Directional bouncing anti-icing surface based on asymmetric super-hydrophobic structure and preparation method thereof

Abstract

The invention discloses a directional bouncing anti-icing surface based on an asymmetric super-hydrophobic structure and a preparation method of the directional bouncing anti-icing surface, and belongs to the technical field of functional material surfaces and anti-icing. The directional bouncing anti-icing surface based on the asymmetric super-hydrophobic structure comprises an asymmetric structure array with a specific shape and a low-surface-energy coating covering the surface of the asymmetric structure array. The asymmetric structure array is composed of a plurality of micron-scale or millimeter-scale columnar structure units, the top ends of the columnar structure units are provided with asymmetric inclined geometric surfaces, and the asymmetric inclined geometric surfaces of the top ends of the columnar structure units have the same inclination direction; a micro-nano composite coarse structure is constructed on the surface of the columnar structure unit, and the surface of the columnar structure unit is modified with the low-surface-energy coating, so that the whole directional bouncing anti-icing surface based on the asymmetric super-hydrophobic structure has the super-hydrophobic characteristic. According to the invention, an active directional anti-icing mechanism is realized.

Description

Technical Field

[0001] This invention belongs to the field of functional material surface and anti-icing technology, specifically relating to a directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure and its preparation method. Background Technology

[0002] Surface icing is a common problem jeopardizing several key sectors. In aerospace, icing on wings or sensors (such as pitot tubes) disrupts aerodynamic shape, leading to lift loss and control failure, and has historically been a key factor in flight accidents. In power transmission and distribution and new energy sectors, icing on transmission lines can cause tower collapses and large-scale power outages; icing on wind turbine blades drastically reduces aerodynamic efficiency, resulting in power generation losses of up to 50%. In cryogenic refrigeration and heat exchange, evaporator frosting reduces heat transfer efficiency by 50%-75%, significantly increasing energy consumption.

[0003] Current mainstream anti-icing and de-icing technologies in engineering applications (such as electrothermal melting, spraying anti-icing fluid, and mechanical de-icing) are active strategies, generally suffering from drawbacks such as high energy consumption, low efficiency, reliance on complex systems, or environmental impact. Passive anti-icing technology aims to physically inhibit ice crystal nucleation and adhesion through special surface design of materials, offering advantages in energy conservation and environmental protection. Inspired by nature, biomimetic superhydrophobic surfaces have attracted widespread attention as a low-energy passive anti-icing strategy. Its basic principle is to construct micro-nano rough structures and modify them with low surface energy materials to form a stable air cushion (Cassie-Baxter state) at the solid-liquid interface, thereby significantly reducing the actual contact area, delaying heat transfer, increasing the energy barrier for ice nucleation, and ultimately achieving delayed icing and reduced ice adhesion strength.

[0004] Studies have shown that superhydrophobic surfaces with specific micron-scale structures (such as columnar and conical shapes) can effectively prolong freezing time. More importantly, when droplets collide with such surfaces, they may undergo a "pancake-like bounce," shortening the solid-liquid contact time to the millisecond level, theoretically shorter than the nucleation time of supercooled droplets. This provides a crucial opportunity to prevent droplet freezing. However, the anti-icing effectiveness of existing superhydrophobic surfaces has fundamental limitations: firstly, the bounce direction of droplets is completely random, and droplets that bounce off are very likely to fall back onto the original surface or merge with other droplets, thus lingering in local areas and creating opportunities for ice nucleation; secondly, on horizontal or slightly inclined surfaces, droplet removal heavily relies on gravity, resulting in low efficiency. Therefore, how to actively control the bounce direction of droplets to enable them to detach from the surface quickly and directionally is the core challenge to overcome the bottleneck of existing passive anti-icing technologies and achieve source control. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing superhydrophobic surfaces, such as random droplet removal direction and low efficiency, and to provide a directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure and its preparation method. This directional bouncing anti-icing surface can induce droplets to bounce or deflect rapidly, thereby greatly reducing the residence time and collision probability of droplets on low-temperature surfaces, and realizing an upgrade of the anti-icing mechanism from "delaying icing" to "actively preventing droplet retention".

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

[0007] A directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure, comprising an array of asymmetric structures with a specific morphology and a low surface energy coating covering the surface of the asymmetric structure array.

[0008] The asymmetric structure array is composed of multiple micrometer- or millimeter-scale columnar structural units. The top of each columnar structural unit has an asymmetric inclined geometric surface, and the asymmetric inclined geometric surface at the top of each columnar structural unit has a consistent inclined direction. The surface of each columnar structural unit is constructed with a micro-nano composite rough structure, and the surface of each columnar structural unit is modified with the low surface energy coating, so that the directional bouncing anti-icing surface based on the asymmetric superhydrophobic structure has superhydrophobic properties as a whole.

[0009] The asymmetry of the structural array, the micro-nano composite rough structure of the columnar structural units, and the low surface energy coating work together to generate an asymmetric interfacial force and Laplace pressure difference when the directional bouncing anti-icing surface based on the asymmetric superhydrophobic structure comes into contact with the droplet, thereby driving the droplet to bounce away from the directional bouncing anti-icing surface based on the asymmetric superhydrophobic structure in a directional manner and at high speed.

[0010] The tilt angle of the asymmetric tilted geometric surface at the top of the columnar structural unit is between 1° and 89°.

[0011] The spacing between adjacent columnar structural units is 0.5 to 10 times the characteristic dimension of the cross-section.

[0012] The columnar structural unit has a cross-sectional characteristic dimension of 5μm to 2mm and a height of 10μm to 5mm.

[0013] The micro-nano composite rough structure is formed in situ on the surface of the columnar structural unit by cleaning the photocurable resin constituting the columnar structural unit with organic solvent and then performing UV post-curing treatment.

[0014] The low surface energy coating is selected from any one of the following: (a) an organic-inorganic hybrid coating formed by blending polydimethylsiloxane with hydrophobic silica nanoparticles; (b) a silica nanoparticle layer formed by dispersing hydrophobic silica nanoparticles in an ethanol solution, followed by spraying and drying; and (c) a fluorosilane monolayer formed by chemical vapor deposition or solution self-assembly.

[0015] The above-mentioned method for preparing a directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure includes the following steps:

[0016] S1: Using surface projection photopolymerization additive manufacturing technology, asymmetric initial structure array is obtained by curing photopolymer resin layer by layer.

[0017] S2: The asymmetric initial structure array obtained in step S1 is cleaned with an organic solvent to dissolve and remove the resin that is not fully cured on the surface, and at the same time roughen the surface. Then, UV post-curing treatment is performed to form the micro-nano composite rough structure on the structure surface to obtain the asymmetric structure array.

[0018] S3: Prepare a low surface energy coating on the surface of the asymmetric structure array obtained in step S2, and perform a thermal curing treatment on the coating to obtain the directional bouncing anti-icing surface based on the asymmetric superhydrophobic structure.

[0019] In step S1, the process parameters for surface projection photopolymerization additive manufacturing include: exposure light intensity per unit area of ​​1-100 mW / cm². 2 The single-layer exposure time ranges from 0.5 seconds to 30 seconds, and the printing layer thickness ranges from 10 μm to 500 μm.

[0020] In step S2, the organic solvent used for cleaning is ethanol, isopropanol, or acetone; the cleaning method in step S2 includes immersion cleaning or ultrasonic-assisted cleaning, and the cleaning time is 1 to 30 minutes; the UV post-curing treatment time in step S2 is 1 to 60 minutes.

[0021] Specifically, the coating thermosetting treatment in step S3 involves heating at 30°C to 100°C for 10 to 120 minutes.

[0022] The aforementioned directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure is used for anti-icing and enhanced heat transfer in low-temperature finned heat exchangers, aerospace equipment, wind turbine blades, or power transmission equipment.

[0023] The beneficial effects of this invention are as follows:

[0024] (1) The directional bouncing anti-icing surface based on the asymmetric superhydrophobic structure of the present invention realizes an active directional anti-icing mechanism: through the asymmetric structure design, the traditional random bouncing or gravity-dependent rolling is transformed into predictable and designable directional rapid bouncing, which greatly shortens the residence time of droplets on the low temperature surface and fundamentally inhibits the formation and growth of ice nuclei.

[0025] (2) The method for preparing the directional bouncing anti-icing surface based on the asymmetric superhydrophobic structure of the present invention has both structural flexibility and performance designability: the preparation method combines the structural design freedom of additive manufacturing with the flexibility of surface chemical modification. By adjusting the printing parameters, structural morphology and coating formulation, the surface anti-icing performance can be precisely controlled, and it is suitable for different material substrates and complex curved surfaces.

[0026] (3) The anti-icing performance of the directional bouncing anti-icing surface based on the asymmetric superhydrophobic structure of the present invention is significant and widely applicable: the surface can maintain the directional bouncing function for a long time at low temperature, which can significantly delay or even prevent icing, providing an efficient passive anti-icing solution for equipment that is prone to icing, such as aircraft wings, wind turbine blades, and high-voltage transmission lines. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure and a schematic diagram of the directional bouncing of droplets of the present invention.

[0028] Figure 2 The image shows a comparison of the static contact angles (CA) of different surfaces prepared in Examples 1, 2, and the comparative example.

[0029] Figure 3 The figures show the droplet bouncing timing of different surfaces prepared in Examples 1 to 4 and the comparative example. Figure 3 (a) in the diagram is a timing diagram of droplet bouncing of the sample prepared in the comparative example; Figure 3 (b) in the figure is a droplet bouncing timing diagram of the sample prepared in Example 2. Figure 3 (c) in the figure is a timing diagram of droplet bouncing of the sample prepared in Example 1.

[0030] Figure 4 The droplet bouncing time data of the directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure prepared in Example 1 under different low temperature conditions is shown in the figure.

[0031] Figure 5 The icing delay time series diagram of the directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure prepared in Example 1 under low temperature conditions. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0033] See Figure 1 The present invention provides a directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure, which includes an array of asymmetric structures and a low surface energy coating covering its surface.

[0034] The asymmetric structure array in this embodiment consists of multiple micrometer- or millimeter-scale columnar structural units. Each columnar structural unit has an asymmetric inclined geometric surface at its top, with the inclination angle ranging from 1° to 89°. The asymmetric inclined geometric surfaces at the top of the columnar structural units have a consistent inclination direction, and the inclination angles can be the same or different. The spacing between adjacent columnar structural units is 0.5 to 10 times the cross-sectional characteristic dimension (5μm to 2mm) of the columnar structural unit, and the height of the columnar structural unit is 10μm to 5mm.

[0035] The columnar structural unit is manufactured by additive manufacturing from photocurable resin. Its surface is cleaned with organic solvent and post-cured under ultraviolet light to form a submicron or nano-scale micro-nano composite rough structure in situ. A low surface energy coating is applied to the surface of this micro-nano composite rough structure.

[0036] The low surface energy coating is selected from any of the following:

[0037] (a) An organic-inorganic hybrid coating formed by blending polydimethylsiloxane (PDMS) with hydrophobic silica nanoparticles;

[0038] (b) A nanoparticle layer formed by spraying an ethanol dispersion of hydrophobic silica nanoparticles;

[0039] (c) Fluorosilane monolayers formed by vapor deposition or solution methods.

[0040] This low surface energy coating, together with the micro-nano composite rough structure, constitutes a robust micro-nano composite superhydrophobic system with a water contact angle greater than 150° and a roll-off angle less than 10°.

[0041] The synergistic effect of the asymmetric inclined geometric surface at the top of the columnar structural unit in this invention (the asymmetry of the structural array), the micro-nano composite rough structure, and the low surface energy coating generates an asymmetric capillary force and Laplace pressure difference at the solid-liquid-gas three-phase contact line of the droplet when the droplet contacts the directional bouncing anti-icing surface of this invention. This forms a significant wettability gradient, thereby converting the surface energy of the droplet into the kinetic energy of directional motion, driving the droplet to bounce rapidly and directionally along a predetermined direction determined by the inclined surface of the structure, and finally completely detaching from the surface.

[0042] This invention also provides a method for preparing the above-mentioned directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure, comprising the following steps:

[0043] 1. Structure Printing: Using surface projection photopolymerization (DLP or LCD) additive manufacturing technology, the asymmetric initial structure array is formed layer by layer by photocurable resin. During printing, the exposure light intensity per unit area is controlled between 1-100 mW / cm². 2 The single-layer exposure time is 0.5-30 seconds.

[0044] 2. Post-treatment and roughening: The printed asymmetric initial structure array is immersed in an organic solvent (such as ethanol or isopropanol) for ultrasonic cleaning for 1-30 minutes to dissolve the incompletely cured resin on the surface and roughen the structure surface in situ. Subsequently, UV post-curing (wavelength 365-405 nm, time 1-60 minutes) is performed to further improve the cross-linking degree and mechanical strength of the structure and stabilize its micro-nano composite rough morphology.

[0045] 3. Superhydrophobic modification: A low surface energy coating (superhydrophobic coating) is prepared on the post-treated structural surface by means of spraying or other methods.

[0046] 4. Coating curing: Place the sample with the low surface energy coating in an oven and heat at 30-100℃ for 10-120 minutes to allow the low surface energy coating to fully cure and bond firmly to the substrate.

[0047] Example 1

[0048] A method for preparing a directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure, specifically including the following steps:

[0049] 1. Structural Design and Printing: An asymmetric structural array was designed using 3D modeling software. The unit design features a 45° tilt angle on one side at the top, a cross-sectional diameter (D) of 300 µm, a height (H) of 900 µm, and a center-to-center distance (P) of 450 µm between adjacent units (i.e., P / D = 1.5). The model was imported into an LCD UV-curing printer using rigid UV-curing resin, with the exposure intensity set to 2.6 mW / cm². 2The single-layer exposure time is 2 seconds, the printing layer thickness is 50 µm, and the printing is performed layer by layer to obtain the printed part. The overall three-dimensional morphology of the resulting structure array is as follows: Figure 1 As shown.

[0050] 2. Post-processing and roughening: Immerse the printed parts in anhydrous ethanol and ultrasonically clean for 10 minutes. After removal, dry with nitrogen gas and cure under ultraviolet light at a wavelength of 405 nm for 30 minutes to form a stable micro-nano composite rough structure on the surface, resulting in an asymmetric structure array.

[0051] 3. Coating Modification: Polydimethylsiloxane (PDMS, Dow Corning SYLGARD 184) prepolymer and curing agent were mixed at a mass ratio of 10:1. Hydrophobic silica nanoparticles (Degussa, R202, average particle size 14 nm) were added at 20% by mass of PDMS. After dilution with n-hexane, the mixture was magnetically stirred for 2 hours to form a uniform hybrid coating. This hybrid coating was then uniformly sprayed onto the surface of the asymmetric structure array.

[0052] 4. Coating curing: Place the sprayed sample in an oven and keep it at 60°C for 4 hours to allow the coating to fully cure and bond firmly to the substrate, thus obtaining sample S1.

[0053] Example 2

[0054] This embodiment differs from Embodiment 1 in that the center-to-center spacing between adjacent units and the coating type are changed. The preparation method is as follows:

[0055] 1. Structural Design and Printing: The basic geometric parameters of the columnar structural unit (top tilt angle 45°, D=300 µm, H=900 µm) are the same as in Example 1, but the center-to-center distance between adjacent units is increased to 600 µm (i.e., P / D=2). The printing and post-processing are exactly the same as in Example 1.

[0056] 2. Coating modification: Hydrophobic silica nanoparticles (Degussa, R202, average particle size 14 nm) were dispersed in anhydrous ethanol to prepare a dispersion with a solid content of 2 wt.%, and ultrasonic treatment was performed for 1 hour to ensure uniform dispersion.

[0057] 3. Coating spraying and curing: The above dispersion is uniformly sprayed onto the surface of the post-treated asymmetric structure array; the sprayed three-dimensional sample is placed in a 60℃ oven to dry and cure for 20 minutes to allow the ethanol to evaporate completely, forming a low surface energy coating composed of hydrophobic silica nanoparticles, to obtain sample S2.

[0058] Example 3

[0059] This embodiment differs from Embodiment 1 in that the height of the columnar structural unit and the coating type are changed. The preparation method is as follows:

[0060] 1. Structural Design and Printing: The same asymmetric structural array design as in Example 1 was adopted. The geometric parameters of the columnar structural units were adjusted to H=1200 µm (H / D=4), and the remaining geometric parameters (top tilt angle 45°, D=300 µm, P=450 µm) and printing parameters were exactly the same as in Example 1. The printing, cleaning, and UV post-curing processes were exactly the same as in Example 1, resulting in a substrate with a micro-nano rough structure.

[0061] 2. Hydrophobication by Vapor Deposition: The treated sample was placed in a vacuum desiccator along with a small dish containing 20 µL of 1H,1H,2H,2H-perfluorooctyltriethoxysilane. After evacuation, the sample was kept at 60°C for 4 hours to allow the fluorosilane vapor to complete chemical vapor deposition on the sample surface, forming a self-assembled monolayer, resulting in sample S3.

[0062] Example 4

[0063] The difference between this embodiment and Embodiment 1 is that the tilt angle of the top of the columnar structural unit is changed. The specific preparation method is as follows:

[0064] 1. Structural Design and Printing: The difference between this embodiment and Embodiment 1 lies in the tilt angle of the top of the columnar structural unit. The tilt angle is adjusted to 30°, while the remaining geometric parameters (D=300 µm, H=900 µm, P=450 µm, i.e., P / D=1.5, H / D=3) and printing parameters are exactly the same as in Embodiment 1. After layer-by-layer curing, a micro-column array with a small asymmetric tilt angle is obtained.

[0065] 2. Post-processing and roughening: Same as step 2 in Example 1.

[0066] 3. Coating modification: Using the same PDMS-silica hybrid coating and spraying process as in Example 1, the coating is uniformly sprayed onto the post-treated microstructure array surface.

[0067] 4. Coating curing: Same as step 4 in Example 1, to obtain sample S4.

[0068] Comparative Example

[0069] A comparative example of preparing a superhydrophobic horizontal plate surface (i.e., only a low surface energy coating) was conducted using the following method:

[0070] To further demonstrate the advantages of the directional bouncing anti-icing surface of the asymmetric superhydrophobic structure of the present invention, a comparative analysis was conducted on the directional bouncing process of a droplet with a diameter of approximately 2.9 mm impacting the surface of the superhydrophobic horizontal plate.

[0071] 1. Substrate preparation: 3D print a resin plate with a size of 20 mm × 20 mm, ultrasonically clean it with acetone or ethanol for 15 minutes, cure it with ultraviolet light, and dry it for later use.

[0072] 2. Coating preparation and spraying: The PDMS-silica hybrid coating and spraying process used in Example 1 were used to coat the surface of the pretreated resin plate.

[0073] 3. Curing: Place the sprayed resin plate in a 60℃ oven for 4 hours to cure, and obtain a superhydrophobic horizontal plate with a smooth surface and no macroscopic characteristic structure, which is denoted as the superhydrophobic horizontal plate surface (S0).

[0074] Performance testing and results analysis:

[0075] 1. Static wettability: The static contact angle (CA) of each sample surface was measured using a contact angle meter. The droplet volume was 5 μL, and each sample was measured 5 times, with the average value taken. The static contact angle test results for each sample are as follows: Figure 2 As shown in the figure. The results indicate that the water contact angles of the samples prepared in Example 1 and Example 2 both exhibit excellent hydrophobic properties.

[0076] 2. Dynamic bouncing behavior: The dynamic process of water droplets with a diameter of about 2.9 mm impacting the surface of each sample from a height of about 30 mm was recorded using a high-speed camera (Olympus, Japan, i-SPEED 2, 10000 fps).

[0077] Figure 3 This is a time-series diagram of droplet bouncing for different samples at the same low Weber number (We≈12). The observation results show that:

[0078] Comparative sample S0: such as Figure 3 As shown in (a), after the water droplet impacts, the droplet vibrates repeatedly, merges, and eventually remains near the impact point, unable to effectively detach from the surface.

[0079] Example sample S1 (reference spacing, P / D=1.5): Due to the small structural spacing, the coupling between adjacent micropillars is strong, and the directional driving force on the droplet is more significant. Figure 3 As shown in (c), even at low Weber numbers, the droplets exhibited significant directional bouncing behavior on the S1 surface, with the droplets bouncing more rapidly and the bouncing time shortened to 71% of that on the S0 sample surface, which was the best among all samples.

[0080] Example 2 Sample S2 (large pitch, P / D=2.0): as follows Figure 3 As shown in (b), the droplet exhibits obvious directional bouncing behavior after impact and undergoes a certain degree of deviation.

[0081] Example 3 Sample S3 (tall structure, H / D=4.0): High-speed camera observations show that water droplets also exhibit directional bouncing behavior on the surface of S3. At a relatively high structural height, it is reasonable to expect that the asymmetric morphology designed in this invention can still effectively induce directional bouncing of droplets. The bouncing speed of S3 is slightly lower than that of S1 and S2, possibly due to subtle changes in local surface energy distribution caused by the tall structure, but its performance is still far superior to the comparative examples.

[0082] Example 4 Sample S4 (tilt angle 30°): It can be inferred that the water droplet also exhibits a clear directional bouncing behavior on the surface of S4, but due to the smaller tilt angle, the generated asymmetric driving force is relatively weak, and the lateral displacement velocity of the droplet is slightly lower than that of S1.

[0083] The results show that regardless of the type of low surface energy coating used (hybrid coating, nanoparticle layer or monolayer), as long as it is combined with the asymmetric structure of the present invention, it can successfully induce the droplet to bounce off rapidly in a predetermined direction.

[0084] 3. Bouncing behavior under different low-temperature conditions:

[0085] Using sample S1 as a typical example, the droplet bouncing time (time from contact to complete detachment) was tested at -5°C, -10°C, -15°C, and -20°C. Figure 4 As shown, the droplet bouncing time increases slightly as the temperature decreases, but it can still be kept within 6 ms at -20℃, indicating that the surface can still effectively induce the droplet to detach quickly in a low-temperature environment.

[0086] 4. Anti-icing performance:

[0087] Taking Example S1 as a typical example, the sample was placed in a constant temperature and humidity chamber, with the ambient temperature controlled at a constant -15°C and the relative humidity at 60%. The freezing delay time of a 20 μL supercooled water droplet was tested. Figure 5 The low-temperature delayed icing timeline is shown. The results demonstrate that the asymmetric structure of this invention can significantly extend the icing time.

[0088] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention. The above embodiments are provided only for the purpose of describing the present invention and are not intended to limit the present invention. Parts not described in detail in this specification are well-known in the art and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principle of the present invention should be covered within the scope of the present invention.

Claims

1. A directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure, characterized in that, The directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure includes an asymmetric structure array with a specific morphology and a low surface energy coating covering the surface of the asymmetric structure array. The asymmetric structure array is composed of multiple micrometer- or millimeter-scale columnar structural units. The top of each columnar structural unit has an asymmetric inclined geometric surface, and the asymmetric inclined geometric surface at the top of each columnar structural unit has a consistent inclined direction. The surface of each columnar structural unit is constructed with a micro-nano composite rough structure, and the surface of each columnar structural unit is modified with the low surface energy coating, so that the directional bouncing anti-icing surface based on the asymmetric superhydrophobic structure has superhydrophobic properties as a whole. The asymmetry of the structural array, the micro-nano composite rough structure of the columnar structural units, and the low surface energy coating work together to generate an asymmetric interfacial force and Laplace pressure difference when the directional bouncing anti-icing surface based on the asymmetric superhydrophobic structure comes into contact with the droplet, thereby driving the droplet to bounce away from the directional bouncing anti-icing surface based on the asymmetric superhydrophobic structure in a directional manner and at high speed.

2. The directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure according to claim 1, characterized in that, The tilt angle of the asymmetric tilted geometry at the top of the columnar structural unit is between 1° and 89°.

3. The directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure according to claim 1, characterized in that, The spacing between adjacent columnar structural units is 0.5 to 10 times the characteristic dimension of the cross-section.

4. The directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure according to claim 1, characterized in that, The cross-sectional characteristic dimension of the columnar structural unit is 5μm to 2mm, and the height of the columnar structural unit is 10μm to 5mm.

5. The directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure according to claim 1, characterized in that, The micro-nano composite rough structure is formed in situ on the surface of the columnar structural unit by cleaning the photocurable resin constituting the columnar structural unit with organic solvent and then performing UV post-curing treatment.

6. The directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure according to claim 1, characterized in that, The low surface energy coating is selected from any of the following: (a) an organic-inorganic hybrid coating formed by blending polydimethylsiloxane with hydrophobic silica nanoparticles; (b) a silica nanoparticle layer formed by dispersing hydrophobic silica nanoparticles in an ethanol solution, followed by spraying and drying; and (c) a fluorosilane monolayer formed by chemical vapor deposition or solution self-assembly.

7. A method for preparing a directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1: Using surface projection photopolymerization additive manufacturing technology, asymmetric initial structure array is obtained by curing photopolymer resin layer by layer. S2: The asymmetric initial structure array obtained in step S1 is cleaned with an organic solvent to dissolve and remove the resin that is not fully cured on the surface, and at the same time roughen the surface. Then, UV post-curing treatment is performed to form the micro-nano composite rough structure on the structure surface to obtain the asymmetric structure array. S3: Prepare a low surface energy coating on the surface of the asymmetric structure array obtained in step S2, and perform a thermal curing treatment on the coating to obtain the directional bouncing anti-icing surface based on the asymmetric superhydrophobic structure.

8. The method for preparing a directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure according to claim 7, characterized in that, In step S1, the process parameters for surface projection photopolymerization additive manufacturing include: exposure light intensity per unit area of ​​1-100 mW / cm². 2 The single-layer exposure time ranges from 0.5 seconds to 30 seconds, and the printing layer thickness ranges from 10 μm to 500 μm.

9. The method for preparing a directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure according to claim 7, characterized in that, The organic solvent used for cleaning in step S2 is ethanol, isopropanol, or acetone; the cleaning method in step S2 includes immersion cleaning or ultrasonic-assisted cleaning, and the cleaning time is 1 to 30 minutes; the UV post-curing treatment time in step S2 is 1 to 60 minutes. The coating thermosetting treatment in step S3 specifically involves heating at 30°C to 100°C for 10 to 120 minutes.

10. An application of a directional bouncing anti-icing surface based on an asymmetric superhydrophobic structure as described in any one of claims 1 to 6 for anti-icing and enhanced heat transfer in low-temperature finned heat exchangers, aerospace equipment, wind turbine blades, or power transmission equipment.

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