Multifunctional super-hydrophobic coating based on in-situ growth nano titanium dioxide as well as preparation method and application of multifunctional super-hydrophobic coating

Abstract

The invention relates to the technical field of functional coatings, in particular to a multifunctional super-hydrophobic coating based on in-situ growth of nano titanium dioxide as well as a preparation method and application of the multifunctional super-hydrophobic coating. The super-hydrophobic coating is composed of a coating matrix material and modified composite particles; the base material of the coating is a high-molecular polymer formed by polymerizing multiple components; the composite particles are carboxyl carbon nanotubes with in-situ growth of titanium dioxide spheres on the surfaces. According to the composite particles, spherical titanium dioxide grows in situ on a carboxyl carbon nanotube tubular structure, surface modification is conducted on titanium dioxide through perfluorooctyltriethoxysilane, so that the surface energy is remarkably reduced, the coating is endowed with the super-hydrophobic performance, carboxyl carbon nanotubes and titanium dioxide spheres are combined with a coating base material through covalent bonds, and the super-hydrophobic performance of the coating is improved. The coating has excellent wear resistance, corrosion resistance and anti-icing performance, and is especially suitable for the fields of resistance reduction, corrosion resistance and the like of marine ships.

Description

Technical Field

[0001] This invention relates to the field of functional coating technology, and in particular to a multifunctional superhydrophobic coating based on in-situ grown nano-titanium dioxide, its preparation method and application. Background Technology

[0002] The information disclosed in the background section of this invention is intended only to enhance the understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] In the fields of marine engineering and shipbuilding, drag reduction technology is one of the core research directions for improving navigation efficiency and reducing operational energy consumption. When ships and marine equipment navigate in complex marine fluid environments, surface roughness and frictional resistance directly affect their overall performance and energy efficiency. Although traditional drag-reducing coatings can reduce water flow resistance to a certain extent, they generally suffer from insufficient wear resistance and short service life. In addition, the adhesion of marine organisms to the hull surface significantly increases drag, further leading to a decrease in navigation efficiency. Therefore, developing high-performance coatings that combine excellent wear resistance, long-term anti-biofouling capabilities, and stable drag-reduction performance in harsh marine environments is of great significance for improving the economic efficiency and sustainable operation of marine equipment.

[0004] Superhydrophobic coatings, with their unique surface-repellent properties and low surface energy, can effectively prevent marine organisms from adhering and reduce drag caused by biofouling, showing broad application potential in the field of marine drag reduction. However, existing superhydrophobic coatings still face many challenges in real marine environments: on the one hand, the high-salt, high-humidity marine environment places extremely high demands on the chemical and physical stability of the coatings, making them susceptible to long-term seawater erosion and performance degradation; on the other hand, existing preparation processes often struggle to achieve a balance between large-scale production and stable coating performance. Therefore, developing a superhydrophobic coating that is simple to process, highly wear-resistant, and environmentally adaptable is of significant research value and application potential for promoting technological advancements in marine engineering and shipbuilding. Summary of the Invention

[0005] In view of this, the present invention provides a multifunctional superhydrophobic coating based on in-situ grown nano-titanium dioxide, its preparation method, and its application. This coating exhibits a drag reduction rate greater than 5% at different Reynolds numbers in water, can delay icing time in low-temperature environments, and simultaneously provides drag reduction and corrosion protection. This coating has broad application prospects in marine engineering and ship drag reduction.

[0006] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides a multifunctional superhydrophobic coating based on in-situ grown nano-titanium dioxide, wherein the superhydrophobic coating is composed of a coating matrix material and modified composite particles; The coating substrate material is a high molecular polymer; The composite particles are carboxyl carbon nanotubes with titanium dioxide grown in situ on the surface.

[0007] In the multifunctional superhydrophobic coating based on in-situ grown nano-titanium dioxide provided by this invention, the coating matrix material plays a crucial role. It can tightly and firmly anchor the modified composite tubular particles to the substrate surface, thereby forming a stable and continuous coating structure. The composite particles possess a unique tubular and spherical micro-nano composite structure, exhibiting a rod-like structure of long spheres (similar to grapes). This structural design not only endows the coating with extremely low surface energy but also significantly improves its contact angle with water, thus enabling the coating to exhibit excellent superhydrophobic properties. This lays a solid foundation for the coating to demonstrate superior waterproof and drag-reducing characteristics in various application scenarios.

[0008] Furthermore, the polymer is selected from at least one of epoxy resin, fluorocarbon resin, fluorosilicone resin, and polydimethylsiloxane.

[0009] Furthermore, the polymer is selected from fluorocarbon resin and polydimethylsiloxane; the mass ratio of fluorocarbon resin to polydimethylsiloxane is 3-5:1.

[0010] Furthermore, the length of the carboxyl carbon nanotubes is 100-200 μm, and the particle size of the titanium dioxide grown in situ is 20-30 nm.

[0011] Furthermore, the modifier is a low surface energy silane, selected from perfluorooctyltriethoxysilane or perfluorodecyltriethoxysilane.

[0012] Furthermore, the mass ratio of the modified composite particles to the coating matrix material is 0.2-0.3:1.

[0013] In a second aspect, the present invention provides a method for preparing the superhydrophobic coating described in the first aspect, comprising the following steps: (1) Disperse carboxylated carbon nanotubes in an ethanol aqueous solution, add glacial acetic acid solution and deionized water, and disperse by ultrasonication; then add tetrabutyl titanate, stir to react, then add modifier to react, and after the reaction is completed, wash, dry and grind to obtain modified composite particles; (2) Add the coating matrix material and crosslinking agent to the diluent, then add the modified composite particles prepared in step (1), and sonicate to make the modified composite particles disperse evenly. (3) After heating the substrate to the preset temperature, a diluted solution containing modified composite particles and coating matrix material is sprayed onto the substrate surface using a spray gun under preset pressure conditions. After the coating is cured and dried, a superhydrophobic coating is obtained.

[0014] Furthermore, in step (1), the ratio of carboxylated carbon nanotubes to tetrabutyl titanate is 1:1-3 g / mL.

[0015] Furthermore, in step (1), the mass fraction of the ethanol aqueous solution is 95%, and the ratio of carboxylated carbon nanotubes to the ethanol aqueous solution is 1:120-180 g / mL.

[0016] Further, in step (1), the mass fraction of glacial acetic acid solution is 99%; the volume ratio of glacial acetic acid solution to deionized water is 1:0.9-1.1; and the volume ratio of glacial acetic acid solution to ethanol aqueous solution is 1:12-18.

[0017] Furthermore, in step (1), the ultrasound time is 20-40 min.

[0018] Furthermore, in step (1), the stirring reaction conditions are: stirring reaction at 20-30 ℃ for 2-4 h.

[0019] Further, in step (1), the modifier is selected from perfluorooctyltriethoxysilane or perfluorodecyltriethoxysilane; the ratio of the modifier to carboxylated carbon nanotubes is 300-500:1 μL / g.

[0020] Furthermore, in step (1), after adding the modifier, the reaction is stirred for 10-15 h.

[0021] Further, in step (2), the crosslinking agent is V-PDMS and N3390 curing agent.

[0022] Furthermore, in step (2), the diluent is ethyl acetate.

[0023] Furthermore, in step (2), the mass ratio of the coating substrate material to the crosslinking agent is 5-15:1.

[0024] Further, in step (2), the coating substrate material is fluorocarbon resin and polydimethylmethylvinylsiloxane; the mass ratio of fluorocarbon resin and polydimethylmethylvinylsiloxane is 3-5:1.

[0025] Further, in step (2), the specific steps are as follows: add fluorocarbon resin and N3390 curing agent to diluent to obtain solution A; add polydimethylmethylvinylsiloxane and V-PDMS to diluent to obtain solution B; mix solution A and solution B evenly, add modified composite particles, and sonicate to make the modified composite particles evenly dispersed.

[0026] Furthermore, in step (2), the ultrasound time is 20-40 min.

[0027] Furthermore, in step (3), the substrate includes, but is not limited to, aluminum plate, wood plate, iron plate, copper plate, aluminum plate, and steel plate.

[0028] Furthermore, in step (3), the preset temperature is 45-60 ℃.

[0029] Furthermore, in step (3), the preset pressure is 0.2-0.5 MPa.

[0030] Furthermore, in step (3), the drying conditions are 150-200 ℃ for 10-30 min.

[0031] Thirdly, the present invention provides the application of the superhydrophobic coating described in the first aspect in the fields of underwater drag reduction, anti-icing, and anti-corrosion.

[0032] Furthermore, the superhydrophobic coating exhibits a drag reduction rate of greater than 5% in water at 200-100000 Reynolds numbers; and can delay icing time at temperatures as low as -15 °C.

[0033] Compared with the prior art, the present invention has achieved the following beneficial effects: (1) The superhydrophobic coating developed in this invention abandons traditional complex processes such as laser processing, photolithography, and template methods, and can achieve rapid construction on any substrate surface and any shape surface. The titanium dioxide connected by covalent bonds on the surface of carboxylated carbon nanotubes developed in this invention has a stable structure, and the amount of attached titanium dioxide can be controlled, demonstrating the controllability of the structure. At the same time, this coating exhibits high impedance in corrosion protection compared with the superhydrophobic coating of micro-nano particles mixed with ordinary physical materials. It has high impedance, strong charge transfer resistance and good barrier properties, which can effectively prevent corrosive media from penetrating the coating and reaching the aluminum plate substrate.

[0034] (2) The superhydrophobic coating developed in this invention can efficiently absorb solar energy and convert it into thermal energy, achieving multiple functions such as low-temperature anti-sticking, delayed icing, and rapid ice melting. Its performance remains stable after multiple freeze-thaw cycles, and the bonding strength between ice and the coating is greatly reduced, which is significantly better than other superhydrophobic coatings. The wear resistance, corrosion resistance, and underwater gas film capture ability are significantly improved. The corrosion current density is reduced by more than 8 orders of magnitude, as measured by an electrochemical workstation.

[0035] (3) The superhydrophobic coating developed by the invention is applied by a one-step spraying method using a diluted solution of particles and coating substrate material, which improves efficiency and facilitates mass production. At the same time, the compatibility control of the coating substrate material greatly improves the bonding strength between the coating and the substrate, which is significantly better than other superhydrophobic coatings. Attached Figure Description

[0036] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0037] Figure 1 SEM images of carboxylated carbon nanotubes and in-situ grown titanium dioxide from carboxylated carbon nanotubes; where (A) is the SEM image of carboxylated carbon nanotubes and (B) is the SEM image of in-situ grown titanium dioxide from carboxylated carbon nanotubes. Figure 2 The image shows the contact angle test results of the superhydrophobic coating prepared in Example 1; Figure 3 The drag reduction effect of the superhydrophobic coating prepared in Example 1 is shown in the figure. Figure 4 The potentiodynamic polarization curves and Nyquist curves of the superhydrophobic coating prepared in Example 1 are shown; where (A) is the potentiodynamic polarization curve and (B) is the Nyquist curve. Figure 5 The image shows the antifouling effect of the superhydrophobic coating prepared in Example 1; where (A) is a SEM image of the blank aluminum plate surface after Chlorella cultivation; (B) is a SEM image of the superhydrophobic coating surface after Chlorella cultivation; and (C) is a statistical result of the algal coverage of the two surfaces. Figure 6 The diagram shows the anti-icing and de-icing effects of the superhydrophobic coating prepared in Example 1; (A) is a schematic diagram of water droplet icing over time in the blank group; (B) is a schematic diagram of water droplet icing over time in the superhydrophobic coating; (C) is a schematic diagram of the reduction of ice shear strength by the superhydrophobic coating; and (D) is a statistical graph of the reduction of ice shear strength by the superhydrophobic coating. Figure 7 SEM images of physically mixed titanium dioxide particles and in-situ grown titanium dioxide particles are shown; where (A) represents physically mixed titanium dioxide particles and (B) represents in-situ grown titanium dioxide particles. Detailed Implementation

[0038] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0039] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0040] Example 1 In this embodiment, an aluminum plate is used as the substrate material, and a micro-nano composite superhydrophobic coating is prepared on its surface. The specific steps are as follows: The aluminum plate was placed in deionized water and anhydrous ethanol in sequence and subjected to ultrasonic treatment for 10 minutes each, then removed and dried.

[0041] One g of carboxylated carbon nanotubes was dispersed in 160 mL of 95% ethanol aqueous solution, followed by the addition of 10 mL of 99% glacial acetic acid solution and 10 mL of deionized water, and the mixture was ultrasonically dispersed for 30 min. Then, 2 mL of tetrabutyl titanate was added, and the mixture was stirred at 25 °C for 3 h. Next, 400 μL of perfluorooctyltriethoxysilane was added to the reaction system, and the mixture was stirred for 12 h. The mixture was then washed three times with ethanol solution, dried, and ground to obtain the modified composite particles.

[0042] A mixture of 1 g fluorocarbon resin and 0.1 g Covestro anti-yellowing curing agent (N3390) was added to 10 mL of ethyl acetate solution for dilution and labeled as solution A. A mixture of 1 g polydimethylmethylvinylsiloxane (H-PDMS) and 0.1 g crosslinking agent (V-PDMS) was added to 10 mL of ethyl acetate solution for dilution and labeled as solution B. 2 mL of solution B and 8 mL of solution A were mixed to obtain solution C. Subsequently, 0.22 g of modified composite particles were added to solution C to obtain a spraying solution. The spraying solution was ultrasonicated for 30 min to ensure uniform dispersion of the modified composite particles.

[0043] The aluminum substrate is heated to 50 ℃, the air pressure of the air compressor is controlled to 0.4 MPa, and then the above solution is sprayed onto the surface of the aluminum plate using a spraying device. The sprayed aluminum plate is then placed in an oven and heated at 200 ℃ for 20 min to obtain a superhydrophobic coating.

[0044] Figure 1 SEM images of carboxylated carbon nanotubes and in-situ grown titanium dioxide from carboxylated carbon nanotubes; where (A) is the SEM image of carboxylated carbon nanotubes and (B) is the SEM image of in-situ grown titanium dioxide from carboxylated carbon nanotubes. Figure 2 The image shows the contact angle test results of the superhydrophobic coating prepared in Example 1. Figure 2 As shown, the contact angle of the superhydrophobic material is 158°±1.8°, as measured by contact angle measurement.

[0045] Performance testing: (1) The drag reduction effect of the superhydrophobic coating was tested using a high-precision rheometer.

[0046] Aluminum plates were used as the substrate material. The specific testing method was as follows: Uncoated blank substrates and substrates coated with superhydrophobic coatings were respectively attached to the underside of the rheometer rotor, ensuring the distance between the sample and the bottom of the container was precisely 100 mm. Subsequently, the rotor speed was gradually increased over a period of 120 s, from 0 to 7.64 rpm, 15.28 rpm, 38.2 rpm, 95.5 rpm, 191 rpm, and 381 rpm. These speeds were then stabilized for a period of time to measure the torque experienced by the rotor during the stabilization process. By comparing the torque values ​​of the uncoated blank substrate and the superhydrophobic coated substrate under the same conditions, the drag reduction rate was calculated. Figure 3 The image shows the drag reduction effect of the superhydrophobic coating prepared in Example 1. Figure 3 As shown, analysis revealed that this superhydrophobic product exhibits drag reduction at the corresponding Reynolds numbers. The five rotational speeds mentioned in the text correspond to five Reynolds numbers, with drag reduction rates of 10.7%, 7.7%, 13.0%, 16.8%, 25.7%, and 5.4%, respectively.

[0047] (2) Adhesion test of Navicula spp. was used to verify the antifouling effect of the superhydrophobic coating.

[0048] The substrate material is aluminum plate, and the specific method is as follows: first, prepare a solution with a concentration of 1.5 × 10⁻⁶. 6 A suspension of *Novoidea* cells / mL was used to completely immerse both uncoated blank substrates and substrates coated with a superhydrophobic coating (sample size: 3 cm × 3 cm) in the suspension, and the samples were shaken at 25 °C for 7 days. After cultivation, the samples were washed with deionized water to remove any loosely attached algal cells, and both groups were fixed in 2.5% glutaraldehyde solution at 4 °C for 4 h. After fixation, the samples were sequentially dehydrated using ethanol-water solutions (concentrations of 70%, 80%, 90%, and 100%), with each concentration treated for 30 min. The samples were air-dried and analyzed using an electron microscope. The antifouling effect was evaluated by measuring the percentage of algal attachment area using ImageJ software. Figure 5 The images show the antifouling effect of the superhydrophobic coating prepared in Example 1; where (A) is a SEM image of the blank aluminum plate surface after Chlorella cultivation; (B) is a SEM image of the superhydrophobic coating surface after Chlorella cultivation; and (C) is a statistical result of the algal coverage on the two surfaces. Figure 5 As shown, Figure A is the blank group and Figure B is the superhydrophobic coating. They were cultured together in the genus *Novoidea* for 7 days. After 7 days of culture, SEM analysis and ImageJ statistics showed that 26.25% of the surface area of ​​the blank group was covered, while the surface of the superhydrophobic coating in Figure B had no (algae) characteristic shapes attached.

[0049] (3) The anti-corrosion effect of the superhydrophobic material surface was verified by using an electrochemical workstation for experimental testing.

[0050] The substrate material was an aluminum plate. The specific method was as follows: testing was conducted using a flat-plate electrolytic cell with a 3.5% sodium chloride solution as the electrolyte and a silver chloride electrode as the reference electrode. The measurement area was 1 cm² (sample size: 1 cm × 1 cm). 2 Set the EIS frequency range to 0.1-10. 5 Hz, EIS amplitude 10 mV, Tafel start and stop potentials: -0.5 V - 0.5 V, Tafel scan rate 1 mV / s, corrosion protection effect is evaluated by analyzing corrosion current density.

[0051] Figure 4 The images show the potentiodynamic polarization curves and Nyquist curves of the superhydrophobic coating prepared in Example 1; where (A) is the potentiodynamic polarization curve and (B) is the Nyquist curve. Figure 4 As shown in Figure A, analysis revealed that the corrosion potential of the blank group was -0.9388 V, and the corrosion current density was 1.239938086 × 10⁻⁶. -5 A·cm 2 The corrosion pitting voltage of the superhydrophobic coating group was -0.0564V, and the corrosion current density was 1.387075178 × 10⁻⁶. -13 A·cm 2 The results showed that the superhydrophobic coating reduced the corrosion current density of the aluminum plate by more than eight orders of magnitude. Figure 4 As shown in Figure B, the Nyquist plot reflects the barrier effect of the coating on the corrosive medium. The capacitive arc diameter of the superhydrophobic coating is significantly larger than that of the blank aluminum plate. The charge transfer resistance R of the coating can be obtained through ZSimpWin fitting. ct R ct R represents the kinetic parameters of the electrochemical reaction process. ct This is a kinetic parameter of the electrochemical reaction process, which is directly proportional to the active corrosion inhibition performance of the coating. Specifically, R0 is the kinetic parameter of the blank aluminum plate. ct 1.592×10 4 Ω·cm 2 R of superhydrophobic coating ct 2.167×10 15 Ω·cm 2 R much higher than that of pure copper sheets ct This indicates that the superhydrophobic coating has high impedance, strong charge transfer resistance and excellent barrier properties, which can effectively prevent corrosive media from penetrating the coating and reaching the metal substrate.

[0052] (4) Use deionized water low-temperature freezing test and de-icing test to verify the anti-icing effect of the superhydrophobic material surface.

[0053] The substrate material is aluminum plate. The specific method is as follows: drop 30 μL of deionized water on a blank substrate without coating and a substrate coated with superhydrophobic coating respectively, and observe the freezing time of deionized water at -15 ℃.

[0054] The specific testing method for the de-icing experiment is as follows: a copper ring is placed on a blank substrate without coating and a substrate coated with superhydrophobic coating. Vaseline is applied to the contact surface between the copper ring and the substrate. The copper ring is filled with deionized water and placed in an environment of -15 ℃ for 2 hours until it is completely solidified. The ring is then removed and the peak pulling force of the ice block is measured by a tensile tester to evaluate the anti-icing effect. Figure 6 The diagrams show the anti-icing and de-icing effects of the superhydrophobic coating prepared in Example 1; (A) is a schematic diagram of water droplet icing over time in the blank group; (B) is a schematic diagram of water droplet icing over time in the superhydrophobic coating group; (C) is a schematic diagram of the reduction of ice shear strength by the superhydrophobic coating group; and (D) is a statistical graph of the reduction of ice shear strength by the superhydrophobic coating group. Figure 6 As shown, the freezing time of the blank group was 196 seconds, and the freezing time of the superhydrophobic coating was 989 seconds. The comparison showed that the superhydrophobic coating could delay freezing by 13 minutes. The de-icing test showed that the superhydrophobic coating could reduce the de-icing shear strength by -50.28%.

[0055] Comparative Example 1: Titanium dioxide is not grown in situ. 1 g of carboxylated carbon nanotubes were mixed with 0.2 g of titanium dioxide particles and added to 160 mL of anhydrous ethanol. Then, 10 mL of deionized water and 10 mL of 99% glacial acetic acid were added and ultrasonically dispersed for 30 min. Then, 400 μL of perfluorooctyltriethoxysilane was added and the mixture was stirred for 12 h. The mixture was then washed three times with ethanol solution, dried, and ground to obtain the modified composite particles.

[0056] A mixture of 1 g fluorocarbon resin and 0.1 g Covestro anti-yellowing curing agent (N3390) was added to 10 mL of ethyl acetate solution for dilution and labeled as solution A. A mixture of 1 g polydimethylmethylvinylsiloxane (H-PDMS) and 0.1 g crosslinking agent (V-PDMS) was added to 10 mL of ethyl acetate solution for dilution and labeled as solution B. 2 mL of solution B and 8 mL of solution A were mixed to obtain solution C. Subsequently, 0.22 g of modified composite particles were added to solution C to obtain a spraying solution. The spraying solution was ultrasonicated for 30 min to ensure uniform dispersion of the modified composite particles.

[0057] The aluminum substrate is heated to 50 ℃, the air pressure of the air compressor is controlled to 0.4 MPa, and then the above solution is sprayed onto the surface of the aluminum plate using a spraying device. The sprayed aluminum plate is then placed in an oven and heated at 200 ℃ for 20 min to obtain a superhydrophobic coating.

[0058] Adding modified composite particles to the composite material can achieve a superhydrophobic effect, but the adhesion is extremely low. According to the international standard GB / T9286 (cross-cut test for paint and varnish films), the physically added titanium dioxide particles hinder the cross-linking of the resin, severely reducing the integrity of the coating itself, resulting in a discrete distribution of the coating on the substrate surface. After multiple tests with the tape, a large amount of coating peeled off from the substrate surface. Figure 7 SEM images of physically mixed titanium dioxide particles and in-situ grown titanium dioxide particles are shown; where (A) represents physically mixed titanium dioxide particles and (B) represents in-situ grown titanium dioxide particles. Figure 7 As shown in Figure A, the area shown exceeds 65%, and the adhesion level is defined as level 5. In contrast, the addition of in-situ grown titanium dioxide particles did not peel off after knife scratching and tape peeling. Figure 7 As shown in B, the adhesion level has also been improved to level 0. At the same time, through wear resistance tests until superhydrophobic failure, it can resist more than 130 more cycles compared to physically mixed titanium dioxide. Through electrochemical tests, the corrosion current density is reduced by 5 orders of magnitude compared to the physical mixture, and the anti-corrosion effect has been significantly improved.

[0059] Comparative Example 2: Using only fluorocarbon resin, without mixing in PDMS One g of carboxylated carbon nanotubes was dispersed in 160 mL of 95% ethanol aqueous solution, followed by the addition of 10 mL of 99% glacial acetic acid solution and 10 mL of deionized water, and the mixture was ultrasonically dispersed for 30 min. Then, 2 mL of tetrabutyl titanate was added, and the mixture was stirred at 25 °C for 3 h. Next, 400 μL of perfluorooctyltriethoxysilane was added to the reaction system, and the mixture was stirred for 12 h. The mixture was then washed three times with ethanol solution, dried, and ground to obtain the modified composite particles.

[0060] A mixture of 1 g of fluorocarbon resin and 0.1 g of Covestro anti-yellowing curing agent (N3390) was added to 10 mL of ethyl acetate solution for dilution, which was denoted as solution A. Then, 0.22 g of modified composite particles were added to solution A to obtain a spraying solution. The spraying solution was ultrasonicated for 30 min to ensure that the modified composite particles were evenly dispersed.

[0061] The aluminum substrate is heated to 50 ℃, the air pressure of the air compressor is controlled to 0.4 MPa, and then the above solution is sprayed onto the surface of the aluminum plate using a spraying device. The sprayed aluminum plate is then placed in an oven and heated at 200 ℃ for 20 min to obtain a superhydrophobic coating.

[0062] Experiments revealed that to achieve superhydrophobic properties using pure resin as the matrix material, the amount of modified composite particles needed to be doubled. After doubling the amount of modified composite particles, the adhesion level became level 3, while the wear resistance decreased. The composite matrix material could withstand more than 70 more cycles compared to the pure resin material.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multifunctional superhydrophobic coating based on in-situ grown nano-titanium dioxide, characterized in that, The superhydrophobic coating is composed of a coating matrix material and modified composite particles; The coating substrate material is a polymer; the polymer is selected from at least one of epoxy resin, fluorocarbon resin, fluorosilicone resin, and polydimethylsiloxane. The composite particles are carboxyl carbon nanotubes with titanium dioxide grown in situ on the surface. The modifier is a low surface energy silane, selected from perfluorooctyltriethoxysilane or perfluorodecyltriethoxysilane.

2. The superhydrophobic coating as described in claim 1, characterized in that, The polymer is selected from fluorocarbon resin and polydimethylsiloxane.

3. The superhydrophobic coating as described in claim 2, characterized in that, The mass ratio of fluorocarbon resin to polydimethylsiloxane is 3-5:

1.

4. The superhydrophobic coating as described in claim 1, characterized in that, The length of the carboxyl carbon nanotubes is 100-200 μm, and the particle size of the titanium dioxide grown in situ is 20-30 nm; or, the mass ratio of the modified composite particles to the coating matrix material is 0.2-0.3:

1.

5. The method for preparing the superhydrophobic coating as described in claim 1, characterized in that, Includes the following steps: (1) Disperse carboxylated carbon nanotubes in an ethanol aqueous solution, add glacial acetic acid solution and deionized water, and disperse by ultrasonication; then add tetrabutyl titanate, stir to react, then add modifier to react, and after the reaction is completed, wash, dry and grind to obtain modified composite particles; (2) Add the coating matrix material and crosslinking agent to the diluent, then add the modified composite particles prepared in step (1), and sonicate to make the modified composite particles disperse evenly. (3) After heating the substrate to the preset temperature, a diluted solution containing modified composite particles and coating matrix material is sprayed onto the substrate surface using a spray gun under preset pressure conditions. After the coating is cured and dried, a superhydrophobic coating is obtained.

6. The preparation method according to claim 5, characterized in that, In step (1), the ratio of carboxylated carbon nanotubes to tetrabutyl titanate is 1:1-3 g / mL; Alternatively, in step (1), the ratio of carboxyl carbon nanotubes to ethanol aqueous solution is 1:120-180 g / mL; Alternatively, in step (1), the volume ratio of glacial acetic acid solution to deionized water is 1:0.9-1.1; the volume ratio of glacial acetic acid solution to ethanol aqueous solution is 1:12-18. Alternatively, in step (1), the ultrasound time is 20-40 min; Alternatively, in step (1), the stirring reaction conditions are: stirring reaction at 20-30 ℃ for 2-4 h; Alternatively, in step (1), the ratio of modifier to carboxylated carbon nanotubes is 300-500:1 μL / g; Alternatively, in step (1), after adding the modifier, stir the reaction for 10-15 h.

7. The preparation method according to claim 5, characterized in that, In step (2), the crosslinking agent is V-PDMS and N3390 curing agent; Alternatively, in step (2), the diluent is ethyl acetate; Alternatively, in step (2), the mass ratio of the coating substrate material to the crosslinking agent is 5-15:1; Alternatively, in step (2), the coating substrate material is fluorocarbon resin and polydimethylmethylvinylsiloxane; the mass ratio of fluorocarbon resin and polydimethylmethylvinylsiloxane is 3-5:1; Alternatively, in step (2), the ultrasound time is 20-40 min.

8. The preparation method according to claim 5, characterized in that, In step (3), the preset temperature is 45-60 ℃; Alternatively, in step (3), the preset pressure is 0.2-0.5 MPa; Alternatively, in step (3), the drying conditions are 150-200 ℃ for 10-30 min.

9. The application of the superhydrophobic coating as described in any one of claims 1-4 in the fields of underwater drag reduction, anti-icing, and anti-corrosion.

10. The application as described in claim 9, characterized in that, The superhydrophobic coating exhibits a drag reduction rate of greater than 5% in water at 200-100000 Reynolds numbers; or, it can delay freezing time at temperatures as low as -15°C.

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