A method for preparing a multi-level micro / nano structured superhydrophobic coating

Abstract

This invention belongs to the field of superhydrophobic surface construction technology, specifically relating to a method for preparing a multi-level micro / nano-structured superhydrophobic coating. The method includes the following steps: pretreatment of the substrate; slow addition of an F-SiO2 nanoparticle dispersion to a fluorinated adhesive solution under synergistic ultrasonic and magnetic stirring to obtain an F-SiO2 / fluorinated adhesive composite solution; determination of the actual amount of adhesive to be applied based on the theoretical adhesive requirement of a PDMS template; spin coating the F-SiO2 / fluorinated adhesive composite solution onto the substrate surface to form a wet film; imprinting the wet film using a PDMS template; curing with ultraviolet light; and then peeling off the template to obtain the multi-level micro / nano-structured superhydrophobic coating. This invention, based on an insufficient adhesive imprinting method, achieves simultaneous construction of micro / nano dual-scale structures by precisely controlling the ratio of coating liquid volume to template pore volume, combined with the curing shrinkage characteristics of polymers. It shows application potential in fields such as anti-icing, microfluidic devices, and marine antifouling.

Description

Technical Field

[0001] This invention belongs to the field of superhydrophobic surface construction technology, specifically relating to a method for preparing a multi-level micro / nano structure superhydrophobic coating. Background Technology

[0002] Superhydrophobic surfaces, due to their excellent water repellency and self-cleaning capabilities, have significant application value in fields such as anti-icing, microfluidics, and marine antifouling. Their core performance lies in the synergistic effect of micron-nano hierarchical structures: micron structures provide mechanical support, while nanostructures achieve superhydrophobicity by trapping air layers and reducing solid-liquid contact. However, existing technologies face bottlenecks in the efficient synergistic construction of multi-level structures. Traditional stepwise methods (such as first fabricating micron-nano structures and then adding nanostructures through vapor deposition / spin coating / spraying) are complex, costly, and the heterogeneous interface leads to weak bonding and easy detachment of nanostructures. As an alternative, directly incorporating nanoparticles into the polymer matrix simplifies the process, but faces challenges: high concentrations induce agglomeration and film cracking, while low concentrations fail to form effective nanostructures, resulting in insufficient hydrophobicity. Therefore, there is an urgent need to develop new methods that can simultaneously construct stable micro-nano structures. This invention proposes a "insufficient adhesive imprinting method," the core of which lies in precisely controlling the ratio of the volume of the coated polymer prepolymer (adhesive) to the total volume of the microcavities in the imprinting template between 50% and 90%. By incorporating the curing shrinkage effect during polymer curing, this method induces the simultaneous self-assembly of micron-scale arrays and surface nanoscale protrusions in a single step. This method overcomes the limitations of stepwise construction and fundamentally avoids the contradiction between nanoparticle dispersibility and interfacial bonding, providing a new approach for the efficient preparation of high-performance, highly robust superhydrophobic surfaces. Summary of the Invention

[0003] The technical problem this invention aims to solve is to address the shortcomings of existing technologies by providing a method for constructing multi-level micro / nano-structured superhydrophobic coatings based on insufficient adhesive imprinting. This method aims to overcome existing technical difficulties and efficiently prepare superhydrophobic coatings with multi-level structures featuring micron-level supports and nano-level protrusions. This method cleverly integrates precise control of the coating liquid volume to template pore volume ratio with the polymer curing shrinkage characteristics, achieving simultaneous construction of micro / nano dual-scale structures. It demonstrates outstanding application potential in diverse fields such as anti-icing, microfluidic devices, and marine antifouling.

[0004] To address the aforementioned technical problems, this invention discloses a method for preparing a multi-level micro / nano structured superhydrophobic coating, comprising the following steps:

[0005] S1. Pre-treat the substrate;

[0006] S2. The F-SiO2 nanoparticle dispersion was slowly added to the fluorinated adhesive solution under the combined treatment of ultrasonic and magnetic stirring to obtain the F-SiO2 / fluorinated adhesive composite solution;

[0007] S3. Based on the theoretical adhesive requirement of the PDMS template, the actual amount of adhesive to be applied is determined. The F-SiO2 / fluorinated adhesive composite solution is then applied to the substrate surface by spin coating to form a wet film.

[0008] S4. Imprint the wet film using a PDMS template, cure it with ultraviolet light, and then peel off the template to obtain the multi-level micro-nano structure superhydrophobic coating.

[0009] The actual amount of adhesive applied is 50-90% of the theoretical amount required.

[0010] Preferably, the actual amount of adhesive applied is 70-80% of the theoretical amount of adhesive required.

[0011] More preferably, the actual amount of adhesive applied is 80% of the theoretical amount of adhesive required.

[0012] In S1, the substrate includes any one of quartz glass, metal, and polymer.

[0013] In some embodiments of the present invention, the substrate is 316L stainless steel.

[0014] Specifically, in S1, the pretreatment involves sequentially ultrasonically cleaning the substrate with acetone, ethanol, and acetone for 5 minutes each (acetone-ethanol three-stage ultrasonic cleaning). Subsequently, the substrate is purged with nitrogen to rapidly dry it until the surface water contact angle is <5°.

[0015] In S2, the mass ratio of the F-SiO2 nanoparticle dispersion to the fluorinated gel solution is (2~10):1.

[0016] In some embodiments of the present invention, in S2, the mass ratio of the F-SiO2 nanoparticle dispersion to the fluorinated gel solution is 6:1.

[0017] Specifically, in S2, the F-SiO2 nanoparticle dispersion is a mixture of F-SiO2 nanoparticles and propylene glycol methyl ether acetate, with a solid-liquid ratio of (0.025~0.15) g:1 mL; the fluorinated adhesive solution is a mixture of fluorinated adhesive and initiator, with the initiator being 1~3 wt% of the fluorinated adhesive.

[0018] In some embodiments of the present invention, in S2, the F-SiO2 nanoparticle dispersion is a mixture of F-SiO2 nanoparticles and propylene glycol methyl ether acetate, and the solid-liquid ratio of F-SiO2 nanoparticles to propylene glycol methyl ether acetate is 0.05 g:1 mL; the fluorinated adhesive solution is a mixture of fluorinated adhesive and initiator, and the initiator is 2 wt% of the fluorinated adhesive.

[0019] Specifically, the particle size of the F-SiO2 nanoparticles is 30~200nm.

[0020] Specifically, in S2, the method for preparing the F-SiO2 nanoparticle dispersion is as follows: F-SiO2 nanoparticles are added to propylene glycol methyl ether acetate and treated with an ultrasonic probe (power set to 200 W, frequency 20 kHz) for 20 minutes to obtain the hydrophobic F-SiO2 nanoparticle dispersion.

[0021] Specifically, in S2, the method for preparing the fluorinated adhesive solution is as follows: the fluorinated adhesive and the initiator are magnetically stirred at 600 rpm for 30 minutes under yellow light or in the dark to ensure that the photoinitiator is fully dissolved in the fluorinated acrylate to form a homogeneous and stable solution system, thereby obtaining the fluorinated adhesive solution.

[0022] In S2, the ultrasonic wave has a power of 150~200 W; the magnetic stirring has a rotation speed of 500~800 rpm.

[0023] In some embodiments of the present invention, in step S3, the specifications of the PDMS template are: area S = 78.54 cm². 2 The pore size D is 2~40 μm, the pore depth H is 2~40 μm, and the porosity P is 60~80%. It should be noted that the specifications of the PDMS template can be adjusted according to the structure of the multi-level micro-nano structure superhydrophobic coating, and are not limited to the structure disclosed in this invention. Furthermore, the area of ​​the PDMS template can be adjusted in real time according to the actual multi-level micro-nano structure superhydrophobic coating to be constructed.

[0024] Specifically, in S3, the formula for calculating the theoretical adhesive requirement of the PDMS template is V. 理 =Sπ(D / 2) 2 HP / 3, where S is the total area of ​​the PDMS template (μm). 2 D is the pore diameter (μm) of the single conical pore of the PDMS template, H is the pore depth (μm) of the single conical pore of the PDMS template, and P is the porosity of the PDMS template.

[0025] In S3, the spin coating process parameters are: rotation speed 1000~3000 rpm, spin coating time 30~50 s.

[0026] In S4, the ultraviolet curing process has the following parameters: wavelength of 365 nm and power of 100~500 W.

[0027] Furthermore, the multi-level micro / nano structured superhydrophobic coatings prepared by the above method are also within the scope of protection of this invention.

[0028] The multi-level micro / nano structure superhydrophobic coating includes a micron cone array and nano protrusions.

[0029] The height of the micron cone array is 1~50 μm; the height of the nanoprotrusions is 30~500 nm.

[0030] Specifically, in some embodiments of the present invention, multiple multi-level micro / nano-structured superhydrophobic coatings prepared by the above method, through characterization of their microstructure and detection of their hydrophobicity, show that the superhydrophobic coatings possess micron-level support (primary structure) and nano-protrusions (secondary structure), and exhibit excellent hydrophobicity. This demonstrates that the present invention, by introducing a low-adhesion imprinting strategy and combining it with the directional shrinkage characteristics of elastomer materials such as polydimethylsiloxane (PDMS), achieves a breakthrough in achieving in-situ self-assembly of multi-scale structures. This technology not only solves the technical contradiction between nanoparticle dispersion and interfacial bonding force, but also exhibits excellent superhydrophobic performance, showing significant application prospects in scenarios such as anti-icing of polar equipment, anti-biofouling of ships, and droplet manipulation in microfluidic chips.

[0031] The core technical means of this invention lies in:

[0032] 1. Volume-Controlled Imprinting: Precisely controlling the volume of the coating liquid to maintain it within 50-90% of the template pore volume is a key parameter range for forming the ideal structure. When the fluorinated adhesive cures and shrinks, this precise volume difference drives the directional migration and enrichment of F-SiO2 nanoparticles on the coating surface, constructing micron-sized supports (primary structure) and nano-sized protrusions (secondary structure) in one step, laying a solid microstructural foundation for the superhydrophobic properties.

[0033] 2. Ultrasonic-Magnetic Synergistic Dispersion: During the preparation of the F-SiO2 / fluorinated adhesive composite solution, ultrasonic and magnetic stirring are applied simultaneously. The powerful cavitation effect of ultrasound effectively breaks up the aggregation between F-SiO2 nanoparticles, while continuous and stable magnetic stirring prevents secondary sedimentation of the dispersed particles. The synergistic effect of the two greatly improves the uniformity of nanoparticle distribution in the composite solution, thereby ensuring the uniformity of the final coating performance. Beneficial effects

[0034] 1. Precise Calculation and Proportioning: Before coating and imprinting, the total pore volume of the template is precisely calculated using theoretical formulas (i.e., the volume calculation formula for the corresponding structure) based on key parameters such as the template's pore size and porosity. The required volume range of the coating liquid is precisely determined, ensuring accurate control of the adhesive amount from the source, laying the foundation for the subsequent formation of ideal micro / nano structures.

[0035] 2. Use appropriate coating tools: Spraying, spin coating, and blade coating each have their advantages. Taking spin coating as an example, by scientifically adjusting the spin speed and time, the distribution and thickness of the coating liquid on the substrate can be precisely controlled. For example, a higher spin speed allows the coating liquid to be evenly distributed under centrifugal force and the coating to be thinner, while a lower spin speed allows for a thicker coating. This allows for flexible and precise control of the adhesive amount, meeting the requirements of different application scenarios for coating thickness and adhesive amount. Attached Figure Description

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0037] Figure 1 The present invention provides a process flow diagram of the preparation method, wherein 1-1 is magnetic stirring treatment, 1-2 is ultrasonic treatment, 1-3 is substrate, 1-4 is F-SiO2 nanoparticles, 1-5 is fluorinated adhesive, 1-6 is spin coater, 1-7 is PDMS template, 1-8 is ultraviolet light, and 1-9 is superhydrophobic coating.

[0038] Figure 2 This is a characterization image of the multi-level micro / nano-structured superhydrophobic coating constructed in Embodiment 1 of the present invention, wherein... Figure 2 In the image, 'a' represents a SEM image of a multi-level micro / nano structure superhydrophobic coating cone array. Figure 2 In the image, b represents the SEM image of the protrusions on the surface of the multi-level micro / nano structure superhydrophobic coating cone array. Figure 2 Image c shows the contact angle of the multi-level micro / nano structure superhydrophobic coating surface.

[0039] Figure 3 This is a characterization image of the multi-level micro / nano structure superhydrophobic coating constructed in Embodiment 2 of the present invention, wherein... Figure 3 In the image, 'a' represents a SEM image of a multi-level micro / nano structure superhydrophobic coating cone array. Figure 3 Image b in the image shows the contact angle of the multi-level micro / nano structure superhydrophobic coating surface.

[0040] Figure 4 This is a characterization image of the multi-level micro / nano structure superhydrophobic coating constructed in Embodiment 3 of the present invention, wherein... Figure 4 In the image, 'a' represents a SEM image of a multi-level micro / nano structure superhydrophobic coating cone array. Figure 4 Image b in the image shows the contact angle of the multi-level micro / nano structure superhydrophobic coating surface.

[0041] Figure 5 This is a characterization image of the multi-level micro / nano structure superhydrophobic coating constructed in Example 4 of the present invention, wherein... Figure 5 In the image, 'a' represents the SEM image of the multi-level micro / nano structured superhydrophobic coating surface. Figure 5 In the image, b represents the SEM image of the protrusions on the surface of the multi-level micro / nano structure superhydrophobic coating cone array. Figure 5 The image shown in Figure 'c' represents the contact angle of the multi-level micro / nano structure superhydrophobic coating surface.

[0042] Figure 6 This is a characterization image of the multi-level micro / nano-structured superhydrophobic coating constructed in Embodiment 5 of the present invention, wherein... Figure 6 In the image, 'a' represents the SEM image of the multi-level micro / nano structured superhydrophobic coating surface. Figure 6 In the image, b is a magnified SEM image of a local area on the surface of a multi-level micro / nano structure superhydrophobic coating cone array. Figure 6 The image shown in Figure 'c' represents the contact angle of the multi-level micro / nano structure superhydrophobic coating surface.

[0043] Figure 7 This is a characterization image of the multi-level micro / nano structure superhydrophobic coating constructed in Embodiment 6 of the present invention, wherein... Figure 7 In the image, 'a' represents a SEM image of a multi-level micro / nano structure superhydrophobic coating cone array. Figure 7 Image b in the image shows the contact angle of the multi-level micro / nano structure superhydrophobic coating surface.

[0044] Figure 8 This is a graph showing the relationship between the actual amount of adhesive applied and the hydrophobic properties in an embodiment of the present invention.

[0045] Figure 9 This is a schematic diagram of the insufficient adhesive amount during imprinting and shrinkage enrichment mechanism in an embodiment of the present invention, wherein 3-1 is an unfilled cavity and 3-2 is the shrunken fluorinated adhesive. Detailed Implementation

[0046] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0047] This invention provides a method for preparing a multi-level micro / nano structured superhydrophobic coating. Figure 1 The present invention provides a process flow diagram of the preparation method, wherein 1-1 is magnetic stirring treatment, 1-2 is ultrasonic treatment, 1-3 is substrate, 1-4 is F-SiO2 nanoparticles, 1-5 is fluorinated adhesive, 1-6 is spin coater, 1-7 is PDMS template, 1-8 is ultraviolet light, and 1-9 is superhydrophobic coating. The specific steps are as follows: F-SiO2 nanoparticles and fluorinated adhesive are mixed and treated with magnetic stirring and ultrasonic synergy to obtain F-SiO2 / fluorinated adhesive composite solution; then, the F-SiO2 / fluorinated adhesive composite solution is coated on the cleaned substrate by spin coating process, and then covered with PDMS template. The volume of F-SiO2 / fluorinated adhesive composite solution is precisely controlled to be 50~90% of the cone pore volume of PDMS template. After photocuring, the PDMS template is removed to obtain a multi-level micro-nano structured superhydrophobic coating. Example 1

[0048] This embodiment provides a method for preparing a multi-level micro / nano structured superhydrophobic coating, comprising the following steps:

[0049] S1. Substrate Pretreatment

[0050] Using 316L stainless steel as a substrate, the substrate was sequentially ultrasonically cleaned with acetone, ethanol, and then acetone for 5 minutes each (acetone-ethanol three-stage ultrasonic cleaning). The high-frequency vibration of the ultrasound thoroughly removed oil, impurities, and other contaminants from the substrate surface. Subsequently, nitrogen gas was used to purge the substrate to allow it to dry rapidly until the surface water contact angle was <5°, ensuring that the substrate was clean and free of contaminants, creating favorable conditions for the firm adhesion of subsequent coatings.

[0051] S2. Preparation of F-SiO2 / fluorinated adhesive composite solution

[0052] S21. Preparation of fluorinated adhesive solution: Accurately weigh 5g of fluorinated acrylate, add 0.1g of Sylgard 184 photoinitiator, and magnetically stir at 600 rpm for 30 minutes under yellow light or in the dark (to avoid premature failure of the initiator due to light or other factors) to ensure that the photoinitiator is fully dissolved in the fluorinated acrylate to form a homogeneous and stable solution system, thus obtaining the fluorinated adhesive solution.

[0053] S22. Preparation of F-SiO2 nanoparticle dispersion: Accurately weigh 1.5 g of hydrophobic F-SiO2 nanoparticles (50 nm in diameter) and disperse them in 30 mL of propylene glycol methyl ether acetate (PGMEA). Treat the dispersion with an ultrasonic probe (power set to 200 W, frequency 20 kHz) for 20 minutes to obtain the hydrophobic F-SiO2 nanoparticle dispersion. Under the high-frequency oscillation of ultrasound, the nanoparticles are fully dispersed, forming a homogeneous dispersion without agglomeration, laying the foundation for subsequent mixing with the fluorinated adhesive solution.

[0054] S23. Preparation of F-SiO2 / Fluoropolymer Composite Solution: Slowly add the F-SiO2 nanoparticle dispersion prepared in S22 dropwise (1~3 drops / second) to the fluoropolymer solution prepared in S21. PGMEA acts as both a dispersant for the F-SiO2 nanoparticles and a diluent for the fluorinated acrylate. Therefore, the mass of the hydrophobic F-SiO2 nanoparticle dispersion is limited by the mass of PGMEA required to dilute the fluorinated acrylate to a specific concentration, i.e., controlled by mass ratio. Simultaneously, immediately start ultrasonic stirring at 180 W and magnetic stirring at 700 rpm, and continue stirring for 40 minutes to obtain the F-SiO2 / fluoropolymer composite solution.

[0055] S3. Coating and Imprinting

[0056] S31. Calculate the amount of adhesive applied: The specific dimensions of the PDMS template selected for embossing are: total area S = 7.854 × 109 μm 2 The single-cone hole has a diameter D = 2 μm, a depth H = 2 μm, and a porosity P = 70%; theoretical adhesive requirement: V 理 =Sπ(D / 2) 2 HP / 3, where S is the total area of ​​the PDMS template (μm). 2 D represents the pore diameter (μm) of the single conical pore in the PDMS template, H represents the pore depth (μm) of the single conical pore in the PDMS template, and P represents the porosity of the PDMS template. The volume of the F-SiO2 / fluorinated adhesive composite solution is precisely controlled to be 80% of the theoretical required amount of adhesive, i.e., the actual amount of adhesive applied, V. 实 =V 理 ×80%.

[0057] S32. Coating with F-SiO2 / fluorinated adhesive composite solution: The F-SiO2 / fluorinated adhesive composite solution is uniformly coated onto the substrate surface using a spin coating method, forming a 1.17 μm thick wet film on the substrate treated in S1. The specific spin coating process is: spin speed 2000 rpm, spin coating time 30 s. This ensures a uniform coating thickness, providing a good foundation for subsequent embossing.

[0058] S33. Imprinting: The PDMS template is imprinted onto the wet film. By controlling the volume of the F-SiO2 / fluorinated adhesive composite solution to 80% of the theoretical required amount of adhesive, the imprinted wet film cannot completely fill the pores of the PDMS template, leaving space for the curing shrinkage of the fluorinated adhesive and the directional enrichment of nanoparticles.

[0059] S34. UV Curing: The imprinted sample was cured under UV light (365 nm, 300 W) in a nitrogen atmosphere. Under the action of UV light of specific wavelength and power, the fluorinated adhesive rapidly cured and crosslinked. After curing for 6 minutes, the template was carefully peeled off to obtain the multi-level micro / nanostructured superhydrophobic coating. At this time, due to the curing shrinkage of the fluorinated adhesive, F-SiO2 nanoparticles were directionally enriched on the coating surface, successfully forming a multi-level, multi-scale microstructured surface. The curing shrinkage rate was 10.5%, and a regular micron cone array with a height of 1.8 μm and densely distributed 50~100 nm protrusions on the surface were successfully constructed.

[0060] The multi-level micro / nano structured superhydrophobic coating constructed in this embodiment was characterized using scanning electron microscopy. The surface contact angle of the multi-level micro / nano structured superhydrophobic coating was measured using a contact angle measuring instrument (manufacturer: Dongguan Shengding Precision Instruments Co., Ltd., model: SDC-100). Figure 2 These are characterization images of the multi-level micro / nano-structured superhydrophobic coating constructed in this embodiment, wherein... Figure 2 In the image, 'a' represents a SEM image of a multi-level micro / nano structure superhydrophobic coating cone array. Figure 2In the image, b represents the SEM image of the protrusions on the surface of the multi-level micro / nano structure superhydrophobic coating cone array. Figure 2 Image c shows the contact angle of the multi-level micro / nano structured superhydrophobic coating surface. Figure 2 As can be seen, obvious wrinkles appear on the smooth substrate surface, and the surface is covered with abundant nanoparticles. This proves that this embodiment successfully constructed a regular micron cone array with a height of 1.8 μm, and densely distributed 50~100 nm nanoparticle aggregates / aggregates on the surface of the micron cone array, with a coverage of up to 94.2% on the surface of the micron cone. Performance tests show that the water contact angle of the multi-level micro-nano structure superhydrophobic coating reaches 173.0°. Example 2

[0061] This embodiment provides a method for preparing a multi-level micro / nano structure superhydrophobic coating. The difference between this embodiment and Embodiment 1 is that in step S3, the volume of the F-SiO2 / fluorinated adhesive composite solution is precisely controlled to be 50% of the theoretical adhesive required for the template cone hole, and a 0.61 μm wet film is formed on the substrate by spin coating (2000 rpm / 30 s). Other processes are completely the same.

[0062] The structure of the multi-level micro / nano-structured superhydrophobic coating constructed in this embodiment was characterized using scanning electron microscopy, and the surface contact angle of the multi-level micro / nano-structured superhydrophobic coating was tested using a contact angle meter. Figure 3 These are characterization images of the multi-level micro / nano-structured superhydrophobic coating constructed in this embodiment, wherein... Figure 3 In the image, 'a' represents a SEM image of a multi-level micro / nano structure superhydrophobic coating cone array. Figure 3 In the image, 'b' represents the contact angle of the multi-level micro / nano structured superhydrophobic coating surface, derived from... Figure 3 It can be seen that the insufficient amount of adhesive caused the microcone pores to be unable to be completely filled, resulting in obvious wrinkles on the surface of the microcone array after curing. At the same time, during the curing process, the shrinkage of the adhesive drove the nanoparticles to migrate and accumulate towards the surface of the microcone, forming agglomerates / aggregates on the surface of the microcone array, making the surface of the microcone array no longer smooth. Furthermore, the height of the microcone is only 1.2 μm, and the contact angle of the sample surface is 155.8°. Example 3

[0063] This embodiment provides a method for preparing a multi-level micro / nano structure superhydrophobic coating. The difference between this embodiment and Embodiment 1 is that in step S3, the volume of the F-SiO2 / fluorinated adhesive composite solution is precisely controlled to be 60% of the theoretical adhesive required for the template cone hole, and a 0.88 μm wet film is formed on the substrate by spin coating (2000 rpm / 30 s). Other processes are completely the same.

[0064] The structure of the multi-level micro / nano-structured superhydrophobic coating constructed in this embodiment was characterized using scanning electron microscopy, and the surface contact angle of the multi-level micro / nano-structured superhydrophobic coating was tested using a contact angle meter. Figure 4 These are characterization images of the multi-level micro / nano-structured superhydrophobic coating constructed in this embodiment, wherein... Figure 4 In the image, 'a' represents a SEM image of a multi-level micro / nano structure superhydrophobic coating cone array. Figure 4 In the image, 'b' represents the contact angle of the multi-level micro / nano structured superhydrophobic coating surface, derived from... Figure 4 It can be seen that wrinkles appear on the surface of the micron cone array due to insufficient adhesive. Similarly, during the curing process, the shrinkage of the adhesive drives the nanoparticles to migrate directionally to the surface of the micron cone and accumulate to form nanoparticle aggregates / aggregates. Moreover, the height of the micron cone is only 1.5 μm, and the contact angle of the sample surface is 160.4°. Example 4

[0065] This embodiment provides a method for preparing a multi-level micro / nano structure superhydrophobic coating. The difference between this embodiment and Embodiment 1 is that in step S3, the volume of the F-SiO2 / fluorinated adhesive composite solution is precisely controlled to be 70% of the theoretical adhesive required for the template cone hole, and a 1.05 μm wet film is formed on the substrate by spin coating (2000 rpm / 30 s). Other processes are completely the same.

[0066] The structure of the multi-level micro / nano-structured superhydrophobic coating constructed in this embodiment was characterized using scanning electron microscopy, and the surface contact angle of the multi-level micro / nano-structured superhydrophobic coating was tested using a contact angle meter. Figure 5 These are characterization images of the multi-level micro / nano-structured superhydrophobic coating constructed in this embodiment, wherein... Figure 5 In the image, 'a' represents the SEM image of the multi-level micro / nano structured superhydrophobic coating surface. Figure 5 In the image, b represents the SEM image of the protrusions on the surface of the multi-level micro / nano structure superhydrophobic coating cone array. Figure 5 In the image, 'c' represents the contact angle of the multi-level micro / nano structured superhydrophobic coating surface, derived from... Figure 5 It can be seen that the surface of the micron cone array is wrinkled and covered with abundant nanoparticles. The height of the micron cone is only 1.64 μm, and the contact angle of the sample surface is 170.5°. Example 5

[0067] This embodiment provides a method for preparing a multi-level micro / nano structure superhydrophobic coating. The difference between this embodiment and Embodiment 1 is that in step S3, the volume of the F-SiO2 / fluorinated adhesive composite solution is precisely controlled to be 90% of the theoretical adhesive required for the template cone hole, and a 1.3 μm wet film is formed on the substrate by spin coating (2000 rpm / 30 s). Other processes are completely the same.

[0068] The structure of the multi-level micro / nano-structured superhydrophobic coating constructed in this embodiment was characterized using scanning electron microscopy, and the surface contact angle of the multi-level micro / nano-structured superhydrophobic coating was tested using a contact angle meter. Figure 6 These are characterization images of the multi-level micro / nano-structured superhydrophobic coating constructed in this embodiment, wherein... Figure 6 In the image, 'a' represents the SEM image of the multi-level micro / nano structured superhydrophobic coating surface. Figure 6 In the image, b is a magnified SEM image of a local area on the surface of a multi-level micro / nano structure superhydrophobic coating cone array. Figure 6 In the image, 'c' represents the contact angle of the multi-level micro / nano structured superhydrophobic coating surface, derived from... Figure 6 It can be seen that the surface of the micron cone array exhibits a uniform morphology (i.e., under sufficient colloid concentration, the directional migration / enrichment effect of nanoparticles to the surface of the micron cone during the curing process is not significant, resulting in the failure of the nano-protrusion structure to form effectively). The height of the micron cone is 1.9 μm, the surface of the micron cone array is flat, and the contact angle of the sample surface is 159.7°. Example 6

[0069] This embodiment provides a method for preparing a multi-level micro / nano structure superhydrophobic coating. The difference between this embodiment and Embodiment 1 is that in step S3, the volume of the F-SiO2 / fluorinated adhesive composite solution is precisely controlled to be 95% of the theoretical adhesive required for the template cone hole, and a 1.4 μm wet film is formed on the substrate by spin coating (2000 rpm / 30 s). Other processes are completely the same.

[0070] The structure of the multi-level micro / nano-structured superhydrophobic coating constructed in this embodiment was characterized using scanning electron microscopy, and the surface contact angle of the multi-level micro / nano-structured superhydrophobic coating was tested using a contact angle meter. Figure 7 These are characterization images of the multi-level micro / nano-structured superhydrophobic coating constructed in this embodiment, wherein... Figure 7 In the image, 'a' represents a SEM image of a multi-level micro / nano structure superhydrophobic coating cone array. Figure 7 In the image, 'b' represents the contact angle of the multi-level micro / nano structured superhydrophobic coating surface, derived from... Figure 7 It can be seen that the surface of the micron cone array exhibits a uniform morphology (i.e., under sufficient colloid concentration, the directional migration / enrichment effect of nanoparticles to the surface of the micron cone during the curing process is not significant, resulting in the failure of the nano-protrusion structure to form effectively). The height of the micron cone is 2 μm, and the contact angle of the sample surface is 153.0°.

[0071] Furthermore, a graph showing the relationship between the actual amount of adhesive applied in Examples 1-6 and the hydrophobic properties was plotted with the actual amount of adhesive applied as the horizontal axis and the contact angle as the vertical axis. Figure 8 This is a graph showing the relationship between the actual amount of adhesive applied and the hydrophobic properties. Figure 8 It can be seen that when the amount of glue is in the optimal range of 70% to 80% ( Figure 8The appropriate amount of adhesive allows for the complete replication of the micron cone structure during the imprinting process (primary structure height retention ≥90%, producing only controllable wrinkles). Simultaneously, the shrinkage of the adhesive during the curing stage drives nanoparticles to migrate and accumulate on the surface of the micron cone, forming nanoscale protrusions (secondary rough structure). The two-level structure works together to stabilize the gas-liquid interface, achieving a superhydrophobic state of 170°~180°. When the amount of adhesive is <70%, the insufficient amount of adhesive during the imprinting stage cannot fully fill the micropores of the mold, resulting in a decrease in the height of the micron cone structure (significant reduction in the height of the primary structure). Although the curing shrinkage can still promote the accumulation of nanoparticles to form a secondary structure, the collapse of the primary structure weakens the capillary effect, resulting in hydrophobicity <170°. When the amount of adhesive is >80%, the excessive amount of adhesive, while ensuring the integrity of the micron cone replication (primary structure height >90%), produces a physical masking effect due to the excessive thickness of the adhesive layer, inhibiting the migration of nanoparticles to the surface (secondary structure loss), resulting in insufficient surface roughness and a significant decrease in hydrophobicity. Figure 9 This diagram illustrates the mechanism of insufficient adhesive application and shrinkage enrichment during printing. In this diagram, 3-1 represents an unfilled cavity, and 3-2 represents the shrunken fluorinated adhesive. Figure 9 It can be seen that during the imprinting process, insufficient adhesive content prevents the adhesive material from completely filling the pores of the imprinting mold, resulting in a special phenomenon of insufficient adhesive filling (3-1). During the curing process, nanoparticles in the adhesive migrate / accumulate directionally to the surface of the micron structure. At the same time, the adhesive material also undergoes a certain shrinkage during the curing process. Both of these factors together lead to the formation of nanoscale protrusions on the surface of the microstructure by the nanoparticles (3-2).

[0072] This invention provides a concept and method for preparing a multi-level micro / nano-structured superhydrophobic coating. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for preparing a multistage micro-nanostructure superhydrophobic coating, characterized in that, The method comprises the following steps: S1. Pre-treating the substrate; S2. Slowly adding F-SiO2 nanoparticle dispersion to fluorine-containing glue solution under the treatment of ultrasonic and magnetic stirring to obtain F-SiO2 / fluorine-containing glue composite solution; S3. Determining the actual glue amount based on the theoretical glue amount of the PDMS template, and coating the F-SiO2 / fluorine-containing glue composite solution on the surface of the substrate by spin coating to form a wet film; S4. Using the PDMS template to imprint the wet film, and stripping the template after ultraviolet curing to obtain the multi-level micro-nano structure super-hydrophobic coating. The volume of the actual glue amount is 50-90% of the volume of the theoretical glue amount.

2. The production method according to claim 1, characterized by, The actual glue amount is 70-80% of the theoretical glue amount.

3. The preparation method according to claim 1, characterized in that, In S2, the mass ratio of the F-SiO2 nanoparticle dispersion to the fluorine-containing glue solution is (2-10):

1.

4. The production method according to claim 3, characterized by, The F-SiO2 nanoparticle dispersion is a mixture of F-SiO2 nanoparticles and propylene glycol methyl ether acetate, and the solid-liquid ratio of F-SiO2 nanoparticles to propylene glycol methyl ether acetate is (0.025-0.15) g:1 mL; the fluorine-containing glue solution is a mixture of fluorine-containing glue and initiator, and the initiator is 1-3 wt% of the fluorine-containing glue.

5. The preparation method according to claim 1, characterized in that, In S2, the ultrasonic power is 150-200 W; and the magnetic stirring speed is 500-800 rpm.

6. The method of claim 1, wherein, In S3, the spin coating process parameters are as follows: the rotation speed is 1000-3000 rpm, and the spin coating time is 30-50 s.

7. The preparation method according to claim 1, characterized in that, In S4, the ultraviolet curing process parameters are as follows: the wavelength is 365 nm, and the power is 100-500 W.

8. The multi-level micro-nano structure super-hydrophobic coating prepared by the method of any one of claims 1-7.

9. The multi-level micro-nano structured superhydrophobic coating according to claim 8, wherein, The multi-level micro-nano structure super-hydrophobic coating comprises a micro-taper array and a nano-protrusion.

10. The multi-level micro-nano structured superhydrophobic coating according to claim 9, wherein, The height of the micro-taper array is 1-50 μm; and the height of the nano-protrusion is 30-500 nm.

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