A smart surface based on the temperature-dependent wettability of a dynamic covalent liquid crystal elastomer and its preparation method.

Abstract

This invention discloses a method for preparing intelligent surfaces based on the temperature-dependent wettability of dynamically covalently bonded liquid crystal elastomers and for heat dissipation control; belonging to the field of liquid crystal elastomer technology. This invention aims to solve the problem of material surfaces failing to adapt to ambient temperature during thermal processes. This invention introduces diallyl disulfide into the liquid crystal polymer molecular chain, introducing a dynamic covalent bond (disulfide bond) into the liquid crystal polymer, giving the elastomer material processability, reusability, and self-healing properties. It also increases the proportion of soft segments in the molecular chain, reducing the energy required for the liquid crystal elastomer molecular chain movement and increasing the elastomer material's elongation. This invention innovatively combines liquid crystal elastomer materials with metal materials and uses hot pressing to prepare microstructures on the composite material, successfully achieving a reversible temperature-dependent change in the surface wettability of the composite material, providing a feasible intelligent surface application solution.

Description

Technical Field

[0001] This invention belongs to the field of liquid crystal elastomers, specifically, it relates to a smart surface based on the temperature-dependent wettability of a dynamic covalent bond liquid crystal elastomer and its preparation method; this invention is applied to heat dissipation control. Background Technology

[0002] Currently, there is a demand for smart surfaces in many fields such as microfluidics, heat dissipation, and condensation. Smart surfaces refer to surfaces that can change their structure and properties in response to external stimuli. For common heat transfer processes, such as boiling heat transfer, nucleation sites are needed in the initial stage of heat transfer, so the required surface should be rough and hydrophobic. In the critical state of heat transfer, it is necessary to ensure the replenishment of liquid, so the required surface should be smooth and hydrophilic. At this time, a smart surface with wettability or surface structure that changes with temperature is needed.

[0003] Traditional methods of changing surface structure or wettability with temperature through material composites, coating with thermally induced phase change materials, or using shape memory alloys have problems such as slow reaction rate, discontinuous deformation, low surface structure control precision, and poor stability in repeated use, making them difficult to adapt to practical applications under complex thermal or multi-cycle operating conditions.

[0004] Liquid crystal elastomers, due to their unique combination of liquid crystal order and elasticity, possess thermo-reversible deformation properties, enabling controllable and reversible morphological changes within a relatively small temperature range, thus improving surface manipulation precision and response rate. Research on constructing smart surfaces using liquid crystal elastomers has gradually begun. However, due to the inherent softness and deformability of liquid crystal elastomers, undesirable deformation in non-target directions is often difficult to avoid during direct processing, affecting structural accuracy and performance stability. Research on compositing liquid crystal elastomers with rigid substrates to enhance their morphological stability and reliability remains relatively limited. Summary of the Invention

[0005] This invention aims to solve the problem of material surfaces failing to adapt to ambient temperature during thermal processes. Based on the demand for smart surfaces in various fields, this invention focuses on the characteristic of surface wettability and provides a simple, low-cost, and effective solution to address problems in practical production or research.

[0006] To address the aforementioned technical problems, the present invention adopts the following technical solution:

[0007] The purpose of this invention is to provide a smart surface with temperature-dependent wettability based on a dynamically covalently bonded liquid crystal elastomer, which is a composite of a liquid crystal elastomer and a copper sheet. The raw materials used are a thiol-terminated liquid crystal prepolymer, a chain extender, a crosslinking agent, a sulfide compound, and a catalyst. First, a smooth liquid crystal elastomer surface is formed on the copper sheet, and then microstructures are formed on the liquid crystal elastomer surface through hot pressing. The liquid crystal elastomer is mainly obtained by mixing a thiol-terminated liquid crystal prepolymer and a sulfide compound, followed by a crosslinking reaction under the action of a thiol crosslinking agent. The microstructures prepared on the material surface using hot pressing technology gradually disappear as the temperature rises and gradually reappear as the temperature falls, achieving temperature-dependent wettability of the material.

[0008] Further specifying, the liquid crystal prepolymer is the liquid crystal monomer RM257. The liquid crystal elastomer is a single-domain liquid crystal elastomer, whose molecular structure contains dynamic disulfide bonds, which break and recombine at 120°C or UV, achieving reusability and self-healing. This invention introduces disulfide ether compounds into the main-chain liquid crystal elastomer, expanding the functional design and performance optimization of the liquid crystal elastomer, enabling the single-domain liquid crystal elastomer to achieve reversible actuation at body temperature, while ensuring the actuation performance and mechanical properties of the liquid crystal elastomer.

[0009] The present invention utilizes hot pressing technology to prepare microstructures on the surface of materials, which gradually disappear as the temperature rises and gradually appear as the temperature falls, thereby achieving the temperature-dependent wettability of the material.

[0010] Another object of the present invention is to provide a method for preparing the above-mentioned smart surface based on the temperature-dependent wettability of a dynamic covalently bonded liquid crystal elastomer, comprising the following steps:

[0011] S1. Dissolve the mercapto-terminated liquid crystal prepolymer, chain extender, and catalyst in tetrahydrofuran, stir and react for 12-24 hours, then add crosslinking agent and sulfide compound, and crosslink reaction for 2-3 hours to obtain liquid crystal elastomer solution.

[0012] S2. Sand one side of the copper sheet (there can be one or more copper sheets) with sandpaper, place it in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning in sequence, then blow it dry with nitrogen gas, then attach PTFE tape to the other side of the copper sheet, and then place it in a PTFE mold with the tape side down.

[0013] S3. Then pour in the liquid crystal elastomer solution obtained in step S1, seal, and react for 24-48 hours. After the reaction is complete, remove the copper sheet, place it in a ventilated place to evaporate naturally, and then dry it.

[0014] S4. Then cut off the excess elastomer material along the edge of the copper sheet, remove the PTFE tape, and then clean it with deionized water using ultrasound.

[0015] S5. Place the stainless steel mask with arrayed micropores on a smooth stainless steel sheet, place the copper sheet placed in the center of the mask with the elastomer material facing down, place a weight on top of the copper sheet, and perform a hot-press reaction to eliminate thermal stress and obtain a smart surface.

[0016] Further specifying, in step S1, the molar ratio of the mercapto-terminated liquid crystal prepolymer, chain extender, crosslinking agent and thioether compound is 1:(0.9-1):(0.05-0.1):(0.05-0.1).

[0017] Further specifying step S4, the drying process is as follows: the liquid crystal elastomer solution from step S2 is poured into the polytetrafluoroethylene tank described in step S3, sealed, and reacted for 24–48 hours. After the reaction is complete, the sealed polytetrafluoroethylene mold is opened, and the product is first placed in a ventilated area to evaporate naturally for 12–24 hours, and then placed in a forced-air drying oven at 80–90°C for 12–24 hours. In this drying process, natural evaporation at room temperature avoids the formation of bubbles in the elastomer material due to excessively rapid evaporation, allowing the liquid crystal polymer network in the material to fully cross-link, thereby forming a dense liquid crystal elastomer film.

[0018] Further defining the design of the microporous stainless steel photomask, the considerations included equipment limitations and contact angle model, based on...

[0019] The surface of the micropillar array fabricated using a stainless steel mask should satisfy the Cassie model, i.e.:

[0020]

[0021] Where, θ c It is the apparent contact angle. It is the area ratio between the wetted area and the planar area, and θ is the initial contact angle. The microporous stainless steel mask used is 0.1 mm thick, with micropore diameters of 0.05–0.1 mm and edge distances of 0.05–0.1 mm. The reason for using a microporous membrane and a smooth stainless steel sheet as the concave mold instead of a one-piece concave mold is to avoid the inability of micropillars to be generated properly due to poor mold permeability.

[0022] Further specifying the process, a weight is placed on top of the copper sheet to bring the stainless steel mask into contact with the elastomer material. The weight should be sufficient to press the stainless steel mask into the elastomer material. Heating is performed at 120–130°C for 12–24 hours. During hot pressing, once the material cools to 100°C, the weight is removed, and the stainless steel mask is removed while still hot. The material is then repeatedly heated to 120–130°C to eliminate thermal stress. The weight used during hot pressing is 250–500g. The method for demolding and eliminating thermal stress involves heating the removed material to approximately 100°C, demolding while still hot, and then repeatedly heating the material to 120–130°C to eliminate thermal stress. In the collimation process, the pre-stretching process effectively ensures the full orientation of the liquid crystal units in the liquid crystal elastomer, while further polymerization and curing occur under ultraviolet light. This results in a single-domain liquid crystal elastomer with excellent reversible driven strain and tensile strength at break.

[0023] Further specifying, during ultrasonic cleaning in acetone, ethanol, and deionized water, the cleaning time for each solution is 5–10 minutes. The cleaned copper sheet is then dried using nitrogen gas, and polytetrafluoroethylene tape is applied to the back of the copper sheet to prevent contamination.

[0024] Further specifying, the chain extender is 1,6-hexanedithiol; the crosslinking agent is pentaerythritol tetra(3-mercaptopropionate); and the thioether compound is diallyl disulfide.

[0025] Further specifying, the catalyst is di-n-propylamine, and the ratio of mercapto-terminated liquid crystal prepolymer to catalyst is 2g:20μL.

[0026] This invention introduces diallyl disulfide into the molecular chain of a liquid crystal polymer, thereby introducing dynamic covalent bonds, particularly disulfide bonds, into the polymer. This enhances the processability, reusability, and self-healing properties of the elastomer material. Furthermore, it increases the proportion of soft segments in the molecular chain, reducing the energy required for chain movement and increasing the elastomer's stretchability. This invention innovatively combines liquid crystal elastomer materials with metallic materials and uses hot pressing to fabricate microstructures on the composite material. This successfully achieves a reversible temperature-dependent change in the surface wettability of the composite material, providing a feasible solution for smart surface applications.

[0027] The technical solution of this invention employs a two-step method to prepare liquid crystal elastomers. The chain extender and liquid crystal monomer undergo an addition reaction under the action of a catalyst to form a liquid crystal oligomer, which then reacts with a disulfide compound and a crosslinking agent. The disulfide compound is selected from those containing diene groups, which can act as a bridge between the oligomer and the crosslinking agent. In this process, di-n-propylamine is used as the catalyst, allowing the reaction to proceed slowly and more completely. This method produces a liquid crystal elastomer containing disulfide bonds located on the main chain of the liquid crystal polymer molecule, enabling it to meet the requirements for driven strain and tensile strength at break.

[0028] Based on the above technical solutions, a smart surface with wettability that varies with temperature based on dynamic covalent liquid crystal elastomer is prepared; it has excellent reversible surface wettability, as well as self-healing and programmable properties. By adopting different surface microstructures, wettability transitions within different ranges can be achieved.

[0029] The thermal braking performance of a material is defined using shrinkage rate, which is defined as follows:

[0030]

[0031] The surface contact angle is used to determine the wettability of a surface.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] This invention prepares a smart surface based on the temperature-dependent wettability of a dynamic covalent liquid crystal elastomer. When the liquid crystal elastomer, which serves as the substrate of this surface, is stretched to twice its original length, the maximum shrinkage rate is about 43%, and the temperature at which the maximum shrinkage is reached is 120°C.

[0034] The smart surface prepared by this invention has a contact angle of 74° without microstructure and a contact angle of 96° with microstructure. The contact angle can switch between the two as the temperature changes, realizing an adaptive change in wettability.

[0035] This invention introduces disulfide bonds into the molecular chain of a liquid crystal polymer network, endowing the material with self-healing ability and programmable properties. The programmed shape can be reversibly deformed from the original shape under 120°C or UV conditions. Microstructures are prepared on the composite material by hot pressing, successfully realizing the reversible change of the surface wettability of the composite material with temperature, providing a feasible solution for smart surface applications.

[0036] To further understand the features and technical content of this invention, please refer to the following detailed description and accompanying drawings. However, the accompanying drawings are for reference and illustration only and are not intended to limit the invention. Attached Figure Description

[0037] Figure 1 This is a diagram illustrating the preparation scheme of the liquid crystal elastomer sample in Example 1 of the present invention;

[0038] Figure 2 The NMR spectrum of the liquid crystal elastomer sample in Example 1 of this invention;

[0039] Figure 3 The infrared spectrum of the liquid crystal elastomer sample in Example 1 of this invention;

[0040] Figure 4 The DSC curve of the liquid crystal elastomer sample in Example 1 of this invention;

[0041] Figure 5 This is a thermally driven deformation diagram of the liquid crystal elastomer sample of Example 1 of the present invention from 25°C to 120°C;

[0042] Figure 6 The thermally driven deformation cycle curve of the liquid crystal elastomer sample in Example 1 of this invention from 25°C to 120°C is shown.

[0043] Figure 7 This is a flowchart illustrating the preparation process of the smart surface sample in Embodiment 1 of the present invention;

[0044] Figure 8 This is a SEM image of the surface micropillars of the smart surface sample from Embodiment 1 of the present invention;

[0045] Figure 9 This is a contact angle diagram of the smart surface sample in Embodiment 1 of the present invention before and after the change in surface wettability;

[0046] Figure 10 This is a surface adaptive test diagram of the smart surface sample in Embodiment 1 of the present invention. Detailed Implementation

[0047] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, while not limiting the invention in any way. 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. These all fall within the protection scope of the present invention.

[0048] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0049] In embodiments of the present invention, the specific sources of the various materials required are as follows:

[0050] Liquid crystal monomer RM257 (97%): 1,4-bis[4-(3-acryloyloxypropoxy)benzoic acid]-2-toluene, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0051] Chain extender HDT (97%): 1,6-hexanedithiol, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0052] Catalyst DPA (99%): di-n-propylamine, Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0053] Solvent THF (99.9%): Tetrahydrofuran, Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0054] Solvent DCM (99.5%): Dichloromethane, Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0055] Disulfide compound DADS (85%): diallyl disulfide, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0056] Crosslinking agent PETMP (95%): Pentaerythritol tetra(3-mercaptopropionate), Shanghai Aladdin Biochemical Technology Co., Ltd.

[0057] Anhydrous ethanol (AR): Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0058] Acetone (AR): Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0059] Nitrogen (AR): Harbin Liming Gas Group;

[0060] Pure copper (TU1): Shanghai Aladdin Biochemical Technology Co., Ltd.

[0061] Example 1: Combination Figure 7 To illustrate, the method for preparing the smart surface based on the dynamic covalent liquid crystal elastomer in this embodiment is achieved through the following steps:

[0062] S1. Preparation of oligomers: First, take a 30mL glass bottle and weigh 2g of solid RM257 on a balance with weighing paper underneath. Pour the weighed solid RM257 into the glass bottle. Then, using a 5000μL pipette, pipette 5650μL (3000μL and 2650μL) of THF in two portions, and use a 5000μL pipette to pipette 1150μL of DCM, adding them to the glass bottle. Add a magnetic stir bar to the glass bottle, seal the bottle, and place it on a magnetic stirrer to dissolve the solid solute. Next, using a 1000μL pipette, pipette 470μL of liquid HDT and add it to the glass bottle. Stir again for five minutes to ensure the reactants are evenly mixed. Open the glass bottle and use a 100μL pipette to add 20μL of DPA. Finally, seal the solution and stir for 12 hours.

[0063] S2. Cleaning and Placement of the Substrate: Take nine copper sheets, each 12mm in diameter and 1mm thick, and polish them with sandpaper (7000# grit). Then, ultrasonically clean them with acetone for 5 minutes, followed by ultrasonic cleaning with anhydrous ethanol for 5 minutes, and finally ultrasonic cleaning with deionized water for 5 minutes. Dry the cleaned copper sheets with nitrogen gas and apply PTFE tape to the back of each sheet. Arrange the copper sheets neatly in a PTFE mold, tape side down. The PTFE mold should be 6cm x 6cm in size.

[0064] S3. Preparation of liquid crystal elastomer-copper bonded material: After the reaction was complete, 0.085 g (approximately 3 drops) of PETMP was added to a glass bottle using a dropper. Since DCM is highly volatile, 1150 μL of DCM was added using a 5000 μL pipette to prevent the solution from becoming a gel. Then, 28 μL of DADS was added to the glass bottle using a 100 μL pipette, followed by sealing and stirring for 2 hours. Finally, all the solution was poured into a polytetrafluoroethylene mold, capped, and sealed for 24 hours of reaction.

[0065] S4. Product removal and drying: After the reaction is complete, open the sealed polytetrafluoroethylene mold, place the product in a ventilated place to evaporate naturally for 24 hours, and then put it in a forced-air drying oven at 80°C for 24 hours.

[0066] S5. Product cutting and cleaning: Take out the dried product, cut off the excess elastomer material along the edge of the copper sheet, remove the polytetrafluoroethylene tape on the back of the copper sheet to obtain the bonding material, and then place the bonding material in deionized water and ultrasonically clean for 10 minutes.

[0067] S6. Pressing of micropillar arrays: A stainless steel mask with an array of micropores (i.e., ...) is pressed into the micropillar array. Figure 7 The microporous array substrate (as shown in the image) is placed on a smooth stainless steel sheet. The micropores on the mask have a diameter of 100 μm and a margin of 100 μm. The bonding material is placed face down in the center of the mask, and a 500g weight is placed on top of the bonding material. The entire system is placed in a forced-air drying oven and heated at 120℃ for 12 hours. After the material cools to room temperature, it is removed. The removed material is then heated to about 100℃ and demolded while hot. Subsequently, the material is repeatedly heated to 120℃ to eliminate thermal stress, resulting in a smart surface.

[0068] The fabrication scheme for a disulfide bond-based liquid crystal elastomer is shown in the figure below. Figure 1 As shown in the figure, the reaction equation is divided into two stages: the preparation of oligomers and the crosslinking of oligomers.

[0069] The product obtained in the first step of the reaction was analyzed by nuclear magnetic resonance spectroscopy (NMR). The solvent used in the test was CDCl3. The resulting NMR spectrum is shown below. Figure 2 As shown in the figure. ¹H NMR (600MHz, Chloroform-d) δ 8.20–8.10 (m, 4H), 7.20–7.05 (m, 3H), 7.02–6.93 (m, 4H), 4.33 (t, J = 8.0 Hz, 4H), 4.18–4.11 (m, 4H), 2.78 (t, J = 8.0 Hz, 4H), 2.62 (t, J = 8.0 Hz, 4H), 2.52 (t, J = 8.0 Hz, 4H), 2.24 (s, 3H), 2.18 (t, J = 8.0 Hz, 4H), 1.62–1.53 (m, 4H), 1.42–1.35 (m, 4H). The figure shows that the reaction proceeded correctly and the target product was obtained, with a calculated yield of approximately 85%.

[0070] Infrared Spectroscopy (IR) was used to analyze the molecular formula of the sample and determine the main chemical bond types in the sample. The resulting infrared spectrum of the sample is shown below. Figure 3 As shown. Among them, 2921cm -1 2855cm -1 Corresponding to the CH stretching vibration in aliphatic hydrocarbons, 1724 cm⁻¹ -1 Corresponding to the C=O stretching vibration of the ester carbonyl group, 1604 cm⁻¹ -1 1510cm -1 Corresponding to the C=C stretching vibration in the benzene ring, 1243 cm⁻¹ -1 Corresponding to CO stretching vibration, 1150cm -1 1066cm -1 Corresponding to the stretching vibration of CoC, 845cm -1 762cm -1 692cm -1 Corresponding to CH bending vibration. 510cm -1 This corresponds to the SS stretching vibration of the disulfide bond. The infrared spectrum of the sample covers the major chemical bonds of the target product.

[0071] The phase transition temperature of the liquid crystal elastomer sample was determined using differential scanning calorimetry (DSC), and the resulting DSC curves are shown below. Figure 4As shown. For liquid crystal elastomer materials, usually only the heating process is of concern. The DSC heating curves show that the prepared sample undergoes two phase transitions at -14.9℃ and 89.3℃, corresponding to the glass transition temperatures (T0, T ... g ) and cleaning point temperature (T iso This verified the liquid crystal properties of the sample.

[0072] Thermally driven deformation tests were conducted on liquid crystal elastomer samples. A 1.5 cm long sample was stretched to 3 cm and then subjected to secondary cross-linking. The thermally driven deformation properties of the cross-linked sample were then tested. Figure 5 As shown, the sample length is approximately 3 cm at 25℃ and approximately 1.7 cm at 120℃. According to the formula, when the sample is stretched to twice its original length, its shrinkage rate is approximately 43%.

[0073] The thermally driven deformation reversibility of the liquid crystal elastomer sample was verified after 20 repeated heating and cooling cycles. The cycle curves are shown in the figure. Figure 6 The shrinkage ratio is defined in the figure as the ratio of the actual length of the elastomer to its initial length.

[0074] The fabrication process for a smart surface with adaptive wettability is shown in the flowchart below. Figure 7 As shown.

[0075] The micropillar array of the smart surface sample was observed using a scanning electron microscope (SEM), such as... Figure 8 As shown, the micropillars have a diameter of approximately 100 μm and a side distance of approximately 100 μm, which is basically the same as the mold and is evenly distributed.

[0076] Figure 9 The contact angle diagram of the smart surface sample tested by the contact angle meter shows that the sample with the micropillar array became hydrophobic, and the contact angle reached 96°, which is 22° higher than the initial contact angle.

[0077] The adaptive capabilities of the smart surface samples were tested, such as... Figure 10 As shown, it can be seen that the micropillars on the sample surface gradually disappear with the change of temperature, and the sample has the ability to be regulated by temperature.

[0078] The specific embodiments of the present invention have been described above. It should be noted that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A smart surface based on the temperature-dependent wettability of a dynamic covalently bonded liquid crystal elastomer, characterized in that, It is a composite of liquid crystal elastomer and copper sheet; firstly, a smooth liquid crystal elastomer surface is formed on the copper sheet, and then microstructures are formed on the liquid crystal elastomer surface by hot pressing; the liquid crystal elastomer is mainly obtained by mixing mercapto-terminated liquid crystal prepolymer and sulfide compound, and then crosslinking reaction under the action of mercapto crosslinking agent. The liquid crystal prepolymer is a liquid crystal monomer RM257; The smart surface is prepared through the following steps: S1. Dissolve the mercapto-terminated liquid crystal prepolymer, chain extender, and catalyst in tetrahydrofuran and stir for 12 h to 24 h. Then add the crosslinking agent and sulfide compound and crosslink for 2 h to 3 h to obtain a liquid crystal elastomer solution. S2. Sand one side of the copper sheet with sandpaper, then place it in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning in sequence, and then blow it dry with nitrogen. Then attach PTFE tape to the other side of the copper sheet, and then place it in a PTFE mold with the tape side down. S3. Then pour in the liquid crystal elastomer solution obtained in step S1, seal, and react for 24 h to 48 h. After the reaction is complete, remove the copper sheet, place it in a ventilated place to evaporate naturally, and then dry it. S4. Then cut off the excess elastomer material along the edge of the copper sheet, remove the PTFE tape, and then clean it with deionized water using ultrasound. S5. Place the stainless steel mask with arrayed micropores on a smooth stainless steel sheet, place the copper sheet placed in the center of the mask with the elastomer material facing down, place a weight on top of the copper sheet, perform a hot-press reaction to eliminate thermal stress, and obtain a smart surface. The chain extender is 1,6-hexanedithiol; the crosslinking agent is pentaerythritol tetra(3-mercaptopropionate); and the thioether compound is diallyl disulfide.

2. The method for preparing the smart surface as described in claim 1, characterized in that, Includes the following steps: S1. Dissolve the mercapto-terminated liquid crystal prepolymer, chain extender, and catalyst in tetrahydrofuran and stir for 12 h to 24 h. Then add the crosslinking agent and sulfide compound and crosslink for 2 h to 3 h to obtain a liquid crystal elastomer solution. S2. Sand one side of the copper sheet with sandpaper, then place it in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning in sequence, and then blow it dry with nitrogen. Then attach PTFE tape to the other side of the copper sheet, and then place it in a PTFE mold with the tape side down. S3. Then pour in the liquid crystal elastomer solution obtained in step S1, seal, and react for 24 h to 48 h. After the reaction is complete, remove the copper sheet, place it in a ventilated place to evaporate naturally, and then dry it. S4. Then cut off the excess elastomer material along the edge of the copper sheet, remove the PTFE tape, and then clean it with deionized water using ultrasound. S5. Place the stainless steel mask with arrayed micropores on a smooth stainless steel sheet, place the copper sheet placed in the center of the mask with the elastomer material facing down, place a weight on top of the copper sheet, and perform a hot-press reaction to eliminate thermal stress and obtain a smart surface.

3. The method according to claim 2, characterized in that, In step S1, the molar ratio of the mercapto-terminated liquid crystal prepolymer, chain extender, crosslinking agent, and thioether compound is 1:(0.9~1):(0.05~0.1):(0.05~0.1).

4. The method according to claim 2, characterized in that, The surface of the micropillar array should satisfy the Cassie model, that is: in, θ c It is the apparent contact angle. φ It is the area ratio between the wetted area and the planar area. θ It is the initial contact angle.

5. The method according to claim 2, characterized in that, The microporous stainless steel mask used has a thickness of 0.1 mm, and the diameter of the micropores on it is 0.05 mm to 0.1 mm, with a side distance of 0.05 mm to 0.1 mm.

6. The method according to claim 2, characterized in that, A weight is placed on top of the copper sheet to bring the stainless steel mask into contact with the elastomer material. The weight is such that the stainless steel mask is pressed into the elastomer material. The material is heated at 120℃~130℃ and held for 12 h~24 h. During the hot pressing process, the material is cooled to 100℃, the weight is removed, and the stainless steel mask is removed while it is still hot. The material is then repeatedly heated to 120℃~130℃ to eliminate thermal stress.

7. The method according to claim 2, characterized in that, The catalyst is di-n-propylamine, and the ratio of mercapto-terminated liquid crystal prepolymer to catalyst is 2 g: 20 μL.

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