A cross-linking agent-free liquid crystal elastomer synthesis method, liquid crystal elastomer and body temperature-driven actuator

Abstract

The present invention provides a cross-linking agent-free liquid crystal elastomer synthesis method, a liquid crystal elastomer, and a body temperature-driven actuator. According to the cross-linking agent-free liquid crystal elastomer synthesis method, a liquid crystal elastomer with polymer chain orientation is prepared. The storage modulus of the liquid crystal elastomer is 0.1-1 MPa, and the temperature T at which the liquid crystal elastomer transitions from the nematic phase to the isotropic phase is 0.1-1 MPa. NI The actuator comprises the liquid crystal elastomer and a polyimide film. The liquid crystal elastomer is located on the surface of the polyimide film, and deformation of the liquid crystal elastomer causes the polyimide film to bend. The polyimide film serves as a constraining layer, enabling the liquid crystal elastomer to elastically reset. The present invention can achieve body temperature-driven deformation of the liquid crystal elastomer.

Description

Technical Field

[0001] The present invention relates to the field of liquid crystal elastomers, actuators or low-temperature robots, and in particular to a cross-linking agent-free liquid crystal elastomer synthesis method, a liquid crystal elastomer and a body temperature-driven actuator. Background Art

[0002] Liquid crystal elastomers (LCEs), as thermoresponsive smart materials, can undergo large, reversible deformations under thermal influence. Fundamentally, by heating the LCEs by inputting energy, the LC polymer chains transform from a nematic phase to an isotropic phase, overcoming strain damping and activating the material's programmable deformations, such as bending, contraction, and twisting.

[0003] The strain temperature window of liquid crystal elastomers in the prior art is about 60-70°C or higher. Currently, the following methods are used to reduce the driving energy of liquid crystal elastomers, i.e., the strain temperature window:

[0004] First, increase the pre-stretch ratio of liquid crystal elastomers. A large pre-stretch ratio causes the liquid crystal molecular chains to form a more ordered single-domain structure, resulting in a greater thermal response deformation of the material. However, since liquid crystal elastomers are primarily stretched using uniaxial stretching, large stretch ratios lead to stress concentration in the material, resulting in tensile fracture. Currently, the maximum pre-stretch ratio for liquid crystal elastomers is approximately 1200%. However, a 1200% pre-stretch ratio does not reduce the strain temperature window.

[0005] Second, lower the nematic-isotropic transition temperature T of the liquid crystal elastomer NI . T of liquid crystal elastomer NI Also known as the clearing point temperature, lowering T NI This can lower the temperature required for the material to fully deform and approach a transparent state when heated. Existing technologies typically utilize a thiol-acrylate reaction to synthesize liquid crystal elastomers. In this conventional thiol-acrylate reaction, pentaerythritol tetrakis(3-mercaptopropionate) PETMP is used as a crosslinker for the liquid crystal elastomer, and 2,2-(1,2-ethylenedioxy)bis(ethanethiol) is used as a chain extender. The resulting liquid crystal elastomer has a phase transition temperature of approximately 72°C, but this does not allow for body temperature-driven deformation of the liquid crystal elastomer. Summary of the Invention

[0006] In response to the shortcomings of the prior art, the present invention provides a cross-linking agent-free liquid crystal elastomer synthesis method, a liquid crystal elastomer, and a body temperature-driven actuator. The cross-linking agent-free liquid crystal elastomer synthesis route significantly reduces the storage modulus of the material. In addition, a spiral stretching device is used to stretch the liquid crystal elastomer to a ratio of 2300% to 2500%, and the temperature T at which the liquid crystal elastomer transitions from the nematic phase to the isotropic phase is reduced. NI It is 60-62℃.

[0007] The present invention achieves the above technical objectives through the following technical means.

[0008] A method for synthesizing a liquid crystal elastomer without a crosslinking agent comprises the following steps:

[0009] 1.9-2.1 g of liquid crystal monomer is added to 0.76-0.84 g of toluene, and the liquid crystal monomer is dissolved by heating. After dissolution, 0.538-0.595 g of 2,2'-(1,2-ethylenedioxy)bis(ethanediol) is added. After stirring to fully mix the solution, 0.0128-0.014 g of photoinitiator is added to obtain a liquid crystal precursor solution;

[0010] Dilute dipropylamine and toluene in a volume ratio of 1:50 to obtain a diluted catalyst solution;

[0011] Add 0.284-0.312 g of the diluted catalyst solution to the liquid crystal precursor solution and mix thoroughly. Place the solution in a vacuum environment to remove bubbles generated during the mixing process to obtain a mixed solution.

[0012] The mixed solution is poured into a glass mold and placed in the dark at room temperature, and then the glass mold is placed in a vacuum oven to evaporate the solvent to obtain a loosely cross-linked liquid crystal elastomer;

[0013] The loosely cross-linked liquid crystal elastomer is pre-stretched to 2300% to 2500% by a spiral stretching device, then removed and laid flat, and cured by ultraviolet irradiation to obtain a liquid crystal elastomer with oriented polymer chains.

[0014] Furthermore, the length of the loosely cross-linked liquid crystal elastomer is 70-80 mm, and the loosely cross-linked liquid crystal elastomer is pre-stretched to 1820-1950 mm by a spiral stretching device.

[0015] Furthermore, the liquid crystal monomer is added to toluene and heated at 80° C. for 5-10 minutes to dissolve the liquid crystal monomer.

[0016] Further, the mixed solution on the glass mold is placed in the dark at room temperature for 10-12 hours, and then placed in a vacuum oven at 80-82° C. for solvent evaporation after 22-24 hours.

[0017] Furthermore, the rotation speed of the spiral stretching device is 0.25 to 0.28 r / s, so that the loosely cross-linked liquid crystal elastomer is pre-stretched to 2300% to 2500%.

[0018] A liquid crystal elastomer, wherein the liquid crystal elastomer is prepared according to the crosslinking agent-free liquid crystal elastomer synthesis method, wherein the liquid crystal elastomer has a storage modulus of 0.1-1 MPa and a temperature T at which the nematic phase of the liquid crystal elastomer transitions to the isotropic phase. NIIt is 60-62℃.

[0019] A body temperature-driven actuator comprises the liquid crystal elastomer and a polyimide film. The liquid crystal elastomer is located on the surface of the polyimide film, and the polyimide film is bent by deformation of the liquid crystal elastomer. The polyimide film serves as a constraint layer for elastically resetting the liquid crystal elastomer.

[0020] Furthermore, under the action of a heat source above 25.2° C., the liquid crystal elastomer is deformed, thereby causing the polyimide film to bend.

[0021] The beneficial effects of the present invention are:

[0022] 1. The crosslinker-free liquid crystal elastomer synthesis method of the present invention significantly reduces the storage modulus of the material by not using a crosslinker. In addition, the liquid crystal elastomer is stretched to a ratio of 2300% to 2500% by using a spiral stretching device, and the temperature T at which the liquid crystal elastomer transitions from the nematic phase to the isotropic phase is reduced to 2300% to 2500%. NI It is 60-62℃.

[0023] 2. The cross-linker-free liquid crystal elastomer synthesis method described in the present invention, combined with the cross-linker-free liquid crystal elastomer synthesis route, significantly reduces the storage modulus of the material; the liquid crystal elastomer finally prepared can be directly driven by human body temperature, greatly reducing the thermal threshold of the material-driven strain.

[0024] 3. The cross-linker-free liquid crystal elastomer synthesis method described in the present invention utilizes a spiral stretching device to allow the pre-stretching of the liquid crystal elastomer to occur within an extremely short distance, and the pre-stretched portion is evenly wound around the stretching shaft, which greatly weakens the effect of stress concentration during uniaxial stretching and reduces the risk of stretching fracture. At the same time, it ensures that the width of the film formed by pre-stretching remains unchanged, greatly improving the pre-stretching ratio of the liquid crystal elastomer.

[0025] 4. The body temperature driven actuator of the present invention can be driven to deform by body temperature or a temperature slightly lower than low temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. The drawings described below are some embodiments of the present invention. For ordinary technicians in this field, it is obvious that other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 Schematic diagram of the body temperature driven actuator according to the present invention.

[0028] Figure 2This is a schematic structural diagram of the spiral stretching device described in the present invention.

[0029] Figure 3 This is a top view of the spiral stretching device described in the present invention.

[0030] Figure 4 Infrared image of a body-temperature-driven actuator driven by human body heat (skin temperature).

[0031] Figure 5 Infrared image of a body-temperature-driven actuator driven by human body temperature (blowing temperature).

[0032] Figure 6 This is a graph showing the relationship between different molar ratios of PETMP cross-linker and the storage modulus of the sample during the synthesis of liquid crystal elastomers.

[0033] Figure 7 This is a graph showing the loss tangent of the liquid crystal elastomer obtained by the cross-linking agent-free preparation method of the present invention.

[0034] In the picture:

[0035] 100-liquid crystal elastomer; 200-polyimide film;

[0036] 1-device housing; 2-device buckle plate; 3-rotating shaft; 4-worm gear; 5-worm; 6-rotatable cylindrical stage; 61-rotatable sleeve; 7-cylindrical sample stretching axis; 8-baffle; 9-limiting block; 10-sample to be stretched; 11-stretched sample; 12-limiting plate. DETAILED DESCRIPTION

[0037] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0038] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "axial", "radial", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are 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, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0039] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0040] The crosslinking agent-free liquid crystal elastomer synthesis method of the present invention comprises the following steps:

[0041] 1.9-2.1 g of liquid crystal monomer is added to 0.76-0.84 g of toluene, and the liquid crystal monomer is dissolved by heating. After dissolution, 0.538-0.595 g of 2,2'-(1,2-ethylenedioxy)bis(ethylenethiol) is added. After the solution is thoroughly mixed by stirring, 0.0128-0.014 g of a photoinitiator is added to obtain a liquid crystal precursor solution. The component of the liquid crystal monomer is 2-methyl-1,4-phenyl-4-(3-acryloyloxypropoxy)benzoate.

[0042] Dilute dipropylamine and toluene in a volume ratio of 1:50 to obtain a diluted catalyst solution;

[0043] Add 0.284-0.312 g of the diluted catalyst solution to the liquid crystal precursor solution and mix thoroughly. Place the solution in a vacuum environment to remove bubbles generated during the mixing process to obtain a mixed solution.

[0044] The mixed solution is poured into a glass mold and placed in the dark at room temperature, and then the glass mold is placed in a vacuum oven to evaporate the solvent to obtain a loosely cross-linked liquid crystal elastomer;

[0045] The loosely cross-linked liquid crystal elastomer is pre-stretched to 2300% to 2500% by a spiral stretching device, then removed and laid flat, and cured by ultraviolet irradiation to obtain a liquid crystal elastomer with oriented polymer chains.

[0046] The cross-linking agent-free liquid crystal elastomer synthesis method of the present invention significantly reduces the storage modulus of the material by not using a cross-linking agent. In addition, the liquid crystal elastomer is stretched to a ratio of 2300% to 2500% by using a spiral stretching device, and the temperature T at which the liquid crystal elastomer transitions from the nematic phase to the isotropic phase is reduced. NI It is 60-62℃.

[0047] like Figure 2 and 3 As shown, the spiral stretching device includes a device housing 1, a worm gear assembly, and a rotatable cylindrical stage 6; the worm gear assembly includes a worm wheel 4, a worm 5, and a rotating shaft 3. A baffle 8 is provided within the device housing 1, dividing the device housing 1 into two areas. The worm wheel 4 is mounted in one area, and the worm 5 passes through one area and is mounted in the other area. One end of the worm 5 passes through the baffle 8 and engages with the worm wheel 4. One end of the worm 5 passes through a hole in the side of the device housing 1 and is restrained by a limit plate 12. The rotating shaft 3 is mounted on the worm wheel 4. By rotating the rotating shaft 3 by hand, the worm wheel 4 rotates, and the rotation of the worm wheel 4 drives the rotation of the worm 5. The worm wheel 4 can also be connected to a stepper motor to precisely control the speed of rotation.

[0048] The other end of the rotating shaft worm 5 passes through the side hole of the device housing 1 and is limited by a limit block 9. The outside of the other end of the rotating shaft worm 5 passing through the side hole of the device housing 1 is a cylindrical sample stretching shaft 7. A rotatable cylindrical stage 6 is set adjacent to the cylindrical sample stretching shaft 7. The rotatable cylindrical stage 6 is fixedly installed close to the side wall of the device housing 1 and is covered with a rotatable sleeve 61. The sample 10 to be stretched is placed on the rotatable cylindrical stage 6, and the end of the sample 10 to be stretched is clamped at the bottom with a sample clamp. One end of the sample 10 to be stretched is wrapped around the cylindrical sample stretching shaft 7 and stretched into a stretched sample 11. A device buckle plate 2 is set above the device housing 1 to enclose the worm wheel 4 and worm 5 in the device housing 1.

[0049] Rotate the hand-held shaft 3, the worm gear 4 rotates to drive the worm 5 to rotate, and the cylindrical sample stretching shaft 7 rotates as the worm 5 rotates. The sample 10 to be stretched is fixed on the rotatable sleeve 61 with a sample clamp. As the sample is spirally stretched, the rotatable sleeve 61 can rotate slowly. The rotation of the rotatable sleeve 61 can release the sample to continue stretching, and finally a stretched sample 11 is formed on the cylindrical sample stretching shaft 7.

[0050] The spiral stretching device utilizes a wrapping stretching method where the forces at both ends are essentially a fixed force on the sample stage and the static friction of the cylindrical stretching axis on the material. This device allows the pre-stretching of the liquid crystal elastomer to occur within the distance between the cylindrical sample stretching axis (7) and the rotatable cylindrical stage. The pre-stretched portion is evenly wrapped around the stretching axis, significantly reducing the effects of stress concentration during uniaxial stretching and the risk of fracture during stretching, while also ensuring that the width of the pre-stretched film remains constant.

[0051] By adjusting the rotation speed of the cylindrical stretching axis, the stretching rate and the width of the formed film can be adjusted, thereby controlling the pre-stretching ratio of the material, as shown in Table 1:

[0052] Table 1

[0053]

[0054] Through experiments, it was found that under this device, the liquid crystal elastomer can reach a pre-stretching ratio of up to about 2500%.

[0055] Table 2: Relationship between the original length of loosely cross-linked liquid crystal elastomer and the multiple length of the liquid crystal elastomer after ultra-stretching

[0056]

[0057] As shown in Table 2, the original length of the loosely cross-linked liquid crystal elastomer is 70-80 mm, and the length of the liquid crystal elastomer after ultra-stretching is stretched to 1820-1950 mm, resulting in a stretching ratio of 23.0-25.0 times.

[0058] Example 1

[0059] The crosslinker-free liquid crystal elastomer synthesis route of Example 1 includes the following methods:

[0060] 1.9 g of liquid crystal monomer (RM-257) was added to 0.76 g of toluene, and the mixture was heated at 80° C. for 5 minutes to dissolve the liquid crystal monomer. 0.538 g of 2,2′-(1,2-ethylenedioxy)bis(ethyl mercaptan) (EDDET) was added, and the mixture was stirred on a magnetic stirrer for 1-2 minutes. After the solution was thoroughly mixed, 0.0128 g of photoinitiator (HHMP) was added to obtain a liquid crystal precursor solution.

[0061] Dipropylamine (DPA) and toluene were diluted in a volume ratio of 1:50 to obtain a diluted catalyst solution;

[0062] Add 0.284 g of the diluted catalyst to the liquid crystal precursor solution and mix thoroughly. Place the solution in a vacuum chamber for 2 minutes to remove bubbles generated during the mixing process.

[0063] The mixture was poured into a glass mold and placed in the dark at room temperature for 10 hours. The glass mold was then placed in a vacuum oven at 80°C to evaporate the solvent. After 22 hours, a loosely cross-linked liquid crystal elastomer was obtained.

[0064] The loosely cross-linked liquid crystal elastomer was pre-stretched to 2500% by a spiral stretching device, then removed from the device and laid flat, and cured by ultraviolet irradiation. After 25 minutes, a liquid crystal elastomer with oriented polymer chains was obtained.

[0065] Example 2

[0066] Example 2 A crosslinker-free liquid crystal elastomer synthesis route comprises the following steps:

[0067] 2 g of liquid crystal monomer (RM-257) was added to 0.8 g of toluene, and the mixture was heated at 80° C. for 8 minutes to dissolve the liquid crystal monomer. 0.5665 g of 2,2'-(1,2-ethylenedioxy)bis(ethyl mercaptan) (EDDET) was added, and the mixture was stirred on a magnetic stirrer for 1-2 minutes. After the solution was thoroughly mixed, 0.0134 g of photoinitiator (HHMP) was added to obtain a liquid crystal precursor solution.

[0068] Dipropylamine (DPA) and toluene were diluted in a ratio of 1:50 to obtain a diluted catalyst solution;

[0069] Add 0.298 g of the diluted catalyst to the liquid crystal precursor solution and mix thoroughly. Place the solution in a vacuum chamber for 2 minutes to remove bubbles generated during the mixing process.

[0070] The mixture was poured into a glass mold and placed in the dark at room temperature for 11 hours. The glass mold was then placed in a vacuum oven at 81°C to evaporate the solvent. After 23 hours, a loosely cross-linked liquid crystal elastomer was obtained.

[0071] The loosely cross-linked liquid crystal elastomer was pre-stretched to 2500% by a spiral stretching device, then removed from the device and laid flat, and cured by ultraviolet irradiation. After 28 minutes, a liquid crystal elastomer with oriented polymer chains was obtained.

[0072] Example 3

[0073] Example 3 A cross-linking agent-free liquid crystal elastomer synthesis route comprises the following steps:

[0074] 2.1 g of liquid crystal monomer (RM-257) was added to 0.84 g of toluene, and the mixture was heated at 80° C. for 10 minutes to dissolve the liquid crystal monomer. 0.595 g of 2,2′-(1,2-ethylenedioxy)bis(ethyl mercaptan) (EDDET) was added, and the mixture was stirred on a magnetic stirrer for 1-2 minutes. After the solution was thoroughly mixed, 0.014 g of photoinitiator (HHMP) was added to obtain a liquid crystal precursor solution.

[0075] Dipropylamine (DPA) and toluene were diluted in a volume ratio of 1:50 to obtain a diluted catalyst solution;

[0076] Add 0.312 g of the diluted catalyst to the liquid crystal precursor solution and mix thoroughly. Place the solution in a vacuum chamber for 2 minutes to remove bubbles generated during the mixing process.

[0077] The mixture was poured into a glass mold and placed in the dark at room temperature for 12 hours. The glass mold was then placed in a vacuum oven at 82°C to evaporate the solvent. After 24 hours, a loosely cross-linked liquid crystal elastomer was obtained.

[0078] The loosely cross-linked liquid crystal elastomer was pre-stretched to 2500% using a super-stretching device, then removed from the device and laid flat, and cured by ultraviolet irradiation. After 30 minutes, a liquid crystal elastomer with oriented polymer chains was obtained.

[0079] The liquid crystal elastomer prepared in Example 1 has a storage modulus of 0.12-1 MPa and a temperature T at which the nematic phase of the liquid crystal elastomer transitions to the isotropic phase. NI It is 61.084-62℃.

[0080] The liquid crystal elastomer prepared in Example 2 has a storage modulus of 0.1-0.96 MPa and a temperature T at which the nematic phase of the liquid crystal elastomer transitions to the isotropic phase. NI It is 60.322-61.722℃.

[0081] The liquid crystal elastomer prepared in Example 3 has a storage modulus of 0.14-0.97 MPa, and a temperature T at which the nematic phase of the liquid crystal elastomer transitions to the isotropic phase. NI It is 60-61.892℃.

[0082] The cross-linking agent-free liquid crystal elastomer synthesis route described in the present invention. Due to the reduction of cross-linking agent, the liquid crystal elastomer of the present invention has a smaller tensile modulus, can produce a larger deformation under a smaller stress, and enhances the pre-stretching performance of the material. On the other hand, the sparser cross-linking network significantly reduces the storage modulus of the liquid crystal elastomer, which means that the molecular chains in the liquid crystal polymer material have higher flexibility and thermal responsiveness. The energy stored in the material due to elastic deformation during the strain process will be reduced, reducing the energy demand during thermal drive. At the same time, the liquid crystal elastomer also has a lower nematic to isotropic phase transition temperature T NI =60-62℃.

[0083] like Figure 1As shown, the body temperature-driven actuator of the present invention comprises the liquid crystal elastomer 100 and a polyimide film 200. The liquid crystal elastomer 100 is positioned on the surface of the polyimide film 200, forming a dual-layer actuator. Temperature changes drive the deformation of the liquid crystal elastomer 100, thereby bending the polyimide film 100. The polyimide film 100 serves as a constraining layer, ensuring the elastic return of the liquid crystal elastomer. The dual-layer actuator bends when heated and automatically returns to its original shape upon cooling.

[0084] like Figure 4 As shown, the straight spoke-shaped actuator is placed on the human skin ( Figure 4 The index finger is the finger, and the human skin temperature is generally 35-37°C. When the straight spoke-shaped actuator is placed on the human skin, the spoke bends to the maximum angle of about 67° in 13 seconds.

[0085] like Figure 5 As shown, the actuator is a bionic crab soft robot. Under the influence of the temperature of human body air (about 26-28°C), the actuator can bend and deform to about 57°C within 3.2 seconds, and return to its original shape after 9 seconds when the heat source is lost.

[0086] The present invention can deform the liquid crystal elastomer under the action of a heat source above 25.2° C., thereby driving the polyimide film to bend. The actuator of the present invention reaches the level of body temperature drive.

[0087] Figure 6 This figure shows the relationship between the storage modulus of samples synthesized using a thiol-acrylate reaction and the presence of different molar ratios of the PETMP crosslinker. When the PETMP crosslinker is present at 0 mol, i.e., when prepared without a crosslinker, the storage modulus of the liquid crystal elastomer obtained is 0.1-1 MPa. This also indicates that the storage modulus of the liquid crystal elastomer prepared without a crosslinker according to the present invention is 0.1-1 MPa.

[0088] Figure 7 The figure shows the loss tangent (the ratio of the loss modulus to the storage modulus) of the liquid crystal elastomer obtained using the crosslinker-free preparation method of the present invention. This value reflects the material's viscoelasticity. It can be seen that the viscosity peak of the liquid crystal elastomer occurs at approximately 61°C (between 60-62°C). When heated at this temperature, the material loses its liquid crystal optical properties and gradually transitions from a turbid state to a transparent, viscous state. In other words, the nematic to isotropic phase transition temperature of the liquid crystal elastomer is approximately 61°C.

[0089] This invention significantly reduces the thermal threshold for deformation of the liquid crystal elastomer material, thanks to a super-stretch ratio of 2300% to 2500% and a cross-linker-free liquid crystal elastomer synthesis route. This cross-linker-free synthesis significantly reduces the material's storage modulus. The resulting liquid crystal elastomer can be driven directly by human body temperature, significantly lowering the thermal threshold for strain.

[0090] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0091] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A body temperature driven actuator, characterized in that The invention comprises a liquid crystal elastomer (100) and a polyimide film (200), wherein the liquid crystal elastomer (100) is located on the surface of the polyimide film (200), and the deformation of the liquid crystal elastomer (100) is driven by temperature change, thereby causing the polyimide film (200) to bend; and the polyimide film (200) serves as a constraint layer for elastically resetting the liquid crystal elastomer (100). A liquid crystal elastomer (100) with polymer chain orientation is prepared using a cross-linking agent-free liquid crystal elastomer synthesis method, and the specific steps are as follows: 1.9-2.1 g of a liquid crystal monomer is added to 0.76-0.84 g of toluene, and the liquid crystal monomer is dissolved by heating. After dissolution, 0.538-0.595 g of 2,2'-(1,2-ethylenedioxy)bis(ethylenethiol) is added. The solution is thoroughly mixed by stirring, and then 0.0128-0.014 g of a photoinitiator is added to obtain a liquid crystal precursor solution. The liquid crystal monomer comprises 2-methyl-1,4-phenyl-4-(3-acryloyloxypropoxy)benzoate. Dilute dipropylamine and toluene in a volume ratio of 1:50 to obtain a diluted catalyst solution; Add 0.284-0.312 g of the diluted catalyst solution to the liquid crystal precursor solution and mix thoroughly. Place the solution in a vacuum environment to remove bubbles generated during the mixing process to obtain a mixed solution. The mixed solution is poured into a glass mold and placed in the dark at room temperature for 10-12 hours. The glass mold is then placed in a vacuum oven at 80-82°C to evaporate the solvent for 22-24 hours to obtain a loosely cross-linked liquid crystal elastomer. The loosely cross-linked liquid crystal elastomer is pre-stretched to 2300%~2500% by a spiral stretching device, then removed and laid flat, and cured by ultraviolet irradiation to obtain a liquid crystal elastomer with oriented polymer chains.

2. The body temperature driven actuator according to claim 1, wherein: Under the action of a heat source above 25.2° C., the liquid crystal elastomer (100) is deformed, thereby causing the polyimide film (200) to bend.

3. The body temperature driven actuator according to claim 1, wherein: The length of the loosely cross-linked liquid crystal elastomer is 70-80 mm, and the loosely cross-linked liquid crystal elastomer is pre-stretched to 1820-1950 mm by a spiral stretching device.

4. The body temperature driven actuator according to claim 1, wherein: After adding the liquid crystal monomer to toluene, the mixture is heated at 80° C. for 5-10 minutes to dissolve the liquid crystal monomer.

5. The body temperature driven actuator according to claim 1, wherein: The rotation speed of the spiral stretching device is 0.25-0.28 r / s, so that the loosely cross-linked liquid crystal elastomer is pre-stretched to 2300%-2500%.

6. The body temperature driven actuator according to claim 1, wherein: The storage modulus of the liquid crystal elastomer (100) is 0.1-1 MPa, and the temperature T at which the nematic phase of the liquid crystal elastomer (100) transitions to the isotropic phase is NI It is 60-62℃.

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