A durable superhydrophobic perfluoroalkoxy ethyl vinyl ether copolymer coating and methods of making and using the same

Abstract

This invention discloses a durable superhydrophobic PFA coating, its preparation method, and its application. Belonging to the field of coating processing and functional material surface modification technology, it grafts γ-aminopropyl groups onto the surface of nanoparticles using a silane coupling agent KH550. These γ-aminopropyl groups are transformed into positively charged ammonium ions in an acidic environment. The repulsion between these ions with the same charge inhibits the aggregation of homogeneous particles, thus fundamentally solving the problem of easy detachment of nanoparticles within the coating. Furthermore, by grafting perfluorinated long chains onto the nanoparticle surface using fluorosilanes, surface energy is reduced, improving the hydrophobicity of the particles. Simultaneously, the similarity and similarity solubility between the long fluorocarbon chains and the PFA coating eliminate interfacial cracks, making it difficult for nanoparticles to peel off when the surface is subjected to friction. The coating prepared by this invention can provide excellent droplet bounce enhancement and droplet adhesion inhibition properties, and is expected to be applied in the field of low-temperature anti-icing.

Description

Technical Field

[0001] This invention belongs to the field of coating processing and functional material surface modification technology, and particularly relates to a durable superhydrophobic perfluoroalkoxy vinyl ether copolymer coating, its preparation method and application. Background Technology

[0002] In cold and rainy regions, high-speed railway contact wires are highly susceptible to severe icing, leading to unstable current collection by the pantograph, arcing, and even wire breakage—a core concern threatening the safe operation of high-speed railways. As my country's high-speed rail network rapidly extends into extreme environments, traditional manual de-icing techniques are no longer adequate to meet the demands of high-frequency train operation. Developing long-lasting active anti-icing and efficient passive de-icing technologies has become a key research focus in the rail transit field. Surface hydrophobic modification to enhance droplet bouncing and inhibit raindrop adhesion has proven to be a crucial means of delaying the icing process. In recent years, researchers have explored a series of anti-icing and de-icing surface preparation schemes, utilizing low-surface-energy coatings, lubricated surfaces, or micro / nano structures, and investigated their icing control mechanisms.

[0003] In existing active de-icing research and applications, drone equipment can break ice layers with strong shear force, and electrothermal and photothermal technologies can efficiently utilize energy to generate Joule heat to melt the ice interface. However, the current active de-icing methods are limited by poor continuity, easy wear on the surface of the sliding contact line, and insufficient coverage of complex geometric parts. While heating technology can melt ice thoroughly, it consumes a lot of energy and can easily cause the sliding contact line material to anneal and soften.

[0004] Currently, research and applications of passive de-icing are relatively limited. Some technologies utilize low-free-energy fluorocarbon coatings to enhance surface hydrophobicity and inhibit droplet adhesion. To further improve the static contact angle of fluorocarbon coatings to achieve superhydrophobicity, various inorganic nanoparticles are often introduced to construct micro / nano-level rough structures. However, directly adding unmodified nanoparticles can easily lead to poor physical compatibility and insufficient wettability due to the significant interfacial energy difference between the inorganic particles and the nonpolar PFA (perfluoroalkoxy vinyl ether copolymer) matrix. This not only causes severe nanoparticle aggregation, forming stress concentration points, but also results in a lack of effective chemical anchoring between the particles and the coating. During actual de-icing or mechanical friction, surface particles are easily detached, leading to rapid degradation of coating performance and difficulty in maintaining stable superhydrophobic properties and low roll-off angles, especially in low-temperature environments where superhydrophobic durability is poor.

[0005] Therefore, solving the problem of how to uniformly disperse nanoparticles in PFA coatings has certain scientific research significance and engineering value. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a durable superhydrophobic perfluoroalkoxy vinyl ether copolymer (PFA) coating, its preparation method, and its application. This invention utilizes a silane coupling agent, KH550, to graft γ-aminopropyl groups onto the surface of nanoparticles. In an acidic environment, these γ-aminopropyl groups are converted into positively charged ammonium ions. The repulsion between these ions with the same charge inhibits the aggregation of homogeneous particles, thus fundamentally solving the problem of easy nanoparticle detachment within the coating. Furthermore, by grafting long-chain perfluorinated fluorosilanes onto the nanoparticle surface, surface energy is reduced, increasing particle hydrophobicity. Simultaneously, the similarity and similarity solubility between the long fluorocarbon chains and the PFA coating allow the coating to completely wet and encapsulate the well-dispersed nanoparticles, eliminating interfacial cracks and making the nanoparticles less prone to peeling off when the surface is subjected to friction. An ultrasonic disperser transfers energy to the nanoparticles, shattering potential nanoparticle clusters and accelerating particle movement, allowing the silane coupling agent and fluorosilane to diffuse to more particle surfaces. The coating is then sprayed onto the surface in one step and sintered to form the final shape. The durable superhydrophobic PFA coating prepared by this invention is a durable superhydrophobic PFA coating based on steric hindrance dispersion modification. Its surface has advantages such as good hydrophobic properties, simple processing technology and low cost. It can provide excellent droplet bouncing enhancement and droplet adhesion inhibition performance, and is expected to be applied in the field of low temperature anti-icing (such as low temperature resistant high-speed rail sliding contact lines).

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a durable superhydrophobic PFA coating. In an acidic environment, nanoparticles are modified using a silane coupling agent and a fluorosilane, and then ultrasonically dispersed. The resulting mixture is uniformly dispersed in a perfluoroalkoxy vinyl ether copolymer coating. The resulting solution is sprayed onto a metal substrate and sintered to obtain the durable superhydrophobic PFA coating. The silane coupling agent is γ-aminopropyltriethoxysilane (KH550). The overall mass concentration of the nanoparticles in the durable superhydrophobic PFA coating is 2.5wt%~15wt%, and the micro-nano structure morphology of the coating surface is controlled by adjusting the overall amount of nanoparticles added.

[0008] This invention addresses the problem of ice accumulation on the surface of high-speed rail contact lines in low-temperature environments. It addresses the issue of "deterioration of hydrophobicity in low-temperature environments and easy partial adhesion of impact droplets" when using PFA as a hydrophobic coating in practical applications. By adding various nanoparticles modified with fluorosilane and silane coupling agent (KH550), the surface roughness and micro / nano structure uniformity of PFA are improved, thereby achieving superhydrophobic low-temperature durability and enhancing raindrop bounce-off.

[0009] Previous modification processes based on PFA coatings have mostly focused on hydrophobic properties in room temperature or high temperature environments. However, in low-temperature environments (such as the surface of high-speed rail conductor rails in cold and rainy areas as mentioned in the background), the hydrophobicity of the PFA surface deteriorates significantly due to particle impact and shedding or residual water vapor within the surface structure. This is specifically manifested in a decrease in the static contact angle and a weakening of droplet bouncing ability. Therefore, this invention mainly addresses the problem of deterioration in the hydrophobic properties of PFA surfaces in low-temperature environments.

[0010] Furthermore, the acidic environment is an environment with a pH of 4 to 5.

[0011] Furthermore, the nanoparticles are selected from hydrophobic nano-silica particles and hydroxylated multi-walled carbon nanotubes.

[0012] Furthermore, the hydrophobic nano-silica particles are hydrophobic nano-silica particles with a particle size of 100~500nm and hydrophobic nano-silica particles with a particle size of 7~40nm.

[0013] Previous processes for doping PFA coatings with nanoparticles to improve surface roughness and hydrophobicity mostly relied on nanoparticles of a single size or monomeric morphology (spherical), resulting in a relatively simple surface roughness structure. However, this invention uses silica nanoparticles of two different particle sizes (spherical particles) and hydroxylated multi-walled carbon nanotubes (one-dimensional linear particles), which further improves surface roughness and increases the static contact angle to 156°, giving the coating prepared by this invention superhydrophobic properties.

[0014] In conventional processes, KH550 is added to nanoparticle dispersions primarily to replace hydroxyl groups on the particle surface and graft γ-aminopropyl groups, thereby enhancing adhesion to other organic nanoparticles or organic coating matrices by introducing organic groups. In contrast, the addition of fluorosilanes in this invention mainly facilitates monolayer self-assembly reactions, utilizing perfluorocarbon chains to reduce surface free energy, thus increasing the static contact angle of surface droplets and improving surface hydrophobicity. These two steps generally have a clear distinction and sequence. Specifically, in processes using two modifiers, after single particles are modified with KH550 and grafted with organic groups, an additional drying process is performed to obtain powder. This powder is then either added to the dispersion and mixed with other nanoparticles, forming molecular bonds through surface group reactions, followed by another drying to obtain combined particle powder, or directly mixed with the coating substrate and added to the dispersion, finally undergoing further hydrophobic modification with fluorosilanes. However, in this invention, for high-viscosity, high-processing-temperature fluorocarbon systems like PFA, the initial uniformity of nanoparticle dispersion is more critical to the final coating performance than the magnitude of interparticle adhesion. Therefore, although KH550 is also used to graft γ-aminopropyl groups onto the particle surface, it is not for enhancing particle coupling, but rather to utilize the protonation of the terminal amino group in an acidic environment (-NH3).+ The electrostatic repulsion generated by these agents inhibits the aggregation of nanoparticles, specifically suppressing the accumulation of silica particles and the disordered entanglement of multi-walled carbon nanotubes. The addition of fluorosilanes serves two purposes: firstly, it reduces surface free energy; secondly, the longer perfluorocarbon molecular chains create greater steric hindrance between homogeneous particles, thus enhancing particle dispersion. The hydroxylated carbon nanotubes used in this invention also provide hydroxyl groups for the substitution reaction of the two modifiers (silane coupling agent and fluorosilane).

[0015] On the other hand, the preparation process of this invention employs a co-modification strategy of KH550 and fluorosilane with dual functional groups. The addition of the two modifiers to the particle dispersion is simultaneous and synchronous. Ultrasonic treatment is introduced for physical particle dispersion, pushing the hydroxyl and protonated amino groups inside the particle clusters to the outside. Local high temperatures are introduced to accelerate the grafting reaction, promoting the comprehensive competitive replacement of hydroxyl groups on the particle surface by γ-aminopropyl and perfluorinated long carbon chains, significantly improving particle dispersion uniformity and reducing the residual hydroxyl group rate. Overall, it provides good bouncing performance for impacting droplets in both normal and low temperature environments; impacting droplets with We = 50 can completely bounce off. Furthermore, it exhibits good surface hydrophobic stability; after a 4-hour droplet impact experiment, the surface contact angle remains above 150°.

[0016] Furthermore, the fluorosilane is 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-17).

[0017] Furthermore, during ultrasonic dispersion, the ultrasonic power is 120 W, the ultrasonic frequency is 20~25 kHz, and the ultrasonic cycle is set to work for 2 seconds and stop for 2 seconds, with the upper temperature limit set to 50 ℃.

[0018] Furthermore, the metal substrate is selected from copper alloys, copper, or stainless steel.

[0019] Furthermore, a stepped heating program is used for sintering, specifically: first, the temperature is raised from room temperature to 150 ℃ and held for 30 min, then raised to 350 ℃ and held for 30 min, and finally cooled naturally with the furnace temperature.

[0020] The present invention also provides a durable superhydrophobic PFA coating prepared according to the above preparation method.

[0021] The present invention also provides an application of the above-mentioned durable superhydrophobic PFA coating in the field of low-temperature anti-icing, wherein the low temperature is ≤0℃, preferably ≤-5℃.

[0022] The present invention also provides an application of the above-mentioned durable superhydrophobic PFA coating in high-speed rail conductor rails in low-temperature environments, wherein the low temperature is ≤0℃, preferably ≤-5℃.

[0023] Compared with the prior art, the present invention has the following advantages and technical effects: 1. The PFA superhydrophobic surface provided by the present invention has roughness provided by nanoparticles, which is conducive to droplets exhibiting a Cassie state of suspension on the surface. The droplets are easy to roll on the surface, and the apparent contact angle of the droplets can still reach more than 150° under normal temperature and low temperature conditions of 0 ℃, thus exhibiting good hydrophobicity.

[0024] 2. This invention addresses particle aggregation by adding silane coupling agents and fluorosilanes to a nanoparticle dispersion. Utilizing the charge repulsion of amino groups and the steric hindrance effect of long fluorocarbon chains, combined with cavitation generated by ultrasound, this process significantly enhances the interfacial adhesion between inorganic nanoparticles and the PFA matrix, constructing a uniform and stable nano-dispersion system. This effectively inhibits surface particle shedding and strengthens the coating's superhydrophobicity, low roll-off angle performance, and superhydrophobic durability while maintaining multi-level roughness. This provides a new approach for optimizing the preparation process of fluorocarbon coatings for applications such as anti-icing and anti-frost functions on high-speed rail contact lines.

[0025] 3. This invention controls the overall content of nanoparticles within the coating by adjusting the amount of nanoparticles added, thereby controlling the morphology and distribution of the surface micro / nano structure, enhancing droplet bouncing ability, and promoting timely droplet detachment from the surface. The preparation method of this invention is simple, the preparation process is precise and controllable, and the structure is simple. Compared to a plain PFA surface, the durable superhydrophobic PFA coating surface exhibits stronger ability to inhibit the adhesion of impacting droplets. Impacting droplets can completely bounce off the surface within 18 ms after impact at room temperature, and can also completely detach within 20 ms at 0℃, while significant droplet bouncing residue remains on the superhydrophobic PFA surface at this low temperature. Furthermore, the durable superhydrophobic PFA coating surface maintains good superhydrophobic properties even after a 4-hour low-temperature droplet impact test, while the superhydrophobic PFA coating surface shows numerous crack structures extending to the metal substrate, severely affecting its hydrophobic properties. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a process flow diagram of the durable superhydrophobic PFA coating based on steric hindrance dispersion modification according to the present invention. Figure 2The basic morphology and wettability characterization of the surfaces prepared in Examples 1, 2, 3, 4, Comparative Examples 1, 2, 4, 6, and 7 are shown below. (a) corresponds to the sandblasted copper surface prepared in Example 4; (b) corresponds to the simple PFA coating surface prepared in Example 6; (c) corresponds to the PFA coating surface without KH550 prepared in Example 2; (d) corresponds to the PFA coating surface without FAS-17 prepared in Example 7; and (e) corresponds to the low nanoparticle content durability surface prepared in Example 3. The superhydrophobic PFA coating surface, (f) corresponds to the durable superhydrophobic PFA coating surface prepared in Example 1, (g) corresponds to the durable superhydrophobic PFA coating surface prepared on the high-speed rail sliding contact line in Example 2 (scale bar is 10 μm), (h) corresponds to the durable superhydrophobic PFA coating surface with high nanoparticle content prepared in Example 4, and (i) corresponds to the PFA coating surface with high nanoparticle content prepared in Example 1. The upper left corner of each small image is the macroscopic morphology, the lower part is the microscope image (magnification 100), and the upper right corner is the static contact angle characterization.

[0027] Figure 3 The dynamic evolution process of impacted droplets bouncing off the copper sheet surface in Comparative Examples 1, 2, 4, 6, 7, 1, 3, and 4 at 20°C is shown in (a)-(h), which correspond to the dynamic evolution process of impacted droplets spreading and retracting on the copper sheet surface in Comparative Examples 4, 6, 2, 7, 3, 1, 4, and 1, respectively.

[0028] Figure 4 The dynamic evolution process of impact droplets bouncing off the surface of copper sheets in Comparative Examples 1, 2, 4, 6, 7, 1, 3 and 4 at a low temperature of -5 ℃ is shown in (a)-(h), which correspond to the dynamic evolution process of impact droplets spreading and retracting on the surface of copper sheets in Comparative Examples 4, 6, 2, 7, 3, 1, 4 and 1, respectively.

[0029] Figure 5 This describes the dynamic evolution of droplets bouncing off the surface of the sliding contact line in Comparative Example 5 at -5 ℃.

[0030] Figure 6 This describes the dynamic evolution of droplets bouncing off the surface of the sliding contact line in Comparative Example 3 at -5 ℃.

[0031] Figure 7 This describes the dynamic evolution of droplets bouncing off the surface of the sliding contact line in a -5℃ low-temperature environment.

[0032] Figure 8Example 2 illustrates the dynamic evolution of droplets bouncing off the surface of the sliding contact line during impact in a -5°C low-temperature environment.

[0033] Figure 9 This is the dynamic evolution process of droplet spreading and retraction during impact on the side of the sliding conductor in a -5 ℃ low-temperature environment (Comparative Example 5).

[0034] Figure 10 This is the dynamic evolution process of droplet spreading and retraction during impact on the side of the sliding conductor in a -5 ℃ low-temperature environment, as described in Comparative Example 3.

[0035] Figure 11 This is a comparative example of the dynamic evolution process of a droplet bouncing off from the side of a sliding contact line in a -5 ℃ low-temperature environment.

[0036] Figure 12 Example 2 illustrates the dynamic evolution of droplet spreading and retraction during impact on the side of the sliding contact line in a -5°C low-temperature environment.

[0037] Figure 13 The surface morphology of the hydrophobic PFA coating surface without KH550 prepared in Comparative Example 2, the hydrophobic PFA coating surface without FAS-17 prepared in Comparative Example 7, and the durable superhydrophobic PFA coating surface prepared in Example 1 before and after 4 h of low temperature droplet impact (i.e. before and after the durability test) in a -5 ℃ low temperature environment is shown in (a) corresponding to Comparative Example 2, (b) corresponding to Comparative Example 7, and (c) corresponding to Example 1.

[0038] Figure 14 The static contact angle changes of the hydrophobic PFA coating surface without KH550 prepared in Comparative Example 2, the hydrophobic PFA coating surface without FAS-17 prepared in Comparative Example 7, and the durable superhydrophobic PFA coating surface prepared in Example 1 before and after 4 h of low temperature droplet impact (i.e. before and after the durability test) in a -5 ℃ low temperature environment. Detailed Implementation

[0039] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0040] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0041] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0042] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0043] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0044] The present invention provides a method for preparing a durable superhydrophobic PFA coating. In an acidic environment, nanoparticles are modified using silane coupling agents and fluorosilanes to increase the steric hindrance between homogeneous particles and strengthen the bonding force with the coating. Then, ultrasonic dispersion is performed using an ultrasonic disperser to uniformly disperse the resulting mixture in a perfluoroalkoxy vinyl ether copolymer coating. The resulting solution is then sprayed onto a metal substrate using compressed air and sintered to obtain a durable superhydrophobic PFA coating. The present invention enhances the superhydrophobic properties of the coating surface by strengthening surface roughness and micro / nano structure uniformity. The silane coupling agent is γ-aminopropyltriethoxysilane (KH550). The overall mass concentration of nanoparticles in the durable superhydrophobic PFA coating is 2.5wt%~15wt%, and the micro-nano structure morphology of the coating surface is controlled by adjusting the overall amount of nanoparticles added.

[0045] The core of this invention lies in using silane coupling agents, fluorosilanes, and ultrasound to enhance the dispersion between nanoparticles and the bonding force between particles and coatings. When added to a PFA coating, it improves the surface durability, superhydrophobic properties, and droplet bouncing ability, driving droplets to bounce off and inhibiting droplet adhesion.

[0046] In a preferred embodiment of the present invention, the acidic environment is an environment with pH=4~5.

[0047] In a preferred embodiment of the present invention, the nanoparticles are selected from hydrophobic nano-silica particles and hydroxylated multi-walled carbon nanotubes.

[0048] In a preferred embodiment of the present invention, the hydrophobic nano-silica particles are hydrophobic nano-silica particles with a particle size of 500 nm and hydrophobic nano-silica particles with a particle size of 7~40 nm.

[0049] In a preferred embodiment of the present invention, the mass ratio of hydrophobic nano-silica particles with a particle size of 100-500 nm, hydrophobic nano-silica particles with a particle size of 7-40 nm, and hydroxylated multi-walled carbon nanotubes is 7:1:0.2.

[0050] In a preferred embodiment of the present invention, the length of the hydroxylated multi-walled carbon nanotubes is 5~30 μm.

[0051] In a preferred embodiment of the present invention, the fluorosilane is 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-17).

[0052] In a preferred embodiment of the present invention, when performing ultrasonic dispersion, the ultrasonic power is 120 W, the ultrasonic frequency is 20~25 kHz, and the ultrasonic operation cycle is set to 2 seconds on and 2 seconds off, with the upper temperature limit set to 50 ℃.

[0053] In a preferred embodiment of the present invention, the metal substrate is selected from copper alloy, copper, or stainless steel.

[0054] For example, copper alloy is used for high-speed railway conductor rails (HSR conductor rails).

[0055] In the following embodiments of the present invention, the metal substrate is a copper sheet with dimensions of 20×20×2 mm or a 5 cm long CTMH-150 high-speed rail sliding contact line.

[0056] In a preferred embodiment of the present invention, a stepped heating program is used for sintering. The specific steps are as follows: first, the temperature is raised from room temperature to 150 °C and held for 30 min, then the temperature is raised to 350 °C and held for 30 min, and finally the temperature is naturally cooled with the furnace temperature.

[0057] In a preferred embodiment of the present invention, when the metal substrate is a copper sheet, a method for preparing a durable superhydrophobic PFA coating includes the following steps: (1) After sandblasting pretreatment (the sand in the sandblasting pretreatment is 100-mesh white corundum, and the sandblasting pressure is 0.7 MPa), the high-purity copper sheet with a size of 20×20×2 mm (purity is 99.999%) is placed in isopropanol, anhydrous ethanol and deionized water for ultrasonic cleaning for 5 min, and then dried for later use.

[0058] (2) Take 5 mL of N-methylpyrrolidone as a solvent, use acetic acid to control the pH of the solvent to 4~5, add 0.7 g of hydrophobic nano silica particles with a particle size of 100~500 nm, 0.1 g of hydrophobic nano silica particles with a particle size of 7~40 nm, 0.02 g of high-purity hydroxylated multi-walled carbon nanotubes with a length of 5~30 μm, 0.2 g of silane coupling agent γ-aminopropyltriethoxysilane and 0.4 g of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, and stir to mix evenly.

[0059] (3) Place the mixture obtained in step (2) in an ultrasonic disperser and ultrasonically disperse for 30 min (power is 120 W, frequency is 20 kHz, and the ultrasonic operation is set to work for 2 s and stop for 2 s cycle, and the upper limit of temperature is set to 50 ℃). Then place it in a water bath and keep it at 50 ℃ for 30 min with magnetic stirring (speed is 600 rpm). Then add 11.67 g of PFA coating to the obtained mixture and keep it in a 50 ℃ constant temperature water bath environment. Stir for 30 min first and then let it stand for 30 min.

[0060] (4) The mixture obtained in step (3) is sprayed onto the copper sheet and CTMH-150 sliding contact line obtained in step (1) in one step using compressed air to enhance the droplet bouncing and detachment of the coating and improve the superhydrophobic properties. The spraying pressure is 0.5 MPa, the spraying time is 8~10s, and the spraying distance is 40~50 cm to obtain a relatively uniform 40 μm thick coating. The sprayed sample is placed in a tube furnace and nitrogen is introduced as a protective gas. The step heating program is used (first, the temperature is increased from room temperature to 150 ℃ at a rate of 1~3℃ / min and held for 30 min, then the temperature is increased to 350 ℃ at a rate of 1~3℃ / min and held for 30 min, and finally the temperature is naturally cooled with the furnace temperature) to complete the sintering and obtain a durable superhydrophobic PFA coating.

[0061] An embodiment of the present invention also provides a durable superhydrophobic PFA coating prepared according to the above preparation method, wherein the thickness is preferably 40 μm.

[0062] The durable superhydrophobic PFA coating prepared by this invention has a high static contact angle, which significantly enhances the bouncing performance of surface droplets and effectively suppresses droplet adhesion in low-temperature environments. It can be used in the field of anti-icing of metal surfaces.

[0063] Embodiments of the present invention also provide an application of the above-mentioned durable superhydrophobic PFA coating in the field of low-temperature anti-icing, where the low temperature is ≤0℃, preferably ≤-5℃.

[0064] Embodiments of the present invention also provide an application of the above-mentioned durable superhydrophobic PFA coating in high-speed rail conductor rails in low-temperature environments, wherein the low temperature is ≤0℃, preferably ≤-5℃.

[0065] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0066] All raw materials used in the examples were purchased commercially. For example, hydrophobic nano-silica particles with a particle size of 500 nm were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., model S433669; hydrophobic nano-silica particles with a particle size of 7~40 nm were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., model S433683; high-purity hydroxylated multi-walled carbon nanotubes were purchased from Suzhou Carbon-rich Graphene Technology Co., Ltd., model TF-24621, with a purity of 95% and a length of 5~30 μm; PFA powder was purchased from Shanghai Huifei Chemical Co., Ltd., model 532G-5011, which was dispersed in N-methylpyrrolidine solvent at a mass fraction of 26 wt%, and 2 wt% carbon black particles were added to obtain PFA coating.

[0067] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0068] The technical solution of the present invention will be further illustrated by the following embodiments.

[0069] Example 1 A method for preparing a durable superhydrophobic PFA coating, comprising the following steps: (1) After the high-purity copper sheet with a size of 20×20×2 mm (purity of 99.999%, the same below) is pretreated by sandblasting (the sand in the sandblasting pretreatment is 100-mesh white corundum, and the sandblasting pressure is 0.7 MPa), it is ultrasonically cleaned in isopropanol, anhydrous ethanol and deionized water for 5 min, and then dried for later use.

[0070] (2) Take 5 mL of N-methylpyrrolidone as a solvent, use acetic acid to control the pH of the solvent to 4, add 0.7 g of hydrophobic nano silica particles with a particle size of 500 nm, 0.1 g of hydrophobic nano silica particles with a particle size of 7~40 nm, 0.02 g of high-purity hydroxylated multi-walled carbon nanotubes with a length of 5~30 μm, 0.2 g of silane coupling agent γ-aminopropyltriethoxysilane and 0.4 g of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, and stir to mix evenly.

[0071] (3) Place the mixture obtained in step (2) in an ultrasonic disperser and ultrasonically disperse for 30 min (power is 120 W, frequency is 20 kHz, and the ultrasonic operation is set to work for 2 s and stop for 2 s cycle, and the upper limit of temperature is set to 50 ℃). Then place it in a water bath and keep it at 50 ℃ for 30 min with magnetic stirring (speed is 600 rpm). Then add 11.67 g of PFA coating to the obtained mixture and keep it in a 50 ℃ constant temperature water bath environment. Stir for 30 min first and then let it stand for 30 min.

[0072] (4) The mixture obtained in step (3) is sprayed onto the copper sheet and CTMH-150 sliding contact line obtained in step (1) in one step using compressed air. The spraying pressure is 0.5 MPa, the spraying time is 8 s, and the spraying distance is 45 cm to obtain a relatively uniform coating with a thickness of 40 μm. The sprayed sample is placed in a tube furnace and nitrogen is introduced as a protective gas. The sintering is completed using a stepped heating program (first, the temperature is increased from room temperature to 150 ℃ at a rate of 2℃ / min and held for 30 min, then increased to 350 ℃ at a rate of 2℃ / min and held for 30 min, and finally cooled naturally with the furnace temperature) to obtain a durable superhydrophobic PFA coating. In this embodiment, the overall mass concentration of nanoparticles in the coating is 7.5%.

[0073] Example 2 Same as Example 1, except that the pure copper sheet is replaced with a 5 cm long CTMH-150 high-speed rail conductor rail.

[0074] Example 3 A method for preparing a durable superhydrophobic PFA coating with low nanoparticle content is disclosed. This comparative example differs from Example 1 in that the overall nanoparticle content is altered. The specific steps are as follows: (1) After sandblasting pretreatment (same as in Example 1), the high-purity copper sheet with a size of 20×20×2 mm was ultrasonically cleaned in isopropanol, anhydrous ethanol and deionized water for 5 min respectively, and then dried for later use.

[0075] (2) Take 5 mL of N-methylpyrrolidone as a solvent, use acetic acid to control the pH of the solvent to 4, and add 0.233 g of hydrophobic nano silica particles with a particle size of 500 nm, 0.033 g of hydrophobic nano silica particles with a particle size of 7~40 nm, 0.006 g of high-purity hydroxylated multi-walled carbon nanotubes with a length of 5~30 μm, 0.066 g of silane coupling agent γ-aminopropyltriethoxysilane and 0.133 g of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, and stir to mix evenly.

[0076] (3) Place the mixture obtained in step (2) in an ultrasonic disperser and ultrasonically disperse for 30 min (power is 120 W, frequency is 20 kHz, and the ultrasonic operation is set to work for 2 s and stop for 2 s cycle, and the upper limit of temperature is set to 50 ℃). Then place it in a water bath and keep it at 50 ℃ for 30 min with magnetic stirring (speed is 600 rpm). Then add 11.67 g of PFA coating with added carbon black particles to the obtained mixture, and then keep it in a 50 ℃ constant temperature water bath environment, stir for 30 min first, and then let it stand for 30 min.

[0077] (4) The mixture obtained in step (3) was sprayed onto the copper sheet and CTMH-150 sliding contact line obtained in step (1) in one step using compressed air (the spraying process is the same as in Example 1). The sprayed sample was placed in a tube furnace, nitrogen was introduced as a protective gas, and sintering was completed using a stepped heating program (the stepped heating program is the same as in Example 1) to obtain a PFA coating. In this comparative example, the overall mass concentration of nanoparticles in the coating was 2.5%.

[0078] Example 4 A method for preparing a durable superhydrophobic PFA coating with high nanoparticle content is disclosed. This comparative example differs from Example 1 in that the overall nanoparticle content is altered. The specific steps are as follows: (1) After sandblasting pretreatment (same as in Example 1), the high-purity copper sheet with a size of 20×20×2 mm was ultrasonically cleaned in isopropanol, anhydrous ethanol and deionized water for 5 min respectively, and then dried for later use.

[0079] (2) Take 5 mL of N-methylpyrrolidone as a solvent, use acetic acid to control the pH of the solvent to 4, add 1.4 g of hydrophobic nano silica particles with a particle size of 500 nm, 0.2 g of hydrophobic nano silica particles with a particle size of 7~40 nm, 0.04 g of high-purity hydroxylated multi-walled carbon nanotubes with a length of 5-30 μm, 0.4 g of silane coupling agent γ-aminopropyltriethoxysilane and 0.8 g of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, and stir to mix evenly.

[0080] (3) Place the mixture obtained in step (2) in an ultrasonic disperser and ultrasonically disperse for 30 min (power is 120 W, frequency is 20 kHz, and the ultrasonic operation is set to work for 2 s and stop for 2 s cycle, and the upper limit of temperature is set to 50 ℃). Then place it in a water bath and keep it at 50 ℃ for 30 min with magnetic stirring (speed is 600 rpm). Then add 11.67 g of PFA coating with added carbon black particles to the obtained mixture, and then keep it in a 50 ℃ constant temperature water bath environment, stir for 30 min first, and then let it stand for 30 min.

[0081] (4) The mixture obtained in step (3) was sprayed onto the copper sheet and CTMH-150 sliding contact line obtained in step (1) in one step using compressed air (the spraying process is the same as in Example 1). The sprayed sample was placed in a tube furnace, nitrogen was introduced as a protective gas, and sintering was completed using a stepped heating program (the stepped heating program is the same as in Example 1) to obtain a PFA coating. In this comparative example, the overall mass concentration of nanoparticles in the coating was 15%.

[0082] Comparative Example 1 A method for preparing a PFA coating with high nanoparticle content is disclosed. This comparative example differs from Example 1 in that the overall nanoparticle content is altered. The specific steps are as follows: (1) After sandblasting pretreatment (same as in Example 1), the high-purity copper sheet with a size of 20×20×2 mm was ultrasonically cleaned in isopropanol, anhydrous ethanol and deionized water for 5 min respectively, and then dried for later use.

[0083] (2) Take 5 mL of N-methylpyrrolidone as a solvent, use acetic acid to control the pH of the solvent to 4, add 2.1 g of hydrophobic nano silica particles with a particle size of 500 nm, 0.3 g of hydrophobic nano silica particles with a particle size of 7~40 nm, 0.06 g of high-purity hydroxylated multi-walled carbon nanotubes with a length of 5~30 μm, 0.6 g of silane coupling agent γ-aminopropyltriethoxysilane and 1.2 g of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, and stir to mix evenly.

[0084] (3) Place the mixture obtained in step (2) in an ultrasonic disperser and ultrasonically disperse for 30 min (power is 120 W, frequency is 20 kHz, and the ultrasonic operation is set to work for 2 s and stop for 2 s cycle, and the upper limit of temperature is set to 50 ℃). Then place it in a water bath and keep it at 50 ℃ for 30 min with magnetic stirring (speed is 600 rpm). Then add 11.67 g of PFA coating with added carbon black particles to the obtained mixture, and then keep it in a 50 ℃ constant temperature water bath environment, stir for 30 min first, and then let it stand for 30 min.

[0085] (4) The mixture obtained in step (3) was sprayed onto the copper sheet and CTMH-150 sliding contact line obtained in step (1) in one step using compressed air (the spraying process is the same as in Example 1). The sprayed sample was placed in a tube furnace, nitrogen was introduced as a protective gas, and sintering was completed using a stepped heating program (the stepped heating program is the same as in Example 1) to obtain a PFA coating. In this comparative example, the overall mass concentration of nanoparticles in the coating was 22.5%.

[0086] Comparative Example 2 A method for preparing a PFA coating containing nanoparticle fillers. This comparative example differs from Example 1 in that it does not include the silane coupling agent γ-aminopropyltriethoxysilane. The specific steps are as follows: (1) After sandblasting pretreatment (same as in Example 1), the high-purity copper sheet with a size of 20×20×2 mm was ultrasonically cleaned in isopropanol, anhydrous ethanol and deionized water for 5 min respectively, and then dried for later use.

[0087] (2) Take 5 mL of N-methylpyrrolidone as a solvent, add 0.7 g of hydrophobic nano silica particles with a particle size of 500 nm, 0.1 g of hydrophobic nano silica particles with a particle size of 7~40 nm, 0.02 g of high-purity hydroxylated multi-walled carbon nanotubes and 0.4 g of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, and stir to mix evenly.

[0088] (3) Place the mixture obtained in step (2) in an ultrasonic disperser and ultrasonically disperse for 30 min (power is 120 W, frequency is 20 kHz, and the ultrasonic operation is set to work for 2 s and stop for 2 s cycle, and the upper limit of temperature is set to 50 ℃). Then place it in a water bath and keep it at 50 ℃ for 30 min with magnetic stirring (speed is 600 rpm). Then add 11.67 g of PFA coating with added carbon black particles to the obtained mixture, and then keep it in a 50 ℃ constant temperature water bath environment, stir for 30 min first, and then let it stand for 30 min.

[0089] (4) The mixture obtained in step (3) is sprayed onto the surface of the copper sheet and CTMH-150 sliding contact line sample obtained in step (1) using compressed air in one step (the spraying process is the same as in Example 1). The sprayed sample is placed in a tube furnace, nitrogen is introduced as a protective gas, and sintering is completed using a stepped heating program (the specific process is the same as in Example 1) to obtain the PFA coating.

[0090] Comparative Example 3 Similar to Comparative Example 2, the only difference is that the high-purity copper sheet is replaced with a 5 cm long CTMH-150 high-speed rail conductor rail.

[0091] Comparative Example 4 This comparative example is a copper sheet obtained only through sandblasting pretreatment and cleaning pretreatment. The specific process is as follows: a high-purity copper sheet with a size of 20×20×2 mm is sandblasted (the sand in the sandblasting pretreatment is 100-mesh white corundum, and the sandblasting pressure is 0.7 MPa), and then ultrasonically cleaned in isopropanol, anhydrous ethanol and deionized water for 5 min respectively, and then dried.

[0092] Comparative Example 5 This comparative example is a CTMH-150 high-speed rail conductor rail obtained only through sandblasting pretreatment and cleaning pretreatment. The specific process is as follows: after sandblasting pretreatment (the sand in the sandblasting pretreatment is 100-mesh white corundum, and the sandblasting pressure is 0.7 MPa), the 5 cm long CTMH-150 high-speed rail conductor rail is ultrasonically cleaned in isopropanol, anhydrous ethanol and deionized water for 5 min respectively, and then dried.

[0093] Comparative Example 6 A high-purity copper sheet with dimensions of 20×20×2 mm was pretreated by sandblasting (the sand used in the sandblasting pretreatment was 100-mesh white corundum, and the sandblasting pressure was 0.7 MPa). It was then ultrasonically cleaned for 5 min in isopropanol, anhydrous ethanol, and deionized water, respectively, and dried. PFA coating was sprayed onto the surface of the copper sheet after the above treatment using compressed air (the spraying process was the same as in Example 1). The coated sample was placed in a tube furnace, nitrogen was introduced as a protective gas, and sintering was carried out using a stepped heating program (same as in Example 1) to obtain the coating, which is the pure PFA coating with copper sheet as the substrate obtained in this comparative example.

[0094] Comparative Example 7 A method for preparing a PFA coating containing nanoparticle fillers. This comparative example differs from Example 1 in that it does not include the addition of fluorosilane 1H,1H,2H,2H-perfluorodecyltriethoxysilane. The specific steps are as follows: (1) After sandblasting pretreatment (same as in Example 1), the high-purity copper sheet with a size of 20×20×2 mm was ultrasonically cleaned in isopropanol, anhydrous ethanol and deionized water for 5 min respectively, and then dried for later use.

[0095] (2) Take 5 mL of N-methylpyrrolidone as a solvent, add 0.7 g of hydrophobic nano silica particles with a particle size of 500 nm, 0.1 g of hydrophobic nano silica particles with a particle size of 7~40 nm, 0.02 g of high-purity hydroxylated multi-walled carbon nanotubes and 0.2 g of silane coupling agent γ-aminopropyltriethoxysilane, and stir to mix evenly.

[0096] (3) Place the mixture obtained in step (2) in an ultrasonic disperser and ultrasonically disperse for 30 min (power is 120 W, frequency is 20 kHz, and the ultrasonic operation is set to work for 2 s and stop for 2 s cycle, and the upper limit of temperature is set to 50 ℃). Then place it in a water bath and keep it at 50 ℃ for 30 min with magnetic stirring (speed is 600 rpm). Then add 11.67 g of PFA coating with added carbon black particles to the obtained mixture, and then keep it in a 50 ℃ constant temperature water bath environment, stir for 30 min first, and then let it stand for 30 min.

[0097] (4) The mixture obtained in step (3) is sprayed onto the surface of the copper sheet and CTMH-150 sliding contact line sample obtained in step (1) using compressed air in one step (the spraying process is the same as in Example 1). The sprayed sample is placed in a tube furnace, nitrogen is introduced as a protective gas, and sintering is completed using a stepped heating program (the specific process is the same as in Example 1) to obtain the PFA coating.

[0098] Technical effects: 1. Surface morphology analysis Figure 2 The basic morphology and wettability characterization of the surfaces prepared in Examples 1, 2, 3, 4, Comparative Examples 1, 2, 4, 6, and 7 are shown below. (a) corresponds to the sandblasted copper surface prepared in Example 4, (b) corresponds to the simple PFA coating surface prepared in Example 6, (c) corresponds to the PFA coating surface without KH550 prepared in Example 2, (d) corresponds to the PFA coating surface without FAS-17 prepared in Example 7, (e) corresponds to the durable superhydrophobic PFA coating surface with low nanoparticle content prepared in Example 3, (f) corresponds to the durable superhydrophobic PFA coating surface prepared in Example 1, (g) corresponds to the durable superhydrophobic PFA coating surface prepared on the high-speed rail conductor in Example 2, (h) corresponds to the durable superhydrophobic PFA coating surface with high nanoparticle content prepared in Example 4, and (i) corresponds to the PFA coating surface with high nanoparticle content prepared in Example 1. The top left corner of each small image shows the macroscopic morphology, and the bottom corner shows the microscope image (magnification 100). Figure 2 As can be seen, the sandblasted copper surface prepared in Comparative Example 4 is covered with a large number of micron-sized pits and protrusions formed by impacts, which enhances the interlocking force between the coating and the surface. The simple PFA surface prepared in Comparative Example 6 is covered with a dense fluorocarbon coating, exhibiting a relatively rough morphology and containing tens of micron-sized pits and nanopores, but the overall micro-nano structure is sparse and cannot effectively form an "air cushion structure". The surface roughness of the superhydrophobic PFA coatings prepared in Comparative Examples 2 and 7 is improved to a certain extent, but their structure is mainly composed of high-depth pores. The durable superhydrophobic PFA coatings prepared in Examples 3, 1, 2, and 4 have more complex and uniformly distributed micro-nano structures, and the roughness and structural uniformity are significantly improved. The high nanoparticle content PFA coating prepared in Comparative Example 1 is similar to the coating surface prepared in Example 1, but it has more deep pit structures that extend directly to the metal substrate surface, which may lead to a more serious particle shedding problem.

[0099] 2. Wettability Analysis Figure 2The basic morphology and wettability characterization of the surfaces prepared in Examples 1, 3, 4, Comparative Examples 1, 2, 4, 6, and 7 are shown below. (a) corresponds to the sandblasted copper surface prepared in Example 4, (b) corresponds to the simple PFA coating surface prepared in Example 6, (c) corresponds to the PFA coating surface without KH550 prepared in Example 2, (d) corresponds to the PFA coating surface without FAS-17 prepared in Example 7, (e) corresponds to the durable superhydrophobic PFA coating surface with low nanoparticle content prepared in Example 3, (f) corresponds to the durable superhydrophobic PFA coating surface prepared in Example 1, (g) corresponds to the durable superhydrophobic PFA coating surface prepared on the high-speed rail conductor rail in Example 2, (h) corresponds to the durable superhydrophobic PFA coating surface with high nanoparticle content prepared in Example 4, and (i) corresponds to the PFA coating surface with high nanoparticle content prepared in Example 1. The upper right corner of each small image represents the static contact angle. It can be seen that the static contact angle of the sandblasted copper surface prepared in Comparative Example 4 is low, with no obvious hydrophobic properties. The static contact angle of the pure PFA surface prepared in Comparative Example 6 has increased to some extent, but still does not meet the superhydrophobic requirements. The contact angles of the superhydrophobic PFA coatings prepared in Comparative Examples 2 and 7 are around 150°, showing a certain improvement in hydrophobic properties. The durable superhydrophobic PFAs prepared in Examples 1, 2, 3, and 4 all exceed 150° to a large extent, with the surface contact angle prepared in Example 1 reaching over 156°, meeting the superhydrophobic requirements. The superhydrophobic PFA coating surface prepared in Comparative Example 1 has a slightly larger contact angle than 150°, indicating better hydrophobic properties.

[0100] 3. Analysis of Droplet Dynamics on Copper Sheet Surface Test Method: A layer of UD7960 thermal grease (purchased from Shenzhen Youdao New Materials Technology Co., Ltd.) with a thermal conductivity of 6 W / m·K was applied to the bottom surface of the following samples: a sandblasted copper sheet prepared in Comparative Example 4; a simple PFA coating prepared in Comparative Example 6; a PFA coating without KH550 prepared in Comparative Example 2; a PFA coating without FAS-17 prepared in Comparative Example 7; a durable superhydrophobic PFA coating with low nanoparticle content prepared in Example 3; a copper sheet with a durable superhydrophobic PFA coating prepared in Example 1; a durable superhydrophobic PFA coating with high nanoparticle content prepared in Example 4; and a copper sheet with a high nanoparticle content PFA coating prepared in Comparative Example 1. All samples were placed on a Peltier cooling stage. A protective cover was placed on the cooling stage, and high-purity nitrogen gas was introduced into the test environment to reduce the influence of residual water vapor on droplet impact behavior (in the -5℃ experiment, after the surface of the cooling stage was lowered to the specified temperature, it was maintained for 30 min to ensure stable ambient temperature and humidity).

[0101] A portion of deionized water was pre-stored in the syringe (more deionized water ice was added in the -5℃ experiment to keep the temperature near zero), and the needle was positioned directly over the center of the sample surface. The needle was raised to 10 cm from the surface, and a 4 μL droplet (a deionized water droplet) was dropped through a hole in the protective cover to impact the sample surface. A high-speed camera was used to record visual data of the droplet's spread, retraction, and bounce after impact at a rate of 5000 frames per second. Emphasis was placed on recording whether any residue remained on the surface after the droplet bounced off.

[0102] Figure 3 , Figure 4 The corresponding ambient temperatures are 20℃ and -5℃, respectively.

[0103] Figure 3 The dynamic evolution process of droplet bouncing and detachment upon impact on the copper sheet surface of Comparative Examples 1, 2, 4, 6, 7, 1, 3, and 4 in a 20℃ environment is shown in (a)-(h), corresponding to the dynamic evolution process of droplet spreading and retraction upon impact on the copper sheet surface of Comparative Examples 4, 6, 2, 7, 1, 3, 4, and 1, respectively. Compared with the sandblasted copper surface prepared in Comparative Example 4, the simple PFA surface prepared in Comparative Example 6, the PFA coating surface with high nanoparticle content prepared in Comparative Example 1, the PFA coating surface without KH550 prepared in Comparative Example 2, the PFA coating surface without FAS-17 prepared in Comparative Example 7, the durable superhydrophobic PFA surface prepared in Example 1, the durable superhydrophobic PFA coating with low nanoparticle content prepared in Example 3, and the durable superhydrophobic PFA coating with high nanoparticle content prepared in Example 4 all exhibit complete droplet bouncing and detachment without any droplet residue.

[0104] Figure 4The dynamic evolution process of droplet bounce and detachment upon impact on the copper sheet surface of Comparative Examples 1, 2, 4, 6, 7, 1, 3, and 4 in a -5℃ low-temperature environment is shown in (a)-(h), corresponding to the dynamic evolution process of droplet spread and retraction upon impact on the copper sheet surface of Comparative Examples 4, 6, 2, 7, 1, 3, 4, and 1, respectively. Compared with the sandblasted copper surface prepared in Comparative Example 4, the pure PFA surface prepared in Comparative Example 6, the PFA coating surface with high nanoparticle content prepared in Comparative Example 1, the PFA coating surface without KH550 prepared in Comparative Example 2, and the PFA coating without FAS-17 prepared in Comparative Example 7, the droplet bounce of the durable superhydrophobic PFA coating surface prepared in Example 1, the durable superhydrophobic PFA coating with low nanoparticle content prepared in Example 3, and the durable superhydrophobic PFA coating with high nanoparticle content prepared in Example 4 is more complete, with no residue remaining after bounce and detachment within 20 ms. The other five surfaces all had some degree of droplet residue.

[0105] 4. Analysis of the dynamic behavior of droplets on the surface of the sliding conductor line Test method: Similar to 3. Analysis of droplet dynamics on copper sheet surface, except that the metal sample is changed from copper sheet to CTMH-150 high-speed rail sliding contact line (that is, the samples of Comparative Example 2, Comparative Example 4, Comparative Example 7 and Example 1 are replaced with the samples of Comparative Example 3, Comparative Example 5, Comparative Example 8 and Example 2). Figures 5-8 The dynamic evolution of the droplet spreading and retraction at the top of the sliding contact line impacted by Comparative Examples 5, 3, 8, and 2 in a -5°C low-temperature environment was respectively compared. Figure 9-12 The dynamic evolution of droplet spread and retraction upon impact on the side of the sliding contact line in a -5 ℃ low-temperature environment was compared with that of Comparative Example 5, Comparative Example 3, Comparative Example 8, and Example 2. Compared with the sandblasted copper surface prepared in Comparative Example 5, the KH550-free hydrophobic PFA surface prepared in Comparative Example 3, and the FAS-17-free hydrophobic PFA coating prepared in Comparative Example 8, the durable superhydrophobic PFA surface prepared in Example 2 exhibited excellent enhanced bouncing effect on droplets impacting the top or side of the sliding contact line, allowing them to completely bounce off within 24 ms.

[0106] 4. Durability test of superhydrophobic PFA coating Test Method: Copper sheets with durable superhydrophobic PFA coatings prepared in Example 1, copper sheets with KH550-free PFA coatings prepared in Comparative Example 2, and copper sheets with FAS-17-free PFA coatings prepared in Comparative Example 7 were placed in a cold chamber and suspended using a hoist to ensure the bottom surface did not contact the chamber wall, preventing water accumulation from affecting the test. After maintaining the ambient temperature at -5 °C, 4 μL low-temperature droplets at 1–3 °C were continuously dripped onto the sample surface at a rate of 5 mL / min. After 4 hours of droplet impact, the samples were removed, dried, and the surface morphology and static contact angle of the samples before and after the test were characterized.

[0107] Figure 13 The surface morphology of the KH550-free hydrophobic PFA coating surface prepared in Comparative Example 2, the FAS-17-free superhydrophobic PFA coating surface prepared in Comparative Example 7, and the durable superhydrophobic PFA coating surface prepared in Example 1 before and after 4 h of low-temperature droplet impact in a -5 ℃ low-temperature environment are shown. (a) corresponds to Comparative Example 2, (b) corresponds to Comparative Example 7, and (c) corresponds to Example 1. Figure 14 The static contact angle changes of the superhydrophobic PFA coating surfaces prepared in Comparative Example 2 (KH550-free), Comparative Example 7 (FAS-17-free), and Example 1 (durable superhydrophobic PFA coating) prepared in a -5 ℃ low-temperature environment before and after 4 h of low-temperature droplet impact. After prolonged impact, the superhydrophobic PFA surfaces prepared in Comparative Examples 2 and 7 exhibited significant particle shedding, forming numerous crack structures extending to the metal substrate, and their hydrophobicity almost entirely decreased to below 150°. In contrast, the durable superhydrophobic PFA surface prepared in Example 1 showed no significant damage to its morphology; the corresponding 7.5 wt% particle concentration durable superhydrophobic PFA surface only experienced a decrease of about 1°, still meeting the superhydrophobic requirements.

[0108] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a durable superhydrophobic perfluoroalkoxy vinyl ether copolymer coating, characterized in that, In an acidic environment, nanoparticles are modified using silane coupling agents and fluorosilanes, and then ultrasonically dispersed. The resulting mixture is uniformly dispersed in a perfluoroalkoxy vinyl ether copolymer coating. The resulting solution is sprayed onto a metal substrate and sintered to obtain the durable superhydrophobic perfluoroalkoxy vinyl ether copolymer coating. The silane coupling agent is γ-aminopropyltriethoxysilane; The overall mass concentration of the nanoparticles in the durable superhydrophobic perfluoroalkoxy vinyl ether copolymer coating is 2.5wt%~15wt%.

2. The method for preparing the durable superhydrophobic perfluoroalkoxy vinyl ether copolymer coating according to claim 1, characterized in that, The nanoparticles are selected from hydrophobic silica nanoparticles and hydroxylated multi-walled carbon nanotubes.

3. The method for preparing the durable superhydrophobic perfluoroalkoxy vinyl ether copolymer coating according to claim 2, characterized in that, The hydrophobic nano-silica particles are hydrophobic nano-silica particles with a particle size of 100~500nm and hydrophobic nano-silica particles with a particle size of 7~40nm.

4. The method for preparing the durable superhydrophobic perfluoroalkoxy vinyl ether copolymer coating according to claim 1, characterized in that, The fluorosilane is 1H,1H,2H,2H-perfluorodecyltriethoxysilane.

5. The method for preparing the durable superhydrophobic perfluoroalkoxy vinyl ether copolymer coating according to claim 1, characterized in that, When performing ultrasonic dispersion, the ultrasonic power is 120 W, the ultrasonic frequency is 20~25 kHz, and the upper temperature limit is set to 50 ℃.

6. The method for preparing the durable superhydrophobic perfluoroalkoxy vinyl ether copolymer coating according to claim 1, characterized in that, The metal substrate is selected from copper alloys, copper, or stainless steel.

7. The method for preparing the durable superhydrophobic perfluoroalkoxy vinyl ether copolymer coating according to claim 1, characterized in that, Sintering is carried out using a stepped heating program. The specific steps are as follows: first, the temperature is raised from room temperature to 150 ℃ and held for 30 min, then the temperature is raised to 350 ℃ and held for 30 min, and finally the temperature is allowed to cool naturally with the furnace temperature.

8. A durable, superhydrophobic perfluoroalkoxy vinyl ether copolymer coating, characterized in that, It is prepared according to any one of claims 1 to 7.

9. The application of the durable superhydrophobic perfluoroalkoxy vinyl ether copolymer coating as described in claim 8 in the field of low-temperature anti-icing, characterized in that, The low temperature is ≤0℃.

10. The application of the durable superhydrophobic perfluoroalkoxy vinyl ether copolymer coating as described in claim 8 in high-speed rail conductor rails under low-temperature environments, characterized in that... The low temperature is ≤0℃.

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