Photo-thermal super-hydrophobic material with stable chemical property, photo-thermal super-hydrophobic coating resistant to acid, alkali and salt soaking and high in adhesive force and preparation method of photo-thermal super-hydrophobic coating

Abstract

The invention discloses a photo-thermal super-hydrophobic material with stable chemical properties, a photo-thermal super-hydrophobic coating resistant to acid, alkali and salt soaking and high in adhesive force and a preparation method of the photo-thermal super-hydrophobic coating. The preparation method of the material comprises the following steps: mixing polytetrafluoroethylene powder, copper oxide powder and multi-walled carbon nanotubes, uniformly stirring, and then carrying out high-temperature composite treatment to obtain the photo-thermal super-hydrophobic material with stable chemical properties. According to the invention, polytetrafluoroethylene (PTFE) powder, copper oxide (CuO) powder and multi-walled carbon nanotubes (MWCNTs) with stable properties are used as raw materials to prepare a stable ternary composite material through high-temperature compounding, and the ternary composite material can be used as a photo-thermal super-hydrophobic material with stable chemical properties; the material can be used for preparing the photo-thermal super-hydrophobic coating which is excellent in photo-thermal conversion performance, high in equilibrium temperature and capable of still keeping excellent chemical stability in acid, alkali and salt soaking.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrophobic coatings, and particularly to a chemically stable photothermal superhydrophobic material, a highly adhesive photothermal superhydrophobic coating resistant to acid, alkali, and salt immersion, and a preparation method thereof. Background Art

[0002] Droplets will freeze at low temperatures, and this icing phenomenon has a great adverse impact on industries such as power transmission, aviation, transportation, and wind power generation. It is necessary to reduce the damage caused by icing. Currently, many technologies have focused on anti-icing / de-icing, such as coating an anti-icing / de-icing coating on the surface of a substrate, specifically including superhydrophobic coatings and photothermal coatings, etc. The former makes the substrate surface have passive anti-icing performance by using the property that droplets are difficult to adhere to the superhydrophobic surface, and the latter can make the substrate have active de-icing performance under sunlight irradiation by using the photothermal conversion performance of the photothermal material.

[0003] The use environment of the above single-functional coatings is limited. The superhydrophobic coating only has anti-icing characteristics and cannot actively remove the covered ice layer at ultra-low temperatures and loses its function. The liquid adhesion on the surface of the photothermal coating is still very large, and dust coverage will weaken its photothermal conversion performance. Therefore, a photothermal superhydrophobic coating combining the two is expected to make up for the deficiencies of the single coating. Summary of the Invention

[0004] The main object of the present invention is to provide a chemically stable photothermal superhydrophobic material, a highly adhesive photothermal superhydrophobic coating resistant to acid, alkali, and salt immersion, and a preparation method thereof.

[0005] To achieve the above object, the present invention provides a preparation method of a chemically stable photothermal superhydrophobic material, including the following steps: mixing polytetrafluoroethylene powder, copper oxide powder, and multi-walled carbon nanotubes, stirring evenly, and then performing high-temperature composite treatment to obtain the chemically stable photothermal superhydrophobic material.

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

[0007] Further, 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 holding at 325°C for 1 h, and finally naturally cooling to room temperature.

[0008] The present invention also provides a chemically stable photothermal superhydrophobic material prepared by the above method.

[0009] The present invention also provides a preparation method of a highly adhesive photothermal superhydrophobic coating resistant to acid, alkali, and salt immersion. The raw material uses the above chemically stable photothermal superhydrophobic material, including the following steps:

[0010] (1) Coat the surface of the substrate with polydimethylsiloxane coating and perform semi-curing treatment to obtain a semi-cured polydimethylsiloxane coating;

[0011] (2) Dissolve a chemically stable photothermal superhydrophobic material in a solvent, then add polydimethylsiloxane and a curing agent, and stir evenly to obtain a photothermal superhydrophobic coating;

[0012] (3) Spray the photothermal superhydrophobic coating on the semi-cured polydimethylsiloxane coating and perform curing treatment to obtain the acid, alkali, and salt immersion-resistant high-adhesion photothermal superhydrophobic coating.

[0013] Further, in step (1), the polydimethylsiloxane coating is composed of polydimethylsiloxane, methyl vinyl cyclosiloxane, and cyclohexane with a mass-to-volume ratio of 1 g: 0.1 g: 1 ml, and the semi-curing treatment is to place it at room temperature for 30 min.

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

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

[0016] Further, in step (3), the curing treatment is to place it at 100 °C for 2 h.

[0017] The present invention also provides an acid, alkali, and salt immersion-resistant high-adhesion photothermal superhydrophobic coating prepared by the above method.

[0018] The substrate of the present invention includes but is not limited to glass, wood, steel, or ceramic chips. The coating methods include but are 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 as follows:

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

[0021] In the present invention, by using different photothermal materials in combination, the coating can obtain a higher equilibrium temperature. Under the illumination condition of 1 kW / m 2 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 de-icing.

[0022] Compared with general photothermal coatings, the coating of the present invention has excellent superhydrophobic performance, and can combine the active photothermal de-icing performance with the passive superhydrophobic anti-icing performance, which can greatly delay the freezing of droplets on the coating surface and endow the coating with the ability to quickly remove the droplets by means of illumination after freezing.

[0023] The multi-walled carbon nanotubes (MWCNTs) used in the present invention have the characteristic of high thermal conductivity, which endows the composite coating with better thermal conductivity. On the one hand, it can enable the coating to obtain a faster heating rate under illumination, and on the other hand, it can enable the coating to transfer heat from the illuminated coating part to the shaded non-illuminated coating part faster, so as to achieve better outdoor use performance.

[0024] The coating preparation method of the present invention does not involve the use of corrosive chemical reagents such as acid, alkali, and salt, and the preparation process is safe and environmentally friendly; the present invention uses the spraying method to prepare the coating, which is applicable to the surfaces of various substrates, and the cost is low, which is convenient for large-scale application. Description of the Drawings

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

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

[0027] Figure 3 3D morphology diagram 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 the photos after the adhesion test of the highly adhesive photothermal superhydrophobic coatings resistant to acid, alkali, and salt immersion prepared in Example 1 (left) and Comparative Example 1 (right).

[0029] Figure 5 This is the heating curve of the highly adhesive photothermal superhydrophobic coating resistant to acid, alkali, and salt immersion prepared in Example 1 under 1 kW / m 2 light illumination conditions.

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

[0031] Figure 7 This is the photo of the melting process of the frozen droplets of the highly adhesive photothermal superhydrophobic coating resistant to acid, alkali, and salt immersion prepared in Example 1 under no light illumination (the three photos above) and 0.5 kW / m 2 light illumination conditions (the three photos below).

[0032] Figure 8 This is the photo of the self-cleaning performance process of the highly adhesive photothermal superhydrophobic coating resistant to acid, alkali, and salt immersion prepared in Example 1.

[0033] Figure 9 This is the WCA diagram of the highly adhesive photothermal superhydrophobic coating resistant to acid, alkali, and salt immersion prepared in Example 1 after acid, alkali, and salt immersion.

[0034] Figure 10 This is the WCA test diagram of the coating prepared in Comparative Example 2 and the heating curve of the coating under 1 kW / m 2 light illumination conditions.

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

[0036] Figure 12 These are the SEM diagrams of the hydrophobic material prepared in Comparative Example 5 (the leftmost one) and the coatings prepared (the second and third from the left).

[0037] Figure 13 This is the 3D surface topography diagram of the coating prepared in Comparative Example 5.

[0038] Figure 14 This is the side view of the WCA of the coating prepared in Comparative Example 5 and the heating curve of the coating under 1 kW / m 2 light illumination conditions. Detailed implementation mode

[0039] To enable those skilled in the art to more clearly understand the technical solutions of the present invention, the following examples are listed for illustration. It should be noted that the following examples do not limit the scope of protection required by the present invention.

[0040] In the following examples, the raw materials, reagents or devices used are commercially available from conventional sources or can be obtained by known methods unless otherwise specified; unless otherwise specified, the methods used in the embodiments of the present invention are those mastered by those skilled in the art. Copper oxide (CuO) powder with an average particle size of 20 nm was purchased from Top Metal Materials Co., Ltd., Qinghe County; polytetrafluoroethylene (PTFE) powder with an average particle size of 500 nm, product number A, grade TM9207, was purchased from Taotao Plastic Raw Materials Co., Ltd., Dongguan City; multi-walled carbon nanotubes (MWCNTs) with an inner diameter of 3 - 5 nm, an outer diameter of 8 - 15 nm, and a length of 5 - 15 μm were purchased from Jiangsu Xianfeng Nano Materials Technology Co., Ltd.; polydimethylsiloxane (PDMS), grade Dow SYLGARD184, was purchased from Dow Chemical; methylvinylcyclosiloxane was purchased from Dow Corning, Midland, Michigan, USA.

[0041] Example 1

[0042] Preparation of a highly adhesive photothermal superhydrophobic coating resistant to acid, alkali, and salt immersion

[0043] (1) Take 2 g of polytetrafluoroethylene powder, 2.25 g of copper oxide powder, and 0.75 g of multi-walled carbon nanotubes in a crucible, stir evenly, then place it in a muffle furnace. Under an air atmosphere, heat from room temperature to 325 °C at a heating rate of 1.5 °C / min and hold at this temperature for 1 h, and finally cool naturally to room temperature and grind through a 300-mesh micro sieve to obtain a chemically stable photothermal superhydrophobic material;

[0044] (2) Take 3 g of polydimethylsiloxane and 0.3 g of methylvinylcyclosiloxane in 3 ml of cyclohexane, stir evenly to obtain a polydimethylsiloxane coating. Spin-coat the polydimethylsiloxane coating on a glass slide with a spin-coating parameter of 3000 r / min and a spin-coating time of 30 s, and then place the glass slide at room temperature for 30 min to obtain a semi-cured polydimethylsiloxane coating;

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

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

[0047] SEM images of different magnifications of the chemically stable photothermal superhydrophobic material prepared in this example are as Figure 1 shown. It can be seen that the smaller nano-CuO particles coat the larger polytetrafluoroethylene (PTFE) particles. Under high magnification images, multi-walled carbon nanotubes can be seen interspersed among them.

[0048] SEM images of the highly adhesive photothermal superhydrophobic coating resistant to acid, alkali, and salt immersion prepared in this example are as Figure 2 shown. It can be seen that the surface of the coating 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 performance of the coating.

[0049] Figure 3 Shows the 3D morphology map and wetting performance test map of the highly adhesive photothermal superhydrophobic coating resistant to acid, alkali, and salt immersion prepared in this example. Its surface roughness reaches 29.19 μm, the WCA is about 155°, and the WSA is about 4.7°.

[0050] Figure 4 In, the left figure shows the appearance of the highly adhesive photothermal superhydrophobic coating resistant to acid, alkali, and salt immersion prepared in this example after the adhesion test (Adhesion test method: Use a cross-cut 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 spray gun to gently remove the coating within the grid area; Adhere the tape to the coating and tear it off evenly; Carefully observe the cut grid area to check whether there are any peeling, blistering or other adhesion problems with the coating. According to relevant standards or specifications (GB / T9286), evaluate the adhesion of the coating). The adhesion grade of the coating in Example 1 is between 0 and 1, and the adhesion grade of the coating in Comparative Example 1 is 2.

[0051] Figure 5 Is the photothermal performance test map of the highly adhesive photothermal superhydrophobic coating resistant to acid, alkali, and salt immersion prepared in this example. The test condition is a light intensity of 1 kW / m 2 After 5 min of light irradiation for heating up, the coating temperature stabilizes at around 139.6 °C, proving that the coating has excellent photothermal conversion performance.

[0052] Figure 6The passive anti-icing performance of the highly adhesive 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 10 μL droplet is placed on the coating. Photos and time during the freezing process of the droplet are recorded. Using a glass slide as a control group, it can be seen that the droplet on the surface of the glass slide shows a diffused shape and is completely frozen at the 30th second, while the droplet on the coating surface shows a spherical shape and is completely frozen at the 220th second. Its complete freezing time is significantly extended by 633% compared to the glass slide.

[0053] Figure 7 The photothermal de-icing performance of the highly adhesive photothermal superhydrophobic coating resistant to acid, alkali, and salt immersion prepared in this example is demonstrated. The frozen droplet in the figure is formed by fully freezing a 10 μL droplet on the refrigeration platform. Under the condition of no light, the frozen droplet completely melts at the 110th second. Under the light condition of 0.5 kW / m 2 Under the light condition, the frost around the frozen droplet completely melts in 16 s, and the frozen droplet completely melts at the 56th second;

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

[0055] Figure 9 It is demonstrated that the highly adhesive photothermal superhydrophobic coating resistant to acid, alkali, and salt immersion prepared in this example still maintains superhydrophobic performance after being immersed in acid (pH = 1), alkali (pH = 13), and salt (3.5% NaCl solution) for 24 h, indicating that the coating has excellent chemical stability.

[0056] Comparative Example 1

[0057] The coating in this comparative example was prepared by the same method 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] According to the test method in Example 1, the adhesion of the coating prepared in this comparative example was tested, and it was found that the adhesion of the coating prepared in this comparative example to the substrate decreased. As Figure 4 shown in the right figure in Figure 11 shown, the WCA of the coating is 156.3°, as

[0059] Comparative Example 2

[0060] The coating in this comparative example was prepared by the same method 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 was found that the coating prepared in this comparative example did not have superhydrophobic properties. However, due to the presence of CuO powder, it still had photothermal properties. The WCA of the coating was only 86.6°, and under 1 kW / m 2 light illumination conditions, the equilibrium temperature of the coating was 108.9 °C.

[0062] Comparative Example 3

[0063] The coating in this comparative example was prepared in the same manner as in Example 1, except 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 WCA of the coating was 99.9°, as shown in Figure 11 the figure.

[0065] Comparative Example 4

[0066] The coating in this comparative example was prepared in the same manner as in Example 1, except 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 WCA of the coating was 136.7°, as shown in Figure 11 the figure.

[0068] Comparative Example 5

[0069] The coating in this comparative example was prepared in the same manner as in Example 1, except that the high-temperature composite process in the muffle furnace was omitted in step (1).

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

[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 photothermal conversion performance of the coating prepared from the material, but also improve the hydrophobic performance of the coating prepared from the material;

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

[0074] From Example 1 and Comparative Example 5, it can be concluded that Figure 1 (the leftmost one) and Figure 12 (the leftmost one) From the SEM images of the materials, it can be seen that by compounding the three powders at high temperature, the material can be made into a shape close to a spherical shape, while the directly mixed material powder is disordered. This kind of powder close to a regular spherical shape can make the prepared coating have a larger light absorption area, making the photothermal effect of the coating better, as Figure 5 and Figure 14 shown. At the same time, this makes the prepared coating show a higher roughness. It can be clearly seen from the SEM images of the coatings in Figure 2 and Figure 12 that the coating in Example 1 has a higher roughness. Figure 3 and Figure 13 shown. The 3D surface topography map of the coating further verifies that the coating in Example 1 has a higher roughness. The higher roughness makes the coating have better hydrophobic performance;

[0075] From Example 1 and Comparative Examples 1, 3, and 4, it can be seen that the ratios of PTFE powder, CuO powder, and MWCNTs affect the hydrophobic and photothermal properties of the final coating. Appropriate ratios can make the coating have excellent superhydrophobic properties, photothermal properties, and the adhesion of the coating to the substrate.

[0076] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a photothermal super-hydrophobic material with stable chemical properties, characterized in that: The following steps are involved: The polytetrafluoroethylene powder, the copper oxide powder and the multi-walled carbon nanotubes are mixed, stirred evenly, and then subjected to high-temperature composite treatment to obtain the photothermal super-hydrophobic material with stable chemical properties.

2. The method for preparing a photothermal super-hydrophobic material having stable chemical properties as claimed in claim 1, characterized in that: The mass ratio of polytetrafluoroethylene powder, copper oxide powder and multi-walled carbon nanotubes is 2:2.25:0.

75.

3. The preparation method of the chemically stable photothermal super-hydrophobic material according to claim 1 or 2, characterized in that, The operation process of high temperature composite treatment is: in air atmosphere, heating from room temperature to 325°C at a heating rate of 1.5°C / min, then keeping at 325°C for 1h, and finally naturally cooling to room temperature.

4. A photothermal super-hydrophobic material with stable chemical properties, characterized in that: Prepared according to the method as claimed in claim 1, 2 or 3.

5. A method for preparing a high-adhesion photothermal super-hydrophobic coating resistant to acid, alkali and salt immersion, characterized in that: The raw material adopts the photothermal super-hydrophobic material with stable chemical properties as claimed in claim 4, comprising the following steps: (1) coating a polydimethylsiloxane coating on a surface of a 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; (3) Spraying the photothermal super-hydrophobic coating on the semi-cured polydimethylsiloxane coating, and curing the coating to obtain the photothermal super-hydrophobic coating with high adhesion that is resistant to acid, alkali and salt immersion.

6. The method for preparing a high-adhesion photothermal super-hydrophobic coating resistant to acid, alkali and salt immersion as claimed in claim 5, characterized in that: 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.

7. The method for preparing a high-adhesion photothermal super-hydrophobic coating resistant to acid, alkali and salt immersion as claimed in claim 5 or 6, 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 0.5g:0.75g:0.075g:15ml.

8. The method for preparing a high-adhesion photothermal super-hydrophobic coating resistant to acid, alkali and salt immersion as claimed in claim 5 or 6, characterized in that, In step (3), spraying is performed using an atomizing spray gun with a caliber of 0.8 mm, a spraying pressure of 0.2 kPa, and a spraying distance of 10 to 20 cm.

9. The method for preparing a high-adhesion photothermal super-hydrophobic coating resistant to acid, alkali and salt immersion as claimed in claim 5 or 6, characterized in that, In step (3), the curing treatment is performed at 100° C. for 2 hours.

10. 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 5 to 9.

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