cystamine (BACA), 230.0 mg of chain extender 2,2'-(1,2-ethylenedioxy)bis(ethylenethiol) (EDDET), 30.5 mg of cross-linker pentaerythritol tetrakis(3-mercaptopropionic acid) ester (PETMP), and 20.6 mg of silver nanowires using an analytical balance and pour them into a glass bottle. Use a syringe to take 4 mL of N,N-dimethylformamide solvent and add it to the glass bottle. Use a magnetic stirrer to stir the mixed solution at room temperature for 1 hour until the solute is evenly dispersed. Then, photoinitiator irgacure 651 and catalyst dipropylamine were added to the mixed solution, ultrasonically vibrated for 3 minutes, and quickly injected into a polytetrafluoroethylene mold with a size of 50mm×20mm×15mm, and dried at 60°C for 12 hours. After drying, the liquid crystal elastomer prepolymer was torn off with tweezers, stretched to twice its original length and fixed with a clamp (mechanical orientation), and completely cured after irradiation with 365nm ultraviolet light for 2 hours to obtain a self-healing, weldable liquid crystal elastomer film.

[0042] Among them, the molecular structure formula of the liquid crystal monomer is as follows:

[0043]

[0044] The molecular structure of the self-healing monomer is as follows:

[0045]

[0046] The molecular structure of the chain extender is as follows:

[0047]

[0048] The molecular structure of the cross-linking agent is as follows:

[0049]

[0050] The self-repairing and weldable liquid crystal elastomer film described in this embodiment can be heated in situ under 808nm infrared light due to the infrared photothermal effect of silver nanowires, and shrink and deform. Figure 1 (a) shown.

[0051] In this embodiment, the thermally responsive liquid crystal monomer RM257 is replaced with a photoresponsive azobenzene liquid crystal monomer, such as 4,4'-bis[11-(acryloyloxy)undecyloxy]azobenzene, etc., to prepare a self-repairing and weldable liquid crystal elastomer film that is deformed in response to ultraviolet light, such as Figure 1 (b) as shown.

[0052] The molecular structure of azobenzene liquid crystal monomer is as follows:

[0053]

[0054] In this embodiment, the self-repairing monomer is replaced with one or more molecular structures of other dynamic covalent bonds, supramolecular effects, and pre-embedded reactive groups to achieve similar self-repairing and weldable effects.

[0055] The molecular structure of the diselenide-containing dynamic covalent bond self-repairing monomer is as follows:

[0056]

[0057] The molecular structure of the borate-containing dynamic covalent bond self-healing monomer is as follows:

[0058]

[0059] The molecular structure of the self-healing monomer containing hydrogen bond supramolecular action is as follows:

[0060]

[0061] Pre-embedded reactive groups: Without adding self-repairing monomers, the molar equivalent of carbon-carbon double bonds in the liquid crystal monomer RM257 is 1.2 to 2 times the molar equivalent of thiol groups in the system.

[0062] Example 2

[0063] The self-repairing liquid crystal elastomer is subjected to efficient ultrasonic welding at room temperature to obtain a liquid crystal elastomer flexible device.

[0064] This embodiment introduces an ultrasonic energy field to efficiently weld and assemble the self-repairing, weldable liquid crystal elastomer film obtained in Example 1 at room temperature, and tests the tensile strength and other mechanical properties of the joint. Specifically, the following steps are included:

[0065] The working mode of the ultrasonic welder is the energy mode. The edges of two randomly cut liquid crystal elastomer films are overlapped by 2-3mm and fixed on the workbench of the ultrasonic welder. The sample thickness is about 300μm. The main ultrasonic welding parameters include an amplitude of 20μm, a welding pressure of 5psi, a frequency of 20kHz, and welding energy ranging from 50J to 300J. According to the equivalent relationship between welding energy and time, once the welding power is recognized by the ultrasonic welder, the welding time (0.17-0.82 seconds) can be automatically determined by the instrument. For example, when the welding energy is set to 250J, the liquid crystal elastomer film can be welded within 0.68 seconds without the need for additional heat input or protective atmosphere. The tensile properties of the liquid crystal elastomer before and after welding are shown in Figure 2. Figure 2 As shown, excellent joint quality is demonstrated.

[0066] The scanning electron microscope photos (SEM images) of the cross-sections of the liquid crystal elastomer before and after welding in this embodiment are as follows: Figure 3 As shown, the weld seam almost completely disappears, proving that seamless welding is achieved.

[0067] The relationship between the shear failure load and welding time of the joint of the liquid crystal elastomer described in this embodiment is shown in the figure. Figure 4 As shown, it can be seen that the shear failure load of the lap joint first increases with the continuous input of welding energy until it reaches the maximum strength of 0.97±0.04N (welding time is 0.68s). When the welding interface strength is sufficient to resist the shear force borne during the stretching process, the thinning of the matrix material caused by the embedding of the ultrasonic pressure head or the base is a key factor restricting the further improvement of the joint strength. Excessive thinning in local areas will cause stress concentration in the lap shear test, and ultimately weaken the bearing capacity of the joint. It can be seen that in this embodiment, when the welding time exceeds 0.68s, the joint fracture will be transformed from interface fracture to through-thickness fracture. Similarly, excessive ultrasonic amplitude and welding pressure will also cause damage to the liquid crystal elastomer during the ultrasonic welding process.

[0068] The two-dimensional wide-angle X-ray diffraction pattern (2D XRD pattern) of the liquid crystal elastomer before and after welding in this embodiment is as follows: Figure 5As shown, the uniaxially oriented liquid crystal elastomer produces two high-intensity arc-shaped areas on the diffraction ring, indicating that due to the friction of ultrasonic high-frequency vibration at the welding interface, the liquid crystal elastomer can maintain its orientation during the welding process, ensuring stable driving for subsequent applications.

[0069] Example 3

[0070] Smart applications of complex structured liquid crystal elastomers.

[0071] This embodiment provides an application idea of ​​the complex structure liquid crystal elastomer in the field of intelligent flexible devices as in the above embodiment 1. Specifically:

[0072] By regulating the orientation direction and heterogeneous structure of the liquid crystal elastomer, various actuation modes such as stretching, bending, and twisting can be achieved. The thermally responsive liquid crystal elastomer with twisting motion and four ultraviolet light responsive liquid crystal elastomer "claws" with bending motion are welded and assembled to prepare a multi-degree-of-freedom intelligent soft robot, such as Figure 6 As shown. Among them, the twisting component is integrated by ultrasonic welding of two layers of liquid crystal elastomer films with mutually perpendicular liquid crystal orientations, and the welded double-layer films are cut at a 45° direction relative to the liquid crystal orientation. The bending component is integrated by ultrasonic welding of a layer of oriented liquid crystal elastomer and a layer of non-oriented liquid crystal elastomer, and is cut along the liquid crystal orientation direction. Under infrared light irradiation and heating conditions, the thermally responsive liquid crystal elastomer twists and rotates, so that the "claws" that respond to ultraviolet light are aimed at the target object. Under ultraviolet light irradiation, the "claws" bend and lock the target object, which can realize remote control of the object. The liquid crystal elastomer is further compounded with conductive particles, piezoelectric polymers and other materials, combined with the structural design of flexible electronic devices (such as resistive, piezoelectric, etc.), and the contraction stress is converted into an electrical signal. Based on the Internet of Things technology, the device is connected to the single-chip microcontroller circuit to realize the actuation / sensing integration function of the liquid crystal elastomer flexible device, and the movement of the soft robot is monitored in real time.

[0073] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for preparing a liquid crystal elastomer flexible device, characterized in that: The steps include: Step S1, preparing a self-healing liquid crystal elastomer by introducing one or more of dynamic covalent bonds, supramolecular interactions or pre-embedded reactive groups into liquid crystal molecules; Step S2, overlapping at least two self-repairing liquid crystal elastomer parts, and then applying pressure to the overlapping parts at room temperature for ultrasonic welding; wherein the self-repairing liquid crystal elastomer is a liquid crystal system responsive to heat, light, electricity, magnetism or humidity stimulation; In step S2, the thickness of the self-repairing liquid crystal elastomer is 0.01-0.5 mm, the vibration frequency of ultrasonic welding is 20-40 kHz, the amplitude is 1-50 μm, the ultrasonic power is not more than 4000 W, the ultrasonic time is not more than 10 s, and the welding head pressure is 0.5-5 MPa; Step S1 comprises: dissolving liquid crystal monomers, self-repairing monomers, fillers, chain extenders, cross-linking agents, and initiators in a solvent, mixing and stirring, and reacting to form a film to obtain a self-repairing liquid crystal elastomer film; wherein the self-repairing monomers include monomers that introduce one or more of dynamic covalent bonds, supramolecular effects, and pre-buried reactive groups; The amount of the self-repairing monomer added is 5% to 50% of the molar amount of the liquid crystal monomer, the amount of the filler added is 0.01 to 5 wt.% of the total mass of the liquid crystal elastomer, the amount of the chain extender added is 50% to 200% of the molar amount of the liquid crystal monomer; the amount of the cross-linking agent added is 0.5% to 10% of the molar amount of the liquid crystal monomer; The dynamic covalent bond includes at least one of a disulfide bond, a diselenide bond, an ester exchange dynamic bond, and a Diels-Alder dynamic bond; the supramolecular action includes introducing substances containing multiple hydrogen bonds, ionic bonds, and metal coordination bonds or introducing high molecular weight polymers for physical entanglement; the pre-embedded reactive group includes introducing excess acrylate double bonds and photo / thermal initiators or introducing active lipid groups.

2. The method for preparing a liquid crystal elastomer flexible device according to claim 1, characterized in that: In step S1, a liquid crystal monomer, a self-healing monomer, a filler, a chain extender, a cross-linking agent, and an initiator are mixed and dissolved in a solvent, stirred at 30 to 90° C. for 0.5 to 6 h using a magnetic stirrer to fully mix and dissolve, and then a film is cast in a polytetrafluoroethylene mold; After drying, the film is initially polymerized by thermal initiation or photoinitiation, stretched to 200% to 500% of its original length for liquid crystal mechanical orientation, and then completely cured by thermal initiation or photoinitiation to obtain a self-repairing liquid crystal elastomer film.

3. The method for preparing a liquid crystal elastomer flexible device according to claim 2, characterized in that: The liquid crystal monomers include biphenyl liquid crystal units, distilbene liquid crystal units or benzoate liquid crystal units.

4. The method for preparing a liquid crystal elastomer flexible device according to claim 3, characterized in that: The benzoate-based liquid crystal element includes at least one of 1,4-bis-[4-(3-acryloxypropoxy)benzoyloxy]-2-methylbenzene and 1,4-bis-[4-(6-acryloxyhexyloxy)benzoyloxy]-2-methylbenzene.

5. The method for preparing a liquid crystal elastomer flexible device according to claim 2, characterized in that: The filler includes at least one of micro-nano silicon dioxide, titanium dioxide, carbon black, graphene, carbon nanotubes, MXene, silver nanomaterials, gold nanomaterials, and ferroferric oxide magnetic particles; the chain extender includes at least one of butanediol, ethylenediamine, and 2,2'-(1,2-ethylenedioxy)bis(ethylenethiol); and the cross-linking agent includes at least one of triallyl isocyanurate and pentaerythritol tetrakis(3-mercaptopropionate).

6. A liquid crystal elastomer flexible device, characterized in that: The liquid crystal elastomer flexible device is prepared by the preparation method of the liquid crystal elastomer flexible device according to any one of claims 1 to 5.

7. The use of the liquid crystal elastomer flexible device according to claim 6, characterized in that: Used in the fields of wearable devices, micro-electromechanical systems, and soft robots.

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