Super-hydrophobic composite coating with super-hydrophobic self-repairing ability and preparation method thereof

Abstract

The application discloses a kind of super-hydrophobic composite coating with super-hydrophobic self-repairing ability and preparation method thereof, the method includes the following steps: methacrylate functionalized polydimethylsiloxane, (methyl) acrylate polymerizable monomer, OTS are mixed uniformly with photo-initiator, to obtain oil phase, nanoparticle and surfactant are dissolved in water, to obtain water phase, oil phase is mixed with water phase and ultrasonic dispersion, to obtain pickering emulsion;Pickering emulsion is irradiated under ultraviolet lamp, then alcohol solvent is replaced, to obtain super-hydrophobic coating alcohol dilution emulsion;Diaminopropyl terminated polydimethylsiloxane and isophorone diisocyanate are dissolved in organic solvent, and mixed chain extender is added, to synthesize polyurea modified polydimethylsiloxane adhesive;Adhesive is mixed with super-hydrophobic coating alcohol dilution emulsion and coated on substrate and dried, to obtain super-hydrophobic composite coating.The composite coating prepared by the application has super-hydrophobic performance and super-hydrophobic self-repairing ability.

Description

Technical Field

[0001] This invention relates to the field of superhydrophobic materials technology, specifically to a superhydrophobic composite coating with superhydrophobic self-healing capabilities and its preparation method. Background Technology

[0002] Superhydrophobic surfaces typically possess a water contact angle greater than 150° and a roll-off angle less than 10°. This unique wetting property primarily stems from the synergistic effect of the material's low surface energy chemical composition and micro / nano-scale roughened structure. Based on these unique surface characteristics, superhydrophobic materials exhibit multiple superior properties, including self-cleaning, antifouling, anti-icing, and drag reduction. Furthermore, they show great application potential and development prospects in corrosion protection and anti-icing applications. However, superhydrophobic coatings are highly susceptible to damage, mainly because their surface relies on micro / nano-scale roughened structures to maintain superhydrophobic properties. These structures are accompanied by fragile mechanical properties, severely impacting the application and development of superhydrophobic coatings. Currently, using organic adhesives is one of the key strategies to enhance the mechanical stability and substrate-coating interfacial adhesion of superhydrophobic materials. This system includes an organic adhesive providing bonding strength and solid particles providing micro / nano-scale roughness. The adhesive component mainly provides strong adhesion and interfacial reinforcement, while the solid particle component is responsible for constructing the roughened micro / nano-scale structure to achieve superhydrophobicity. However, this system faces the following problems in application: (1) Poor interfacial compatibility between inorganic particles and adhesives not only easily leads to uneven distribution and aggregation of inorganic particles, but also low interfacial bonding force between inorganic particles and adhesives, which makes inorganic particles easy to fall off and cause superhydrophobic performance failure. (2) The superhydrophobic properties decrease after the rough structure caused by the particles on the coating surface is worn away. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a superhydrophobic composite coating with superhydrophobic self-healing capabilities and its preparation method.

[0004] The technical solution adopted in this invention is as follows: This invention provides a method for preparing a superhydrophobic composite coating with superhydrophobic self-healing capabilities, comprising the following steps: Methacrylate-functionalized polydimethylsiloxane, (meth)acrylate polymerizable monomers, trimethoxy(octadecyl)silane, and a photoinitiator were mixed evenly to obtain an oil phase; nanoparticles and surfactants were added to an aqueous solution and mixed evenly to obtain an aqueous phase; the oil phase was added to the aqueous phase, mixed evenly, and ultrasonically dispersed to obtain a Pickering emulsion. Pickering emulsion was photocured under a UV lamp to obtain a water-based superhydrophobic coating emulsion. The water-based superhydrophobic coating emulsion was centrifuged and then washed and replaced multiple times with an alcohol solvent to obtain a superhydrophobic coating alcohol-diluted emulsion. Diaminopropyl-terminated polydimethylsiloxane and isophorone diisocyanate were dissolved in an organic solvent and mixed chain extenders were added to synthesize polyurea-modified polydimethylsiloxane adhesives. A superhydrophobic coating mixed emulsion was prepared by using the polyurea-modified polydimethylsiloxane adhesive and the superhydrophobic coating alcohol-diluted emulsion. The superhydrophobic coating mixed emulsion was then coated onto a substrate and dried to obtain a superhydrophobic composite coating.

[0005] Furthermore, the polymerizable monomers of (meth)acrylates in the oil phase are at least one of ethylene glycol dimethacrylate, ethyl 2-dimethacrylate, and trimethylpropane triacrylate; the photoinitiator in the oil phase is at least one of 2-hydroxy-2-methylphenylpropanone, 1-hydroxycyclohexylphenyl ketone, and diphenyl ketone. In step (1), the mass ratio of methacrylate-functionalized polydimethylsiloxane to (meth)acrylate polymerizable monomers in the oil phase is 0.5 to 3:1; the concentration of the photoinitiator in the oil phase is 1 to 15 wt%.

[0006] Furthermore, the concentration of the trimethoxy(octadecyl)silane in the Pickering emulsion is 4~10 g / L.

[0007] Furthermore, the nanoparticles in the aqueous phase are at least one of silica nanoparticles, carbon nanotubes, polysaccharides, titanium dioxide, and starch; The surfactant in the aqueous phase is at least one of sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, FS-48, FS-61, and alkylphenol polyoxyethylene ether; The concentration of the nanoparticles in the aqueous phase is 0.2~1.0 wt%, and the concentration of the surfactant in the aqueous phase is 0.01~2 wt%.

[0008] Furthermore, in the preparation of the Pickering emulsion, the volume ratio of the oil phase to the water phase is 1:10~40.

[0009] Furthermore, the alcohol solvent in the superhydrophobic coating alcohol-diluted emulsion is one of ethanol, butanol, n-butanol, and isopropanol, and the solid content of the superhydrophobic coating alcohol-diluted emulsion is 40~80wt%.

[0010] Furthermore, during the synthesis of the polyurea-modified polydimethylsiloxane adhesive, the molar ratio of diaminopropyl-terminated polydimethylsiloxane to isophorone diisocyanate is 1:1 to 2.5. The mixed chain extender includes isophorone diamine and polyetheramine, and the molar ratio of isophorone diamine to polyetheramine is 0.5~2:1; The total molar number of the mixed chain extender is 0.1 to 0.5 times the total molar number of diaminopropyl-terminated polydimethylsiloxane and isophorone diisocyanate.

[0011] Furthermore, the polyurea-modified polydimethylsiloxane adhesive is synthesized using a two-step method: Diaminopropyl-terminated polydimethylsiloxane and isophorone diisocyanate are dissolved in an organic solvent and then reacted at 50-80°C for 2-5 hours to generate isocyanate-terminated prepolymers. Add a mixed chain extender to the prepolymer, and then continue the reaction at 50~80℃ for 2~5h. After the reaction is completed, evaporate the organic solvent to obtain polyurea-modified polydimethylsiloxane adhesive.

[0012] Furthermore, the preparation process of the superhydrophobic composite coating is as follows: The polyurea-modified polydimethylsiloxane adhesive is dissolved in an organic solvent to form an adhesive solution; The superhydrophobic coating alcohol-diluted emulsion is mixed with the adhesive solution and stirred at 500-1000 rpm for 5-15 min to obtain an adhesive-superhydrophobic coating mixed emulsion. The adhesive-superhydrophobic coating emulsion is applied to the substrate and dried to obtain a superhydrophobic coating.

[0013] Furthermore, the volume ratio of the polyurea-modified polydimethylsiloxane adhesive to the superhydrophobic coating concentrate emulsion is 3~5:1.

[0014] The beneficial effects of this invention are as follows: (1) The present invention proposes a superhydrophobic composite coating with superhydrophobic self-healing ability, which is prepared by organosilicon microsphere particle emulsion and organosilicon binder. Compared with inorganic particles, organosilicon microsphere particles and binder have good interfacial compatibility, which makes it easier for the two to bond firmly. (2) This invention proposes a superhydrophobic composite coating with superhydrophobic self-healing ability, which is prepared by organosilicon microsphere particle emulsion and organosilicon binder. The alcohol solvent of the microsphere particles and the solvent of the organosilicon binder are miscible, ensuring that the microsphere particles can be uniformly dispersed in the binder, so that the coating surface has a uniform micro-nano rough structure, which gives it superhydrophobic properties. In addition, based on its superhydrophobic properties, the coating also has good anti-pollution and anti-icing properties. (3) This invention proposes a superhydrophobic composite coating with superhydrophobic self-healing ability. OTS is added when preparing the oil phase. The addition of OTS not only induces new nanoscale structures on the surface of microspheres, forming richer micro-nano structures and increasing the surface water contact angle; but also when mechanical wear occurs, the internal material of the microspheres is exposed, and the newly exposed inner surface still contains OTS. When the exposed surface comes into contact with water, OTS is rapidly hydrolyzed, thereby restoring the surface roughness and giving the coating superhydrophobic self-healing ability. Attached Figure Description

[0015] To clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 These are microscopic photographs of the microspheres after freeze-drying the waterborne superhydrophobic coating emulsions of Examples 1, 1, and 2 of the present invention; wherein, (a) is a SEM photograph of the microspheres of Comparative Example 1, (b) is a SEM photograph of the microspheres of Example 1, and (c) is a SEM photograph of the microspheres of Comparative Example 2. Detailed Implementation

[0017] This invention provides a superhydrophobic composite coating with superhydrophobic self-healing capabilities and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0018] The present invention will now be described in detail with reference to the accompanying drawings.

[0019] It should be noted that the methacrylate-functionalized polydimethylsiloxane (MA-PDMS) used in the following examples and comparative examples is a polydimethylsiloxane with photocurable properties, and its preparation process is as follows: First, weigh PDMS (22g), 3-methylpropenylpropylmethyldimethylsiloxane (KH-571, 3.6g), dibutyltin dilaurate (DTBL, 0.34g), and deionized water (1g) according to the predetermined ratio. Then, mix continuously at 600 rpm for 12 hours at room temperature, ensuring uniform mixing during this process. After mixing, place the mixture at 60°C for rotary evaporation for 12 hours to effectively remove residual moisture from the MA-PDMS system, and store at room temperature for later use.

[0020] Example 1 This embodiment provides a superhydrophobic composite coating with superhydrophobic self-healing capabilities, and the specific preparation process is as follows: (1) Preparation of Pickering emulsion 3g of methacrylate-functionalized polydimethylsiloxane (MA-PDMS), 3g of ethylene glycol dimethacrylate (EGDMA), 0.54g of 2-hydroxy-2-methylphenylacetone (1173) and 0.6g of trimethoxy(octadecyl)silane (OTS) were ultrasonically dispersed for 10 minutes and mixed evenly to obtain the oil phase; 0.306 g of silica nanoparticles (particle size 15 nm) and 0.1 g of sodium dodecyl sulfate were added to 100 mL of deionized water and ultrasonically dispersed for 30 minutes to obtain an aqueous phase. The oil phase and the water phase were mixed at a volume ratio of 1:13 and ultrasonically dispersed for 10 min to obtain an oil-in-water Pickering emulsion; the concentration of OTS in the emulsion was approximately 6 g / L. (2) Preparation of waterborne superhydrophobic coating emulsion A highly stable waterborne superhydrophobic coating emulsion was obtained by photocuring the Pickering emulsion under ultraviolet light for 5 minutes at room temperature. The obtained waterborne superhydrophobic coating emulsion was centrifuged and then washed three times with ethanol to replace the water in the original emulsion, resulting in an alcohol-diluted superhydrophobic coating emulsion. The solid content of the alcohol-diluted superhydrophobic coating emulsion was controlled to be 60 wt%. (3) Preparation of polyurea-modified polydimethylsiloxane adhesive 1 mmol of diaminopropyl-terminated polydimethylsiloxane with a molecular weight of 2500 and 2 mmol of isophorone diisocyanate (IPDI) were dissolved in tetrahydrofuran and reacted at 60 °C for 3 hours to generate a prepolymer with terminal isocyanate groups (-NCO). Subsequently, a mixed chain extender with a total molar amount of 1 mmol was added to the prepolymer, wherein the amount of isophorone diamine (IPDA) added to the mixed chain extender was 0.6 mmol and the amount of polyetheramine (PEA) with a molecular weight of 600 was 0.4 mmol. The reaction was continued at 60 °C for 3 hours. After the reaction was completed, the solvent was evaporated to obtain the product, polyurea-modified polydimethylsiloxane adhesive, denoted as U-PDMS adhesive. (4) Superhydrophobic composite coating U-PDMS was dissolved in a mixed solvent of 30 wt% butyl acetate and 70 wt% tetrahydrofuran to form a 10 wt% transparent and well-flowing solution, denoted as U-PDMS solution; The superhydrophobic coating alcohol-diluted emulsion and the adhesive solution were mixed at a volume ratio of 1:5 and stirred at 800 rpm for 10 min to obtain the adhesive-superhydrophobic coating mixed emulsion. Cut the substrate to a suitable size, place it in anhydrous ethanol for ultrasonic cleaning for 30 minutes, then place it in n-hexane for ultrasonic rinsing for 10 minutes to remove surface impurities, and dry it for later use. The adhesive-superhydrophobic coating emulsion was sprayed onto the substrate at room temperature and dried in an oven at 100°C to obtain a superhydrophobic coating, denoted as U-PDMS / PESO@SiO2 composite coating.

[0021] Example 2 This embodiment provides a superhydrophobic composite coating with superhydrophobic self-healing capabilities, and the specific preparation process is as follows: (1) Preparation of Pickering emulsion 2g of methacrylate-functionalized polydimethylsiloxane (MA-PDMS), 3g of trimethylpropane triacrylate, 0.54g of 2-hydroxy-2-methylphenylacetone (1173) and 0.5g of trimethoxy(octadecyl)silane (OTS) were ultrasonically dispersed for 10 minutes and mixed evenly to obtain the oil phase; 0.5 g of silica nanoparticles (particle size 15 nm) and 0.1 g of sodium dodecyl sulfate were added to 100 mL of deionized water and ultrasonically dispersed for 30 minutes to obtain an aqueous phase. The oil phase and the water phase were mixed at a volume ratio of 1:10 and ultrasonically dispersed for 10 min to obtain an oil-in-water Pickering emulsion. (2) Preparation of waterborne superhydrophobic coating emulsion A highly stable waterborne superhydrophobic coating emulsion was obtained by photocuring the Pickering emulsion under ultraviolet light for 3 minutes at room temperature. The obtained waterborne superhydrophobic coating emulsion was centrifuged and then washed three times with butanol to replace the water in the original emulsion, resulting in an alcohol-diluted superhydrophobic coating emulsion. The solid content of the alcohol-diluted superhydrophobic coating emulsion was controlled to be 50 wt%. (3) Preparation of polyurea-modified polydimethylsiloxane adhesive 1 mmol of diaminopropyl-terminated polydimethylsiloxane with a molecular weight of 2500 and 1.5 mmol of isophorone diisocyanate (IPDI) were dissolved in tetrahydrofuran and reacted at 60 °C for 3 hours to generate a prepolymer with terminal isocyanate groups (-NCO). Subsequently, a mixed chain extender with a total molar amount of 1 mmol was added to the prepolymer, wherein the amount of isophorone diamine (IPDA) added to the mixed chain extender was 0.5 mmol and the amount of polyetheramine (PEA) with a molecular weight of 600 was 0.5 mmol. The reaction was continued at 60 °C for 3 hours. After the reaction was completed, the solvent was evaporated to obtain the product, polyurea-modified polydimethylsiloxane adhesive, denoted as U-PDMS adhesive. (4) Superhydrophobic composite coating U-PDMS was dissolved in a mixed solvent of 30 wt% butyl acetate and 70 wt% tetrahydrofuran to form an 8 wt% transparent and well-flowing solution, denoted as U-PDMS solution; The superhydrophobic coating alcohol-diluted emulsion and the adhesive solution were mixed at a volume ratio of 1:5 and stirred at 800 rpm for 10 min to obtain the adhesive-superhydrophobic coating mixed emulsion. Cut the substrate to a suitable size, place it in anhydrous ethanol for ultrasonic cleaning for 30 minutes, then place it in n-hexane for ultrasonic rinsing for 10 minutes to remove surface impurities, and dry it for later use. The adhesive-superhydrophobic coating emulsion was sprayed onto the substrate at room temperature and dried in an oven at 100°C to obtain a superhydrophobic coating, denoted as U-PDMS / PESO@SiO2 composite coating.

[0022] Example 3 This embodiment provides a superhydrophobic composite coating with superhydrophobic self-healing capabilities, and the specific preparation process is as follows: (1) Preparation of Pickering emulsion 3g of methacrylate-functionalized polydimethylsiloxane (MA-PDMS), 3g of ethylene glycol dimethacrylate (EGDMA), 0.54g of 2-hydroxy-2-methylphenylacetone (1173) and 0.6g of trimethoxy(octadecyl)silane (OTS) were ultrasonically dispersed for 10 minutes and mixed evenly to obtain the oil phase; 0.8 g of silica nanoparticles (particle size 15 nm) and 0.1 g of sodium dodecyl sulfate were added to 100 mL of deionized water and ultrasonically dispersed for 30 minutes to obtain an aqueous phase. The oil phase and the water phase were mixed at a volume ratio of 1:13 and ultrasonically dispersed for 10 min to obtain an oil-in-water Pickering emulsion. (2) Preparation of waterborne superhydrophobic coating emulsion A highly stable waterborne superhydrophobic coating emulsion was obtained by photocuring the Pickering emulsion under ultraviolet light for 5 minutes at room temperature. The obtained waterborne superhydrophobic coating emulsion was centrifuged and then washed three times with butanol to replace the water in the original emulsion, resulting in an alcohol-diluted superhydrophobic coating emulsion. The solid content of the alcohol-diluted superhydrophobic coating emulsion was controlled to be 70 wt%. (3) Preparation of polyurea-modified polydimethylsiloxane adhesive 1 mmol of diaminopropyl-terminated polydimethylsiloxane with a molecular weight of 2500 and 2 mmol of isophorone diisocyanate (IPDI) were dissolved in tetrahydrofuran and reacted at 60 °C for 3 hours to generate a prepolymer with terminal isocyanate groups (-NCO). Subsequently, a mixed chain extender with a total molar amount of 1 mmol was added to the prepolymer, and the amount of isophorone diamine (IPDA) added to the mixed chain extender was 0.4 mmol. Polyetheramine with a molecular weight of 600 was added at a molar ratio of 6:4 (PEA). The reaction was continued at 60 °C for 3 hours. After the reaction was completed, the solvent was evaporated to obtain the product, polyurea-modified polydimethylsiloxane adhesive, denoted as U-PDMS adhesive. (4) Superhydrophobic composite coating U-PDMS was dissolved in a mixed solvent of 30 wt% butyl acetate and 70 wt% tetrahydrofuran to form a 15 wt% transparent and well-flowing solution, denoted as U-PDMS solution; The superhydrophobic coating alcohol-diluted emulsion and the adhesive solution were mixed at a volume ratio of 1:3 and stirred at 800 rpm for 10 min to obtain the adhesive-superhydrophobic coating mixed emulsion. Cut the substrate to a suitable size, place it in anhydrous ethanol for ultrasonic cleaning for 30 minutes, then place it in n-hexane for ultrasonic rinsing for 10 minutes to remove surface impurities, and dry it for later use. The adhesive-superhydrophobic coating emulsion was sprayed onto the substrate at room temperature and dried in an oven at 100°C to obtain a superhydrophobic coating, denoted as U-PDMS / PESO@SiO2 composite coating.

[0023] Comparative Example 1 The difference between this comparative example and Example 1 is that OTS was not added when preparing the oil phase in this comparative example. The superhydrophobic coating prepared in this comparison is denoted as U-PDMS / PES@SiO2 composite coating.

[0024] Comparative Example 2 The difference between this comparative example and Example 1 is that the concentration of OTS in the Pickering emulsion prepared in this comparative example is 38 mg / L.

[0025] Comparative Example 3 The difference between this comparative example and Example 1 is that the adhesive used in the composite coating prepared in this comparative example is epoxy resin, while everything else is the same as in Example 1. In this comparative example, the epoxy resin adhesive emulsion is prepared by mixing epoxy resin E-51 and curing agent T-31 at a mass ratio of 1:5, and then mixing epoxy resin E-51 and curing agent T-31 with anhydrous ethanol at a mass ratio of 1:2 to obtain an epoxy resin solution; then, the superhydrophobic coating concentrated emulsion and the adhesive solution are mixed at a volume ratio of 1:5 and stirred at 800 rpm for 10 min to obtain an adhesive-superhydrophobic coating mixed emulsion; and the superhydrophobic coating is obtained by spraying according to the method of Example 1, denoted as EP / PESO@SiO2 composite coating.

[0026] In addition, to facilitate the analysis of the superhydrophobic properties of the waterborne superhydrophobic coating emulsion when applied directly, a portion of the waterborne superhydrophobic coating emulsions prepared in Examples 1-3 and Comparative Examples 1 and 2 were taken and uniformly sprayed onto the substrate. After 15 minutes of UV exposure, the coatings were crosslinked and cured, and finally heat-treated at 60°C for 30 minutes to obtain a PESO@SiO2 functionalized coating without binder. Comparative Example 1 was a PES@SiO2 functionalized coating.

[0027] The static water contact angles of the binder-free functionalized coatings and binder-containing composite coatings prepared in Examples 1-3 and Comparative Examples 1-3 were tested, and the test results are shown in Table 1 below.

[0028] Table 1. Results of Static Water Contact Angle Test As can be seen from Table 1 above, the amount of OTS added has a significant impact on the water contact angle of the coating. Further surface roughness and surface energy tests were conducted on the functionalized coatings prepared in Example 1 and Comparative Example 1. The surface roughnesses of the functionalized coatings prepared in Example 1 and Comparative Example 1 were 3.37 μm and 0.93 μm, respectively; the surface energies of the functionalized coatings prepared in Example 1 and Comparative Example 1 were 6.7 mJ·m⁻¹, respectively. -2 11.5 mJ·m -2 That is, after adding an appropriate amount of OTS, the surface roughness of the coating increases and the surface energy decreases. The synergistic effect of the rough surface structure and low surface energy of the coating increases the water contact angle of the coating, thereby improving its hydrophobicity.

[0029] To investigate the cause of the induced surface roughness change, the waterborne superhydrophobic coating emulsions prepared in Example 1, Comparative Example 1, and Comparative Example 2 were taken and freeze-dried. The freeze-dried emulsions were then subjected to SEM testing. The test results are as follows: Figure 1 As shown. From Figure 1As can be seen, the addition of OTS induces new nanoscale structures on the surface of microspheres, forming richer micro-nano structures, which leads to an increase in surface roughness, manifested as an increase in the surface water contact angle. However, the hydrolysis of OTS is very rapid, and excessive OTS will affect the construction of surface roughness, resulting in no obvious "microsphere structure" and the microspheres being embedded in OTS hydrolysates. Therefore, it is necessary to control the amount of OTS added.

[0030] Table 1 also shows that the water contact angles of the functionalized coatings without binder and the composite coatings prepared with binder in Examples 1-3 both exceed 165°, exhibiting superhydrophobic properties. Furthermore, the water contact angle of the composite coatings prepared with binder did not decrease significantly. This is because: in the mixture of superhydrophobic coating emulsion and binder, the superhydrophobic coating emulsion is actually a paste containing water. During stirring, water, as a non-solvent, can induce phase separation in the U-PDMS / butyl acetate-tetrahydrofuran system. The U-PDMS-enriched phase gradually precipitates and solidifies during solvent evaporation, forming a dendritic network structure. Simultaneously, the presence of water in the superhydrophobic coating emulsion causes microspheres to tend to be exposed on the surface rather than embedded in the matrix. The microspheres also adhere together through U-PDMS, generating a larger rough structure. Therefore, the surface of the composite coating exhibits a typical micro / nano-level rough structure, which is beneficial for constructing surface hydrophobicity.

[0031] Furthermore, the composite coatings of Example 1 and Comparative Example 1 were subjected to mechanical wear treatment, and the static water contact angles of the composite coating surfaces after mechanical wear treatment were tested to be 167.2° and 135.6°, respectively. That is, the surface hydrophobicity of the composite coating prepared by adding OTS in Example 1 did not decrease significantly after wear, while the hydrophobicity of the composite coating prepared without adding OTS in Comparative Example 1 decreased significantly after wear. This is because: in the micro-nano composite structure of the composite coating surface, the roughness of the microsphere surface is provided by SiO2 nanoparticles and OTS hydrolysis products. When mechanical wear occurs, the internal material of the microspheres is exposed, and since the "oil phase" is homogeneous during emulsification, the newly exposed inner surface still contains OTS. When the exposed surface comes into contact with water, the OTS rapidly hydrolyzes, thereby restoring the surface roughness; moreover, since this superhydrophobic surface is isotropic, when the surface microspheres are worn away, the exposed surface still has a similar micro-nano composite structure surface morphology, thereby maintaining a similar surface contact angle, giving it superhydrophobic self-healing ability.

[0032] In addition to the superhydrophobic performance tests described above, mechanical stability tests were also conducted on the composite coatings of Example 1 and Comparative Example 3, specifically through reciprocating abrasion with sandpaper. After 80 cycles of reciprocating friction (800-grit sandpaper, 100g load, 10cm / s pushing speed, 20cm single stroke), the static water contact angle of the composite coating of Example 1 remained above 165°, showing a significant decrease after 80 cycles. After 50 cycles of reciprocating friction, the static water contact angle of the composite coating of Comparative Example 3 remained above 150°, showing a significant decrease after 50 cycles. The significant decrease in the static water contact angle indicates that the microsphere particles have begun to detach. Comparing the results of the sandpaper reciprocating abrasion test between Example 1 and Comparative Example 2, the composite coating prepared in Example 1 exhibits superior mechanical stability. This is because: the U-PDMS adhesive prepared in this example itself has high adhesion strength. When the adhesive from Example 1 is coated onto a glass substrate and dried, a pure U-PDMS coating is obtained. According to ASTM D3359 standard (tape peel test method), its adhesion level is determined to be 5B, the highest level in this standard, indicating that the coating and the glass substrate have excellent interfacial bonding strength. In addition, the U-PDMS adhesive prepared in this example is an organosilicon adhesive, and the microspheres are also organosilicon particles. The two have good interfacial compatibility, making it easier for them to bond firmly and exhibiting high interfacial bonding strength.

[0033] In addition, the anti-icing performance of the composite coatings of Example 1 and Comparative Example 2, as well as the pure U-PSMS coating (obtained by applying the binder of Example 1 to a glass substrate and drying it), and the pure epoxy resin coating (obtained by applying the binder of Comparative Example 3 to a glass substrate and drying it), were tested. Specifically, the time for the liquid to completely freeze on the glass was tested in a -15°C chamber. The freezing time of the composite coating of Example 1 was 516 s, the freezing time of the composite coating of Comparative Example 3 was 330 s, the freezing time of the pure U-PSMS coating was 122 s (water contact angle 111.5°), and the freezing time of the pure epoxy resin coating was 60 s (water contact angle 93.7°). By comparison, the composite coating of Example 1 showed excellent anti-icing performance.

[0034] It should be noted that any parts not mentioned in this invention can be achieved by using or referencing existing technologies.

[0035] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for preparing a superhydrophobic composite coating with superhydrophobic self-healing capability, characterized in that, Including the following steps: Methacrylate-functionalized polydimethylsiloxane, (meth)acrylate polymerizable monomers, trimethoxy(octadecyl)silane, and a photoinitiator were mixed evenly to obtain an oil phase; nanoparticles and surfactants were added to water and mixed evenly to obtain an aqueous phase; the oil phase was added to the aqueous phase, mixed evenly, and ultrasonically dispersed to obtain a Pickering emulsion. Pickering emulsion was photocured under a UV lamp to obtain a water-based superhydrophobic coating emulsion. The water-based superhydrophobic coating emulsion was centrifuged and then washed and replaced multiple times with an alcohol solvent to obtain a superhydrophobic coating alcohol-diluted emulsion. Diaminopropyl-terminated polydimethylsiloxane and isophorone diisocyanate were dissolved in an organic solvent and mixed chain extenders were added to synthesize polyurea-modified polydimethylsiloxane adhesives. A superhydrophobic coating mixed emulsion was prepared by using the polyurea-modified polydimethylsiloxane adhesive and the superhydrophobic coating alcohol-diluted emulsion. The superhydrophobic coating mixed emulsion was then coated onto a substrate and dried to obtain a superhydrophobic composite coating.

2. The method for preparing a superhydrophobic composite coating with superhydrophobic self-healing capability according to claim 1, characterized in that, The polymerizable monomers of (meth)acrylates in the oil phase include at least one of ethylene glycol dimethacrylate, ethyl 2-dimethacrylate, and trimethylpropane triacrylate; the photoinitiator in the oil phase includes at least one of 2-hydroxy-2-methylphenylpropanone, 1-hydroxycyclohexylphenyl ketone, and diphenyl ketone. The mass ratio of methacrylate-functionalized polydimethylsiloxane to (meth)acrylate polymerizable monomers in the oil phase is 0.5~3:1; the concentration of the photoinitiator in the oil phase is 1~15wt%.

3. The method for preparing a superhydrophobic composite coating with superhydrophobic self-healing capability according to claim 1, characterized in that, The concentration of the trimethoxy(octadecyl)silane in the Pickering emulsion is 4~10 g / L.

4. The method for preparing a superhydrophobic composite coating with superhydrophobic self-healing capability according to claim 1, characterized in that, The nanoparticles in the aqueous phase include at least one of silica nanoparticles, carbon nanotubes, polysaccharides, titanium dioxide, and starch. The surfactant in the aqueous phase includes at least one of sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, FS-48, FS-61, and alkylphenol polyoxyethylene ether; The concentration of the nanoparticles in the aqueous phase is 0.2~1.0 wt%, and the concentration of the surfactant in the aqueous phase is 0.01~2 wt%.

5. The method for preparing a superhydrophobic composite coating with superhydrophobic self-healing capability according to claim 1, characterized in that, When preparing the Pickering emulsion, the volume ratio of the oil phase to the aqueous phase is 1:10~40; The solid content of the superhydrophobic coating alcohol-diluted emulsion is 40~80wt%.

6. The method for preparing a superhydrophobic composite coating with superhydrophobic self-healing capability according to claim 1, characterized in that, When the polyurea-modified polydimethylsiloxane adhesive is synthesized, the molar ratio of diaminopropyl-terminated polydimethylsiloxane to isophorone diisocyanate is 1:1 to 2.

5. The mixed chain extender includes isophorone diamine and polyetheramine, and the molar ratio of isophorone diamine to polyetheramine is 0.5~2:1; The total molar number of the mixed chain extender is 0.1 to 0.5 times the total molar number of diaminopropyl-terminated polydimethylsiloxane and isophorone diisocyanate.

7. The method for preparing a superhydrophobic composite coating with superhydrophobic self-healing capability according to claim 1, characterized in that, The polyurea-modified polydimethylsiloxane adhesive is synthesized using a two-step method: Diaminopropyl-terminated polydimethylsiloxane and isophorone diisocyanate are dissolved in an organic solvent and then reacted at 50-80°C for 2-5 hours to generate isocyanate-terminated prepolymers. Add a mixed chain extender to the prepolymer, and then continue the reaction at 50~80℃ for 2~5h. After the reaction is completed, evaporate the organic solvent to obtain polyurea-modified polydimethylsiloxane adhesive.

8. The method for preparing a superhydrophobic composite coating with superhydrophobic self-healing capability according to claim 1, characterized in that, The specific preparation process of the superhydrophobic composite coating is as follows: The polyurea-modified polydimethylsiloxane adhesive is dissolved in an organic solvent to form an adhesive solution with a concentration of 5-15 wt%. The superhydrophobic coating alcohol-diluted emulsion is mixed with the adhesive solution and stirred at 500-1000 rpm for 5-15 min to obtain an adhesive-superhydrophobic coating mixed emulsion. The adhesive-superhydrophobic coating emulsion is applied to the substrate and dried to obtain a superhydrophobic coating.

9. The method for preparing a superhydrophobic composite coating with superhydrophobic self-healing capability according to claim 8, characterized in that, The volume ratio of the polyurea-modified polydimethylsiloxane adhesive to the superhydrophobic coating concentrate emulsion is 3~5:

1.

10. A superhydrophobic composite coating with superhydrophobic self-healing capability, characterized in that, It is prepared using the method described in any one of claims 1-9.

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