Intelligent surface with wettability changing along with temperature based on dynamic covalent bond liquid crystal elastomer and preparation method of intelligent surface

Abstract

The invention discloses an intelligent surface preparation method based on temperature change of wettability of a dynamic covalent bond liquid crystal elastomer and a method for heat dissipation regulation and control. Belongs to the technical field of liquid crystal elastomers. The invention aims to solve the problem that the material surface cannot adapt to the environment temperature in the thermal process. Diallyl disulfide is introduced into a liquid crystal polymer molecular chain, a dynamic covalent bond, i.e., a disulfide bond, is introduced into the liquid crystal polymer, so that the elastomer material has processability, reusability and self-healing property, and the proportion of a soft segment in the molecular chain is increased, so that energy required by movement of the liquid crystal elastomer molecular chain is reduced; and the expansion and contraction rate of the elastomer material is increased. According to the invention, the liquid crystal elastomer material and the metal material are creatively compounded, and the microstructure is prepared on the composite material by adopting a hot pressing mode, so that the reversible transformation of the surface wettability of the composite material along with the temperature is successfully realized, and a feasible intelligent surface application scheme is provided.

Description

Technical Field

[0001] The present invention belongs to the field of liquid crystal elastomers, and specifically relates to an intelligent surface based on a dynamic covalent bond liquid crystal elastomer whose wettability changes with temperature and a preparation method thereof; the present invention is applied to heat dissipation regulation. Background Art

[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 own structure and properties with external field stimulation. For common heat transfer processes, such as boiling heat transfer, nucleation sites are required in the initial stage of heat transfer, and the required surface should be rough and hydrophobic. The critical state of heat transfer requires liquid replenishment, and the required surface should be smooth and hydrophilic. At this time, a smart surface whose wettability or surface structure changes with temperature is needed.

[0003] Traditional methods of changing surface structure or wettability with temperature through material composites, coating of thermoinduced phase change materials, or use of memory alloys have problems such as slow reaction rate, discontinuous deformation, low surface structure control accuracy, and poor stability during repeated use. These methods make it 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 thermoreversible deformation properties, enabling controllable and reversible morphological changes within a narrow temperature range, improving both surface control precision and response rate. Research on constructing smart surfaces using liquid crystal elastomers has been gradually expanded. 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 compounding liquid crystal elastomers with rigid substrates to enhance their morphological stability and operational reliability remains relatively limited. Summary of the Invention

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

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention aims to provide a temperature-dependent smart surface based on a dynamic covalently bonded liquid crystal elastomer (LCE). The LCE is composited with a copper sheet and made from a mercapto-terminated liquid crystal prepolymer, a chain extender, a crosslinker, a thioether compound, and a catalyst. A smooth LCE surface is formed on the copper sheet, and then a microstructure is formed on the LCE surface by hot pressing. The LCE is primarily formed by mixing a LCE prepolymer and a thioether compound, followed by a crosslinking reaction with a thiol crosslinker. The microstructures formed on the surface of the material by hot pressing gradually disappear as the temperature rises and reappear as the temperature drops, achieving temperature-dependent wettability.

[0008] It is further specified that 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 that break and reconnect at 120°C or under UV light, achieving reusability and self-healing. The present invention introduces a disulfide compound into the main-chain liquid crystal elastomer, expanding the functional design and performance optimization of the liquid crystal elastomer, enabling reversible actuation of the single-domain liquid crystal elastomer at body temperature while maintaining the liquid crystal elastomer's actuation and mechanical properties.

[0009] The microstructure prepared on the surface of the material by the hot pressing technology of the present invention gradually disappears as the temperature rises and gradually appears as the temperature drops, thereby realizing the wettability of the material that changes with temperature.

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

[0011] S1, dissolving a thiol-terminated liquid crystal prepolymer, a chain extender, and a catalyst in tetrahydrofuran, stirring and reacting for 12 to 24 hours, then adding a crosslinking agent and a thioether compound, and crosslinking reacting for 2 to 3 hours to obtain a liquid crystal elastomer solution;

[0012] S2. Polish one side of a copper sheet (one or more copper sheets) with sandpaper, ultrasonically clean it in acetone, anhydrous ethanol, and deionized water, and blow dry it with nitrogen. Then, apply polytetrafluoroethylene tape to the other side of the copper sheet and place it in a polytetrafluoroethylene mold with the tape facing downward.

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

[0014] S4, then trimming off the excess elastomer material along the edge of the copper sheet, removing the polytetrafluoroethylene tape, and then ultrasonically cleaning with deionized water;

[0015] S5. Place the stainless steel mask with arrayed micropores on a stainless steel sheet with a smooth surface, place the copper sheet prepared in step S4 in the center of the mask, with the elastomer material facing downward, place a heavy object on top of the copper sheet, and perform hot pressing reaction to eliminate thermal stress and obtain a smart surface.

[0016] It is further defined that in step S1, the molar ratio of the mercapto-terminated liquid crystal prepolymer, the chain extender, the cross-linking agent and the sulfide compound is 1:(0.9-1):(0.05-0.1):(0.05-0.1).

[0017] Further, in 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 allowed to react for 24 to 48 hours. After the reaction is completed, the sealed polytetrafluoroethylene mold is opened, and the product is first placed in a well-ventilated area to naturally evaporate for 12 to 24 hours, and then dried in a forced air drying oven at 80 to 90°C for 12 to 24 hours. During this drying process, natural evaporation at room temperature can prevent the formation of bubbles in the elastomer material due to excessive evaporation, thereby fully cross-linking the liquid crystal polymer network in the material, thereby forming a dense liquid crystal elastomer film.

[0018] Further definition, the design of the microporous stainless steel mask takes into account the equipment limitations and contact angle model, according to the different

[0019] The surface of the micropillar array prepared by the stainless steel mask should satisfy the Cassie model, that is:

[0020]

[0021] Among them, θ c is the apparent contact angle, is the area ratio between the wetted area and the flat area, and θ is the initial contact angle. The microporous stainless steel mask used is 0.1 mm thick, with micropores ranging in diameter from 0.05 to 0.1 mm and margins from 0.05 to 0.1 mm. The reason for using a microporous membrane and a smooth stainless steel sheet as the concave mold rather than a one-piece mold is to avoid the problem of micropillar formation due to poor mold permeability.

[0022] Furthermore, a weight is placed on top of the copper sheet to ensure contact between the stainless steel mask and the elastomer material. The weight of the weight is such that the stainless steel mask is pressed into the elastomer material. The material is heated at 120-130°C and maintained for 12-24 hours. During the hot pressing process, 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 placed during the hot pressing process weighs 250-500g. The material is demolded and thermally stressed by heating the removed material to approximately 100°C, demolding it while still hot, and then repeatedly heating it to 120-130°C to eliminate thermal stress. During the alignment process, the pre-stretching process effectively aligns the liquid crystal elements in the liquid crystal elastomer, while further polymerizing and curing it under ultraviolet light. This results in a monodomain liquid crystal elastomer with excellent reversible drive strain and tensile strength at break.

[0023] Furthermore, ultrasonic cleaning in acetone, ethanol, and deionized water was performed for 5 to 10 minutes per solution. The cleaned copper sheet was dried with nitrogen and polytetrafluoroethylene tape was applied to the back of the sheet to prevent contamination.

[0024] It is further defined that the chain extender is 1,6-hexanedithiol; the cross-linking agent is pentaerythritol tetrakis(3-mercaptopropionate); and the sulfide compound is diallyl disulfide.

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

[0026] The present invention introduces diallyl disulfide into the liquid crystal polymer molecular chain, creating dynamic covalent bonds, particularly disulfide bonds, that make the elastomeric material processable, reusable, and self-healing. It also increases the proportion of soft segments in the molecular chain, reducing the energy required for the liquid crystal elastomer molecular chain to move and increasing the elasticity of the elastomeric material. The present invention innovatively combines liquid crystal elastomer materials with metal materials and uses hot pressing to create microstructures on the composite material, successfully achieving a reversible temperature-dependent change in the composite material's surface wettability, providing a viable solution for smart surface applications.

[0027] The present invention utilizes a two-step process to prepare liquid crystal elastomers. A chain extender and liquid crystal monomer undergo an addition reaction in the presence of a catalyst, forming a liquid crystal oligomer that then reacts with a disulfide compound and a crosslinker. The disulfide compound is preferably a diene disulfide compound, acting as a bridge between the oligomer and the crosslinker. The catalyst used is di-n-propylamine, which allows for a slow and more complete reaction. 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 required actuation strain and tensile strength at break performance requirements.

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

[0029] The shrinkage rate is used to define the thermal braking performance of the material. The definition of the shrinkage rate is as follows:

[0030]

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

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

[0033] The present invention prepares an intelligent surface based on a dynamic covalent liquid crystal elastomer whose wettability changes with temperature. The liquid crystal elastomer used as the substrate of the surface has a maximum shrinkage rate of about 43% when stretched to twice its original length, and the temperature at which the maximum shrinkage is reached is 120°C.

[0034] The smart surface prepared by the present invention has a contact angle of 74° without a microstructure and a contact angle of 96° with a microstructure. The contact angles can be converted between the two as the temperature changes, achieving an adaptive transition in wettability.

[0035] The present invention introduces disulfide bonds into the liquid crystal polymer network molecular chain, giving the material the ability to self-heal and programmable properties, achieving reversible deformation between the programmed shape and the original shape at 120°C or under UV; microstructures are prepared on the composite material by hot pressing, successfully achieving reversible transformation of the surface wettability of the composite material with temperature, providing a feasible smart surface application solution.

[0036] In order to further understand the features and technical contents of the present invention, please refer to the following detailed description of the present invention and the accompanying drawings. However, the accompanying drawings are provided for reference and illustration only and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0038] Figure 2 This is the NMR spectrum of the liquid crystal elastomer sample of Example 1 of the present invention;

[0039] Figure 3 This is the infrared spectrum of the liquid crystal elastomer sample of Example 1 of the present invention;

[0040] Figure 4 is the DSC curve of the liquid crystal elastomer sample of Example 1 of the present invention;

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

[0042] Figure 6 This is a heat-driven deformation cycle curve of the liquid crystal elastomer sample from 25°C to 120°C in Example 1 of the present invention;

[0043] Figure 7 This is a flow chart of preparing a smart surface sample according to Example 1 of the present invention;

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

[0045] Figure 9 Graphs showing contact angles before and after changes in surface wettability of the smart surface sample of Example 1 of the present invention;

[0046] Figure 10 This is a surface adaptive test diagram of the smart surface sample in Example 1 of the present invention. DETAILED DESCRIPTION

[0047] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art further understand the present invention and are not intended to limit the present invention in any way. It should be noted that those skilled in the art may make various modifications and improvements without departing from the scope of the present invention. These modifications and improvements are all within the scope of protection of the present invention.

[0048] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0049] In the 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)benzoyl]-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] Cross-linking agent PETMP (95%): pentaerythritol tetrakis (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 For illustration, the preparation method of 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, place weighing paper on the balance, weigh 2g of solid RM257, and pour it into the glass bottle. Then use a 5000μL pipette to draw 5650μL (3000μL and 2650μL) of THF in two times, and use a 5000μL pipette to draw 1150μL of DCM, and drop it into the glass bottle. Add a magnet to the glass bottle, seal the glass bottle, and place it on a magnetic stirrer to stir to dissolve the solid solute. Next, use a 1000μL pipette to draw 470μL of liquid HDT and drop it into the glass bottle. Stir again for five minutes to mix the reactants evenly. Open the glass bottle, use a 100μL pipette to add 20μL of DPA to the glass bottle, and finally seal the solution and stir for 12h.

[0063] S2. Cleaning and placement of the substrate: Take nine copper sheets with a diameter of 12 mm and a thickness of 1 mm and polish them with 7000 grit sandpaper. Then, ultrasonically clean them with acetone for 5 minutes, then with anhydrous ethanol for 5 minutes, and finally with deionized water for 5 minutes. Dry the cleaned copper sheets with nitrogen gas and apply Teflon tape to the back of the sheets. Then, neatly arrange the copper sheets in a Teflon mold, tape side down. The Teflon mold measures 6 cm x 6 cm.

[0064] S3. Preparation of Liquid Crystal Elastomer-Copper Composite Material: After the reaction is complete, use a rubber-tipped pipette to pipette 0.085 g (approximately 3 drops) of PETMP into a glass bottle. Because DCM is highly volatile, use a 5000 μL pipette to add an additional 1150 μL of DCM to prevent the solution from becoming a colloid. Then, use a 100 μL pipette to dropwise add 28 μL of DADS into the glass bottle, seal, and stir for 2 h. Finally, pour the entire solution into a polytetrafluoroethylene mold, seal, and incubate for 24 h.

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

[0066] S5. Cutting and cleaning of the product: 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 it for 10 minutes.

[0067] S6. Pressing of micropillar array: a stainless steel mask with array micropores (i.e. Figure 7 A microporous display substrate (in the reticle) was placed on a smooth stainless steel sheet. The micropores on the reticle had a diameter of 100μm and a margin of 100μm. The bonded material was placed face down in the center of the reticle, and a 500g weight was placed on top of the bonded material. The entire system was placed in a forced air drying oven and heated at 120°C for 12 hours. After cooling to room temperature, the material was removed. The removed material was heated to approximately 100°C and demolded while hot. The material was then repeatedly heated to 120°C to eliminate thermal stress, resulting in a smart surface.

[0068] Preparation of disulfide bond-based liquid crystal elastomers, the preparation scheme is shown in the figure Figure 1 As shown in the figure, the reaction equation is divided into two stages, namely the preparation of oligomers and the cross-linking 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 NMR spectrum of the obtained sample is shown in the figure below. Figure 2 1H NMR (600 MHz, 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). As can be seen from the figure, the reaction proceeded correctly and the target product was obtained. The calculated yield was about 85%.

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

[0071] Differential Scanning Calorimetry (DSC) was used to test the phase transition temperature of the liquid crystal elastomer sample. The DSC curve of the sample was as follows: Figure 4As shown. For liquid crystal elastomer materials, we usually only care about the heating process. From the DSC heating curve, we can see that the prepared sample has two phase transitions at -14.9℃ and 89.3℃, which correspond to the glass transition temperature (T g ) and clearing point temperature (T iso ), verifying the liquid crystal properties of the sample.

[0072] The heat-driven deformation test of liquid crystal elastomer samples was carried out. The 1.5 cm long sample was stretched to 3 cm and then cross-linked for the second time. The heat-driven deformation performance of the cross-linked sample was tested, such as Figure 5 As shown in the figure, the length of the sample is about 3 cm at 25°C and about 1.7 cm at 120°C. According to the formula, when the sample is stretched to twice its original length, its shrinkage rate is about 43%.

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

[0074] Prepare smart surfaces with adaptive wettability. The preparation process is as follows: Figure 7 shown.

[0075] Scanning electron microscope (SEM) was used to observe the micropillar array of the smart surface sample. Figure 8 As shown, the diameter of the microcolumns is about 100 μm, the edge distance is about 100 μm, which is basically the same as that of the mold, and the distribution is uniform.

[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 becomes hydrophobic, with a contact angle of 96°, which is 22° higher than the initial contact angle.

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

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

Claims

1. A smart surface based on a dynamic covalent liquid crystal elastomer with temperature-dependent wettability, characterized in that: It is a composite of liquid crystal elastomer and copper sheet; first, a smooth liquid crystal elastomer surface is formed on the copper sheet, and then a microstructure is formed on the surface of the liquid crystal elastomer by hot pressing; wherein, the liquid crystal elastomer is mainly obtained by mixing a mercapto-terminated liquid crystal prepolymer with a thioether compound, and then cross-linking reaction under the action of a mercapto cross-linking agent.

2. The smart surface according to claim 1, characterized in that The dynamic covalent bond is a dynamic disulfide bond.

3. The smart surface according to claim 1, characterized in that The liquid crystal prepolymer is liquid crystal monomer RM257.

4. The method for preparing a smart surface according to claim 1, 2 or 3, wherein: The following steps are involved: S1, dissolving a thiol-terminated liquid crystal prepolymer, a chain extender, and a catalyst in tetrahydrofuran, stirring and reacting for 12 to 24 hours, then adding a crosslinking agent and a thioether compound, and crosslinking reacting for 2 to 3 hours to obtain a liquid crystal elastomer solution; S2. Polish one side of the copper sheet with sandpaper, ultrasonically clean it in acetone, anhydrous ethanol, and deionized water, blow dry it with nitrogen, and then apply polytetrafluoroethylene tape to the other side of the copper sheet. Then, place it in a polytetrafluoroethylene mold with the tape facing down. S3, then pour the liquid crystal elastomer solution obtained in step S1, seal, and react for 24 to 48 hours. After the reaction is completed, remove the copper sheet, place it in a ventilated place for natural evaporation, and then dry it; S4, then trimming off the excess elastomer material along the edge of the copper sheet, removing the polytetrafluoroethylene tape, and then ultrasonically cleaning with deionized water; S5. Place the stainless steel mask with arrayed micropores on a stainless steel sheet with a smooth surface, place the copper sheet prepared in step S4 in the center of the mask, with the elastomer material facing downward, place a heavy object on top of the copper sheet, and perform hot pressing reaction to eliminate thermal stress and obtain a smart surface.

5. The method according to claim 4, characterized in that: In step S1, the molar ratio of the mercapto-terminated liquid crystal prepolymer, the chain extender, the cross-linking agent and the sulfide compound is 1:(0.9-1):(0.05-0.1):(0.05-0.1).

6. The method according to claim 4, characterized in that: The surface of the micropillar array should satisfy the Cassie model, that is:

7. Among them, θ c is the apparent contact angle, is the area ratio between the wetted area and the flat area, and θ is the initial contact angle. The microporous stainless steel mask used is 0.1 mm thick, with micropores ranging in diameter from 0.05 mm to 0.1 mm and margins from 0.05 mm to 0.1 mm.

8. The method according to claim 4, characterized in that: Place a heavy object on the top of the copper sheet to make the stainless steel mask contact with the elastomer material. The weight of the heavy object makes the stainless steel mask pressed into the elastomer material. Heat it at 120℃~130℃ and keep it for 12h~24h. During the hot pressing process, wait for the material to cool to 100℃, remove the heavy object, remove the stainless steel mask while it is hot, and then repeatedly heat it to 120℃~130℃ to eliminate thermal stress.

9. The method according to claim 4, characterized in that: The chain extender is 1,6-hexanedithiol; the cross-linking agent is pentaerythritol tetrakis (3-mercaptopropionate); and the sulfide compound is diallyl disulfide.

10. The method according to claim 4, characterized in that: The catalyst is di-n-propylamine, and the ratio of the mercapto-terminated liquid crystal prepolymer to the catalyst is 2 g: 20 μL.

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