Dynamic liquid crystal elastomer material and preparation method of actuator of dynamic liquid crystal elastomer material

Abstract

The invention relates to a preparation method of a dynamic liquid crystal elastomer material and an actuator thereof, and belongs to the technical field of intelligent materials. Aiming at the problems of high driving temperature, high energy consumption, difficulty in repeated processing and the like of a traditional liquid crystal elastomer, the invention provides a dynamic liquid crystal elastomer material driven by near human body temperature or natural light and an actuator of the dynamic liquid crystal elastomer material through material-structure collaborative design, C6BAPE and RM257 are copolymerized and combined with a dynamic Diels-Alder bond cross-linked network, and the dynamic liquid crystal elastomer material and the actuator of the dynamic liquid crystal elastomer material have the advantages of high driving temperature, high energy consumption, difficulty in repeated processing and the like. The nematic phase-isotropic phase transition temperature (Tni) is reduced to 30 DEG C; the photo-thermal response efficiency is improved by introducing the multi-walled carbon nanotubes; the driving strain and the strain rate are amplified through the homochiral twist winding (HOTC) structure design; and the reprogrammability and 3D printing forming of the material are realized through high-temperature decrosslinking. According to the invention, human body temperature or natural light driving actuation is realized, the response rate is improved, the driving energy consumption is reduced, and the device is suitable for self-rolling robots, wearable medical equipment and solar driving devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of intelligent materials, and relates to a method for preparing a dynamic liquid crystal elastomer material and its actuator. Background Art

[0002] The fast, large-amplitude, reversible, and programmable deformation response of liquid crystal elastomers (LCEs) under stimuli (heat, electricity, light, magnetism, etc.) has effectively promoted the development of physical intelligent soft robots. Different from traditional LCE soft robots, traditional LCE soft robots require intermittent stimuli and continuous human / instrument intervention to move continuously. Physical intelligent LCE actuators adopt a new paradigm: they work autonomously, continuously, and adaptively in an environment without human control (intermittent stimuli and continuous human / instrument intervention) through built-in sensing, judgment, action, and regulation processes. For example, self-sustaining LCE actuators, such as self-excited oscillators, self-rollers, self-walkers, self-swimmers, self-rotators, and self-dancers, can deform periodically or move continuously when exposed to a static light beam or heat source. These devices demonstrate motion autonomy, allowing amplified work output, continuous energy generation, self-escape from mazes, and exploration of enclosed spaces.

[0003] In a physical intelligent autonomous system, the sustainable mechanical work output by the actuator requires a sustainable energy input. Since the transition temperature from liquid crystal anisotropy to isotropy needs to be particularly high, current self-sustaining LCE actuators usually rely on high-power artificial energy sources (such as high temperature and strong light). Maintaining these high-intensity energy sources over a large area or for a long time is challenging and easily causes thermal or light damage to the surrounding environment, making these drive systems impractical and unsafe for current applications, while wasting energy and not conforming to the concept of sustainable development.

[0004] In recent years, significant progress has been made in the research of LCE self-sustaining drivers, especially in the design and application of self-excited oscillators and self-sustaining walkers. However, current research still faces some challenges, such as deficiencies in driving conditions, efficiency, and intelligence. Traditional liquid crystal elastomers (LCEs) usually require high-energy artificial light sources or high temperatures to drive, which limits their feasibility and safety in practical applications. Traditional LCEs often exhibit low actuation strain rates and amplitudes under low-temperature conditions, making it difficult to achieve stable self-sustaining motion. Traditional LCEs are prone to structural damage during repeated use, affecting their long-term stability and reliability. The processability and flexibility of traditional LCEs are limited, making it difficult to fabricate complex structures. The application range of traditional LCEs is limited and difficult to meet various practical needs. Summary of the Invention

[0005] In view of this, to solve this problem, the present invention provides a carbon nanotube-doped LCE with low Tni and reversible Diels-Alder crosslinking, called DALCE-CNT (reconfigurable dynamic liquid crystal elastomer), which can be (re)processed into a specific structure (e.g., twisted winding or bimorph shape). By utilizing the material-structure synergy effect, both low Tni and high driving strain rate are achieved, thus realizing self-rolling, self-breathing, and autonomous twisting-untwisting motions driven by environmental / body temperature or natural sunlight. This low-energy, self-sustaining actuator design opens up new possibilities for LCE-based biomedical applications and nature-driven automatic devices. One of the objectives of the present invention is to provide a dynamic liquid crystal elastic material, the second objective is to provide a preparation method of the dynamic liquid crystal elastic material, and the third objective is to provide a dynamic liquid crystal elastic actuator.

[0006] To achieve the above objectives, the present invention provides the following technical solutions:

[0007] The present invention provides a dynamic liquid crystal elastomer material, and the chemical structural formula of the dynamic liquid crystal elastomer material is shown as follows:

[0008]

[0009] Preferably, the dynamic liquid crystal elastomer material is synthesized from RM257, C6BAPE, 2-phenylethylamine, furfurylamine, and BMI as raw materials;

[0010] Furthermore, a preparation method of the dynamic liquid crystal elastomer material comprises the following steps:

[0011] Synthesis of liquid crystal prepolymer: Mix RM257, C6BAPE, 2-phenylethylamine, and furfurylamine in a three-neck flask, deoxygenate for 15 minutes, and then heat and stir at 100 °C for 24 hours;

[0012] Synthesis of dynamic liquid crystal elastomer material: Mix the liquid crystal prepolymer with BMI and react in dichloromethane to form the dynamic liquid crystal elastomer material;

[0013] The mass ratio of RM257 is a%, the mass ratio of C6BAPE is b%, the total molar ratio of 2-phenylethylamine in 2-phenylethylamine and furfurylamine is x%, and the total molar ratio of furfurylamine in 2-phenylethylamine and furfurylamine is (a + b - x)%, wherein a + b = 100, b is any one of 0, 25, 50, 75, 100, and x = 50;

[0014] In the synthesis of the dynamic liquid crystal elastomer material, the molar ratio of amino group to acrylate group is 1:2;

[0015] The molar ratio of furyl group to BMI is 8:1, and the ratio of phenyl group to furyl group is 5:5;

[0016] Further, a doped carbon nanotube dynamic liquid crystal elastomer material, which is composed of a dynamic liquid crystal elastomer material and carbon nanotubes, and the content of the carbon nanotubes is 4 wt%.

[0017] The doped carbon nanotube dynamic liquid crystal elastomer material is prepared as follows: The carbon nanotubes are ultrasonically treated in dichloromethane, then added to the liquid crystal prepolymer and ultrasonically treated again, and finally BMI is added and mixed evenly, and then cast to prepare. Further, a homochiral twisted and coiled fiber actuator, which is composed of a dynamic liquid crystal elastomer material or a doped carbon nanotube dynamic liquid crystal elastomer material;

[0018] Further, the preparation steps of the homochiral twisted and coiled fiber actuator are as follows:

[0019] Raw material preparation: Heat the doped nanotube dynamic liquid crystal elastomer material to 125 °C for 15 minutes to de-crosslink. Actuator preparation: Use a 3D printer and a KR2-15 nozzle, print and then stretch and twist at room temperature, store at 4 °C for 24 hours for initial crosslinking, and then store at room temperature for 3 days to complete crosslinking to prepare the homochiral twisted and coiled fiber actuator.

[0020] The beneficial effects of the present invention:

[0021] 1. Performance improvement

[0022] High actuation strain rate and amplitude. Through the collaborative design of materials and structures, the present invention significantly improves the actuation strain rate and amplitude of LCE, realizes self-sustained motion driven by low energy sources (such as human body temperature or natural sunlight), and significantly reduces the demand for high energy input. In the present invention, the actuation strain of the HOTC actuator can reach 890% at 30 °C during cycling, while that of a single-domain optical fiber (without material-structure synergy) is only 35.6% at 50 °C. The strain rate of the HOTC actuator can reach 480% / s at 30 °C, while that of the single-domain optical fiber DALCE is only 16.0% / s at 50 °C.

[0023] Low - energy consumption drive. By introducing C6BAPE monomer, the phase transition temperature of DALCE is significantly reduced (this property of reducing the phase transition temperature is mainly attributed to the intermolecular interaction of C6BAPE. The π - π interaction between C6BAPE molecules is weak, which makes the arrangement of liquid crystal molecules easier to be disrupted, thus reducing the energy required to maintain the nematic phase. Therefore, at a lower temperature, the LCE material can transform from the nematic phase to the isotropic phase, achieving a reduction in the phase transition temperature). In the present invention, the driving temperature of DALCE is around 30 °C, and the driving temperature of DALCE - CNT doped with multi - walled carbon nanotubes does not change much, about 32 °C. In addition, DALCE also has a small driving strain when cycling between 0 °C and 30 °C. For example, self - sustaining untwisting - twisting motion can be achieved at 22 °C.

[0024] Structural stability, repeatable processing and reprogramming. Through the reversible Diels - Alder reaction, DALCE of the present invention has the ability to be re - processed and re - constructed at low temperature, enhancing the structural stability, repeatable processing and reprogramming of the material. In the present invention, DALCE - C75 - CNT can still maintain stable actuation performance after 7 times of repeated processing and reconstruction.

[0025] Versatility and application scope. By designing a specific mechanical structure (such as a chiral twisting and coiling (HOTC) actuator), the present invention realizes various self - sustaining motion modes: self - rolling, self - breathing, and autonomous twisting - untwisting, etc., expanding the application scope of LCE.

[0026] Processability and flexibility of the material. By introducing C6BAPE monomer and multi - walled carbon nanotubes, the present invention improves the flexibility and processability of LCE, enabling it to be fabricated into various complex structures, further expanding its application potential.

[0027] 2. Cost reduction

[0028] Material cost. Materials used in the present invention such as RM257, C6BAPE, 2 - phenylethylamine, furfurylamine, and BMI can be directly purchased, and the preparation method is simple, reducing the material cost.

[0029] Preparation cost. The preparation process of the present invention is simple. The synthesis of DALCE - CX only requires heating and stirring at 100 °C for 24 hours, and the preparation of the HOTC actuator only requires stretching, twisting and coiling at room temperature. Compared with traditional LCE, DALCE does not require ultraviolet light to form cross - linked points to cure the programmed shape (moreover, ultraviolet light can only cure the shape on the surface of the material, and it is difficult to cure shapes with a relatively thick thickness or complex shapes). It only needs to be placed at room temperature and can fix the shape, reducing the use of instruments and lowering the labor cost.

[0030] Equipment cost: The preparation equipment of the present invention, such as 3D printers and ordinary ovens, are all common equipment, and there is no need for the traditional LCE ultraviolet curing shape, reducing the equipment cost.

[0031] 3. Lifespan and reliability

[0032] The DALCE of the present invention has excellent mechanical properties and thermal stability. The Young's modulus of DALCE-C75 is 6.1 MPa, the tensile strength is 4.2 MPa, and the elongation at break is 610%. The reconfigurable DALCE can be repeatedly processed and remade into various shapes, and can basically maintain the basic properties of the original material, significantly improving the lifespan and reliability of the material.

[0033] 4. Precision and efficiency

[0034] The HOTC actuator of the present invention has a high strain response rate and amplitude at low temperatures. As mentioned in the text, under simulated sunlight of 67 mW / cm 2 , the photoinduced strain rate of the HOTC actuator reaches about 33% / s, and the maximum strain is 905%. It is supported in the literature that the precision, efficiency, and productivity of the actuator are significantly improved. The preparation process of the present invention is simple. The synthesis of DALCE-CX only requires heating and stirring at 100 °C for 24 hours, and the preparation of the HOTC actuator only requires stretching, twisting, and winding at room temperature. In addition, fibers can be mass-produced by 3D printing, significantly improving the productivity.

[0035] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. Brief description of the drawings

[0036] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0037] Figure 1 (a) Schematic diagram of 3D printing of de-crosslinked ink (DALCE-C75-CNT) fibers. (b) Photo of the homochiral twisted coiled (HOTC) fiber actuator during the self-locking process, and (c) photo after being removed from the metal mandrel.

[0038] Figure 2(a) Chemical formula structure of the material components for preparing low-Tni DALCEs; (b) Schematic diagram of the reprogramming process of CNT-doped DALCE actuators, including extrusion of the DALCE ink pyrolytically crosslinked by the inverse DA reaction into fibers, room-temperature liquid crystal alignment / actuator forming, and network self-locking through the DA reaction at room temperature or below; (c) Schematic diagram of the direct self-winding of the DALCE actuator on a warm skin; (d) Schematic diagram of the self-winding of the DALCE actuator under natural sunlight;

[0039] Figure 3 (a) DSC curve of DALCE-CXs during the second heating scan, (b) Tni diagram of DALCE-CXs and their prepolymers, inset: Transparency of DALCE-C75 upon finger-touch heating, (c) Tensile stress-strain curve of DALCE-CXs and (d) Young's modulus at the fracture strain, tested at 17 °C, (e) Shrinkage strain of single-domain structure DALCE-C75 and DALCE-C50 during heating / cooling cycles, recorded by DMA in the 0N equal stress mode, (f) Reversible shrinkage / elongation of the single-domain structure DALCE-C75 strip (upper figure) and its length change during ten actuation cycles (lower figure), (g) Azimuthal diffraction profile (showing nematic order) and 2D-XRD pattern of the single-domain structure DALCE-C75 strip at 20 °C and 50 °C, the double-headed arrow indicates the film stretching direction, (h) 1D-XRD pattern of DALCEs, showing signal segments in the low-angle region (measured from 1–10°) and wide-angle region (measured from 5–90°), (i) DSC curves of DALCE-C75 with different phenyl to furan molar ratios, (j) Variation of the Young's modulus of DALCE-C75-CNT with the reformation time of DA bonds at 22 °C, corresponding tensile curve, (k) Photos showing the reconfigurability of DALCE-C75-CNT, where a single film can achieve four reversible folding / unfolding modes through reprogramming, (l) Schematic diagram of the pyrolytically crosslinked DALCE-C75-CNT as a reusable 4D printing ink, with the extruded fiber radii of 0.1 mm and 0.3 mm, (m,n) Homochiral twisted and coiled (HOTC) actuators reprogrammed from DALCE-C75-CNT, with enhanced actuation strain, showing the elongation actuation strain and strain rate under mild temperature (m) and sunlight (n), the inset shows the deformation behavior of HOTC and single-domain actuators, the coil diameter (Dcoil) and fiber diameter (Dfiber) of the left HOTC actuator are 2.8 mm and 0.30 mm respectively; the Dcoil and Dfiber of the right HOTC actuator are 1.6 mm and 0.30 mm respectively.

[0040] Figure 4(a) Schematic illustration of the self - coiling of the DALCE - C75 - CNT - based HOTC actuator under body heat, (b) showing the self - coiling motion of the HOTC actuator on the palm, back of the hand, and arm, with coil diameter (Dcoil) and fiber diameter (Dfiber) of 2.7 mm and 0.27 mm respectively, (c) displacement - time curve and (d) instantaneous velocity - time relationship diagram, (e) schematic illustration (top) and time - lapse composite image (bottom) showing the autonomous rolling of the HOTC actuator (Dcoil: 3.4 mm; Dfiber: 0.68 mm) on a flat surface at 30 °C, and the displacement - time curve is as shown in (f), (g, h) The HOTC actuator with a closed - loop topology (Dcoil: 3.0 mm; Dfiber: 0.67 mm) contracts to conform to the arm and self - coils, (g) shows the diameter and displacement changing with time, and (h) is a motion photo.

[0041] Figure 5 (a) Schematic illustration (left), photo (right) of the stable downward rolling of an annular HOTC actuator (Dcoil: 5.6 mm; Dfiber: 1.50 mm) on a cylinder when exposed to natural sunlight, and (b) displacement - time curve, (c) schematic illustration (left), photo (right) of the self - rolling of the same annular HOTC actuator under natural sunlight gating, and (d) displacement - time curve, (e) displacement - time curves of a single annular HOTC actuator when heated to 22 °C and 26 °C by sunlight of different intensities, (f) adaptability of the self - rolling behavior on cylinders of different radii, materials, and textures, (g) schematic illustration (left), photo (right) of the autonomous rolling of an annular HOTC actuator (Dcoil: 5.3 mm; Dfiber: 1.20 mm) on a horizontally placed cylinder, and (h) displacement - time curve.

[0042] Figure 6 (a) The self - breathing behavior of a HOTC actuator (Dcoil: 2.1 mm; Dfiber: 0.29 mm) with both ends fixed to an ice pack and suspended in air at 22 °C, and (b) the change in the height of the corresponding section with time, (c) the self - torsional oscillation of a HOTC actuator (Dcoil: 1.7 mm; Dfiber: 0.25 mm) with one end fixed to an ice pack and suspended in air at 22 °C, and (d) the change in the corresponding length and torsional angle with time, (e) The annular actuator formed by bonding the DALCE - C75 - CNT / Kapton bilayer tape undergoes self - swinging motion under simulated sunlight, and (f) the change in the corresponding deformation angle with time, (g) The asymmetrically bent DALCE - C75 - CNT / Kapton bilayer tape at 97 mW / cm 2 simulated sunlight 2Simulate the self - winding and unwinding cycles under sunlight, and (h) the corresponding angle - time curves, (i) the HOTC actuator (Dcoil: 9.1mm; Dfiber: 1.93mm) at 83mW / cm 2 Simulate self - rolling under sunlight to transport goods, and (j) the corresponding displacement - time curves. Detailed implementation mode

[0043] The following uses specific examples to illustrate the implementation mode of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0044] Among them, the drawings are only for exemplary illustration, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation to the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, which do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well - known structures and their descriptions in the drawings may be omitted.

[0045] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or position relationship, it is based on the orientation or position relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only for exemplary illustration and should not be construed as a limitation to the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0046] Embodiment 1

[0047] 4-(4-((6-(acryloyloxy)hexyl)oxy)phenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate (C6BAPE) was provided by Hunan Huayu Pharmaceutical Co., Ltd. (1,4-bis[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene) (RM257) was purchased from Leyan.com. 2-phenylethylamine, furfurylamine, 4,4'-bismaleimidodiphenylmethane / bismaleimide (BMI) were purchased from Aldrich. Other solvents and reagents used in the present invention were provided by Chengdu Hengxin Chemical Reagent Co., Ltd.

[0048] The liquid crystal prepolymer (LCP) was synthesized by mixing RM257, C6BAPE, 2-phenylethylamine and furfurylamine, followed by an Aza-Michael addition reaction as shown below.

[0049]

[0050] Then, LCP and BMI reacted through a Diels-Alder reaction to generate DALCE-CXs. The chemical compositions of the synthesized DALCE and their respective codes are shown in Tables S1 - S3. The preparation process first deoxygenated RM257, C6BAPE, furfurylamine and 2-phenylethylamine in a three-necked flask for 15 minutes, and then heated and stirred the mixture at 100 °C for 24 hours. Subsequently, BMI as a crosslinking agent was added to the prepolymer solution to form DALCE-CXs samples in dichloromethane. The molar ratio of amino groups to acrylate groups was maintained at 1:2 in all samples. The molar ratios of 2-phenylethylamine to furfurylamine and BMI to furfurylamine in each DALCE sample are detailed in Tables S1 - S3.

[0051] For the preparation of DALCE-CX-CNT (dynamic liquid crystal elastomer material doped with carbon nanotubes) samples (Table S4), the standard procedure was slightly modified, mainly involving the addition of multi-walled carbon nanotubes (MWCNTs). First, MWCNTs were sonicated in dichloromethane for more than 8 hours to ensure proper dispersion. Subsequently, the dispersed MWCNTs were added to the prepolymer solution and further sonicated in dichloromethane for 1 hour to obtain a homogeneous mixture. Then, the crosslinking agent BMI was added to the solution. The resulting mixture was vortexed for 10 minutes to ensure thorough mixing, and then poured into a mold and dried to finally obtain DALCE-CX-CNT samples.

[0052] Table S1: DALCE-CX components with different C6BAPE contents. Molar ratio of phenyl to furan (5:5) and molar ratio of furan to BMI (4:1).

[0053]

[0054]

[0055] Table S2: DALCE-CX components with different phenyl contents. The mass ratio of RM257 to C6BAPE is (1:3), and the addition amount of BMI is 0.200 mmol (12.3 mol% relative to the mesogenic monomer, the same as DALCE-C75 in Table S1).

[0056]

[0057] Table S3: DALCE-CX components with different crosslinking densities. The mass ratio of RM257 to C6BAPE is (1:3) and the molar ratio of phenyl to furan is (5:5).

[0058]

[0059] Table S4: Compound composition of DALCE-C75-CNT.

[0060]

[0061] Preparation of the DALCE actuator in Example 2

[0062] Reprogramming of DALCE-CX (dynamic liquid crystal elastomer) or DALCE-CX-CNT (dynamic liquid crystal elastomer material doped with carbon nanotubes) samples is carried out as follows: The sample is heated in an oven at 115 °C (DALCE-CX) or 125 °C (DALCE-CX-CNT) for 5 minutes to partially unlock the polymer network; it is programmed and shaped at room temperature; it is stored at 4 °C for 1 day for initial crosslinking; then it is returned to room temperature for 3 days to complete crosslinking.

[0063] Preparation of the homochiral twisted coiled (HOTC) fiber actuator based on DALCE-C75-CNT

[0064] The DALCE-C75-CNT fibers were prepared using a Hyrel System 30M 3D printer equipped with a KR2-15 print head. Before printing, the sample was heated to 125 °C and held for 15 minutes to de-crosslink the DALCE-C75-CNT material. The initial stage of printing was carried out at a slower speed to remove air bubbles and voids in the molten ink, and then the fibers were extruded and deposited on a PTFE-coated surface to prevent adhesion. The nozzle diameter can be set from 0.1 mm to 1 mm (the range can be expanded, and only this range of nozzles was designed in this experiment) to meet specific requirements. After printing, the fibers were stretched, twisted, and wound around an iron rod at room temperature to achieve a homochiral twist and helix (HOTC, the twist and winding directions are the same) structure, and the fiber ends were fixed. Then the sample was stored at 4 °C for 24 hours for initial crosslinking and then held at room temperature for 3 days to complete crosslinking. After this self-locking process, a spring-shaped actuator was obtained.

[0065] Example 3

[0066] The 1H NMR spectra of the synthesized liquid crystal prepolymers were recorded at room temperature using a Bruker Avance-III 300 NMR instrument. The thermal phase transitions of the samples were measured using a Netzsch DSC 204F differential scanning calorimeter (DSC). The samples were heated from room temperature to 150 °C at a rate of 30 °C / min, cooled to -50 °C at a rate of 10 °C / min, and then reheated to 150 °C at a rate of 10 °C / min. The data of the phase transition temperature (Tni) and the glass transition temperature (Tg) were obtained from the second heating scan curve. The actuation strain-temperature curves were obtained using a TA Instruments DMA 850 in the 0 N equal force mode, using a single-domain thin film actuator. The fixed sample was first cooled to 5 °C and equilibrated at this temperature for 3 minutes. Then the temperature was raised to 60 °C at a rate of 2 °C / min and further equilibrated for 3 minutes, and subsequently the temperature was lowered to 5 °C again at a rate of 2 °C / min. Each sample was tested for three cycles. The stress-strain data were tested using a QLW-51 tensile machine, using a single-domain thin film actuator. The samples were stretched at a rate of 8 mm / min. To further determine the formation of DA bonds, nine samples of the same size were treated at 125 °C for 5 minutes, and then the changes in mechanical properties were recorded after being placed at 22 °C for different periods of time. The increase in Young's modulus over time confirmed the self-locking process of DALCE-C75-CNT. The 2D-XRD patterns were collected on a Bruker AXS Nanostar system, equipped with a microfocus copper anode of 45 kV / 0.65 mA, Montel optics, and a VANTEC 2000 2D detector, calibrated using a Silver Behenate standard. A 360-degree azimuthal scan was recorded at 2θ = 17.7 - 20.9° (for nematic order). To examine the effect of light intensity on DALCE, an Oriel Sol3A solar simulator was used, with an output range of 0.1 to 1.0 SUN (10 mW / cm 2 to 100 mW / cm 2 2) for light-driven deformation and motion.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered by the scope of the claims of the present invention.

Claims

1. Dynamic liquid crystal elastomer material, characterized in that: The chemical structure of the dynamic liquid crystal elastomer material is as follows:

2. The dynamic liquid crystal elastomer material according to claim 1, characterized in that: The dynamic liquid crystal elastomer material is synthesized from RM257, C6BAPE, 2-phenylethylamine, furfurylamine and BMI as raw materials.

3. The method for preparing the dynamic liquid crystal elastomer material according to claim 1 or 2, characterized in that: The steps are as follows: Synthesis of liquid crystal prepolymer: RM257, C6BAPE, 2-phenylethylamine and furfurylamine were mixed in a three-necked flask and deoxygenated for 15 min, followed by heating and stirring at 100 °C for 24 h; Synthesis of the dynamic liquid crystal elastomer material: a liquid crystal prepolymer is mixed with BMI and reacted in dichloromethane to form the dynamic liquid crystal elastomer material.

4. The preparation method according to claim 3, characterized in that: The mass ratio of RM257 is a%, the mass ratio of C6BAPE is b%, the total molar ratio of 2-phenylethylamine to 2-phenylethylamine and furfural amine is x%, and the total molar ratio of furfural amine to 2-phenylethylamine and furfural amine is (a+bx)%, wherein a+b=100, b=0, 25, 50, 75, 100, and x=50.

5. The preparation method according to claim 3, characterized in that: In the synthesis of the dynamic liquid crystal elastomer material, the molar ratio of the amino group to the acrylate group is 1:

2.

6. The preparation method according to claim 3, characterized in that: The molar ratio of the furyl group to BMI is 8:1, and the ratio of the phenyl group to the furyl group is 5:

5.

7. A dynamic liquid crystal elastomer material doped with carbon nanotubes, characterized in that: The carbon nanotube-doped dynamic liquid crystal elastomer material is composed of the dynamic liquid crystal elastomer material according to any one of claims 1 to 2 and carbon nanotubes, and the carbon nanotube content is 4 wt%.

8. The carbon nanotube-doped dynamic liquid crystal elastomer material according to claim 7, characterized in that: The preparation method is as follows: the carbon nanotubes are ultrasonically treated in dichloromethane, then added into liquid crystal prepolymer and ultrasonicated again, and finally BMI is added and mixed evenly, and cast to prepare the carbon nanotubes.

9. Homochiral twisted and coiled fiber actuator, characterized in that The homochiral twisted and wound fiber actuator is composed of the dynamic liquid crystal elastomer material described in any one of claims 1-2 or the dynamic liquid crystal elastomer material doped with carbon nanotubes described in any one of claims 7-8.

10. The homochiral twisted and wound fiber actuator according to claim 9, characterized in that The preparation steps are as follows: Raw material preparation: The nanotube-doped dynamic liquid crystal elastomer material is heated to 125° C. for 15 minutes to de-crosslink. Actuator preparation: Using a 3D printer and a KR2-15 nozzle, the actuator was stretched and twisted at room temperature after printing, stored at 4°C for 24 hours for initial cross-linking, and then stored at room temperature for 3 days to complete cross-linking to prepare the homochiral twisted and coiled fiber actuator.

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