Super-hydrophobic coating with anti-icing / photo-thermal deicing function as well as preparation method and application of super-hydrophobic coating

Abstract

The invention discloses a super-hydrophobic coating with an anti-icing / photo-thermal deicing function and a preparation method and application thereof, and belongs to the technical field of coatings. The super-hydrophobic coating comprises the following components in parts by weight: 1-2 parts of GP; 2 to 6 parts of TiO2; and 1.5-6 parts of a PDMS main agent and a corresponding cross-linking agent. The preparation method comprises the following steps: firstly, adding a PDMS main agent and a corresponding cross-linking agent into EA, dissolving to obtain a PDMS solution, then jointly adding GP and TiO2 into the PDMS solution, and magnetically stirring to obtain a GP / TiO2 / PDMS dispersion liquid; the obtained dispersion liquid is used in a cable protection system. The prepared coating can effectively remove ice on the surface of the cable through an anti-icing and deicing integrated strategy, and the problems of short circuit, breakage and the like of the cable caused by ice accumulation are effectively solved.

Description

Technical Field

[0001] The present invention relates to a superhydrophobic coating with anti-icing / photo-thermal de-icing function, its preparation method and application, belonging to the technical field of coatings. Background Art

[0002] China has a vast territory and complex terrain, so long-distance cables are often used for power transmission to ensure the power supply in remote areas. However, in recent years, with the continuous deterioration of the environment, disastrous weather such as severe cold, sudden precipitation, and freezing rain has occurred frequently. Such extreme climate is extremely likely to cause large-area icing on long-distance transmission lines. The icing will bring a series of electrical accidents to the transmission lines, such as flashover, short circuit, and burning of the transmission lines. Seriously, the weight brought by the icing may even directly cause the transmission line to break. The breakage of the long-distance transmission line will lead to large-area power outages. And because the long-distance transmission lines are usually erected in areas with harsh environments and few people, it is usually difficult to restore power supply through maintenance in a short time after a fault occurs. Therefore, it usually causes serious economic losses and huge social impacts.

[0003] Constructing a hydrophobic coating on the surface of a cable can make it difficult for water droplets to adhere to the cable surface, significantly reducing the adhesion force between the ice formed by water droplets under cold conditions and the cable surface, enabling the ice on the cable surface to naturally fall off under natural conditions such as wind force, the self-gravity of the ice layer, temperature changes in the external environment, and radiation. This method is simple to operate and low in cost, can be applied to the anti-icing of large-area transmission lines, and can endow the cable with long-term anti-icing ability. Therefore, it has received extensive attention in recent years. Wang L et al. (Wang L, Gong Q, Zhan S, et, al. Robust Anti-Icing Performance of a Flexible Superhydrophobic Surface[J]. Advanced Materials, 2016,28(35):7729-7735.) combined nano-ZnO with PDMS to prepare a flexible superhydrophobic surface; Jin M et al. (Jin M, Shen Y, Luo X, et, al. A combination structure of microblock and nanohair fabricated by chemical etching for excellent water repellency and icephobicity[J]. Applied Surface Science, 2018,455:883-890.) prepared a superhydrophobic surface by modifying the anti-icing performance of specific micro-nano structures. Although great achievements have been made in anti-icing, these materials still have a high probability of icing at extremely low temperatures. Therefore, researchers have begun to try to load de-icing materials into hydrophobic coating materials and effectively solve the icing problem of cables under extreme weather conditions through an integrated strategy of "de-icing" + "anti-icing". Photothermal de-icing can use clean and renewable solar energy for de-icing, so it has become a research hotspot in the field of anti-icing / de-icing materials in recent years. Adding materials with photothermal conversion ability into the hydrophobic coating can generate a relatively high surface temperature under sunlight irradiation, thus quickly melting a small amount of ice crystals formed by the liquid that has not slipped off the cable surface by itself.Mitridis E et al. (Mitridis E, Schutzius T, Sicher A, et, al. Metasurfaces Leveraging Solar Energy for Icephobicity[J]. ACS Nano, 2018, 12(7): 7009-7017.) fabricated plasmonic metasurfaces by using gold and titanium dioxide to design an array of nanoscale noble metal particles embedded in a dielectric matrix, endowing the surface with a good photothermal effect; Wang T et al. (Wang T, Zheng Y, Raji A, et, al. Passive Anti-Icing and Active Deicing Films[J]. ACS Applied Materials & Interfaces, 2016, 8(22): 14169-14173.) fabricated an active deicing coating by incorporating particles with a photothermal effect, which can melt ice under sunlight irradiation. However, these methods are usually complex to prepare and costly, making it difficult to apply them on a large scale. Therefore, it is urgent to develop convenient and inexpensive methods to achieve the integration of ice prevention and ice melting. Summary of the Invention

[0004] Aiming at the icing problem of cables under low temperature and humid conditions, the present invention provides a preparation method of a superhydrophobic coating with anti-icing / photothermal deicing ability. The coating prepared by this method can effectively remove the ice on the cable surface through an integrated strategy of "anti-icing + deicing", effectively avoiding problems such as short circuit and fracture caused by ice accumulation on the cable.

[0005] In the present invention, GP and TiO2 powders are doped in a PDMS matrix material to construct a GP / TiO2 / PDMS hydrophobic coating. GP, TiO2, and PDMS are all low-surface-energy materials. The coating formed by mixing GP, TiO2, and PDMS exhibits good hydrophobicity, making it difficult for water droplets to adhere to the coating surface. The microstructure of the coating surface is one of the key factors affecting the hydrophobic performance of the coating. A high-porosity snowflake-like micro / nano structure is constructed on the coating surface by flame ablation. The air in the micro / nano structure can transform the liquid droplets on the coating surface from the Wenzel state to the Cassie state, enabling the hydrophobicity of the cable coating surface to reach the superhydrophobic critical point. The droplets can naturally roll off the cable surface, making it difficult to form ice on the cable surface. In addition, the good photothermal conversion ability of TiO2 and the high thermal conductivity of GP enable the coating to generate a relatively high surface temperature under sunlight irradiation, thereby quickly melting a small amount of ice crystals formed by the liquid that has not slipped off the cable surface, forming an integrated strategy of "ice prevention + photothermal de-icing", enabling the cable to operate normally in a low-temperature and humid environment, and effectively reducing problems such as cable fracture and short circuit caused by cable icing. In addition, the well-insulated coating may break when the cable is struck by lightning. Therefore, adding GP with good conductivity to the cable coating can also significantly improve the lightning resistance of the cable, enabling the cable to operate better under extreme weather conditions.

[0006] The present invention provides a superhydrophobic coating with ice prevention / photothermal de-icing functions, comprising the following components in parts by weight: GP: 1 - 2 parts; TiO2: 2 - 6 parts; PDMS main agent and corresponding cross-linking agent: 1.5 - 6 parts.

[0007] The present invention provides a preparation method for the above-mentioned superhydrophobic coating with ice prevention / photothermal de-icing functions, comprising the following steps: (1) Add PDMS and the cross-linking agent to EA, and completely dissolve PDMS and the cross-linking agent by magnetic stirring at room temperature to obtain a PDMS solution; (2) Add GP and TiO2 together to the PDMS solution obtained in step (1), and uniformly disperse the GP and TiO2 powders in the PDMS solution by magnetic stirring to obtain a GP / TiO2 / PDMS dispersion; (3) Coat the dispersion on the surface of the substrate to form a superhydrophobic coating.

[0008] In the above preparation method, in step (1), the usage amount of PDMS is 5-15 g of PDMS main agent dissolved in every 100 mL of EA. The mass ratio of the PDMS main agent to the corresponding cross-linking agent is 8-12:1, and the magnetic stirring speed is 500-600 rpm. The PDMS main agent and the corresponding cross-linking agent are purchased from Dow Corning Corporation, model: dc184.

[0009] In the above preparation method, in step (2), the mass ratio of GP to TiO2 is 1~2 ∶2~6, and the mass ratio of GP to PDMS is 1~2∶1.5-6, where PDMS contains the sum of the main agent and the corresponding cross-linking agent; the rotation speed of the magnetic stirring used is 800-1000 rpm. Preferably, in this step, the mass ratio of GP to TiO2 is 1 ∶1-2.5, and the mass ratio of GP to PDMS is 1∶1.5-3, where PDMS contains the sum of the main agent and the corresponding cross-linking agent.

[0010] The present invention provides the application of the above superhydrophobic coating with anti-icing / photo-thermal de-icing function in cables.

[0011] In the above application, the GP / TiO2 / PDMS dispersion liquid is coated on the cable surface multiple times until the thickness reaches 100-200 μm, and the cable is placed in an oven for drying until the EA in the coating is completely evaporated; then the cable is burned with a flame until a uniform carbonized layer is formed on the coating surface, and then it is placed at room temperature for natural cooling. The hydrophobic performance of the coating is further increased by the flame burning treatment.

[0012] In the above application process, the number of times of coating the cable surface with the GP / TiO2 / PDMS dispersion liquid is 3-5 times, the temperature of the oven used is 60-80 °C. The flame burning time is 10-40 s, and the cooling time at room temperature is 30-60 min.

[0013] Advantages of the present invention: (1) In this method, GP and TiO2 powders with low surface energy are doped in the PDMS matrix material with low surface energy, and a snowflake-like micro / nano structure carbonized layer is constructed on the coating surface by the flame burning method. This carbonized layer has a high porosity and forms a stable gas film by storing air, making the contact angle of the coating reach about 157°, realizing superhydrophobic performance; (2) The nano-TiO2 and GP improve the photo-thermal performance of the coating through synergistic effects: the nano-TiO2 has good photo-thermal conversion function, GP realizes rapid heat conduction through high thermal conductivity, and at the same time, the micro / nano structure on the coating surface strengthens its own light absorption ability by increasing the specific surface area, making the heating rate of the coating reach 56 °C / min under illumination, realizing rapid melting of ice crystals, and ensuring the normal operation of the cable under extreme weather conditions; (3) A coating with good insulation will cause the cable to break when struck by lightning, while GP with good conductivity can significantly improve the lightning resistance of the cable, enabling the cable to operate better under extreme weather conditions; (4) A Schottky junction may form at the interface between GP and TiO2, promoting the directional migration of electrons, further reducing the interface resistivity, and synergistically enhancing the conductivity and environmental adaptability of the coating; (5) The flame burning method can effectively change the micro / nano structure of the coating surface, thereby affecting the hydrophobicity of the coating. The GP / TiO2 / PDMS coating is subjected to flame burning treatment, and the micro / nano structure generated by burning can further improve the hydrophobicity of the coating. Description of the Drawings

[0014] Figure 1 are SEM images of GP, TiO2, GP / TiO2 / PDMS coating, and the burned GP / TiO2 / PDMS coating in Example 3; Figure 2 are EDS and XPS images of the burned GP / TiO2 / PDMS coating in Example 3, where: (a) EDS surface scan image of the burned GP / TiO2 / PDMS coating; (b) XPS survey spectrum of the burned GP / TiO2 / PDMS coating; (c) high-resolution XPS images of C element, (d) Ti element, and (e) O element; Figure 3 are the experimental results of the hydrophobicity of the burned GP / TiO2 / PDMS coating in Example 3, where: (a) experimental results of the contact angle of the burned GP / TiO2 / PDMS coating; (b) experimental results of the roll-off angle of the burned GP / TiO2 / PDMS coating; Figure 4 are the experimental results of the photothermal conversion ability of the burned GP / TiO2 / PDMS coating under sunlight irradiation in Example 3; Figure 5 are the experimental results of the anti-icing ability and photothermal de-icing ability of the burned GP / TiO2 / PDMS coating in Example 3, where: (a) and (c) are the experimental results of the anti-icing ability comparison of different coatings; (b) and (d) are the experimental results of the photothermal de-icing ability comparison of different coatings. Specific Embodiments

[0015] To better understand the present invention, the following further detailed description of the present invention is provided in conjunction with the drawings and embodiments, but the scope of protection required by the present invention is not limited to the scope represented by the embodiments. Example 1

[0016] A preparation method of a cable coating with anti-icing / photothermal de-icing ability is provided, and this preparation method is carried out according to the following steps: Step 1: Weigh 3 g of PDMS and 0.3 g of crosslinking agent, add them to 20 mL of EA, and perform magnetic stirring at a speed of 600 rpm at room temperature until the PDMS and crosslinking agent are completely dissolved.

[0017] Step 2: Weigh 1 g of GP and 2.5 g of TiO2 powder, add them to the PDMS solution obtained in Step 1, and perform magnetic stirring at a speed of 1000 rpm at room temperature to uniformly disperse GP and TiO2 in the PDMS solution, obtaining a GP / TiO2 / PDMS dispersion.

[0018] Step 3: Use the GP / TiO2 / PDMS dispersion obtained in Step 2 to coat the cable surface 3 times, and place the cable in an oven at 60 °C for baking until the EA in the coating is completely dried.

[0019] Step 4: Use a flame to burn the coating constructed in Step 3 for 30 s until the surface of the coating is completely carbonized, and then place the workpiece in the air to cool for 30 min to obtain a GP / TiO2 / PDMS superhydrophobic coating. Example 2

[0020] A method for preparing a cable coating with anti-icing / de-icing ability is carried out according to the following steps: Step 1: Weigh 1.5 g of PDMS and 0.15 g of crosslinking agent, add them to 20 mL of EA, and perform magnetic stirring at a speed of 600 rpm at room temperature until the PDMS and crosslinking agent are completely dissolved.

[0021] Step 2: Weigh 1 g of GP and 2 g of TiO2 powder, add them to the PDMS solution obtained in Step 1, and perform magnetic stirring at a speed of 800 rpm at room temperature to uniformly disperse GP and TiO2 in the PDMS solution, obtaining a GP / TiO2 / PDMS dispersion.

[0022] Step 3: Use the GP / TiO2 / PDMS dispersion obtained in Step 2 to coat the cable surface 4 times, and place the cable in an oven at 60 °C for baking until the EA in the coating is completely dried.

[0023] Step 4: Use a flame to burn the coating constructed in Step 3 for 40 s until the surface of the coating is completely carbonized, and then place the workpiece in the air to cool for 40 min to obtain a GP / TiO2 / PDMS superhydrophobic coating. Example 3

[0024] A preparation method of a cable coating with anti-icing / de-icing ability is carried out according to the following steps: Step 1: Weigh 1 g of PDMS and 0.1 g of cross-linking agent and add them to 20 mL of EA, and perform magnetic stirring at a speed of 500 rpm at room temperature until the PDMS and cross-linking agent are completely dissolved.

[0025] Step 2: Weigh 0.5 g of GP and 1.5 g of TiO2 powder and add them to the PDMS solution obtained in Step 1, and perform magnetic stirring at a speed of 800 rpm at room temperature to uniformly disperse GP and TiO2 in the PDMS solution to obtain a GP / TiO2 / PDMS dispersion.

[0026] Step 3: Coat the cable surface 5 times with the GP / TiO2 / PDMS dispersion obtained in Step 2, and place the cable in an oven at 80 °C for baking until the EA in the coating is completely dried.

[0027] Step 4: Burn the coating constructed in Step 3 with a flame for 40 s until the surface of the coating is completely carbonized, and then place the workpiece in the air to cool for 60 min to obtain a GP / TiO2 / PDMS superhydrophobic coating.

[0028] The microscopic morphology, chemical composition, hydrophobic performance, and photothermal performance of the materials prepared in the above examples were experimentally studied, and the experimental results are as shown in the appendix Figures 1 - 5 as follows.

[0029] Figure 1 Figure 1 is the SEM images of GP, TiO2, GP / TiO2 / PDMS coating, and the GP / TiO2 / PDMS superhydrophobic coating after burning treatment (Example 3). Each column in the figure represents SEM images at different magnifications. It can be seen from the figure that the GP used to construct the coating is a micron-scale flaky material with a size of 6-8 μm, while the TiO2 used to construct the coating is a nano-scale particle with a diameter between 30-40 nm. After doping GP and TiO2 in the PDMS matrix and coating it on the cable surface, the GP / TiO2 / PDMS dispersion forms a coating with a micron-scale structure on the cable surface (corresponding to the third column in Figure 1 Figure 1). After burning the GP / TiO2 / PDMS coating with a flame for 40 s, the SEM image shows that a uniform snowflake-like micro / nano structure carbonized layer is formed on the coating surface (corresponding to the fourth column in Figure 1 Figure 1).

[0030] Figure 2EDS and XPS images of the GP / TiO2 / PDMS coating (Example 3). It can be seen from the figure that Ti, C, and O elements are evenly distributed on the coating surface. At the same time, the high-resolution XPS spectrum of the Ti element proves that the Ti in the coating is +4 valence, while the high-resolution XPS spectrum of the C element proves the existence of graphite and PDMS. The high-resolution XPS spectra of Ti and C elements can jointly prove that GP and TiO2 are successfully doped into the PDMS matrix material.

[0031] Figure 3 (a) shows the contact angle test results of the GP / TiO2 / PDMS superhydrophobic coating (Example 3). Figure 3 (b) shows the roll-off angle test results of the GP / TiO2 / PDMS superhydrophobic coating (Example 3). The test results show that the contact angle of the unmodified cable surface is 34.24°, showing hydrophilicity. After coating the GP / TiO2 / PDMS coating on the cable surface, the contact angle of the cable surface increases to 94.27°. At this time, the cable surface shows hydrophobic characteristics, but it has not reached the superhydrophobic critical point required for the rapid de-icing coating. After burning the coating surface with a flame, the contact angle of the coating rapidly rises to 157.19°, reaching the superhydrophobic critical point. The contact angle test results prove that the highly porous carbonized layer formed by the GP / TiO2 / PDMS coating when burned by a flame can significantly improve the hydrophobic performance of the coating by storing a large amount of air. Subsequently, a microinjector hanging a 5 μL droplet was used to impact the coating surface, and the morphological changes of the droplet were observed. The test results show that the liquid did not disperse after being impacted, and there was no obvious liquid residue after the droplet contacted the burned GP / TiO2 / PDMS coating. The droplet was always adsorbed at the end of the microinjector, proving that the burned GP / TiO2 / PDMS coating has good superhydrophobic performance. The workpiece was tilted, and a high-speed camera was used to record the rolling process of the droplet on the inclined workpiece plane to measure the roll-off angle of the coating, as shown in Figure 3 (b). The test results show that the droplet can freely roll on the surface of the burned GP / TiO2 / PDMS coating with an inclination angle less than 1°, and the contact angle between the droplet and the inclined plane is greater than 150°. In contrast, the droplet did not show good rolling on the surface of the unburned GP / TiO2 / PDMS coating with a larger inclination angle, and the contact angle between the droplet and the inclined plane was only 71.52°. The test results confirm that the droplet can spontaneously roll on the coating surface under extremely small inclination angle conditions. This characteristic stems from the synergistic effect of the micro-nano hierarchical structure and low surface energy characteristics of the material surface. The breakthrough performance of the superhydrophobic property of this coating effectively reduces the solid-liquid interface adhesion force, not only endowing the coating with excellent self-cleaning effect, but more importantly, providing a physical basis for inhibiting ice crystal heterogeneous nucleation and reducing ice layer adhesion force, thus significantly improving the anti-icing performance.

[0032] Figure 4 For the experiment on the photothermal conversion ability of the GP / TiO2 / PDMS coating (Example 3) after burning treatment under simulated sunlight irradiation conditions, the experimental results show that the surface temperature of the cable without the coating did not change significantly after being irradiated by the xenon lamp source for 60 s, indicating that the cable itself does not have the ability of photothermal de-icing. After the GP / TiO2 / PDMS coating was applied to the workpiece surface, the surface temperature of the workpiece reached 42 °C after being irradiated by the xenon lamp source for 60 s, proving that the GP / TiO2 / PDMS coating has good photothermal conversion ability. After the GP / TiO2 / PDMS coating after flame burning was irradiated by the xenon lamp source for 60 s, its surface temperature reached 56.6 °C, indicating that the formed snowflake-like micro / nano structure further improved the photothermal conversion ability of the coating.

[0033] Figure 5 For the experimental results of the anti-icing ability and photothermal de-icing ability of the burned GP / TiO2 / PDMS coating (Example 3), the experimental results show that the burned GP / TiO2 / PDMS coating exhibits good anti-icing and photothermal de-icing performance. To sum up, under the synergistic effect of the good superhydrophobic performance and photothermal performance of the GP / TiO2 / PDMS coating, the effective removal of ice on the cable surface under sunlight irradiation was achieved through the "anti-icing + photothermal de-icing" integrated strategy.

Claims

1. A superhydrophobic coating with anti-icing / photo-thermal de-icing function, characterized in that: Comprising the following components in parts by weight: GP: 1 - 2 parts; TiO2: 2 - 6 parts; PDMS main agent and corresponding crosslinking agent: 1.5 - 6 parts.

2. A method for preparing a superhydrophobic coating with anti-icing / photo-thermal de-icing function according to claim 1, characterized in that Comprising the following steps: (1) Add the PDMS main agent and the corresponding crosslinking agent to EA, and completely dissolve the PDMS and the crosslinking agent by magnetic stirring at room temperature to obtain a PDMS solution; (2) Add GP and TiO2 together to the PDMS solution obtained in step (1), and make the GP and TiO2 powders uniformly dispersed in the PDMS solution by magnetic stirring to obtain a GP / TiO2 / PDMS dispersion; (3) Coat the dispersion on the surface of the substrate to form a superhydrophobic coating.

3. The preparation method of the superhydrophobic coating with anti-icing / photo-thermal de-icing function according to claim 2, characterized in that: In step (1), the dosage of the PDMS main agent is 5 - 15 g of the PDMS main agent dissolved in every 100 mL of EA, the mass ratio of the PDMS main agent to the corresponding crosslinking agent is 8 - 12:1, and the rotational speed of magnetic stirring is 500 - 600 rpm.

4. The preparation method of the superhydrophobic coating with anti-icing / photo-thermal de-icing function according to claim 3, characterized in that: The PDMS main agent and the corresponding crosslinking agent are purchased from Dow Corning Corporation, model: dc184.

5. The preparation method of the superhydrophobic coating with anti-icing / photo-thermal de-icing function according to claim 2, characterized in that: In step (2), the mass ratio of GP to TiO2 is 1 - 2:2 - 6, and the mass ratio of GP to PDMS is 1 - 2:1.5 - 6, where PDMS contains the sum of the main agent and the corresponding crosslinking agent; the rotational speed of the magnetic stirring used is 800 - 1000 rpm.

6. The preparation method of the superhydrophobic coating with anti-icing / photo-thermal de-icing function according to claim 5, characterized in that: In step (2), the mass ratio of GP to TiO2 is 1:1 - 2.5, and the mass ratio of GP to PDMS is 1:1.5 - 3, where PDMS contains the sum of the main agent and the corresponding crosslinking agent.

7. Application of the superhydrophobic coating with anti - icing / photo - thermal de - icing function described in claim 1 in a cable.

8. The application according to claim 7, wherein Comprising the following steps: (1) Coat the GP / TiO2 / PDMS dispersion on the surface of the cable multiple times until the thickness reaches 100 - 200 μm, and place the cable in an oven for drying until the EA in the coating completely evaporates; (2) Burn the cable with a flame until a uniform carbonized layer is formed on the surface of the coating, and then place it at room temperature for natural cooling.

9. The application according to claim 8, wherein: The number of times of coating the surface of the cable with the GP / TiO2 / PDMS dispersion is 3 - 5 times, and the temperature of the oven used is 60 - 80 °C.

10. The application according to claim 8, wherein: In step (2), the flame burning time is 10 - 40 s, and the cooling time at room temperature is 30 - 60 min.

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