Environmentally friendly durable super-slippery superhydrophobic coating and method of making the same

Abstract

The application discloses an environment-friendly and durable super-slippery super-hydrophobic coating and a preparation method thereof. The coating takes a zirconium-based metal organic framework material UIO-66 as a carrier, utilizes the characteristics of the regular structure and rich pores of the material, coats a layer of polydimethylsiloxane (PDMS) as a low surface energy and adhesive on the outer layer, and after one-step calcination for a specific time, the UIO-66 and the PDMS are partially decomposed to generate ZrO2-SiO2 composite particles, while the three-dimensional network structure of the UIO-66 is reserved. The unique porous structure makes the coating have a water contact angle greater than 160 degrees and a rolling angle less than 3 degrees, and the coating has the characteristics of super-slippery super-hydrophobicity. The product has the characteristics of fluorine-free environmental protection, simple process and economic efficiency, and is suitable for various high-temperature-resistant surfaces and has good universality.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of super-hydrophobic materials, and particularly relates to an environmentally-friendly and durable super-slippery super-hydrophobic coating and a preparation method thereof. BACKGROUND

[0002] There are many surfaces with special wettability in nature. In addition to lotus leaves, many other biological surfaces have super-hydrophobicity, such as mosquito compound eyes, water strider legs, butterfly wings, gecko footpads, and desert crustacean backs. In recent years, researchers have applied the micro-nano structures of these biological surfaces to various substrate surfaces to endow them with super-hydrophobicity. Generally speaking, a surface with a water droplet contact angle ≥ 150° and a rolling angle ≤ 10° is called a super-hydrophobic surface. A super-hydrophobic surface generally has two characteristics: a certain degree of roughness and low surface energy. For a super-hydrophobic surface, how to design the micro-nano roughness of the coating is the key. Good roughness can significantly improve the surface contact angle and reduce the sliding angle to make the water droplets quickly slide off. At the same time, the selection of the material will also determine the performance of the super-hydrophobic coating. At present, metal oxides (ZnO, Al2O3, Fe3O4, SiO2) and other nanoparticles are the most commonly used particles for constructing super-hydrophobic coatings. Researchers often use one or more particles to combine to construct micro-nano structures. Compared with the above commonly used metal oxides, ZrO2 has high-temperature chemical stability, corrosion resistance, oxidation resistance, thermal shock resistance, non-volatility, and no pollution. Its acid and alkali corrosion resistance is much stronger than that of SiO2 and Al2O3. Moreover, ZrO2 nanoparticles are relatively less used in the field of super-hydrophobicity, and are of great application value.

[0003] At present, there are still key technical problems in the research on the durability and stability of super-hydrophobic coatings: most commonly used particles are easily eroded by the external environment due to their active properties, which leads to the destruction of the coating and the loss of super-hydrophobic effect. In addition, a large part of low-surface-energy materials are fluorine-containing modifiers, which are expensive and can poison the human body and cause great pollution to the environment. On the other hand, most super-hydrophobic coating preparation processes are complicated, and the production cost is high. At present, they are still only at the laboratory research stage and have not been industrialized for mass production. Finally, the liquid-repellent performance of the coating is unstable, the rolling angle is still large, and the rolling angle increases after long-term use, which leads to the retention of water droplets on the coating, and the water droplets cannot normally roll off on relatively flat surfaces, and so on.

[0004] Therefore, it is of great significance to construct an environmentally-friendly super-slippery super-hydrophobic coating that is firm, chemically stable, and simple to prepare. SUMMARY

[0005] To address the aforementioned problems, the present invention aims to provide an environmentally friendly and durable ultra-slip superhydrophobic coating and its preparation method. This coating incorporates two materials: a novel and stable zirconium-based metal-organic framework, UIO-66, and fluorine-free polydimethylsiloxane (PDMS). After high-temperature calcination, the materials partially decompose, generating a stable porous mesh-like ZrO2-SiO2@PDMS composite coating. This coating features low raw material costs, a simple preparation process, is environmentally friendly and pollution-free, stable and durable, and due to its unique structure, it possesses excellent superhydrophobic properties (contact angle >160°, roll-off angle <3°), allowing water droplets to easily roll off the coating, resulting in an ultra-slip effect. This coating is widely applicable to high-temperature resistant substrates such as copper plates, stainless steel mesh, glass, and alloy plates, and is suitable for large-scale industrial production.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for preparing an environmentally friendly and durable ultra-slippery superhydrophobic coating, characterized by comprising the following steps:

[0008] (1) Add UIO-66 particles and PDMS to n-hexane, and disperse by ultrasonication to obtain a suspension;

[0009] (2) Spray the suspension obtained in step (1) onto the substrate, or immerse the substrate in the suspension and dry it to obtain a substrate covered with UIO-66@PDMS coating;

[0010] (3) The substrate covered with UIO-66@PDMS coating obtained in step (2) is calcined and then cooled to obtain an extremely slippery ZrO2-SiO2@PDMS coating.

[0011] Preferably, the mass ratio of UIO-66 particles to PDMS in step (1) is 1:(1-3); the type of PDMS is SYLGARD 184.

[0012] Preferably, the ultrasonic dispersion time in step (1) is 0.5 to 1 hour.

[0013] Preferably, the soaking time in step (2) is 1 to 6 hours.

[0014] Preferably, the drying temperature in step (2) is 80-120°C and the drying time is 1-3 hours.

[0015] Preferably, the calcination temperature in step (3) is 350-500℃ and the calcination time is 2 min-2 h.

[0016] Preferably, the UIO-66 particles in step (1) are prepared by the following method: zirconium oxide, terephthalic acid and acetic acid are added to N,N-dimethylformamide, ultrasonically treated and stirred, heated, cooled and centrifuged to dry to obtain UIO-66 particles.

[0017] Preferably, the ultrasonic treatment time is 10-20 min, the stirring time is 30 min-1 h, the heating temperature is 120-150 °C, and the heating time is 6-48 h.

[0018] Preferably, the substrate is one or more of glass, alloy, copper sheet, and stainless steel mesh.

[0019] The method described in this invention produces an extremely slippery superhydrophobic coating.

[0020] The superhydrophobic material of this invention has an extremely low roll-off angle, does not adhere to water, and can be used for antifouling on high-temperature surfaces, such as metal sheets, alloys, and glass. When used in building wall materials, this invention provides excellent self-cleaning properties, effectively addressing issues like humid weather in the south and wall icing in northern winters, offering excellent moisture-proof and anti-condensation effects. When used in exterior coatings for automobiles, trains, and airplanes, this invention allows water droplets to quickly slide off and carry away dust during rain and snow, leaving no water stains and providing excellent anti-icing properties. When used on ship surfaces, this invention reduces drag and provides corrosion protection, and the porous structure of the coating facilitates the formation of a thin air cushion between the coating and the substrate, achieving a load-bearing effect. Furthermore, when used in the casings of electronic devices such as computers, mobile phones, and cameras, this invention effectively isolates common aqueous solutions such as milk, coffee, juice, and cola, improving the antifouling and waterproof functions of these devices.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] (1) The coating preparation process of the present invention is simple and the raw materials are cheap and readily available; the use of fluorine-free low surface energy modifiers greatly reduces the risk of environmental pollution.

[0023] (2) The coating of the present invention has excellent superhydrophobic properties, with a water contact angle of up to 160° and a roll-off angle as low as 2°. Water droplets can easily roll off the coating surface and will not remain on the surface.

[0024] (3) The coating of the present invention is based on porous ZrO2-SiO2 composite particles with a micro-nano composite structure obtained by high-temperature decomposition of UIO-66 and polydimethylsiloxane. The polydimethylsiloxane wrapped on the outer surface of the ZrO2-SiO2 composite particles further improves the roughness of the coating and enhances the adhesion of the particles to the substrate. Figure 1This coating is widely applicable to high-temperature resistant substrates and has advantages such as good durability and long service life.

[0025] (4) Compared with traditional methods for preparing oxides, the metal-organic framework (MOF) pyrolysis method used in this invention is a simple method for controlling the morphology, composition, pore structure, and particle size of oxides. UIO-66, as a MOF material with a regular structure, high chemical stability, and hexagonal pore structure, can decompose at high temperatures to generate porous nano-ZrO2, while retaining the characteristics of UIO-66 such as high specific surface area, uniformly distributed metal sites, and high tunability. Furthermore, the extremely slippery superhydrophobic coating of this invention can be widely applied in various fields such as building materials, transportation, and energy chemicals, showing broad application prospects in self-cleaning, corrosion prevention, and anti-condensation of metal surfaces. Attached Figure Description

[0026] Figure 1 The image shows a scanning electron microscope (SEM) image of the stainless steel mesh with an extremely slippery superhydrophobic coating prepared in Example 1. The upper right corner of the image shows the contact angle value and image of a water droplet on its surface.

[0027] Figure 2 The images are scanning electron microscope (SEM) images of the porous ZrO2-SiO2@PDMS structure in the coating prepared in Example 1, magnified 5000x (left) and 50000x (right).

[0028] Figure 3 An optical photograph of a water droplet on the surface of a stainless steel mesh with an extremely slippery superhydrophobic coating, prepared in Example 1.

[0029] Figure 4 An optical photograph of a water droplet on the surface of a glass slide with an extremely slippery superhydrophobic coating, prepared in Example 2.

[0030] Figure 5 An optical photograph of a water droplet on the surface of a copper sheet with an extremely slippery superhydrophobic coating, prepared in Example 3.

[0031] Figure 6 An optical photograph of a water droplet on the surface of an alloy sheet with an extremely slippery superhydrophobic coating, prepared in Example 4.

[0032] Figure 7 The images show the self-cleaning effect of water droplets on the stainless steel mesh with an extremely slippery superhydrophobic coating prepared in Example 1. The left, middle, and right images are photos before, during, and after water droplets are applied, respectively. In each image, the superhydrophobic stainless steel mesh is placed on the upper side, and the original stainless steel mesh is placed on the lower side. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. All raw materials involved in the present invention can be purchased directly from the market. For process parameters not specifically specified, conventional techniques can be referred to.

[0034] The UIO-66 used in the following examples was prepared by the following method: Zirconium chloride powder and terephthalic acid powder were dissolved in N,N-dimethylformamide, acetic acid was added as a catalyst, the suspension was sonicated for 15 min, stirred in a magnetic stirrer for 45 min, transferred to a high-pressure hydrothermal autoclave and heated in a drying oven at 130°C for 24 h, then removed, cooled to room temperature, and centrifuged to obtain UIO-66 powder.

[0035] Example 1

[0036] The preparation method of this embodiment includes the following steps:

[0037] (1) Substrate treatment: The stainless steel mesh was ultrasonically cleaned with deionized water, anhydrous ethanol and acetone respectively. The stainless steel mesh size was 3×3cm. It was then dried and set aside.

[0038] (2) Preparation of UIO-66@PDMS coating: Weigh 0.1g of UIO-66 and disperse it in n-hexane solution, add 0.2g of PDMS and 0.02g of curing agent, and ultrasonically disperse for 30min to obtain a uniform UIO-66@PDMS suspension. Spray the suspension onto the stainless steel mesh described in step (1) using a spray gun, and cure at 80℃ for 1h to obtain the UIO-66@PDMS coating. In this embodiment of the invention, the PDMS is Dow Corning SYLGARD 184, a two-component product consisting of PDMS prepolymer and curing agent, and the mass ratio of PDMS prepolymer to curing agent is 10:1 when used.

[0039] (3) Preparation of ZrO2-SiO2@PDMS coating: The UIO-66@PDMS stainless steel mesh obtained in step (2) is placed in a muffle furnace and calcined at 400℃ for 4 min. After cooling, the extremely smooth ZrO2-SiO2@PDMS stainless steel mesh can be obtained.

[0040] like Figure 3 As shown, water droplets on the surface of the superhydrophobic stainless steel mesh prepared by spraying form approximately spherical shapes. The water contact angle is measured to be 163.8° and the roll-off angle is 2.6°, demonstrating excellent superhydrophobic properties.

[0041] Example 2

[0042] The preparation method of this embodiment includes the following steps:

[0043] (1) Substrate treatment: The glass slides were ultrasonically cleaned with deionized water, anhydrous ethanol and acetone respectively. The size of the glass slides was 2.6×7.6cm. They were then dried and ready for use.

[0044] (2) Preparation of UIO-66@PDMS coating: Weigh 0.2g of UIO-66 and disperse it in n-hexane solution, add 0.4g of PDMS and 0.04g of curing agent, and ultrasonically disperse for 40min to obtain a uniform UIO-66@PDMS suspension. Spray the suspension onto the glass slide described in step (1) using a spray gun, and cure at 85℃ for 1h to obtain the UIO-66@PDMS coating.

[0045] (3) Preparation of ZrO2-SiO2@PDMS coating: The UIO-66@PDMS stainless steel mesh obtained in step (2) is placed in a muffle furnace and calcined at 420°C for 10 min. After cooling, the extremely smooth ZrO2-SiO2@PDMS glass slide can be obtained.

[0046] like Figure 4 As shown, water droplets on the surface of a superhydrophobic glass slide prepared by spraying form approximately spherical shapes. The water contact angle is measured to be 161.6° and the roll-off angle is 2.2°, demonstrating excellent superhydrophobic properties.

[0047] Example 3

[0048] The preparation method of this embodiment includes the following steps:

[0049] (1) Substrate treatment: The copper sheet was ultrasonically cleaned with deionized water, anhydrous ethanol and acetone respectively. The copper sheet size was 3×3cm. It was then dried and set aside.

[0050] (2) Preparation of UIO-66@PDMS coating: Weigh 0.3g of UIO-66 and disperse it in n-hexane solution, add 0.6g of PDMS and 0.06g of curing agent, and ultrasonically disperse for 50min to obtain a uniform UIO-66@PDMS suspension. Spray the suspension onto the copper sheet described in step (1) using a spray gun, and cure at 90℃ for 2h to obtain the UIO-66@PDMS coating.

[0051] (3) Preparation of ZrO2-SiO2@PDMS coating: The UIO-66@PDMS copper sheet obtained in step (2) is placed in a muffle furnace and calcined at 440℃ for 30 min. After cooling, the extremely smooth ZrO2-SiO2@PDMS copper sheet can be obtained.

[0052] like Figure 4 As shown, water droplets on the surface of the superhydrophobic copper sheet prepared by spraying form approximately spherical shapes. The water contact angle is measured to be 160.1° and the roll-off angle is 2.6°, demonstrating excellent superhydrophobic properties.

[0053] Example 4

[0054] The preparation method of this embodiment includes the following steps:

[0055] (1) Substrate treatment: The alloy sheet was ultrasonically cleaned with deionized water, anhydrous ethanol and acetone respectively. The alloy sheet was 3×3cm in size and dried for later use.

[0056] (2) Preparation of UIO-66@PDMS coating: Weigh 0.4g of UIO-66 and disperse it in n-hexane solution, add 0.80g of PDMS and 0.08g of curing agent, and ultrasonically disperse for 1h to obtain a uniform UIO-66@PDMS suspension. Spray the suspension onto the alloy sheet described in step (1) with a spray gun and cure at 100℃ for 2h to obtain the UIO-66@PDMS coating.

[0057] (3) Preparation of ZrO2-SiO2@PDMS coating: The UIO-66@PDMS alloy sheet obtained in step (2) is placed in a muffle furnace and calcined at 460°C for 1 hour. After cooling, the extremely smooth ZrO2-SiO2@PDMS alloy sheet can be obtained.

[0058] like Figure 4 As shown, water droplets on the surface of the superhydrophobic alloy sheet prepared by spraying form approximately spherical shapes. The water contact angle is measured to be 160.3° and the roll-off angle is 2.1°, demonstrating excellent superhydrophobic properties.

[0059] Example 5

[0060] The preparation method of this embodiment includes the following steps:

[0061] (1) Substrate treatment: The stainless steel mesh was ultrasonically cleaned with deionized water, anhydrous ethanol and acetone respectively. The stainless steel mesh size was 3×3cm. It was then dried and set aside.

[0062] (2) Preparation of UIO-66@PDMS coating: Weigh 0.5g of UIO-66 and disperse it in n-hexane solution, add 1g of PDMS and 0.1g of curing agent, and ultrasonically disperse for 1h to obtain a uniform UIO-66@PDMS suspension. Immerse the stainless steel mesh described in step (1) in the suspension, continue ultrasonication for 1h, and then cure at 120℃ for 2h to obtain UIO-66@PDMS stainless steel mesh.

[0063] (3) Preparation of ZrO2-SiO2@PDMS coating: The UIO-66@PDMS stainless steel mesh obtained in step (2) is placed in a muffle furnace at 480℃ and calcined for 1 hour. After cooling, the extremely smooth ZrO2-SiO2@PDMS stainless steel mesh can be obtained.

[0064] Measurements showed that the water contact angle of the superhydrophobic stainless steel mesh prepared by dip coating was 162.1° and the roll-off angle was 2.5°, demonstrating excellent superhydrophobic properties.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an environmentally durable, extremely slippery, superhydrophobic coating, characterized in that, The method comprises the following steps: (1) adding UIO-66 particles and PDMS into n-hexane, and obtaining a suspension after ultrasonic dispersion; the UIO-66 particles are prepared by the following method: adding zirconium oxide, terephthalic acid and acetic acid into N,N-dimethylformamide, stirring after ultrasonic treatment, heating, cooling, centrifugal drying to obtain UIO-66 particles; (2) spraying the suspension obtained in step (1) onto a substrate, or immersing the substrate in the suspension, and drying to obtain a substrate covered with UIO-66@PDMS coating; (3) calcining the substrate covered with UIO-66@PDMS coating obtained in step (2) and cooling to obtain an extremely smooth ZrO2-SiO2@PDMS coating.

2. The production method according to claim 1, characterized by, The mass ratio of the UIO-66 particles to PDMS in step (1) is 1:(1-3); the type of the PDMS is SYLGARD 184.

3. The production method according to claim 2, characterized by, The ultrasonic dispersion time in step (1) is 0.5-1 h.

4. The production method according to claim 3, characterized by, The immersion time in step (2) is 1-6 h.

5. The preparation method according to claim 4, characterized in that, The drying temperature in step (2) is 80-120℃, and the drying time is 1-3 h.

6. The production method according to claim 5, wherein The calcination temperature in step (3) is 350-500℃, and the calcination time is 2 min-2 h.

7. The method of any one of claims 1 to 6, wherein the method further comprises the step of: The ultrasonic treatment time is 10-20 min, the stirring time is 30 min-1 h, the heating temperature is 120-150℃, and the heating time is 6-48 h. ​ 8. The method of claim 7, wherein, The substrate is one or more of glass, alloy, copper sheet and stainless steel mesh.

9. An environmentally friendly and durable extremely smooth super-hydrophobic coating prepared by the method of any one of claims 1-8.

Images