SEBS-based liquid crystal elastomer and preparation method thereof

Abstract

The application provides a SEBS-based liquid crystal elastomer and a preparation method, and belongs to the field of synthesis and application of thermoreversible deformation liquid crystal polymers. The liquid crystal elastomer is a low-crosslinking polymer network prepared by light crosslinking solidification of ethylene-ethylene / butylene-styrene block copolymer SEBS and a main-chain type liquid crystal oligomer with two terminal mercapto groups, is prepared by a two-step crosslinking method, is prepared by a two-step method of PS segment physical domain pre-crosslinking and mercapto-alkene click reaction light crosslinking, and has bidirectional reversible deformation capability. The application realizes the regulation of the phase transition temperature and reversible deformation capability of the polymer material by controlling the content of liquid crystal units and the crosslinking solidification degree; provides a new idea and method for preparing intelligent flexible driver materials with novel functions; and is beneficial to the development of SBS and SEBS materials in the direction of high performance and intelligence based on the liquid crystal polymer network.

Description

Technical Field

[0001] This invention belongs to the field of thermally reversible deformation liquid crystal polymer synthesis and application, and relates to a SEBS-based liquid crystal elastomer and its preparation method. Background Technology

[0002] With the rapid development of science and technology in human society, the importance of materials in social development is increasing day by day. As the functions of traditional materials can no longer cover the requirements of various emerging fields and technologies, intelligent materials integrating sensing, actuation, and information processing have become a research hotspot. Liquid crystal elastomers (LCEs) are three-dimensional polymer networks obtained by moderately cross-linking liquid crystal polymers. They can respond to external stimuli by undergoing a liquid crystal phase transition to an isotropic phase, possessing advantages such as reversible bidirectional deformation memory, rapid and large-amplitude deformation, and programmable macroscopic deformation. They have broad application prospects in fields such as biomimetic devices, soft braking, and biomedicine.

[0003] Styrene-ethylene / butene-styrene block copolymers (SEBS) with varying degrees of hydrogenation, serving as the backbone of liquid crystal elastomers, possess a unique biphase structure. In styrene-butadiene-styrene triblock copolymers (SBS), the styrene segments used for physical crosslinking are dispersed within a continuous polybutadiene phase, giving the material the dual advantages of room-temperature elasticity and high-temperature processability, making it a typical high-performance thermoplastic elastomer. Furthermore, SBS rubber materials are currently among the most produced, lowest-cost, and most widely used rubber materials. Developing high-value-added downstream products not only enriches the types of smart polymers but also plays a crucial role in upgrading the value chain.

[0004] Currently, the main methods for preparing liquid crystal elastomers (LCEs) are the "one-step method" and the "two-step method." The "one-step method" uses triboelectric alignment, electro-alignment, magnetic alignment, or optical alignment to induce the molten liquid crystal monomers to align within a liquid crystal cell, and then uses light or heat to initiate free radical polymerization to form a liquid crystal elastomer film. However, the "one-step method" is primarily limited by production conditions; the size of the liquid crystal cell directly determines the size and shape of the prepared liquid crystal, making it unsuitable for large-scale production of non-small-sized thin-film liquid crystals. Secondly, to obtain single-domain alignment of the liquid crystal, the "one-step method" often requires an in-situ alignment mechanism; otherwise, under external stimuli, the multi-domain aligned liquid crystal system cannot undergo reversible macroscopic deformation. The "two-step method" first obtains a lightly cross-linked liquid crystal network, and then uses light or heat to initiate free radical polymerization based on mechanical stretching, thereby solidifying the orientation and alignment of the liquid crystal monomers. Liquid crystal elastomers prepared by this method are not limited by the liquid crystal cell and can better exhibit programmable macroscopic deformation advantages during the liquid crystal phase-isotropic phase transition. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a SEBS-based liquid crystal elastomer and its preparation method. The aim is to prepare a dual-thiol-terminated main-chain liquid crystal oligomer via Michael addition reaction, and then prepare a styrene-ethylene / butene-styrene block copolymer (SEBS) via hydrogenation reaction with a styrene-butadiene-styrene triblock copolymer (SBS) prepared by anionic polymerization. A low-degree crosslinked polymer network is obtained through photocrosslinking and curing, thereby preparing the SEBS-based liquid crystal elastomer, which exhibits superior thermal and mechanical properties. This invention adjusts the properties of the liquid crystal elastomer by controlling the component ratio, developing a new isotropic phase transition temperature (LCE) control mode. Specifically, by controlling the ratio of thiol components to acrylate components, and the ratio of liquid crystal moieties to chain extenders in the acrylate components, the structural composition and properties of the liquid crystal oligomer are controlled, further regulating the LCE's phase transition temperature and thermally driven properties.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] On one hand, this invention provides a SEBS-based liquid crystal elastomer. This liquid crystal elastomer is a low-crosslinked polymer network prepared by photocrosslinking and curing of an ethylene-ethylene / butene-styrene block copolymer (SEBS) and a main-chain liquid crystal oligomer with dual-thiol terminals. It possesses reversible bidirectional deformation memory function, providing new possibilities for the fabrication of more precise and controllable flexible actuation devices. The ethylene-ethylene / butene-styrene block copolymer (SEBS) is prepared by hydrogenation of a styrene-butadiene-styrene triblock copolymer (SBS) prepared by anionic polymerization; the main-chain liquid crystal oligomer with dual-thiol terminals is prepared by Michael addition reaction.

[0008] Furthermore, the main-chain liquid crystal oligomer with dual-thiol end groups is a main-chain liquid crystal oligomer composed of the liquid crystal unit 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82), the chain extender polyethylene glycol diacrylate (PEGDA), and the thiol end-capping component 2,2′-(1,2-ethylenedioxy)bis(ethylenedioxide)thiol (EDDT), and its liquid crystal formation region is [T g (-20~50℃)-LC-T i (-10~85℃)).

[0009] Furthermore, the main-chain liquid crystal oligomer with dual-thiol terminals has a weight-average molecular weight (M... w ) is 1-20 kg·mol -1 The molecular weight distribution index (PDI) is 1.5-3.0, and the glass transition temperature T of the main-chain liquid crystal oligomers is... g The temperature range is -20 to 50℃, and the isotropic transition temperature T of the liquid crystal phase is... iIts temperature range is -10 to 85℃, and its structural formula is as follows:

[0010]

[0011] Furthermore, in the main-chain liquid crystal oligomer with dual-thiol terminals, the content of the liquid crystal unit RM82 is 5-50 mol%, and its structural formula is as follows:

[0012]

[0013] Furthermore, in the main-chain liquid crystal oligomer with dual-thiol terminals, the content of the chain extender PEGDA is 0-43 mol%, preferably 0-15 mol%, and its structural formula is as follows:

[0014]

[0015] Furthermore, the styrene-butadiene-styrene triblock copolymer (SBS) has a weight-average molecular weight (M... w ) is 50-400 kg·mol -1 The molecular weight distribution index (PDI) is 1.05-1.40, and the styrene mass fraction is 15-50% based on a total mass of styrene and butadiene of 100%.

[0016] Furthermore, the styrene-butadiene-styrene triblock copolymers (SEBS) with different degrees of hydrogenation have a weight-average molecular weight (M). w ) is 50-400 kg·mol -1 The molecular weight distribution index (PDI) is 2.1-2.5, and the degree of hydrogenation is... It is 50-100%, melting point T m Its temperature range is 45-90℃, and its structural formula is as follows:

[0017]

[0018] Furthermore, the SBS and SEBS are preferably of a weight-average molecular weight of 100-250 kg·mol⁻¹. -1 The degree of hydrogenation of SEBS is 50-70%.

[0019] Secondly, a method for preparing a SEBS-based liquid crystal elastomer includes the following steps:

[0020] Step S1: Synthesize the main-chain liquid crystal oligomer with dual-thiol terminals, as follows:

[0021] Under anhydrous and oxygen-free argon atmosphere, liquid crystal building blocks RM82, PEGDA, EDDT, and acetone were added to a three-necked flask equipped with a mechanical stirrer. A Michael addition catalyst was also added to the flask, and the reaction was carried out at room temperature for 20-25 hours. After the reaction was complete, a main-chain liquid crystal oligomer with two-terminated thiol groups was obtained. In this step, the Michael addition reaction was the primary reaction.

[0022] The molar ratio of RM82, PEGDA, and EDDT is (0.3-1):(0-0.7):(1.1-2).

[0023] The synthetic route for the liquid crystal oligomers is as follows:

[0024]

[0025] Step S2, synthesizing SEBS-based liquid crystal elastomer, as detailed below:

[0026] A main-chain liquid crystal oligomer and SEBS are dissolved in a solvent, with the main-chain liquid crystal oligomer comprising 20-50% of the total mass of the main-chain liquid crystal oligomer and SEBS (100% by mass). After mechanical stirring and uniform mixing, a photoinitiator is added to initiate a photocrosslinking reaction. Following the reaction, a film is coated, and after solvent evaporation, the film material is obtained. This film is cut into strips, stretched and oriented to 100-500% strain, and then subjected to a further double-sided photocrosslinking reaction for 0.5-4 hours. After the reaction is complete, a SEBS-based liquid crystal elastomer with an adjustable phase transition temperature is obtained. In this step, a "thiol-olefin" click reaction mainly occurs.

[0027] Furthermore, in step S2, the solvent may be toluene, chloroform, tetrahydrofuran, etc.

[0028] Further, in step S2, the initiator for the photocrosslinking reaction includes (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (photoinitiator TPO), 2-methyl-4'-(methylthio)-2-morpholinyl benzophenone (photoinitiator 907), and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (photoinitiator 819), preferably 2-methyl-4'-(methylthio)-2-morpholinyl benzophenone (photoinitiator 907); its structural formula is as follows:

[0029]

[0030] Further, in step S2, the amount of photoinitiator added is: 0.3 to 0.6 g of main-chain liquid crystal oligomer is added for every 1 μmol of photoinitiator.

[0031] Furthermore, in step S2, the strain of the spline is preferably 200-300%.

[0032] Furthermore, in step S2, the photocrosslinking reaction is carried out at room temperature for a time preferably 2-4 hours.

[0033] Further, in step S1, the catalyst for the Michael addition reaction is di-n-propylamine (DPA), triethylamine (TEA), or N,N-diisopropylethylamine (DIPEA), preferably di-n-propylamine (DPA).

[0034] Further, in step S1, the amount of catalyst added for the Michael addition reaction is 2-4% of the total mass of the main-chain liquid crystal oligomer with two-terminated thiol groups, and its structural formula is as follows:

[0035]

[0036] Experimental tests of this invention:

[0037] Liquid crystal performance analysis: The liquid crystal texture of SEBS-based liquid crystal elastomers was observed using a polarizing microscope (POM) equipped with a hot stage and a digital camera. The molecular weight and molecular weight distribution index (weight-average molecular weight to number-average molecular weight) of the polymers were determined by gel permeation chromatography (GPC), and the glass transition temperature To of the liquid crystal oligomers was determined using differential calorimetry (DSC). g Heqing Highlights T i .

[0038] The innovation of this invention is:

[0039] This invention prepares SEBS-based liquid crystal elastomers by physically crosslinking double-terminated thiol-containing liquid crystal oligomers with SEBS of varying hydrogenation degrees using solvents such as toluene, chloroform, and tetrahydrofuran, followed by photocuring with a photoinitiator for secondary crosslinking. These elastomers exhibit bidirectional reversible crosslinking capabilities. By controlling the ratio of thiol-containing to acrylate components, and the ratio of liquid crystal building blocks to chain extenders within the acrylate components, the structural composition and properties of the liquid crystal oligomers can be regulated. Furthermore, the phase transition temperature and thermal actuation properties of the LCE can be controlled, providing a new approach and method for preparing intelligent flexible actuation materials with novel functions.

[0040] The beneficial effects of this invention are as follows:

[0041] This invention synthesizes double-thiol-terminated liquid crystal oligomers and SEBS with tunable hydrogenation degree based on methods such as Michael addition, and obtains SEBS-based liquid crystal elastomers through a two-step photocuring and secondary crosslinking process. By controlling the liquid crystal unit content and the degree of crosslinking and curing, the phase transition temperature and reversible deformation capability of the polymer material are regulated. This provides a new approach and method for preparing intelligent flexible actuator materials with novel functions. Based on this liquid crystal polymer network, it is beneficial to develop SBS and SEBS materials towards higher performance and greater intelligence. Attached Figure Description

[0042] Figure 1 DSC curves for liquid crystal oligomers with different proportions of liquid crystal building blocks; Figure 1 (a) DSC curves of four liquid crystal oligomers with molar ratios of RM82, PEGDA, and EDDT of 0.7:0.3:1.1, 0.7:0.3:1.3, 0.7:0.3:1.5, and 0.7:0.3:2; Figure 1 (b) shows the DSC curves of four liquid crystal oligomers with molar ratios of RM82, PEGDA, and EDDT of 0.5:0.5:2, 0.7:0.3:2, 0.8:0.2:2, and 0.9:0.1:2.

[0043] Figure 2 Polarized texture photographs of liquid crystal elastomers with a molar ratio of RM82, PEGDA, and EDDT of 0.9:0.1:2 under different strains; Figure 2 (a) Photograph of polarized liquid crystal texture at a strain of 50% and a deflection angle of 45°; Figure 2 (b) A photograph of the polarized liquid crystal texture at a strain of 100% and a deflection angle of 45°. Figure 2 (c) A photograph of the polarized liquid crystal texture at a strain of 200% and a deflection angle of 45°; Figure 2 (d) Photograph of polarized liquid crystal texture at a strain of 50% and a deflection angle of 90°; Figure 2 (e) A photograph of the polarized liquid crystal texture at a strain of 100% and a deflection angle of 90°. Figure 2 (f) A photograph of the polarized liquid crystal texture at a strain of 200% and a deflection angle of 90°; Figure 2 (g) Photograph of polarized liquid crystal texture at a strain of 300% and a deflection angle of 45°; Figure 2 (h) is a photograph of the polarized liquid crystal texture under a strain of 400% and a deflection angle of 45°. Figure 2 (i) A photograph of the polarized liquid crystal texture at a strain of 500% and a deflection angle of 45°; Figure 2 (j) is a photograph of the polarized liquid crystal texture under a strain of 300% and a deflection angle of 90°; Figure 2 (k) is a polarized liquid crystal texture photograph with a strain of 400% and a deflection angle of 90°. Figure 2 (l) is a polarized liquid crystal texture photograph with a strain of 500% and a deflection angle of 90°. Detailed Implementation

[0044] The following specific embodiments are provided to further illustrate the present invention, but are not intended to limit the scope of protection of the claims of the present invention.

[0045] Example 1

[0046] S1, Synthetic liquid crystal oligomers with dual-thiol terminals

[0047] Under anhydrous and oxygen-free argon atmosphere, liquid crystal building blocks RM82 (6.179 g, 0.009 mol), EDDT (3.76 g, 0.02 mol), PEGDA (0.2 g, 0.001 mol), and 40 mL of acetone were added to a 250 mL three-necked flask equipped with a mechanical stirrer. TEA (0.1 g) was added as a catalyst, and the reaction was carried out at room temperature for 20 h. After the reaction was complete, the resulting product was added dropwise to ethanol, and after standing for 12 h, the solution was discarded to obtain a liquid crystal oligomer with thiol-terminated ends. Number average molecular weight (M0.05) n The value is 2.6 kg·mol⁻¹ -1 The molecular weight distribution index (PDI) is 2.4, and the liquid crystal formation range is [T]. g (-40.1℃)-LC-T i (29.1℃)).

[0048] S2, Synthesis of SEBS-based liquid crystal elastomer

[0049] 0.12 g of SEBS with a hydrogenation degree of 50% and 0.03 g of a liquid crystal oligomer with two-terminated thiol groups were dissolved in chloroform and mixed thoroughly. Then, 1 μmol of photoinitiator 907 was added and poured into a mold. After the solvent evaporated, a 0.04 mm film material was obtained. The film material was cut into strips and stretched to 200% strain for orientation. Further double-sided photocrosslinking reactions were then carried out for 3 hours each. After the reaction was completed, an SEBS-based liquid crystal elastomer was obtained.

[0050] Depend on Figure 1 The DSC curves of the liquid crystal oligomer with a molar ratio of RM82, PEGDA, and EDDT of 0.8:0.2:2 show that the liquid crystal formation range is [T]. g (-40.1℃)-LC-T i [29.1℃] The phase transition temperature of liquid crystal oligomers is correlated with the relative content of thiol groups and liquid crystal building blocks.

[0051] Depend on Figure 2 The POM image shows that the liquid crystal elastomer strip exhibits a liquid crystal texture when stretched to 200%, demonstrating liquid crystal properties.

[0052] Example 2

[0053] S1, Synthetic liquid crystal oligomers with dual-thiol terminals

[0054] Under anhydrous and oxygen-free argon atmosphere, liquid crystal building blocks RM82 (6.864 g, 0.01 mol), EDDT (3.76 g, 0.02 mol), and 40 mL of acetone were added to a 250 mL three-necked flask equipped with a mechanical stirrer. DPA (2.025 g) was added as a catalyst, and the reaction was carried out at room temperature for 25 h. After the reaction was complete, the resulting product was added dropwise to ethanol, and after standing for 12 h, the solution was discarded to obtain the liquid crystal oligomers with thiol-terminated ends. Number average molecular weight (M0.05) n The value is 2.9 kg·mol⁻¹ -1 The molecular weight distribution index (PDI) is 2.5, and the liquid crystal formation range is [T]. g (-40.1℃)-LC-T i (29.1℃)).

[0055] S2, Synthesis of SEBS-based liquid crystal elastomer

[0056] 0.12 g of SEBS with a hydrogenation degree of 50% and 0.03 g of a liquid crystal oligomer with two-terminated thiol groups were dissolved in toluene and mixed thoroughly. 1 μmol of photoinitiator TPO was then added, and the mixture was poured into a mold. After the solvent evaporated, a 0.04 mm film material was obtained. The film material was cut into strips and stretched to 300% strain for orientation. Further double-sided photocrosslinking reactions were then carried out for 4 hours each. After the reaction was completed, an SEBS-based liquid crystal elastomer was obtained.

[0057] As can be seen from the POM image, the liquid crystal oligomer with a molar ratio of RM82, PEGDA, and EDDT of 1:0:2 exhibits a liquid crystal texture and has liquid crystal properties.

[0058] As can be seen from the DSC curve, the liquid crystal formation range is [T]. g (-40.1℃)-LC-T i (29.1℃)).

[0059] Example 3

[0060] S1, Synthetic liquid crystal oligomers with dual-thiol terminals

[0061] Under anhydrous and oxygen-free argon atmosphere, liquid crystal building blocks RM82 (2.059 g, 0.003 mol), EDDT (2.068 g, 0.011 mol), PEGDA (1.4 g, 0.007 mol), and 40 mL of acetone were added to a 250 mL three-necked flask equipped with a mechanical stirrer. DIPEA (0.911 g) was added as a catalyst, and the reaction was carried out at room temperature for 24 h. After the reaction was complete, the resulting product was added dropwise to ethanol, and after standing for 12 h, the solution was discarded to obtain a liquid crystal oligomer with thiol-terminated ends. Number average molecular weight (M0.05) n The value is 2.5 kg·mol⁻¹ -1The molecular weight distribution index (PDI) is 2.1, and the liquid crystal formation range is [T]. g (-50.9℃)-LC-T i (-3.2℃)).

[0062] S2, Synthesis of SEBS-based liquid crystal elastomer

[0063] 0.12 g of SEBS with a hydrogenation degree of 50% and 0.03 g of a liquid crystal oligomer with two-terminated thiol groups were dissolved in chloroform. After thorough mixing, 1 μmol of photoinitiator 819 was added, and the mixture was poured into a mold. After the solvent evaporated, a 0.04 mm film material was obtained. The film material was cut into strips and stretched to 200% strain for orientation. Then, a double-sided photocrosslinking reaction was carried out for 2 hours each. After the reaction was completed, a SEBS-based liquid crystal elastomer was obtained.

[0064] As can be seen from the POM image, the liquid crystal oligomer with a molar ratio of RM82, PEGDA, and EDDT of 0.3:0.7:1.1 exhibits a liquid crystal texture and has liquid crystal properties.

[0065] As can be seen from the DSC curve, the liquid crystal formation range is [T]. g (-50.9℃)-LC-T i (-3.2℃)).

[0066] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A SEBS-based liquid crystal elastomer, characterized in that, The liquid crystal elastomer is a low-crosslinked polymer network prepared by photocrosslinking and curing of a styrene-ethylene / butene-styrene block copolymer (SEBS) and a main-chain liquid crystal oligomer with dual-thiol groups. It possesses reversible bidirectional deformation memory function and can be used to fabricate controllable flexible actuation devices. The styrene-ethylene / butene-styrene block copolymer (SEBS) is prepared by hydrogenation of a styrene-butadiene-styrene triblock copolymer (SBS) prepared by anionic polymerization. The main-chain liquid crystal oligomer with dual-thiol groups is prepared by Michael addition reaction. The main-chain liquid crystal oligomers with dual-thiol terminals are specifically as follows: The dual-thiol-terminated main-chain liquid crystal oligomer is a main-chain liquid crystal oligomer composed of the liquid crystal unit 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene RM82, the optional chain extender polyethylene glycol diacrylate PEGDA, and the thiol-terminated component 2,2′-(1,2-ethylenedioxy)bis(ethyl mercaptan) EDDT. Its liquid crystal formation region is [T g (-20~50℃)-LC-T i (-10~85℃)]; The main-chain liquid crystal oligomer with dual-thiol terminals has a weight-average molecular weight M. w 1-20 kg∙mol -1 The molecular weight distribution index (PDI) is 1.5-3.0, and the glass transition temperature (T) of the main-chain liquid crystal oligomers is... g The range is -20 to 50 °C, and the isotropic transition temperature T of the liquid crystal phase is... i Its temperature range is -10 to 85℃, and its structural formula is as follows: 。 2. The SEBS-based liquid crystal elastomer according to claim 1, characterized in that, In the main-chain liquid crystal oligomer with dual-thiol terminals, the content of the liquid crystal unit RM82 is 5-50 mol%, and the content of the chain extender PEGDA is 0-43 mol%.

3. The SEBS-based liquid crystal elastomer according to claim 2, characterized in that, The styrene-butadiene-styrene triblock copolymer (SBS) has a weight-average molecular weight (M). w The value is 50-400 kg / mol. -1 The molecular weight distribution index (PDI) is 1.05-1.40, and the styrene mass fraction is 15-50% based on a total mass of styrene and butadiene of 100%.

4. The SEBS-based liquid crystal elastomer according to claim 3, characterized in that, The styrene-ethylene / butene-styrene block copolymer SEBS has a weight-average molecular weight M. w 50-400 kg·mol -1 The molecular weight distribution index (PDI) is 2.1-2.5, and the degree of hydrogenation is... It is 50-100%, melting point T m Its temperature range is 45-90 ℃, and its structural formula is as follows: 。 5. The SEBS-based liquid crystal elastomer according to claim 4, characterized in that, The chain extender PEGDA content is 0-15 mol%; the SBS weight-average molecular weight is 100-250 kg.mol%. -1 The SEBS described herein has a weight-average molecular weight of 100-250 kg·mol⁻¹. -1 The degree of hydrogenation of the SEBS is 50-70%.

6. A method for preparing the SEBS-based liquid crystal elastomer according to any one of claims 1-5, characterized in that, Includes the following steps: Step S1: Synthesize the main-chain liquid crystal oligomer with dual-thiol terminals, as follows: Under anhydrous and oxygen-free argon protection, liquid crystal building blocks RM82, PEGDA, EDDT, and acetone were added to a reaction vessel equipped with a mechanical stirrer, and then a Michael addition reaction catalyst was added to carry out the Michael addition reaction. The reaction was carried out at room temperature for 20-25 hours. After the reaction was completed, a main-chain liquid crystal oligomer with double-thiol groups was obtained. Step S2, synthesizing SEBS-based liquid crystal elastomer, as detailed below: A main-chain liquid crystal oligomer and SEBS are dissolved in a solvent. The main-chain liquid crystal oligomer has a mass fraction of 20-50%, with the total mass of the main-chain liquid crystal oligomer and SEBS being 100%. After mechanical stirring and mixing, a photoinitiator is added to initiate a photocrosslinking reaction. After the reaction, a film is coated. After the solvent evaporates, the film material is obtained, cut into strips, stretched and oriented to 100-500% strain, and then subjected to a double-sided photocrosslinking reaction for 0.5-4 hours. After the reaction is completed, an SEBS-based liquid crystal elastomer with an adjustable phase transition temperature is obtained.

7. The method for preparing a SEBS-based liquid crystal elastomer according to claim 6, characterized in that, In step S1: The molar ratio of RM82, PEGDA, and EDDT is (0.3-1):(0-0.7):(1.1-2). The catalyst is di-n-propylamine (DPA), triethylamine (TEA), or N,N-diisopropylethylamine (DIPEA), and the amount of catalyst added is 2-4% of the total mass of the main-chain liquid crystal oligomer with thiol-terminated ends.

8. The method for preparing a SEBS-based liquid crystal elastomer according to claim 7, characterized in that, The catalyst in step S1 is di-n-propylamine (DPA).

9. The method for preparing a SEBS-based liquid crystal elastomer according to claim 6, characterized in that, In step S2: The solvents include toluene, chloroform, and tetrahydrofuran; The initiators for the photocrosslinking reaction include (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 2-methyl-4'-(methylthio)-2-morpholinobenzophenone, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide; The amount of photoinitiator added is: 0.3~0.6g of main-chain liquid crystal oligomer for every 1 μmol of photoinitiator; The strain of the spline is 200-300%; The photocrosslinking reaction is carried out at room temperature for 2-4 hours.

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