Side chain type liquid crystal elastomer bionic actuator, preparation method and application thereof

Abstract

The invention provides a side chain type liquid crystal elastomer bionic actuator as well as a preparation method and application thereof, and belongs to the field of liquid crystal elastomer actuators. The bionic actuator is constructed by cooperating with the vertical orientation of azobenzene mesocrystal on the microscopic level and the structure bionic design on the macroscopic level of a single domain side chain type azobenzene liquid crystal elastomer SC-AZO-LCEs strip. According to the invention, a series of SC-AZO-LCEs with adjustable liquid crystal phase transition temperature are prepared by grafting two azobenzene monomers with different terminal groups on a polybutadiene PB section, and a glassy PS phase locked single domain band is obtained through mold coating and casting and mechanical stretching treatment and has excellent remoldability and recoverability; and then bionic design is carried out by simulating a unique double-layer orthogonal fiber structure of the pod to construct the double-layer bionic actuator. The large-amplitude and multi-form actuating behavior of thermal response is achieved, application of different scenes such as a soft robot, a bionic flower and an underwater gripper is created, and a new thought and method are provided for developing an intelligent flexible actuator in the future.

Description

Technical Field

[0001] The invention belongs to the field of liquid crystal elastomer actuators, and in particular relates to a side chain liquid crystal elastomer bionic actuator, a preparation method and application thereof. Background Art

[0002] Since the beginning of the 21st century, the field of intelligent material systems has been continuously broadened, the connotation has gradually expanded, and it has shown the characteristics of being closely integrated with bionic technology. Based on the original materials in nature or artificial synthetic materials (such as organic polymer materials, etc.), according to the concept of bionic design and multifunctional composite of materials, constructing intelligent bionic materials with supernatural capabilities through multi-level and multi-scale scientific assembly is one of the major directions of material development today. As a kind of intelligent soft material, liquid crystal elastomers (LCEs) combine the self-assembly characteristics and stimulus responsiveness of liquid crystals with the entropy elasticity of polymer networks, and can convert molecular-level phase changes into macroscopic deformations. They are considered to be the most promising candidate materials for mimicking the movement of organisms. The concept was first proposed by Nobel Prize winner in Physics de Gennes in 1975, who speculated that LCEs can produce reversible deformations similar to human muscle fibers. Subsequently, in 1994, Finkelmann et al. took the lead in preparing the first side-chain liquid crystal elastomer (SCLCEs) actuator. Under thermal stimulation, the ordered-disordered phase transition of liquid crystal primitives will trigger the macroscopic reversible deformation of the material. SCLCEs have the advantages of fast response speed and strong designability. Since the liquid crystal unit is connected to the main chain through a flexible spacer, it has a high degree of orientation freedom. However, at the same time, the decoupling effect between the main chain and the liquid crystal unit also causes the SCLCE actuator to generally have the problem of small macroscopic deformation. Based on the microscopic deformation mechanism and macroscopic control means, it is of great scientific value and research significance to design and develop SCLCE actuators that can achieve large and complex deformations in a coordinated multi-scale manner.

[0003] Intelligent modification of traditional materials is an important means to achieve efficient resource utilization and promote sustainable development. As a commercial thermoplastic elastomer, styrene-butadiene-styrene triblock copolymer (SBS) has good economic benefits and high accessibility, and is in urgent need of intelligent modification to break the limitations of traditional application fields. The microphase separation structure generated by the thermodynamic incompatibility of the block components and the presence of unsaturated double bonds on the polybutadiene chain segments make SBS have excellent flexibility, outstanding mechanical strength and post-modification potential.

[0004] Researchers Yin et al. (L. Yin, L. Han, F. Ge, et al. A novel side-chain liquid crystal elastomer exhibiting anomalous reversible shape change [J]. Angewandte Chemie International Edition, 2020, 59, 15129.) used SBS as the main chain to prepare a SCLCEs actuator with anomalous reversible deformation. By introducing acrylate groups to construct a photo-cross-linked network to lock the mesocrystal orientation, a single-domain actuator was obtained. However, this traditional covalent cross-linking method makes the system lose its recyclability and reprocessing capabilities.

[0005] Researchers Yin et al. (L. Yin, T. Miao, X. Cheng, et al. Chiral liquid crystalline elastomer for twisting motion without preset alignment of mesogens. ACS Macro Letters, 2021, 10, 690.) used SBS as the main chain to develop a chiral SCLCEs actuator that does not require pre-orientation. By introducing chiral dopants, the actuator can undergo macroscopic twisting deformation under thermal stimulation. However, this work also uses traditional acrylate covalent cross-linking networks, which are difficult to reshape and reprocess.

[0006] Researcher Huang Shuai (Huang Shuai. Synthesis of multifunctional liquid crystal polymers regulated by polybutadiene [D]. Dalian University of Technology, 2020.) used SBS grafted liquid crystal monomers 6-(4-((methoxyphenyl)azo)phenoxy)hexanoic acid and 6-(4-((sec-butyloxyphenyl)azo)phenoxy)hexanoic acid to prepare SCLCEs actuators, and introduced ureidopyrimidone isocyanate containing reversible quadruple hydrogen bonds as a dynamic cross-linker to give the system good reprocessing and recycling capabilities. The thermal response deformation of the actuator was achieved by utilizing the ordered-disordered phase transition of oriented mesocrystals, but the actuation deformation was still small and difficult to observe, and this work did not make improvements to this technical problem.

[0007] A Chinese patent with publication number CN115850618A discloses a dynamically cross-linked azobenzene liquid crystal elastomer with a linear / star-shaped SBS block copolymer as the main chain and a preparation method thereof. The linear / star-shaped SBS is used as the main chain, the liquid crystal monomer 6-(4-((methoxyphenyl)azo)phenoxy)hexanoic acid is grafted, and ureidopyrimidone isocyanate containing a reversible quadruple hydrogen bond is introduced as a dynamic cross-linking agent. The resulting material has good self-repair and recyclability, dynamically reversible rapid light response performance, and dynamically thermally reversible cross-linking and de-cross-linking characteristics. However, the macroscopic deformation caused by the ordered-disordered phase transition of the oriented mesogens under thermal stimulation is not involved, and the technical problem of small deformation of the SCLCEs actuator is not solved.

[0008] Although relevant research has made important progress, it is still difficult to balance the recycling and reconfiguration of the actuator with the significant actuation brought about by the oriented mesocrystal phase transition. Therefore, based on the inherent characteristics of SBS, it is very challenging but particularly important to cleverly and synergistically embed smart elements into it to design and develop new reconfigurable SCLCEs actuators with excellent actuation capabilities. The microphase separation structure is a prominent feature of SBS, in which the glassy polystyrene (PS) phase domains can act as physical cross-linking points and have been widely used in one-way shape memory materials to fix temporary shapes and memorize initial shapes. Then, an interesting idea emerged: when developing SCLCEs actuators with SBS as the main chain, can the glassy PS phase domains be used to construct a cross-linked network of LCEs, and reversibly lock and unlock the mesocrystal arrangement through its aggregation-dissociation effect? Then, the geometrically isomerized bionic features are introduced into the active deformation system by synergizing the anisotropic orientation arrangement of SCLCEs at the microscopic level and the precise construction of the actuator morphology at the macroscopic level. Thanks to the cross-integration of multiple disciplines such as materials science, thermodynamics and mechanics, the structural-functional integration of the SCLCEs actuator is realized, thereby obtaining significant actuation behavior. In summary, the present invention prepares a side-chain azobenzene liquid crystal elastomer (SC-AZO-LCEs) bionic actuator based on the phase separation structure design of SBS, uses the glassy PS phase as a physical crosslink to fix the vertically oriented azobenzene mesogens, and the dynamic physical action of the PS phase gives the system excellent recycling and reconstruction properties. Then, a bionic design is performed by simulating the unique double-layer orthogonal fiber organization of the bean pod, and a double-layer bionic actuator is constructed to achieve macroscopic large-scale, multi-morphological actuation deformation, and the bionic actuator is used to realize bionic applications in different scenarios, such as the blooming and closing of flowers, athletes exercising, and underwater grippers, etc., providing new ideas and methods for the development of intelligent flexible actuators. Summary of the invention

[0009] In order to solve the technical problem that it is difficult to balance the recyclability and reconfiguration of SCLCEs actuators with the significant actuation brought about by the oriented mesomorphic phase transition, and to realize the intelligent modification of thermoplastic elastomer SBS to break the limitations of traditional application fields, a series of liquid crystal phase transition temperatures (T ) of SCLCEs actuators were prepared by using SBS as the main chain and grafting two azobenzene monomers with different terminal groups by using polybutadiene (PB) segments. i ) with adjustable side-chain azobenzene liquid crystal elastomers (SC-AZO-LCEs), and obtained single-domain oriented strips locked in glassy polystyrene (PS) phase through mold casting and mechanical stretching treatment, which have excellent remodeling and recyclability. Then, a double-layer bionic actuator was constructed based on structural bionic design, which can realize large-scale and multi-morphological actuation behavior with thermal response, and it is used to create bionic applications in multiple scenarios, providing new ideas and methods for the development of intelligent flexible actuators.

[0010] In order to achieve the above object, the present invention adopts the following technical solution:

[0011] In the first aspect, the present invention provides a side-chain liquid crystal elastomer bionic actuator, specifically a SC-AZO-LCEs bionic actuator, which is composed of two identical single-domain SC-AZO-LCEs strips. Based on structural bionic design, the two single-domain strips are subjected to thermal relaxation, orthogonal stacking, self-welding and other treatments to obtain the SC-AZO-LCEs bionic actuator. The SC-AZO-LCEs bionic actuator has a double-layer orthogonal orientation structure, can achieve large-scale, multi-morphological actuation deformation in thermal response, and has a wide range of application scenarios.

[0012] Furthermore, the single-domain SC-AZO-LCEs strip is obtained by mold casting and mechanical stretching, has a vertical liquid crystal orientation, and the orientation is locked by the glassy PS phase.

[0013] Furthermore, the structural bionic design refers to utilizing the oriented structure of the single-domain SC-AZO-LCEs strips to perform an orthogonal stacking design to simulate the unique double-layer orthogonal fiber structure of the peapod.

[0014] In a second aspect, a method for preparing a side chain liquid crystal elastomer bionic actuator, specifically a method for preparing a SC-AZO-LCEs bionic actuator, mainly comprises the following steps:

[0015] S1, preparation of single-domain SC-AZO-LCEs strips;

[0016] First, the methoxy-terminated azobenzene monomer M was synthesized by click reaction and esterification reaction. m and sec-butyloxy-terminated azobenzene monomer M bGrafted onto the SBS main chain, a multi-domain SC-AZO-LCEs film was obtained by solution casting; secondly, the multi-domain SC-AZO-LCEs film was placed in an environment above the dissociation temperature of the glassy PS phase and mechanically stretched to a certain strain, and then slowly cooled to obtain a single-domain SC-AZO-LCEs strip locked in the glassy PS phase, which has a series of mild T i (<100℃), good welding performance, excellent recycling and reconstruction and unique vertical orientation.

[0017] S2, preparation of double-layer SC-AZO-LCEs biomimetic actuator;

[0018] Two single-domain SC-AZO-LCEs strips are thermally relaxed at a certain temperature, and the two relaxed single-domain SC-AZO-LCEs strips are orthogonally stacked in the stretching direction, and then welded under appropriate conditions using liquid crystal self-assembly and hydrogen bond interaction. After completion, the unwelded edges of the strips are trimmed off, leaving only the square, double-layer welded parts. Finally, based on the stretching direction of the upper film, the strips are trimmed at any angle within the range of -90°-+90°, with the clockwise direction being positive and the counterclockwise direction being negative. To obtain a double-layer SC-AZO-LCEs bionic actuator capable of large and complex deformations (such as chiral spirals, curling, and shape inversion),

[0019] Further, in step S1, the glassy PS phase-locked single-domain SC-AZO-LCEs strip is obtained by changing the two azobenzene monomers M m and M b The feed ratio can regulate its T i (40-90°C), preferably 60-76°C; without additional covalent crosslinking, the self-assembly of azobenzene liquid crystals and the hydrogen bonding interaction between the residual hydroxyl groups on the main chain give the system good self-welding performance, with a welding efficiency of 40-100%, preferably 59-82%; the single-domain SC-AZO-LCEs strip can be reprogrammed into different actuation modes by using different deformation forces, and can also be reshaped without considering the arrangement of the mesogens, and can be repeatedly dissolved with excellent recyclability; the single-domain SC-AZO-LCEs strip is composed of SBS-based side chain azobenzene liquid crystal elastomer, and its structural formula is as follows:

[0020]

[0021] Furthermore, in step S1, the SBS main chain is a styrene-butadiene-styrene triblock copolymer prepared by living anionic polymerization; the number average molecular weight of the SBS main chain is n 10.0-300.0kg·mol -1, the molecular weight distribution index PDI is 1.03-1.8; based on the mass of styrene and butadiene as 100%, the mass fraction of styrene polymerization units in the SBS is 10-30wt%, and the mass fraction of butadiene polymerization units is 70-90wt%; based on the total number of double bonds in the butadiene polymerization units as 100%, the 1,4-structure content in the butadiene polymerization units is 80-100mol%; the SBS is a polystyrene block PS, a polybutadiene block PB, and a polystyrene block PS copolymer in sequence, and its structural formula is as follows:

[0022]

[0023] Further, in step S1, the methoxy-terminated azobenzene monomer M m (50-75 mol%), its liquid crystal formation interval is [T m (153-159℃)-LC-T i (160-165°C)], an obvious liquid crystal texture can be observed, which is a smectic liquid crystal; the sec-butyloxyazobenzene monomer M b (15-40mol%) Its melting temperature T m At 140-150°C, no obvious liquid crystal texture was observed; the azobenzene monomer M m and M b , whose structural formula is as follows:

[0024]

[0025] Furthermore, in step S1, the environment higher than the dissociation temperature of the glassy PS phase is 110-130°C.

[0026] Furthermore, in step S1, the strain degree is 100-300%.

[0027] Furthermore, in step S2, the heat relaxation temperature is 50-70°C.

[0028] Furthermore, in step S2, the welding condition is 56-72°C.

[0029] Furthermore, in step S2, the cutting angle is preferably -45° to +90°.

[0030] In a third aspect, an application of a double-layer SC-AZO-LCEs bionic actuator is provided. The application of the double-layer SC-AZO-LCEs bionic actuator includes but is not limited to being used for making soft robots, underwater grippers, bionic flowers, etc.

[0031] Experimental tests of the present invention:

[0032] (1) Liquid crystal performance analysis: Azobenzene monomer M m and M b The liquid crystal texture was observed by polarizing microscope (POM). The molecular weight and molecular weight distribution index of the main chain SBS were determined by gel permeation chromatography (GPC), and the melting point T of the azobenzene monomer was determined by differential scanning calorimetry (DSC). m and clear point T i And the liquid crystal phase transition temperature T of the side chain liquid crystal elastomer SC-AZO-LCEs i .

[0033] (2) Welding performance analysis: Welding was performed using an Instron 5567A material testing machine at room temperature at a speed of 10 mm / min. -1 The specimens before and after welding were tensile tested at a rate of 1.5 % and the welding efficiency was calculated using the fracture strength before and after welding.

[0034] (3) Vertical orientation characterization: In situ polarized infrared spectroscopy (FT-IR) testing was performed using a Bruker Equinox55 infrared spectrometer with a polarizer; two-dimensional wide-angle X-ray diffraction (2D-WAXD) testing was performed using a Bruker D8 X-ray diffractometer with a CuKa radiation source.

[0035] The beneficial effects of the present invention are:

[0036] (1) The present invention develops a new type of side chain azobenzene liquid crystal elastomer (SC-AZO-LCEs) actuator based on the microphase separation structure of thermoplastic elastomer styrene-butadiene-styrene triblock copolymer (SBS), realizes the intelligent modification of SBS and effectively broadens its application field. No additional covalent crosslinking is required, and polybutadiene (PB) block grafted azobenzene monomer (M m 、M b ), glassy polystyrene (PS) phase to build a cross-linked network of the system. The preparation process is simple, efficient and easy to execute. The prepared system has excellent recycling and reconstruction properties. By controlling the feed ratio of the two monomers, the liquid crystal phase transition temperature (T i ) regulation.

[0037] (2) Based on the macroscopic bionic design of the mesocrystal orientation coordination of the single-domain SC-AZO-LCEs strips locked in the glassy PS phase, the present invention successfully prepared a double-layer bionic actuator by utilizing the self-welding ability of the system, realizing structural-functional integration. The bionic actuator can exhibit large-scale, multi-morphological macroscopic deformation and can be applied in a variety of scenarios, providing new ideas and methods for the development of intelligent flexible actuators. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1The DSC curves of the side chain liquid crystal elastomer SC-AZO-LCEs strips obtained in Examples 1-4.

[0039] Figure 2 These are stress-strain curves of the side chain liquid crystal elastomer SC-AZO-LCEs strips of Examples 1-4 before and after welding; (a) Example 1; (b) Example 2; (c) Example 3; (a) Example 4.

[0040] Figure 3 Characterization diagram of the vertical orientation and reversibility of the single-domain strip of side chain liquid crystal elastomer SC-AZO-LCEs in Example 1; (a) in-situ polarization-variable temperature infrared spectrum of the single-domain SC-AZO-LCEs strip; (b) two-dimensional wide-angle X-ray diffraction pattern of the single-domain SC-AZO-LCEs strip.

[0041] Figure 4 Schematic diagram of the preparation process of the double-layer SC-AZO-LCEs biomimetic actuator.

[0042] Figure 5 The multi-morphological actuation behaviors of the double-layer SC-AZO-LCEs bionic actuator. (a) The actuation deformation of the double-layer bionic actuator cut at -45°, +45°, 0°, and 90° when the thermal relaxation temperature is 70°C; (b) The actuation deformation of the double-layer bionic actuator cut at -45°, +45°, 0°, and 90° when the thermal relaxation temperature is 50°C.

[0043] Figure 6 This is an application example of a double-layer SC-AZO-LCEs bionic actuator (soft robot).

[0044] Figure 7 This is an application example of a double-layer SC-AZO-LCEs bionic actuator (bionic flower).

[0045] Figure 8 This is an application example of a double-layer SC-AZO-LCEs bionic actuator (underwater gripper).

[0046] Fig. 9 The reshaping and recycling behavior of the double-layer SC-AZO-LCEs bionic actuator; (a) Schematic diagram showing the recyclability of the double-layer SC-AZO-LCEs bionic actuator; (b) Schematic diagram showing the reshaping of the double-layer SC-AZO-LCEs bionic actuator. DETAILED DESCRIPTION

[0047] The present invention is further described with reference to the following specific embodiments, but they are not intended to limit the scope of protection of the claims of the present invention.

[0048] Example 1

[0049] S1, preparation of single-domain SC-AZO-LCEs strips;

[0050] First, M m (0.60 g, 1.92 mmol) and M b (0.14 g, 0.38 mmol) was grafted onto the SBS main chain, and a multi-domain SC-AZO-LCEs film was obtained by solution casting. Secondly, the multi-domain SC-AZO-LCEs film was mechanically stretched to 100% at a temperature above 110 °C, and then slowly cooled to obtain a single-domain SC-AZO-LCEs strip locked in a glassy PS phase. Its T i The temperature is 76°C, the welding efficiency is 62%, and it has excellent recycling and reconstruction properties and a unique vertical orientation.

[0051] S2, preparation of double-layer SC-AZO-LCEs biomimetic actuator;

[0052] Two single-domain SC-AZO-LCEs strips were thermally relaxed at 70°C and orthogonally stacked in the stretching direction. They were then welded at 72°C using liquid crystal self-assembly and hydrogen bonding interactions. The unwelded edges of the strips were trimmed off, leaving only the square, double-layer welded parts. Finally, the stretching direction of the upper film was used as a reference, with the clockwise direction being positive and the counterclockwise direction being negative, and the strips were trimmed at +90° to obtain a double-layer SC-AZO-LCEs bionic actuator that can achieve large-scale, positive curling (including the upper film).

[0053] Depend on Figure 1 From the DSC curves, we can see that the SC-AZO-LCEs strips prepared with different monomer ratios all show a unique liquid crystal phase transition peak, and the liquid crystal phase transition temperature T i It is component-dependent.

[0054] Depend on Figure 2 The stress-strain curves of the medium side chain liquid crystal elastomer SC-AZO-LCEs strips before and after welding show that the SC-AZO-LCEs strips have good welding properties.

[0055] Depend on Figure 3 It can be seen that the characteristic peak of the aromatic ring of azobenzene mesogen is about 1600cm -1 At the point where the absorption peak in the perpendicular direction is significantly higher than that in the stretching direction, it exhibits infrared dichroism, indicating that the azobenzene mesocrystals are oriented perpendicular to the stretching direction. After heating, the oriented mesocrystals transform from liquid crystal phase to isotropic phase, and the infrared dichroism disappears. During the heating and cooling process, the reversible appearance and disappearance of infrared dichroism and two-dimensional diffraction arcs indicate the reversibility of the orientation of azobenzene mesocrystals.

[0056] Figure 4 The process of designing and preparing a double-layer SC-AZO-LCEs bionic actuator to simulate the double-layer orthogonal fiber structure of a peapod.

[0057] Figure 5 The double-layer SC-AZO-LCEs bionic actuator cut at -45°, 0°, +45° and +90° respectively exhibits right-handed spiral, left-handed spiral, reverse curling and forward curling deformations, and the deformation is reversible, which can be reversibly cycled between the initial one-dimensional shape and the three-dimensional shape after thermal triggering.

[0058] Figure 6 The soft robot is made of double-layer SC-AZO-LCEs bionic actuators and can simulate the movements of humans exercising by hanging on a horizontal bar.

[0059] Figure 7 The bionic flowers prepared using double-layer SC-AZO-LCEs bionic actuators can undergo repeated closing and blooming processes.

[0060] Figure 8 The underwater gripper prepared by double-layer SC-AZO-LCEs bionic actuator can grasp and transfer underwater objects by utilizing changes in water temperature.

[0061] Fig. 9 It was demonstrated that the double-layer SC-AZO-LCEs bionic actuator can be reshaped into different shapes such as letters and spirals, and can also be dissolved and re-coated, showing excellent recycling and reconstruction properties.

[0062] Example 2

[0063] S1, preparation of single-domain SC-AZO-LCEs strips;

[0064] First, M m (0.51 g, 1.65 mmol) and M b (0.23 g, 0.66 mmol) was grafted onto the SBS main chain, and a multi-domain SC-AZO-LCEs film was obtained by solution casting. Secondly, the multi-domain SC-AZO-LCEs film was mechanically stretched to 200% at above 120 °C, and then slowly cooled to obtain a single-domain SC-AZO-LCEs strip locked in a glassy PS phase. Its T i The temperature is 72°C, the welding efficiency is 60%, and it has excellent recycling and reconstruction properties and a unique vertical orientation.

[0065] S2, preparation of double-layer SC-AZO-LCEs biomimetic actuator;

[0066] Two single-domain SC-AZO-LCEs strips were thermally relaxed at 70°C and orthogonally stacked in the stretching direction. They were then welded at 68°C using liquid crystal self-assembly and hydrogen bonding interactions. The unwelded edges of the strips were trimmed off, leaving only the square, double-layer welded parts. Finally, the stretching direction of the upper film was used as a reference, with the clockwise direction being positive and the counterclockwise direction being negative, and the strips were trimmed at +45° to obtain a double-layer SC-AZO-LCEs bionic actuator capable of large, left-handed spiral deformation.

[0067] Example 3

[0068] S1, preparation of single-domain SC-AZO-LCEs strips;

[0069] First, M m (0.451 g, 1.44 mmol) and M b (0.304 g, 0.864 mmol) was grafted onto the SBS main chain, and a multi-domain SC-AZO-LCEs film was obtained by solution casting. Secondly, the multi-domain SC-AZO-LCEs film was mechanically stretched to 300% at above 130 °C, and then slowly cooled to obtain a single-domain SC-AZO-LCEs strip locked in a glassy PS phase. Its T i The temperature is 68°C, the welding efficiency is 82%, and it has excellent recycling and reconstruction properties and a unique vertical orientation.

[0070] S2, preparation of double-layer SC-AZO-LCEs biomimetic actuator;

[0071] Two single-domain SC-AZO-LCEs strips were thermally relaxed at 50°C and orthogonally stacked in the stretching direction. They were then welded at 64°C using liquid crystal self-assembly and hydrogen bonding interactions. The unwelded edges of the strips were trimmed off, leaving only the square, double-layer welded parts. Finally, the stretching direction of the upper film was used as a reference, with the clockwise direction being positive and the counterclockwise direction being negative, and the strips were trimmed at 0° to obtain a double-layer SC-AZO-LCEs bionic actuator that can achieve large-scale, forward-reverse reversal curling deformation.

[0072] Example 4

[0073] S1, preparation of single-domain SC-AZO-LCEs strips;

[0074] First, M m (0.40 g, 1.28 mmol) and M b(0.36 g, 1.024 mmol) was grafted onto the SBS main chain, and a multi-domain SC-AZO-LCEs film was obtained by solution casting. Secondly, the multi-domain SC-AZO-LCEs film was mechanically stretched to 200% at a temperature above 120 °C, and then slowly cooled to obtain a single-domain SC-AZO-LCEs strip locked in a glassy PS phase. Its T i The temperature is 60°C, the welding efficiency is 59%, and it has excellent recycling and reconstruction properties and a unique vertical orientation.

[0075] S2, preparation of double-layer SC-AZO-LCEs biomimetic actuator;

[0076] Two single-domain SC-AZO-LCEs strips were thermally relaxed at 50°C and orthogonally stacked in the stretching direction. They were then welded at 56°C using liquid crystal self-assembly and hydrogen bonding interactions. The unwelded edges of the strips were trimmed off, leaving only the square, double-layer welded parts. Finally, the stretching direction of the upper film was used as a reference, with the clockwise direction being positive and the counterclockwise direction being negative, and the strips were trimmed at -45° to obtain a double-layer SC-AZO-LCEs bionic actuator that can achieve large, right-handed-left-handed reverse spiral deformation.

[0077] The above-described embodiments merely express the implementation methods of the present invention, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A side chain liquid crystal elastomer bionic actuator, characterized in that: The side chain liquid crystal elastomer bionic actuator is a SC-AZO-LCEs bionic actuator, which is composed of two identical single-domain SC-AZO-LCEs strips. Based on the structural bionic design, the two single-domain strips are subjected to thermal relaxation, orthogonal stacking, and self-welding to obtain the SC-AZO-LCEs bionic actuator, which has a double-layer orthogonal orientation structure.

2. A side chain liquid crystal elastomer bionic actuator according to claim 1, characterized in that: The single-domain SC-AZO-LCEs strip is obtained by mold casting and mechanical stretching, and has a vertical liquid crystal orientation, and the orientation is locked by the glassy PS phase.

3. A side chain liquid crystal elastomer bionic actuator according to claim 2, characterized in that: The structural bionic design refers to the orthogonal stacking design using the oriented structure of the single-domain SC-AZO-LCEs strips to simulate the unique double-layer orthogonal fiber structure of the peapod.

4. A method for preparing a side chain liquid crystal elastomer bionic actuator according to claim 1, 2 or 3, characterized in that: The following steps are involved: S1, preparation of single-domain SC-AZO-LCEs strips; First, a multi-domain SC-AZO-LCEs film was prepared. Second, the multi-domain SC-AZO-LCEs film was mechanically stretched to a certain strain in an environment above the dissociation temperature of the glassy PS phase, and after cooling, a single-domain SC-AZO-LCEs strip locked in the glassy PS phase was obtained. S2, preparation of double-layer SC-AZO-LCEs biomimetic actuator; Two single-domain SC-AZO-LCEs strips were thermally relaxed and orthogonally stacked in the stretching direction. They were welded under suitable conditions using liquid crystal self-assembly and hydrogen bonding interactions, and after completion, the unwelded edges of the strips were trimmed off to obtain a double-layer welded part. The strips were trimmed at different angles based on the stretching direction of the upper film to obtain a double-layer SC-AZO-LCEs bionic actuator that can achieve large and complex deformations.

5. The method for preparing the side chain liquid crystal elastomer bionic actuator according to claim 1, 2 or 3 according to claim 4, characterized in that: In the S1: The methoxy-terminated azobenzene monomer M was synthesized by click reaction and esterification reaction. m and sec-butyloxy-terminated azobenzene monomer M b Grafted onto the SBS backbone, multi-domain SC-AZO-LCEs films were obtained by solution casting; The environment above the dissociation temperature of the glassy PS phase is 110-130°C; The strain degree is 100-300%.

6. The method for preparing the side chain liquid crystal elastomer bionic actuator according to claim 1, 2 or 3 according to claim 5, characterized in that: In the S1: The SBS main chain is a styrene-butadiene-styrene triblock copolymer prepared by living anionic polymerization; the number average molecular weight of the SBS main chain is M n 10.0-300.0kg·mol -1 , the molecular weight distribution index PDI is 1.03-1.8; based on the mass of styrene and butadiene as 100%, the mass fraction of styrene polymerization units in the SBS is 10-30wt%, and the mass fraction of butadiene polymerization units is 70-90wt%; based on the total number of double bonds in the butadiene polymerization units as 100%, the 1,4-structure content in the butadiene polymerization units is 80-100mol%; the SBS is a polystyrene block PS, a polybutadiene block PB, and a polystyrene block PS copolymer in sequence, and its structural formula is as follows: The methoxy-terminated azobenzene monomer M m Its liquid crystal formation interval is [T m (153-159℃)-LC-T i (160-165°C)], is a smectic liquid crystal; the sec-butyloxyazobenzene monomer M b Its melting temperature T m is 140-150°C; the azobenzene monomer M m and M b , whose structural formula is as follows:

7. The method for preparing the side chain liquid crystal elastomer bionic actuator according to claim 1, 2 or 3 according to claim 6, characterized in that: In S1, the glassy PS phase-locked single-domain SC-AZO-LCEs strips are formed by changing the two azobenzene monomers M m and M b The feed ratio is adjusted to adjust its T i The temperature is 40-90°C; the self-assembly of azobenzene liquid crystals and the hydrogen bonding interaction between the residual hydroxyl groups on the main chain give the system good self-welding performance, and the welding efficiency is 40-100%; the single-domain SC-AZO-LCEs strip is composed of SBS-based side chain azobenzene liquid crystal elastomer, and its structural formula is as follows:

8. The method for preparing the side chain liquid crystal elastomer bionic actuator according to claim 1, 2 or 3 according to claim 4, characterized in that: In the S2: Based on the stretching direction of the upper film, the clockwise direction is defined as positive and the counterclockwise direction is defined as negative, and cutting is performed at any angle within the range of -90° to +90°; The heat relaxation temperature of the heat relaxation treatment is 50-70°C The welding condition is 56-72°C.

9. The method for preparing the side chain liquid crystal elastomer bionic actuator according to claim 1, 2 or 3 according to claim 8, characterized in that: The cutting angle is preferably -45° to +90°.

10. An application of the side chain liquid crystal elastomer bionic actuator according to claim 1, 2 or 3, characterized in that: The applications of the side-chain liquid crystal elastomer bionic actuator include, but are not limited to, use in making soft robots, underwater grippers, and bionic flowers.

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