Super-hydrophobic coating based on controllable aluminum dihydrogen phosphate-based micro-nano structure and preparation method

Abstract

The invention provides a super-hydrophobic coating based on a controllable aluminum dihydrogen phosphate-based micro-nano structure and a preparation method, and relates to the field of super-hydrophobic coatings. The method comprises the following steps: dissolving dihydrophosphoric acid in ethanol, adding dodecyl trimethoxy silane, stirring at room temperature, and centrifuging to obtain modified aluminum dihydrogen phosphate; the preparation method comprises the following steps: dissolving silicon dioxide in ethanol, adding phenyltriethoxysilane, stirring, adding glacial acetic acid, and reacting to obtain a mixed solution A; dissolving acrylic resin in ethyl acetate, dropwise adding the mixed solution A, and stirring to obtain a mixed solution B; dissolving modified aluminum dihydrogen phosphate into ethanol, dropwise adding into the mixed solution B, and stirring to obtain a spraying solution; the spraying liquid is sprayed on the surface of a base material according to spraying parameters, and a coating is obtained; and curing the coating according to curing conditions to obtain the super-hydrophobic coating. In the process of preparing the super-hydrophobic coating by adopting a simple spraying method, controllable preparation of a micro-nano structure and enhancement of the durability of the coating are realized by regulating and controlling curing conditions.

Description

Technical Field

[0001] This invention relates to the field of superhydrophobic coatings, and more specifically, to a superhydrophobic coating based on a controllable aluminum dihydrogen phosphate-based micro / nano structure and its preparation method. Background Technology

[0002] Under external loads, the micro-nano structure of superhydrophobic coatings is easily worn away, causing them to lose their superhydrophobic properties and thus their self-cleaning, anti-icing, and other properties, which seriously restricts the practical application prospects of superhydrophobic coatings.

[0003] Existing technologies for enhancing the durability of superhydrophobic coatings include using laser etching to construct armor-like protective structures, introducing dynamic self-healing structures, and utilizing chemical bonds to enhance the bonding strength between binders and fillers. While simple spraying methods can achieve large-area, easy preparation of superhydrophobic coatings, superhydrophobic coatings prepared with organic binders (such as epoxy resins, acrylic resins, and silicone-based binders) exhibit poor durability. In contrast, superhydrophobic coatings prepared using inorganic binders such as aluminum dihydrogen phosphate and silicates possess advantages in high-temperature resistance and mechanical stability.

[0004] Guo et al. first reported improving the interfacial force between coatings and substrates through a combination of "inorganic adhesives + functional nanomaterials". In this strategy, aluminum phosphate was used as a reinforcing agent to improve the interfacial force between the coating and substrate, and combined with different inorganic nanoparticles (TiO2, SiO2, Al2O3) to prepare robust superwetting surfaces on stainless steel mesh, ceramics, and glass. The prepared coatings maintained excellent underwater oil repellency, oil-water separation performance, and self-cleaning properties after 100 (20 m) abrasion cycles on 320-grit sandpaper under a 200 g load. Dong et al. mixed hydrophobic silica and halloysite composite carbon nanotubes with ADP, and the prepared superhydrophobic coating maintained its superhydrophobic state after 150 friction cycles. Huang et al. directly sprayed hydrophobic particles onto the uncured ADP surface, and the coating could withstand 100 friction cycles. However, single ADP has defects such as brittle fracture tendency and low substrate adhesion strength. Although organic-inorganic hybridization can improve adhesion. Zhao et al. combined ADP with hydrophobic silica and PDMS, and the superhydrophobic coating prepared by a simple spraying method maintained the integrity of the surface micro-nano structure after 2000 cm of frictional cycling. Xue et al. proposed to improve the durability and stability of superhydrophobic surfaces by utilizing the synergistic effect of inorganic and organic adhesives. First, polystyrene (PS) microspheres were fixed on the fabric surface using aluminum phosphate to construct a rough structure; then, the treated fabric was immersed in polydimethylsiloxane (PDMS) for low surface energy modification and secondary interface strengthening of the polystyrene microspheres. The prepared fabric surface could withstand 35 machine washes and 72 hours of immersion in acid, alkali, salt, organic solvents, and ultraviolet radiation. However, the mismatch in thermal expansion coefficients easily led to the propagation of microcracks. Crucially, in the process of preparing superhydrophobic coatings using the spraying method, the formation of micro- and nano-structures depends entirely on the morphology of the filler itself and its random stacking behavior, resulting in poor controllability of the cavitation structure. Furthermore, ADP only serves as a passive bonding medium and fails to actively participate in the construction of micro- and nano-structures, which greatly limits the stability of the coating under mechanical / temperature fluctuations. Summary of the Invention

[0005] The purpose of this invention is to provide a superhydrophobic coating based on a controllable aluminum dihydrogen phosphate micro / nano structure and its preparation method. This method achieves controllable preparation of the micro / nano structure and enhances the durability of the coating by controlling the curing conditions during the preparation of the superhydrophobic coating using a simple spraying method.

[0006] The technical problem solved by this invention is achieved by the following technical solution.

[0007] On one hand, embodiments of this application provide a method for preparing a superhydrophobic coating based on a controllable aluminum dihydrogen phosphate-based micro / nano structure, comprising the following steps: S1: Dissolve dihydrogen phosphoric acid in ethanol, add dodecyltrimethoxysilane, stir and centrifuge at room temperature to obtain modified aluminum dihydrogen phosphate; S2: Dissolve silicon dioxide in ethanol, add phenyltriethoxysilane, stir, and then add glacial acetic acid to obtain mixture A; S3: Dissolve acrylic resin in ethyl acetate, add mixture A dropwise, stir, and obtain mixture B; then dissolve modified aluminum dihydrogen phosphate in ethanol, add it dropwise to mixture B, stir, and obtain the spraying liquid; S4: Spray the coating liquid onto the substrate surface according to the spraying parameters to obtain the coating; S5: Curing the coating according to the curing conditions yields a superhydrophobic coating.

[0008] Furthermore, in step S1, the mass ratio of dihydrogen phosphoric acid, ethanol and dodecyltrimethoxysilane is 1-3:20-30:0.5-1.5 by mass fraction, the stirring time is 12-24h, and the centrifugation conditions are centrifugation at 8000r / min for 3min.

[0009] Furthermore, in step S2, the mass ratio of silicon dioxide, ethanol, phenyltriethoxysilane and glacial acetic acid is 0.3-0.6:10-20:0.3-0.6:1-2, and the reaction conditions are 50°C for 6-10 hours.

[0010] Furthermore, in step S3, the mass ratio of acrylic resin to ethyl acetate is 0.5-1.5:4-5, and the mass ratio of modified aluminum dihydrogen phosphate to ethanol is 1-3:2-3.

[0011] Furthermore, in step S4, the spraying parameters include: spray gun nozzle diameter 0.5mm, spraying pressure 0.3-0.5Mpa, and spraying distance 15-20cm.

[0012] Furthermore, the substrate can be any one of wood, glass, steel, and fiber materials.

[0013] Furthermore, in step S5, the curing conditions include curing the coating at a temperature of 80-200°C for 3-4 hours.

[0014] On the other hand, embodiments of the present invention also provide a superhydrophobic coating based on a controllable aluminum dihydrogen phosphate-based micro / nano structure, which is prepared by the above-described preparation method.

[0015] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: 1. This invention prepares superhydrophobic coatings with different morphologies by changing the curing conditions; the in-situ growth of micro-nano structures restricts the binder embedding effect, enhances the Cassie state stability of the coating, and enables the coating to have anti-icing function. 2. This invention introduces acrylic resin to enhance the bonding strength with the substrate while guiding the directional growth of aluminum dihydrogen phosphate. The aluminum dihydrogen phosphate generates aluminum phosphate-based conical and nanosheet structures in situ, which enhances the mechanical resistance of the micro-nano structures. 3. By adding a phenyl silica prepolymer network, this invention enables in-situ growth of filler particles, further enhancing the bonding strength between the filler and the matrix and improving the coating roughness. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 These are images showing the micro / nano structure morphology of the coating surface obtained in Examples 1-4 of this invention. Figure 2 XPS analysis images of the coatings obtained in Examples 1-4 of this invention. Figure 3 These are EDS analysis images of the coatings obtained in Examples 1-4 of this invention; Figure 4 This is a comparison diagram of the surface contact angle size and scratch morphology of the coating obtained in Example 1 of the present invention; Figure 5 This is a comparison chart of the delayed icing time of the coatings obtained in Examples 1-4 of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to specific embodiments.

[0020] Example 1 This embodiment provides a detailed method for preparing a superhydrophobic coating based on a controllable aluminum dihydrogen phosphate-based micro / nano structure, including the following steps: S1: Weigh 2g of dihydrogen phosphate and ultrasonically disperse it in 30mL of anhydrous ethanol. Add 1mL of dodecyltrimethoxysilane and stir at room temperature for 12h. Then centrifuge at 8000r / min for 3min to obtain milky white hydrophobic particles. These hydrophobic particles are modified aluminum dihydrogen phosphate.

[0021] It should be noted that in this embodiment, dihydrogen phosphate refers to dihydrogen phosphate salts with a phosphate concentration ≥95%, including but not limited to sodium dihydrogen phosphate, potassium dihydrogen phosphate, etc.

[0022] S2: Weigh 0.45g of silicon dioxide and place it in 15mL of anhydrous ethanol. After sonicating for 10min, add 0.5mL of phenyltriethoxysilane and continue stirring for 10min. Then add 1.5mL of glacial acetic acid and react at 50℃ for 6h to obtain mixture A. This mixture is a mixture containing a phenyl silicon dioxide prepolymer network.

[0023] S3: Dissolve 1g of acrylic resin in 5ml of ethyl acetate solution, add mixture A dropwise at a rate of 30 drops / min, stir for 10min to obtain mixture B, set aside; then take 2g of modified aluminum dihydrogen phosphate and ultrasonically disperse it in 3mL of anhydrous ethanol. After ultrasonication, add it to mixture B at a drop rate of 2ml / min, and stir at 200 r / min for 30min to obtain a spraying liquid containing micro-nano structures.

[0024] S4: First, set the spraying parameters, including: spray gun nozzle diameter 0.5mm, spraying pressure 0.3Mpa, and spraying distance 15cm. Place the spraying liquid in the spray gun and spray it evenly onto the wood surface according to the parameters to obtain a coating.

[0025] S5: Place the coating obtained in step 4 in a vacuum drying oven and cure it at 120°C for 3 hours to obtain a superhydrophobic coating.

[0026] Example 2 The steps in this embodiment are largely the same as those in Embodiment 1, with the following differences: S1: Weigh 1g of dihydrogen phosphate and ultrasonically disperse it in 20mL of anhydrous ethanol. Add 0.5mL of dodecyltrimethoxysilane and stir at room temperature for 16h. Then centrifuge at 8000r / min for 3min to obtain milky white hydrophobic particles. These hydrophobic particles are modified aluminum dihydrogen phosphate.

[0027] S2: Weigh 0.3g of silicon dioxide and place it in 10mL of anhydrous ethanol. After sonicating for 10min, add 0.3mL of phenyltriethoxysilane and continue stirring for 10min. Then add 1mL of glacial acetic acid and react at 50℃ for 7h to obtain mixture A. This mixture is a mixture containing a phenyl silicon dioxide prepolymer network.

[0028] S3: Dissolve 0.5g of acrylic resin in 4ml of ethyl acetate solution, add mixture A dropwise at a rate of 30 drops / min, stir for 10min to obtain mixture B, set aside; then take 1g of modified aluminum dihydrogen phosphate and ultrasonically disperse it in 2mL of anhydrous ethanol. After ultrasonication, add it to mixture B at a drop rate of 2mL / min, and stir at 200 r / min for 30min to obtain a spraying liquid containing micro-nano structures.

[0029] S4: First, set the spraying parameters, including: spray gun nozzle diameter 0.5mm, spraying pressure 0.3Mpa, and spraying distance 15cm. Place the spraying liquid in the spray gun and spray it evenly onto the glass surface according to the parameters to obtain the coating.

[0030] S5: Place the coating obtained in step 4 in a vacuum drying oven and keep it at 80°C for 4 hours to obtain a superhydrophobic coating.

[0031] Example 3 The steps in this embodiment are largely the same as those in Embodiment 1, with the following differences: S1: Weigh 1.5g of dihydrogen phosphate and ultrasonically disperse it in 24mL of anhydrous ethanol. Add 0.8mL of dodecyltrimethoxysilane and stir at room temperature for 20h. Then centrifuge at 8000r / min for 3min to obtain milky white hydrophobic particles. These hydrophobic particles are modified aluminum dihydrogen phosphate.

[0032] S2: Weigh 0.4g of silicon dioxide and place it in 14mL of anhydrous ethanol. After sonicating for 10min, add 0.4mL of phenyltriethoxysilane and continue stirring for 10min. Then add 1.5mL of glacial acetic acid and react at 50℃ for 8h to obtain mixture A. This mixture is a mixture containing a phenyl silicon dioxide prepolymer network.

[0033] S3: Dissolve 1g of acrylic resin in 4.5ml of ethyl acetate solution, add mixture A dropwise at a rate of 30 drops / min, stir for 10min to obtain mixture B, set aside; then take 2g of modified aluminum dihydrogen phosphate and ultrasonically disperse it in 2.5mL of anhydrous ethanol. After ultrasonication, add it to mixture B at a drop rate of 2mL / min, and stir at 200 r / min for 30min to obtain a spraying liquid containing micro-nano structures.

[0034] S4: First, set the spraying parameters, including: spray gun nozzle diameter 0.5mm, spraying pressure 0.4Mpa, and spraying distance 18cm. Place the spraying liquid in the spray gun and spray it evenly onto the glass surface according to the parameters to obtain the coating.

[0035] S5: Place the coating obtained in step 4 in a vacuum drying oven, heat it to 120°C at a rate of 5°C / min, and keep it at that temperature for 3 hours to obtain the superhydrophobic coating.

[0036] Example 4 The steps in this embodiment are largely the same as those in Embodiment 1, with the following differences: S1: Weigh 3g of dihydrogen phosphate and ultrasonically disperse it in 30mL of anhydrous ethanol. Add 1.5mL of dodecyltrimethoxysilane and stir at room temperature for 16h. Then centrifuge at 8000r / min for 3min to obtain milky white hydrophobic particles. These hydrophobic particles are modified aluminum dihydrogen phosphate.

[0037] S2: Weigh 0.6g of silicon dioxide and place it in 20mL of anhydrous ethanol. After sonicating for 10min, add 0.6mL of phenyltriethoxysilane and continue stirring for 10min. Then add 2mL of glacial acetic acid and react at 50℃ for 10h to obtain mixture A. This mixture is a mixture containing a phenyl silicon dioxide prepolymer network.

[0038] S3: Dissolve 1.5g of acrylic resin in 5ml of ethyl acetate solution, add mixture A dropwise at a rate of 30 drops / min, stir for 10min to obtain mixture B, set aside; then take 2g of modified aluminum dihydrogen phosphate and ultrasonically disperse it in 3mL of anhydrous ethanol. After ultrasonication, add it to mixture B at a drop rate of 2mL / min, and stir at 200 r / min for 30min to obtain a spraying liquid containing micro-nano structures.

[0039] S4: First, set the spraying parameters, including: spray gun nozzle diameter 0.5mm, spraying pressure 0.5Mpa, and spraying distance 20cm. Place the spraying liquid in the spray gun and spray it evenly onto the glass surface according to the parameters to obtain the coating.

[0040] S5: Place the coating obtained in step 4 in a vacuum drying oven and keep it at 200°C for 3 hours to obtain a superhydrophobic coating.

[0041] The physicochemical properties of the superhydrophobic coatings obtained in Examples 1-4 were then analyzed, including: ① Characteristic identification: Fourier transform infrared spectroscopy was used to determine the composition of particles and coating. The surface morphology of the coating was obtained by scanning with field emission scanning electron microscopy at an accelerating voltage of 3 kV. The surface chemical composition was determined using KratosAxis-Ultra HAS X-ray photoelectron spectroscopy. The water contact angle (WCA) and water slip angle (WSA) were measured using a contact angle meter. A 10 μL drop of distilled water was used, and the average value was taken for every five measurements in different areas of the coating surface and the standard error was reported.

[0042] Experimental results are as follows Figure 1 - Figure 3 As shown, superhydrophobic coatings with different morphologies were prepared by changing the curing conditions. Specifically: After direct curing at 120℃ for 3 hours, the coating surface was relatively smooth with grooves ranging from 28μm to 36μm in width. Magnification revealed densely packed triangular pyramidal nanosheets on the surface, with SiO2 particles distributed within them, increasing the contact angle to 158.9°. After holding the coating at 80℃ for 4 hours, the surface remained composed of stacked triangular pyramidal nanosheets, achieving a contact angle as high as 157.6°. After heating to 120℃ at a rate of 5℃ / min and holding for 3 hours, the surface micropores (43μm) increased, and sheet-like nanosheets were distributed on the raised surface, resulting in a contact angle of 158.3°. After curing at 200℃ for 3 hours, the nanosheets were sparsely distributed, and the contact angle decreased to 157.4°.

[0043] The chemical composition of the coating is as follows Figure 2 As shown in the O1s spectrum, all three coatings exhibit characteristic peaks: 531.6 eV Si-O for SiO2, 532.9 eV C=O for AR, and 534.3 eV PO for SADP. In Si 2p, characteristic peaks appear at 101.7 eV Si-C, 102.5 eV Si-O-Si, and 103.6 eV Si-OP. Meanwhile, as... Figure 3 As shown in the EDS results, the dense distribution of P and Si elements in the nanocones or nanosheets proves that the nanocones and nanosheets are generated by in-situ directional growth of aluminum dihydrogen phosphate, and the surface is covered with phenyl silica particles. The resulting tertiary structure enhances the hydrophobicity of the coating.

[0044] ② Durability test: The coating prepared in Example 1 was used as a sample, and the coatings constructed with acrylic resin-phenyl silica network and aluminum dihydrogen phosphate-phenyl silica network were used as controls. The coating sample with a size of 2 cm × 2 cm × 1 mm was fixed on the bottom of a 200 g weight and pulled on 600 grit sandpaper at a uniform speed. Every 40 cm pull was counted as one wear cycle, and the change in surface contact angle was tested once to characterize the change in surface wettability with wear distance, thereby judging the wear resistance of the coating.

[0045] Experimental results are as follows Figure 4 As shown, after rubbing with 600-grit sandpaper for 96 μm, the coating still maintains its superhydrophobic state, while the coatings constructed with acrylic resin-phenyl silica network and aluminum dihydrogen phosphate-phenyl silica network have lost their superhydrophobic properties. This demonstrates that the nanostructure generated by aluminum dihydrogen phosphate and the synergistic reinforcement of the phenyl silica network and acrylic resin improve the durability of the coating's micro / nano structure.

[0046] ③ Anti-icing experiment: A 20μL water droplet was placed in a constant temperature and humidity chamber at a temperature of -20±0.3℃ and a relative humidity of 75±3%. High-speed cameras were used to record the morphological changes and time of the water droplet from its initial state to the beginning of freezing and then to complete freezing. The moment when dendrites form on the surface of the water droplet is the delayed freezing time.

[0047] Experimental results are as follows Figure 5 As shown, on all surfaces, the freezing process of water droplets preferentially generates dendrites, followed by the formation of an ice shell. However, on the coating surface cured at 120℃ for 3 hours, the freezing time of water droplets reached as high as 1667 seconds, and the water droplets formed spherical ice droplets, while on other surfaces, elliptical ice droplets formed. This proves that the freezing kinetics of water droplets are affected by the micro-nano structure characteristics of the coating. On surfaces with microporous structures, water droplets are more likely to penetrate the micropores during the freezing process, leading to the formation of ellipsoidal ice droplets. On surfaces with dense nanocones, the micro-structural penetration of supercooled water droplets is suppressed, promoting the formation of spherical ice droplets. This indicates that the anti-icing performance of the coating depends on the surface micro-nano structure characteristics. Therefore, the in-situ controllable preparation of micro-nano structures is a necessary means to achieve the regulation of surface water droplet freezing kinetics. The dense formation of nanoparticles on the surface of the in-situ generated nanosheets successfully constructed a tertiary structure with stable hydrophobic properties, significantly suppressing the heterogeneous nucleation process, thereby delaying water droplet freezing.

[0048] In summary, this invention provides a superhydrophobic coating based on a controllable aluminum dihydrogen phosphate-based micro / nano structure, and demonstrates how changing the curing conditions can produce superhydrophobic coatings with different nanostructure morphologies. It achieves in-situ growth and controllable morphology of the micro / nano hierarchical structure, avoiding the weakening of hydrophobicity due to binder embedding. Simultaneously, the introduction of a phenyl silica network strengthens the micro / nano structure itself, thereby improving the overall mechanical durability and Cassius stability of the coating, and endowing it with excellent anti-icing and de-icing properties.

[0049] This invention enhances the bonding strength between the aluminum dihydrogen phosphate and the substrate by introducing acrylic resin, while simultaneously guiding the directional growth of aluminum dihydrogen phosphate. Aluminum dihydrogen phosphate not only acts as an inorganic binder but also allows for the in-situ growth of nanostructures with different morphologies. Furthermore, the controllable preparation of aluminum phosphate-based conical or nanosheet structures can be achieved through specific curing conditions. This breaks with the conventional method of preparing nanosheet or conical structures via hydrothermal modification and surface hydrophobic modification, realizing the controllable in-situ preparation of micro / nanostructures through a simple spraying method. This invention achieves in-situ growth of nanoparticles on the surface of nanosheets by incorporating a phenyl silica prepolymer network, thus constructing a micro-nano tertiary structure and enhancing the hydrophobic stability of the coating. This successfully avoids the binder embedding effect inherent in conventional methods that involve first synthesizing multi-level fillers and then mixing them with binders to prepare the tertiary structure surface. Furthermore, the organic-inorganic hybridization of the phenyl silica prepolymer network and acrylic resin further enhances the bonding strength between the filler and the matrix and improves the coating durability, enabling the simple spraying preparation of durable superhydrophobic coatings.

[0050] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a superhydrophobic coating based on a controllable aluminum dihydrogen phosphate-based micro / nano structure, characterized in that, Includes the following steps: S1: Dissolve aluminum dihydrogen phosphate in ethanol, add dodecyltrimethoxysilane, stir and centrifuge at room temperature to obtain modified aluminum dihydrogen phosphate; S2: Dissolve silicon dioxide in ethanol, add phenyltriethoxysilane, stir, and then add glacial acetic acid to obtain mixture A; S3: Dissolve acrylic resin in ethyl acetate, add the mixture A dropwise, stir to obtain mixture B; then dissolve the modified aluminum dihydrogen phosphate in ethanol, add it dropwise to mixture B, stir to obtain a spraying liquid; S4: The spraying liquid is sprayed onto the surface of the substrate according to the spraying parameters to obtain a coating; S5: The coating is cured according to the curing conditions to obtain a superhydrophobic coating.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of aluminum dihydrogen phosphate, ethanol and dodecyltrimethoxysilane is 1-3:20-30:0.5-1.5 by mass fraction, the stirring time is 12-24h, and the centrifugation conditions are centrifugation at 8000r / min for 3min.

3. The preparation method according to claim 1, characterized in that, In step S2, the mass ratio of the silicon dioxide, the ethanol, the phenyltriethoxysilane and the glacial acetic acid is 0.3-0.6:10-20:0.3-0.6:1-2, and the reaction conditions are 6-10 h at 50 °C.

4. The preparation method according to claim 1, characterized in that, In step S3, the mass ratio of the acrylic resin to the ethyl acetate is 0.5-1.5:4-5, and the mass ratio of the modified aluminum dihydrogen phosphate to the ethanol is 1-3:2-3.

5. The preparation method according to claim 1, characterized in that, In step S4, the spraying parameters include: spray gun nozzle diameter 0.5mm, spraying pressure 0.3-0.5Mpa, and spraying distance 15-20cm.

6. The preparation method according to claim 5, characterized in that, The substrate includes any one of wood, glass, steel, and fiber materials.

7. The preparation method according to claim 1, characterized in that, In step S5, the curing conditions include curing the coating at a temperature of 80-200℃ for 3-4 hours.

8. A superhydrophobic coating based on a controllable aluminum dihydrogen phosphate-based micro / nano structure, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

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