Photo-thermal super-hydrophobic material with stable chemical properties, high-adhesion photo-thermal super-hydrophobic coating resistant to acid, alkali and salt immersion and preparation method thereof

Abstract

The application discloses a kind of chemical property stable photo-thermal super-hydrophobic material, acid, alkali and salt soaking resistant high adhesion photo-thermal super-hydrophobic coating and preparation method thereof.The preparation method of material includes the following steps: polytetrafluoroethylene powder, copper oxide powder and multi-walled carbon nanotube are mixed, stirred uniformly, then high-temperature composite treatment is carried out, and the chemical property stable photo-thermal super-hydrophobic material is obtained.The application uses stable polytetrafluoroethylene (PTFE) powder, copper oxide (CuO) powder and multi-walled carbon nanotube (MWCNTs) as raw materials to prepare a stable ternary composite material by high-temperature compounding, which can be used as a chemical property stable photo-thermal super-hydrophobic material.Using the material, a photo-thermal super-hydrophobic coating with excellent photo-thermal conversion performance, high equilibrium temperature and excellent chemical stability in acid, alkali and salt soaking can be prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrophobic coatings, and in particular to a photothermal super-hydrophobic material with stable chemical properties, a high-adhesion photothermal super-hydrophobic coating resistant to acid, alkali and salt immersion, and a preparation method thereof. Background Art

[0002] Liquid droplets freeze at low temperatures. This icing phenomenon has significant adverse effects on industries such as power transmission, aviation, transportation, and wind power generation, necessitating the reduction of damage caused by icing. Currently, numerous technologies are being developed to address this issue, such as coating substrates with anti-icing / de-icing coatings. These include super-hydrophobic coatings and photothermal coatings. The former utilizes the resistance of super-hydrophobic surfaces to droplet adhesion, imparting passive anti-icing properties to the substrate surface. The latter utilizes the photothermal conversion properties of photothermal materials to impart active de-icing properties to the substrate under sunlight.

[0003] The use environment of the above-mentioned single-functional coating is limited. The superhydrophobic coating only has anti-icing properties and cannot actively remove the covering ice layer at ultra-low temperatures, thus losing its function. The liquid adhesion on the surface of the photothermal coating is still very strong, and the dust coverage will weaken its photothermal conversion performance. Therefore, the photothermal superhydrophobic coating that combines the two is expected to make up for the shortcomings of a single coating. Summary of the Invention

[0004] The main purpose of the present invention is to provide a photothermal super-hydrophobic material with stable chemical properties, a high-adhesion photothermal super-hydrophobic coating resistant to acid, alkali and salt immersion, and a preparation method thereof.

[0005] To achieve the above objectives, the present invention provides a method for preparing a photothermal super-hydrophobic material with stable chemical properties, comprising the following steps: mixing polytetrafluoroethylene powder, copper oxide powder and multi-walled carbon nanotubes, stirring evenly, and then subjecting them to high-temperature composite treatment to obtain the photothermal super-hydrophobic material with stable chemical properties.

[0006] Furthermore, the mass ratio of the polytetrafluoroethylene powder, the copper oxide powder and the multi-walled carbon nanotubes is 2:2.25:0.75.

[0007] Furthermore, the operation process of the high temperature composite treatment is: in an air atmosphere, heating from room temperature to 325°C at a heating rate of 1.5°C / min, then keeping at 325°C for 1 hour, and finally naturally cooling to room temperature.

[0008] The present invention also provides a photothermal super-hydrophobic material with stable chemical properties, which is prepared according to the above method.

[0009] The present invention also provides a method for preparing a high-adhesion photothermal super-hydrophobic coating that is resistant to acid, alkali and salt immersion, wherein the raw material is the above-mentioned photothermal super-hydrophobic material with stable chemical properties, and the method comprises the following steps:

[0010] (1) applying a polydimethylsiloxane coating on a substrate surface and semi-curing the coating to obtain a semi-cured polydimethylsiloxane coating;

[0011] (2) dissolving the chemically stable photothermal super-hydrophobic material in a solvent, adding polydimethylsiloxane and a curing agent, and stirring evenly to obtain a photothermal super-hydrophobic coating;

[0012] (3) Spraying the photothermal super-hydrophobic coating onto the semi-cured polydimethylsiloxane coating and performing a curing treatment to obtain the acid-alkali-salt immersion-resistant high-adhesion photothermal super-hydrophobic coating.

[0013] Furthermore, in step (1), the polydimethylsiloxane coating comprises polydimethylsiloxane, methylvinylcyclosiloxane and cyclohexane in a mass volume ratio of 1g:0.1g:1ml, and the semi-curing treatment is placed at room temperature for 30 minutes.

[0014] Furthermore, in step (2), the solvent is n-hexane, the curing agent is methyl vinyl cyclosiloxane, and the mass volume ratio of the chemically stable photothermal superhydrophobic material, polydimethylsiloxane, methyl vinyl cyclosiloxane and n-hexane is 0.5g:0.75g:0.075g:15ml.

[0015] Furthermore, in step (3), a 0.8 mm diameter atomizing spray gun is used for spraying, the spraying pressure is 0.2 kPa, and the spraying distance is 10 to 20 cm.

[0016] Furthermore, in step (3), the curing treatment is performed at 100° C. for 2 hours.

[0017] The present invention also provides a high-adhesion photothermal super-hydrophobic coating that is resistant to acid, alkali and salt immersion, which is prepared according to the above method.

[0018] The substrate of the present invention includes but is not limited to glass, wood, steel or ceramic sheets. The coating method includes but is not limited to spraying, brushing or spin coating, and different methods can be selected according to the shape of the substrate.

[0019] The beneficial effects of the present invention are embodied in:

[0020] The present invention uses stable polytetrafluoroethylene (PTFE) powder, copper oxide (CuO) powder and multi-walled carbon nanotubes (MWCNTs) as raw materials to prepare a stable ternary composite material through high-temperature compounding. The ternary composite material can be used as a chemically stable photothermal super-hydrophobic material. The photothermal super-hydrophobic coating can be prepared using the material, which has excellent photothermal conversion performance, a high equilibrium temperature, and can maintain excellent chemical stability even in acid, alkali and salt immersion. The preparation process does not involve corrosive chemical raw materials, which controls the preparation cost. The coating can also be applied by spraying, which is conducive to large-scale application.

[0021] The present invention utilizes different photothermal materials to cooperate with each other, and the coating can obtain a higher equilibrium temperature. 2 Under light conditions, the equilibrium temperature is as high as 137.3°C, the static contact angle is 155°, and the rolling angle is about 4.7°, which can greatly accelerate the process of photothermal deicing.

[0022] Compared with general photothermal coatings, the present invention has excellent superhydrophobic properties. It can combine active photothermal deicing performance with passive superhydrophobic anti-icing performance, and on the basis of greatly delaying the freezing of droplets on the coating surface, it gives the coating the ability to quickly remove the droplets after they are frozen with the help of light.

[0023] The multi-walled carbon nanotubes (MWCNTs) used in the present invention have high thermal conductivity, which gives the composite coating better thermal conductivity. On the one hand, it can enable the coating to obtain a faster heating rate under light, and on the other hand, it can enable the coating to transfer heat more quickly from the illuminated coating to the shaded non-illuminated coating, thereby achieving better outdoor performance.

[0024] The coating preparation method of the present invention does not involve the use of corrosive chemical reagents such as acids, bases and salts, and the preparation process is safe and environmentally friendly; the present invention uses a spraying method to prepare the coating, which is suitable for various substrate surfaces, has low cost, and is convenient for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The SEM images of the chemically stable photothermal superhydrophobic material prepared in Example 1 at different magnifications are shown.

[0026] Figure 2 SEM images of the high-adhesion photothermal super-hydrophobic coating resistant to acid, alkali and salt immersion prepared in Example 1 at different magnifications.

[0027] Figure 3 3D morphology and wetting performance test diagram of the high-adhesion photothermal superhydrophobic coating resistant to acid, alkali and salt immersion prepared in Example 1.

[0028] Figure 4These are photos of the high-adhesion photothermal super-hydrophobic coatings resistant to acid, alkali and salt immersion obtained in Example 1 (left) and Comparative Example 1 (right) after adhesion testing.

[0029] Figure 5 The high adhesion photothermal super hydrophobic coating resistant to acid, alkali and salt immersion prepared in Example 1 is 1kW / m 2 Temperature rise curve under lighting conditions.

[0030] Figure 6 This is a diagram of the droplet freezing process on the surface of the high-adhesion photothermal superhydrophobic coating resistant to acid, alkali and salt immersion obtained in Example 1 (six photos below) and its comparison with the surface of the glass slide (three photos above).

[0031] Figure 7 The high adhesion photothermal super hydrophobic coating resistant to acid, alkali and salt immersion obtained in Example 1 is in the absence of light (the three photos above) and 0.5kW / m 2 Photos of the melting process of frozen droplets under light conditions (three photos below).

[0032] Figure 8 This is a photo of the self-cleaning performance process of the high-adhesion photothermal super-hydrophobic coating resistant to acid, alkali and salt immersion prepared in Example 1.

[0033] Figure 9 This is the WCA diagram of the high-adhesion photothermal superhydrophobic coating resistant to acid, alkali and salt immersion obtained in Example 1 after acid, alkali and salt immersion.

[0034] Figure 10 The WCA test graph of the coating obtained in comparative example 2 and the coating at 1kW / m 2 Temperature rise curve under lighting conditions.

[0035] Figure 11 It is a WCA comparison chart of the coatings prepared in Example 1 and Comparative Examples 1, 3, and 4.

[0036] Figure 12 These are SEM images of the hydrophobic material (first from the left) and the coating (second and third from the left) prepared in Comparative Example 5.

[0037] Figure 13 This is a 3D surface morphology image of the coating prepared in Comparative Example 5.

[0038] Figure 14 The WCA side view of the coating obtained in Example 5 and the coating at 1kW / m 2 Temperature rise curve under lighting conditions. DETAILED DESCRIPTION

[0039] In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the following examples are given for illustration. It should be noted that the following examples do not limit the scope of protection claimed by the present invention.

[0040] Unless otherwise specified, the raw materials, reagents, or devices used in the following examples can be obtained from conventional commercial channels or by existing known methods. Unless otherwise specified, the methods used in the examples of the present invention are all methods known to those skilled in the art. Copper oxide (CuO) powder, average particle size 20 nm, purchased from Qinghe County Top Metal Materials Co., Ltd.; polytetrafluoroethylene (PTFE) powder, average particle size 500 nm, item A, brand TM9207, purchased from Dongguan Taotao Plastic Raw Materials Co., Ltd.; multi-walled carbon nanotubes (MWCNTs), inner diameter 3-5 nm, outer diameter 8-15 nm, length 5-15 μm, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.; polydimethylsiloxane (PDMS), brand Dow SYLGARD 184, purchased from Dow Chemical; methylvinylcyclosiloxane, purchased from Dow Corning Corporation in Midland, Michigan, USA.

[0041] Example 1

[0042] Preparation of high-adhesion photothermal superhydrophobic coating resistant to acid, alkali and salt immersion

[0043] (1) 2 g of polytetrafluoroethylene powder, 2.25 g of copper oxide powder and 0.75 g of multi-walled carbon nanotubes were taken in a crucible, stirred evenly, and then placed in a muffle furnace. In an air atmosphere, the mixture was heated from room temperature to 325 ° C at a heating rate of 1.5 ° C / min and kept at this temperature for 1 h. Finally, the mixture was naturally cooled to room temperature and ground to pass through a 300-mesh micron sieve to obtain a photothermal superhydrophobic material with stable chemical properties;

[0044] (2) 3 g of polydimethylsiloxane and 0.3 g of methylvinylcyclosiloxane were dissolved in 3 ml of cyclohexane and stirred to obtain a polydimethylsiloxane coating. The polydimethylsiloxane coating was spin-coated on a glass slide at a spin coating parameter of 3000 rpm for 30 s. The glass slide was then placed at room temperature for 30 min to obtain a semi-cured polydimethylsiloxane coating.

[0045] (3) Take 0.5g of chemically stable photothermal super-hydrophobic material in 15ml of n-hexane, add 0.75g of polydimethylsiloxane and 0.075g of methylvinylcyclosiloxane, ultrasonicate at room temperature for 0.5h, and then magnetically stir for 2h to obtain a photothermal super-hydrophobic coating;

[0046] (4) Use a 0.8 mm caliber atomizing spray gun to spray the photothermal superhydrophobic coating on the semi-cured polydimethylsiloxane coating with a spraying pressure of 0.2 MPa, a spraying distance of 15 cm, and a spraying time of 25 seconds. Finally, place it in an oven at 100°C for curing for 2 hours to obtain a high-adhesion photothermal superhydrophobic coating that is resistant to acid, alkali, and salt immersion, which is recorded as CPM@glass.

[0047] The SEM images of the chemically stable photothermal super-hydrophobic material prepared in this embodiment at different magnifications are shown in FIG. Figure 1 As shown, it can be seen that the smaller nano-CuO particles are coated with the larger polytetrafluoroethylene (PTFE) particles, and in the high-magnification picture, multi-walled carbon nanotubes can be seen interspersed therein.

[0048] The SEM image of the acid, alkali and salt immersion resistant high adhesion photothermal super hydrophobic coating prepared in this embodiment is as follows: Figure 2 As shown, it can be seen that the coating surface is very rough, and a rough micro-nano structure is formed on the coating surface. This micro-nano structure can capture air and form an air cushion structure, which is the source of the superhydrophobic property of the coating.

[0049] Figure 3 The 3D morphology and wetting performance test diagram of the high-adhesion photothermal super-hydrophobic coating resistant to acid, alkali and salt immersion prepared in this embodiment are shown. The surface roughness reaches 29.19 μm, the WCA is about 155°, and the WSA is about 4.7°.

[0050] Figure 4 In the figure on the left, the appearance of the acid-, alkali- and salt-resistant high-adhesion photothermal superhydrophobic coating prepared in this embodiment after adhesion test (adhesion test method: use a grid test knife to cut a set of horizontal and vertical grid lines on the sample surface. The cutting depth should penetrate the coating to reach the substrate; use a soft brush or air pressure spray gun to gently remove the coating in the grid area; adhere the tape to the coating and tear it off at a uniform speed; carefully observe the grid area after cutting to check whether the coating has peeling, blistering or other adhesion problems. According to relevant standards or specifications (GB / T9286), the adhesion of the coating is evaluated). The adhesion level of the coating in Example 1 is between 0 and 1, and the adhesion level of the coating in Comparative Example 1 is 2.

[0051] Figure 5 The photothermal performance test diagram of the acid, alkali and salt immersion-resistant high-adhesion photothermal super-hydrophobic coating prepared in this embodiment, the test condition is 1kW / m 2 The light intensity was 500 nm, and after 5 minutes of light heating, the coating temperature stabilized at around 139.6°C, proving that the coating has excellent light-to-heat conversion performance.

[0052] Figure 6The passive anti-icing performance of the high-adhesion photothermal superhydrophobic coating resistant to acid, alkali and salt immersion prepared in this example is demonstrated. The coating is placed on a refrigeration platform that can be cooled to -20°C, and a 10μL droplet is placed on the coating. The photos and time of the droplet freezing process are recorded. Using a glass slide as a control group, it can be seen that the droplets on the surface of the glass slide are diffuse and completely frozen in the 30th second, while the droplets on the coating surface are spherical and completely frozen in the 220th second. The complete freezing time is significantly extended by 633% compared with the glass slide.

[0053] Figure 7 The photothermal deicing performance of the high-adhesion photothermal super-hydrophobic coating prepared in this example is demonstrated. In the figure, the frozen droplet is formed by fully freezing a 10μL droplet on a refrigeration platform. Under no light conditions, the frozen droplet completely melts in the 110th second. 2 Under light conditions, the frost around the frozen droplets completely melted in 16 seconds, and the frozen droplets completely melted in 56 seconds;

[0054] Figure 8 The super-hydrophobic self-cleaning performance of the high-adhesion photothermal super-hydrophobic coating resistant to acid, alkali and salt immersion prepared in this embodiment is demonstrated. It can be seen that the dust pollutants on the surface of the coating are easily carried away by the rolling droplets.

[0055] Figure 9 It is demonstrated that the high-adhesion photothermal superhydrophobic coating resistant to acid, alkali and salt immersion prepared in this embodiment still maintains superhydrophobic properties after being immersed in acid (PH=1) and alkali (PH=13) salt (3.5% NaCl solution) for 24 hours, indicating that the coating has excellent chemical stability.

[0056] Comparative Example 1

[0057] In this comparative example, a coating was prepared in the same manner as in Example 1, with the only difference being that in step (1), the amount of copper oxide powder was adjusted to 2 g, and the amount of multi-walled carbon nanotubes was adjusted to 1 g.

[0058] The adhesion test of the coating prepared in this comparative example was carried out according to the test method in Example 1. It was found that the adhesion of the coating prepared in this comparative example to the substrate decreased. Figure 4 As shown in the middle right figure, the WCA of the coating is 156.3°. Figure 11 shown.

[0059] Comparative Example 2

[0060] In this comparative example, a coating was prepared in the same manner as in Example 1, with the only difference being that in step (1), the addition of multi-walled carbon nanotubes was omitted, and only 2 g of polytetrafluoroethylene powder and 3 g of copper oxide powder were added.

[0061] The coating prepared in this comparative example was tested according to the test method in Example 1, and the results are as follows: Figure 10 As shown, it is found that the coating prepared in this comparative example does not have super hydrophobic properties, but still has photothermal properties due to the presence of CuO powder. The WCA of the coating is only 86.6° at 1kW / m 2 Under light conditions, the equilibrium temperature of the coating is 108.9℃.

[0062] Comparative Example 3

[0063] In this comparative example, a coating was prepared in the same manner as in Example 1, with the only difference being that in step (1), the amount of copper oxide powder was adjusted to 2.75 g, and the amount of multi-walled carbon nanotubes was adjusted to 0.25 g.

[0064] The coating prepared in this comparative example was tested according to the test method in Example 1, and it was found that the coating WCA was 99.9°. Figure 11 shown.

[0065] Comparative Example 4

[0066] In this comparative example, a coating was prepared in the same manner as in Example 1, with the only difference being that in step (1), the amount of copper oxide powder was adjusted to 2.5 g, and the amount of multi-walled carbon nanotubes was adjusted to 0.5 g.

[0067] The coating prepared in this comparative example was tested according to the test method in Example 1, and it was found that the coating WCA was 136.7°. Figure 11 shown.

[0068] Comparative Example 5

[0069] In this comparative example, the coating was prepared in the same manner as in Example 1, with the only difference being that the high-temperature compounding process in the muffle furnace was omitted in step (1).

[0070] The SEM images of the hydrophobic material prepared in step (1) of this comparative example and the coating finally prepared are as follows: Figure 12 As shown, the 3D morphology of the coating is shown in Figure 13 As shown, at 1kW / m 2 Under light conditions, the WCA of the coating is 83.6° and the equilibrium temperature is 98.3°C. Figure 14 shown.

[0071] In summary:

[0072] By comparing Example 1 and Comparative Example 2, it can be concluded that the introduction of multi-walled carbon nanotubes (MWCNTs) can not only improve the light-to-heat conversion performance of the coating prepared from the material, but also improve the hydrophobicity of the coating prepared from the material;

[0073] It can be concluded from Example 1 and Comparative Example 1 that excessive multi-walled carbon nanotubes (MWCNTs) will reduce the adhesion between the photothermal superhydrophobic coating and the substrate;

[0074] It can be concluded from Example 1 and Comparative Example 5 that Figure 1 (first from left) and Figure 12 (First from the left) The SEM image of the material shows that the high-temperature compounding of the three powders can make the material nearly spherical, while the powders of the materials directly mixed are disordered. This nearly regular spherical powder can make the prepared coating have a larger light absorption area, making the coating's photothermal effect better, such as Figure 5 and Figure 14 As shown, this also makes the prepared coating show higher roughness. Figure 2 and Figure 12 The SEM images of the coatings clearly show that the coating in Example 1 has a higher roughness. Figure 3 and Figure 13 As shown, the 3D surface morphology of the coating further verifies that the coating in Example 1 has a higher roughness, and the higher roughness makes the coating have better hydrophobic properties;

[0075] It can be seen from Example 1 and Comparative Examples 1, 3, and 4 that the ratio of PTFE powder, CuO powder, and MWCNTs affects the hydrophobicity and photothermal properties of the final coating. A suitable ratio can make the coating have excellent superhydrophobicity, photothermal properties, and adhesion of the coating to the substrate.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a high-adhesion photothermal super-hydrophobic coating resistant to acid, alkali and salt immersion, characterized in that: The raw materials are photothermal super-hydrophobic materials with stable chemical properties, including the following steps: (1) coating the polydimethylsiloxane coating on the surface of the substrate and semi-curing the coating to obtain a semi-cured polydimethylsiloxane coating; (2) dissolving the chemically stable photothermal super-hydrophobic material in a solvent, adding polydimethylsiloxane and a curing agent, and stirring evenly to obtain a photothermal super-hydrophobic coating; The preparation method of the chemically stable photothermal super-hydrophobic material comprises the following steps: mixing polytetrafluoroethylene powder, copper oxide powder and multi-walled carbon nanotubes, wherein the mass ratio of the polytetrafluoroethylene powder, the copper oxide powder and the multi-walled carbon nanotubes is 2:2.25:0.75; stirring evenly, and then performing high-temperature composite treatment to obtain the chemically stable photothermal super-hydrophobic material; The operation process of high temperature composite treatment is as follows: in air atmosphere, heating from room temperature to 325℃ at a heating rate of 1.5℃ / min, then keeping at 325℃ for 1h, and finally cooling naturally to room temperature; (3) Spraying the photothermal super-hydrophobic coating onto the semi-cured polydimethylsiloxane coating and performing a curing treatment to obtain the acid-alkali-salt immersion-resistant high-adhesion photothermal super-hydrophobic coating.

2. The method for preparing a high-adhesion photothermal super-hydrophobic coating resistant to acid and alkali salt immersion as claimed in claim 1, wherein In step (1), the polydimethylsiloxane coating comprises polydimethylsiloxane, methylvinylcyclosiloxane and cyclohexane in a mass volume ratio of 1 g:0.1 g:1 mL, and the semi-curing treatment is to place the coating at room temperature for 30 minutes.

3. the preparation method of the high adhesion photothermal super hydrophobic coating of acid and alkali salt immersion as claimed in claim 1 or 2, is characterized in that, In step (2), the solvent is n-hexane, the curing agent is methyl vinyl cyclosiloxane, and the mass volume ratio of the chemically stable photothermal superhydrophobic material, polydimethylsiloxane, methyl vinyl cyclosiloxane and n-hexane is 0.5 g:0.75 g:0.075 g:15 mL.

4. The preparation method of the high-adhesion photothermal super-hydrophobic coating resistant to acid and alkali salt immersion as claimed in claim 1 or 2, wherein In step (3), a 0.8 mm diameter atomizing spray gun is used for spraying, the spraying pressure is 0.2 kPa, and the spraying distance is 10 to 20 cm.

5. the preparation method of the high adhesion photothermal super hydrophobic coating of acid and alkali salt immersion as claimed in claim 1 or 2, is characterized in that, In step (3), the curing treatment is performed at 100°C for 2 hours.

6. A high-adhesion photothermal super-hydrophobic coating resistant to acid, alkali and salt immersion, characterized in that: Prepared according to the method according to any one of claims 1 to 5.

Images