A photothermal self-healing superhydrophobic coating, its preparation method and application

Abstract

This invention belongs to the field of functional coating materials technology, specifically relating to a photothermal self-healing superhydrophobic coating, its preparation method, and its application. The invention employs a multi-layer synergistic design: the bottom layer is a primer layer; the middle layer is a photothermal self-healing functional layer containing mesoporous polydopamine photothermal microcapsules loaded with a low surface energy repair agent, silicone resin, and a curing agent; the top layer is a superhydrophobic layer containing modified two-dimensional nanosheets with hydrophobic properties and a high aspect ratio, silicone resin, and a curing agent. The modified two-dimensional nanosheets form a stable, loosely packed micro / nano structure. This synergistic system achieves full-cycle closed protection through low-temperature passive anti-icing, photothermal active de-icing, and photothermal triggered repair.

Description

Technical Field

[0001] This invention belongs to the field of functional coating materials technology, specifically relating to a photothermal self-healing superhydrophobic coating and its preparation method and application. Background Technology

[0002] Surface icing poses a significant threat to the safe operation of aviation, power, and transportation industries. Traditional de-icing methods (such as electrothermal de-icing, mechanical de-icing, and chemical de-icing) suffer from high energy consumption, low efficiency, and environmental pollution. In recent years, superhydrophobic surfaces have attracted widespread attention due to their excellent passive anti-icing capabilities.

[0003] Superhydrophobic surfaces facilitate water droplet roll-off through the Cassie-Baxter wetting state, while the trapped air in the surface micro / nanostructures provides thermal insulation, delaying the icing process. However, in low-temperature, high-humidity environments, superhydrophobic surfaces readily transition from the Cassie-Baxter wetting state to the Wenzel state, leading to anti-icing failure. The fundamental reason for this transition is that the surface tension of water droplets increases at low temperatures, making it easier for them to penetrate the low Laplace pressure micro / nanostructures. Improving the wetting stability of superhydrophobic coatings at low temperatures has long been a challenging technical problem. On the other hand, photothermal materials combined with superhydrophobic surfaces are used for active de-icing, melting ice layers through light-induced heating. However, photothermal coatings are susceptible to mechanical wear or chemical corrosion during long-term outdoor use, potentially losing their superhydrophobic properties. Furthermore, once icing occurs, the photothermal effect alone is insufficient to restore the coating's superhydrophobic structure.

[0004] To address the above issues, researchers have attempted to introduce self-healing capabilities into superhydrophobic coatings. Existing self-healing technologies often employ microcapsules loaded with low surface energy materials, releasing a repair agent through microcapsule rupture to restore the surface chemical composition. However, existing technologies often mix microcapsules with structural fillers in the same coating, which presents the following problems: (1) Microcapsules encroach on the stacking space of the structural fillers, weakening the coating's low-temperature resistance; (2) After release, the repair agent must pass through the structural filler layer to reach the surface, resulting in a long migration path and low repair efficiency; (3) More importantly, existing self-healing methods only address chemical damage and are ineffective against physical structural damage (such as the destruction of the stacked structure of two-dimensional materials), while the low-temperature resistance of superhydrophobic properties is highly dependent on the integrity of the micro / nano structure.

[0005] Therefore, developing a coating that combines excellent low-temperature resistance and superhydrophobic properties, efficient photothermal de-icing and chemical-structural dual-mode self-healing functions, and can achieve functional synergy rather than simple superposition, is a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0006] This invention proposes a novel multi-layer synergistic design: the bottom layer is a primer layer; the middle layer is a photothermal self-healing functional layer, comprising mesoporous polydopamine photothermal microcapsules loaded with a low surface energy repair agent, silicone resin, and a curing agent; the top layer is a superhydrophobic layer, comprising modified two-dimensional nanosheets with hydrophobic properties and a high aspect ratio, silicone resin, and a curing agent, wherein the modified two-dimensional nanosheets form a stable, loosely packed micro / nano structure. Unlike existing technologies that simply mix multiple functional components to achieve repair and anti-icing, this invention achieves the following three synergistic mechanisms:

[0007] Synergistic Mechanism 1: Chemical-Structure Dual-Mode Self-Healing. Under photothermal triggering, the intermediate layer microcapsules release a repair agent. This agent not only rapidly migrates to the surface to repair chemical damage (restoring low surface energy), but also utilizes its low surface energy to penetrate the gaps between the stacked two-dimensional nanosheets. Through interfacial energy, it induces micro-motion rearrangement of the nanosheets, partially restoring the loosely stacked structure that collapsed due to physical wear. This mechanism overcomes the fundamental deficiency of existing self-healing coatings, which can only repair chemical damage and cannot repair physical structures.

[0008] Synergistic Mechanism Two: Photothermal-Thermal Conduction Synergistic Effect. The surface two-dimensional material has high thermal conductivity, which can efficiently conduct the heat generated by photothermal conversion to the underlying microcapsule layer, realizing heat-mass coupling transfer: on the one hand, it actively de-ices, and on the other hand, it precisely and quickly triggers the release of the repair agent. Compared with traditional external heat sources or inefficient heat conduction, the self-healing response speed of this invention is improved by more than 50%.

[0009] Synergistic Mechanism 3: Structure-Self-Healing Closed Loop. The loosely packed surface of two-dimensional materials is the core of superhydrophobicity. When structural damage leads to a decrease in superhydrophobic performance, the self-healing process not only restores the chemical composition, but more importantly, it partially restores the superhydrophobic structure through the assistance of repair agents, forming a full-cycle closed protection system encompassing low-temperature passive anti-icing, photothermal active de-icing, and photothermal triggered repair.

[0010] Based on the above-mentioned collaborative mechanism, the present invention provides the following technical solution:

[0011] The first aspect of the technical solution provided by the present invention is a photothermal self-healing superhydrophobic coating, the coating comprising a primer layer disposed on the surface of a substrate, and a photothermal self-healing functional layer and a superhydrophobic surface layer disposed sequentially on the primer layer;

[0012] The photothermal self-healing functional layer includes photothermal self-healing microcapsules, silicone resin and curing agent; the mass ratio of the photothermal self-healing microcapsules, silicone resin and curing agent is (5~10):10:1; the photothermal self-healing microcapsules are mesoporous polydopamine microspheres, and low surface energy repair agents are loaded in their mesopores.

[0013] The superhydrophobic surface layer comprises hydrophobic modified two-dimensional nanosheets with a high aspect ratio obtained by hydrophobic modification with fluorosilane, silicone resin, and curing agent; the mass ratio of the modified two-dimensional nanosheets, silicone resin, and curing agent is (5~10):10:1; the modified two-dimensional nanosheets are loosely stacked in the surface layer to form a stable micro-nano porous structure, enabling the coating to stably maintain the Cassie-Baxter wetting state under low temperature conditions.

[0014] The thickness ratio of the photothermal self-healing functional layer to the superhydrophobic surface layer is 1:(1~2).

[0015] The repair agent in the photothermal self-healing functional layer provided by this invention can be released and migrated to the low-temperature superhydrophobic surface under light irradiation to repair surface chemical damage. At the same time, the high thermal conductivity of the two-dimensional nanosheets conducts photothermal energy to the bottom layer, accelerating the release of the repair agent. The released repair agent penetrates into the gaps between the stacked two-dimensional nanosheets, and through interfacial energy, it induces the two-dimensional nanosheets to undergo micro-motion and re-tapping, restoring part of the loosely stacked structure degraded due to physical damage, thus achieving synergistic self-healing of chemical repair and structure-assisted repair.

[0016] Preferably, the two-dimensional nanosheets are selected from one or more of ZIF-67 two-dimensional leaf-shaped nanosheets, graphene oxide, boron nitride nanosheets, MXene nanosheets, or molybdenum disulfide nanosheets.

[0017] Preferably, the photothermal self-healing microcapsules have a particle size of 200~800nm; the modified two-dimensional nanosheets have a thickness of 10~50nm and a length / width of 500~2000nm; and the modified two-dimensional nanosheets have an aspect ratio ≥10.

[0018] Preferably, the low surface energy repair agent is one or more of perfluorodecyltrimethoxysilane, perfluorodecyltriethoxysilane, tridecafluorooctyltriethoxysilane, octadecyltrichlorosilane, and dodecyltrimethylsilane; the loading amount of the low surface energy repair agent in the photothermal microcapsule is 20~40 wt.%.

[0019] Preferably, the silicone resin is a dual-mechanism silicone resin that combines photocuring and moisture curing, containing acrylic photocuring groups. This allows for rapid UV curing after spraying.

[0020] The second aspect of the technical solution provided by this invention is a method for preparing any of the aforementioned photothermal self-healing superhydrophobic coatings, comprising the following steps:

[0021] S1. Preparation of two-dimensional nanosheets: Two-dimensional nanosheets with high aspect ratio are prepared by solvent control method or ultrasonic method.

[0022] S2. Prepare hydrophobically modified two-dimensional nanosheets. Disperse the two-dimensional nanosheets obtained in step S1 in an organic solvent, add fluorosilane for hydrophobic modification, and after separation and drying, obtain hydrophobic modified two-dimensional nanosheets with a high aspect ratio.

[0023] S3. Photothermal self-healing microcapsules were prepared by self-assembling dopamine into mesoporous polydopamine microspheres in the presence of a template agent under alkaline conditions. After removing the template agent, the mesoporous polydopamine microspheres were immersed in a low surface energy repair agent solution, vacuum loaded, dried and separated to obtain photothermal self-healing microcapsules.

[0024] S4. Apply the primer layer to the substrate surface and allow it to semi-cur.

[0025] S5. Configure the photothermal self-healing functional layer: The photothermal self-healing microcapsules, silicone resin, curing agent and organic solvent prepared in step S3 are mixed and stirred evenly to obtain the functional surface layer slurry. The slurry is sprayed onto the semi-cured primer layer in S4 and semi-cured to form the photothermal self-healing functional layer.

[0026] S6. Configure the superhydrophobic surface layer: Mix the modified two-dimensional nanosheets prepared in step S2 with silicone resin, curing agent and organic solvent to obtain a superhydrophobic surface slurry. Spray the slurry onto the photothermal self-healing functional layer in S5 and cure to obtain a photothermal self-healing superhydrophobic coating.

[0027] Preferably, in step S6, the directional arrangement of the modified two-dimensional nanosheets is achieved by controlling the spraying parameters: the spraying distance is 15~25cm, the spraying angle is 45~60°, and the spraying pressure is 0.2~0.5bar. This step can utilize the shadowing effect during the spraying process to enable the two-dimensional nanosheets to form a more advantageous directional stacking structure, which is beneficial to enhancing the wettability stability of the coating at low temperatures.

[0028] Preferably, the curing method for steps S5 and S6 is as follows: after spraying, the coating is first irradiated with ultraviolet light for 1 to 5 minutes to achieve rapid shaping, and then placed at room temperature for 12 to 24 hours to complete complete curing.

[0029] The third aspect of the technical solution provided by the present invention is the application of any of the aforementioned coatings. The coating is used for anti-icing, de-icing, self-repairing or self-cleaning of machinery and materials. By adjusting the intensity and time of light, it can achieve full-cycle closed protection of low-temperature passive anti-icing, photothermal active de-icing and photothermal triggered repair.

[0030] Preferably, the coating has a delayed freezing time of >600s for water droplets at -15℃, an ice adhesion strength of <12kPa, and under irradiation of 1 solar intensity, the surface temperature of the coating rises to 60℃ and surface ice can be melted within 300s. After 10 photothermal self-repair cycles, the water contact angle of the coating still remains above 150°, and the low-temperature superhydrophobic performance retention rate is >90%.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) Synergistic innovation of chemical-structural dual-mode self-healing: Existing self-healing superhydrophobic coatings (such as CN111534190A) can only restore the surface chemical composition and are powerless against physical structural damage. This invention utilizes the interfacial energy-driven effect after the repair agent penetrates into the gaps between two-dimensional nanosheets to achieve chemical repair-assisted physical structure reconstruction for the first time. After 10 repair cycles, the contact angle is restored to more than 85% of the initial value.

[0033] (2) Photothermal-thermal synergistic effect: Compared with traditional photothermal self-healing coatings (such as CN121495458A, where photothermal is only used for de-icing and triggering release), this invention utilizes the high thermal conductivity of the surface two-dimensional material to construct an efficient heat conduction channel, thereby improving the response speed of the underlying microcapsules and achieving a repair efficiency far higher than existing technologies that rely on the thermal conduction of the resin matrix.

[0034] (3) Structure-self-repair closed loop: This invention is the first to link structure and self-repair function through the "repair agent-assisted rearrangement" mechanism, realizing a closed loop of performance self-recovery. In contrast, the self-repair in existing technologies (such as CN121517991A) only relies on tribomechanical reconstruction and lacks chemically driven precise repair.

[0035] (4) Full-cycle closed-loop protection: Through the above synergy, the coating has an ice-freezing delay time of ≥800 s at -15℃ (better than most existing photothermal superhydrophobic coatings), ice adhesion strength of ≤12 kPa, and low-temperature performance degradation is minimal after multiple repairs. Attached Figure Description

[0036] Figure 1 This is a SEM image of the ZIF-67 two-dimensional leaf-shaped nanosheets prepared in Example 1 of the present invention.

[0037] Figure 2 This is a SEM image of the photothermal self-healing microcapsule prepared in Example 1 of the present invention.

[0038] Figure 3 This is a SEM cross-sectional image of the coating functional layer prepared in Example 1 of the present invention.

[0039] Figure 4 This is a SEM image of the hydrophobic coating layer prepared in Example 1 of the present invention.

[0040] Figure 5 The image shows the contact angle self-healing diagram of the photothermal self-healing superhydrophobic coating prepared in Example 1 of this invention.

[0041] Figure 6The image shows a three-dimensional laser confocal image of the contact angle before and after self-healing of the photothermal self-healing superhydrophobic coating prepared in Example 1 of this invention.

[0042] Figure 7 The X-ray photoelectron spectra of the photothermal self-healing superhydrophobic coating prepared in Example 1 of the present invention are shown.

[0043] Figure 8 This is a SEM image of the hexagonal boron nitride nanosheets prepared in Example 2 of the present invention.

[0044] Figure 9 This is a SEM image of the MXene nanosheets prepared in Example 3 of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0046] The preparation method of the coating described in this application and the preparation of the comparative example can be illustrated as follows:

[0047] Example 1

[0048] Preparation of S1 and two-dimensional ZIF-67 leaf-like nanosheets

[0049] 10 g of Co(NO3)2·6H2O and 60 g of 2-methylimidazole were dissolved in 105 mL of deionized water. The mixture was stirred at room temperature for 1 hour and then allowed to stand for 12 hours. After centrifugation, the nanosheets were washed three times with ethanol and dried under vacuum at 60 °C for 12 hours to obtain two-dimensional leaf-like ZIF-67 nanosheets. (SEM image) Figure 1 The results showed that the obtained ZIF-67 had a two-dimensional leaf-like morphology, with a thickness of about 20-40 nm, a length of about 1-2 μm, and an aspect ratio of about 30-50.

[0050] S2, Preparation of hydrophobically modified ZIF-67 two-dimensional nanosheets

[0051] 5 g of the ZIF-67 two-dimensional nanosheets obtained in step S1 were dispersed in 100 g of ethyl acetate, and 2.5 g of fluorosilane, such as perfluorodecyltrimethoxysilane, was added. The mixture was stirred at room temperature for 2 hours. After centrifugation, the nanosheets were washed three times with ethyl acetate and dried under vacuum at 60 °C for 12 hours to obtain hydrophobic modified ZIF-67 nanosheets with a high aspect ratio.

[0052] S3. Preparation of photothermal self-healing microcapsules

[0053] 8 g of poloxamer 407 and 4 g of PDMS (10 mPa·s) were added to 100 mL of deionized water / ethanol mixture (volume ratio 1:1), and ultrasonically dispersed for 30 min to form a stable emulsion. 25 g of Tris-HCl dissolved in 50 mL of deionized water was added, and after stirring for 10 min, 4 g of dopamine hydrochloride was added. The reaction was carried out at room temperature in the dark for 20 hours. After centrifugation, the microspheres were washed three times with an ethanol / acetone mixture to remove the template agent, and then vacuum dried at 60 °C for 12 hours to obtain mesoporous polydopamine (MPDA) microspheres. Figure 2 As shown.

[0054] 2 g of MPDA microspheres were dispersed in 100 mL of ethanol, and 2 g of a low surface energy repair agent, such as perfluorodecyltrimethoxysilane, was added. The mixture was sonicated for 10 minutes and then stirred at room temperature for 24 hours. After centrifugation, the microspheres were washed three times with ethanol and dried under vacuum at 60°C for 12 hours to obtain photothermal self-healing microcapsules. (SEM image) Figure 2 The results show that the MPDA microspheres have a particle size of approximately 300–500 nm and a distinct mesoporous structure on their surface.

[0055] S4. Preparation of primer layer

[0056] The aluminum plate was ultrasonically cleaned with acetone and ethanol for 10 minutes and then dried with nitrogen. 100 g of silicone resin, 10 g of curing agent, and 50 g of ethyl acetate were mixed and stirred evenly, and then sprayed onto the surface of the aluminum plate. The mixture was semi-cured at 70°C for 0.5 hours to obtain a semi-cured primer layer.

[0057] S5. Prepare the photothermal self-healing functional layer: Take 5g of the photothermal self-healing microcapsules prepared in step S3, 10g of silicone resin, 1g of curing agent, and 10g of ethyl acetate and mix them (the solvent will evaporate during the curing process). After uniform stirring, obtain the functional surface layer slurry. Spray the slurry onto the semi-cured primer layer from step S4 at a distance of 20cm, a spraying angle of 70°, and a spraying pressure of 0.3bar. Allow it to semi-cur to form the photothermal self-healing functional layer. Figure 3 As shown;

[0058] S6. Preparation of Superhydrophobic Surface Layer: Mix 5g of the modified ZIF-67 two-dimensional nanosheets prepared in step S2 with 10g of silicone resin, 1g of curing agent, and 10g of ethyl acetate (the solvent will evaporate during the curing process) to obtain a superhydrophobic surface layer slurry. Spray the slurry onto the photothermal self-healing functional layer in S5 at a spraying distance of 20cm, a spraying angle of 70°, and a spraying pressure of 0.3bar. After curing, a photothermal self-healing superhydrophobic coating is obtained. Figure 4 As shown.

[0059] In the coating of Example 1, the thickness ratio of the photothermal self-healing functional layer to the superhydrophobic surface layer is 1:(1~2).

[0060] The photothermal self-healing superhydrophobic coating surface material exhibits a loosely packed two-dimensional material arrangement, forming numerous micro- and nano-pores with an average pore spacing of approximately 0.05 μm. It possesses extremely high superhydrophobic properties, with a surface water contact angle of 156.5°. After the surface superhydrophobic properties are disrupted by oxygen plasma, the surface contact angle drops to 0°. Figure 5 As shown, after photothermal self-healing, the surface contact angle returned to a superhydrophobic state. This is mainly attributed to the release of a repair agent from the self-healing microcapsules inside the coating, restoring the surface hydrophobicity. Figure 7 As shown, XPS results confirm the presence of fluorine-containing molecules with low surface energy efficiency on the coating surface before and after repair. Simultaneously, the repair agent not only rapidly migrates to the surface to repair chemical damage (restoring low surface energy), but also utilizes its low surface energy properties to penetrate the gaps between the stacked two-dimensional nanosheets. Through interfacial energy-driven micro-motion rearrangement of the nanosheets, it partially restores the loosely packed structure that collapsed due to physical wear, such as... Figure 6 As shown, the surface roughness increased significantly before and after the repair.

[0061] Example 2

[0062] Preparation of S1 and boron nitride nanosheets

[0063] 2g of hexagonal boron nitride powder was dispersed in 200mL of isopropanol, ultrasonically exfoliated at 600W for 6h under ice bath conditions, centrifuged, and dried at 60℃ to obtain boron nitride nanosheets, such as... Figure 8 As shown.

[0064] S2, Preparation of hydrophobically modified boron nitride nanosheets

[0065] 10 g of the boron nitride nanosheets obtained in step S1 were dispersed in 100 g of ethanol, and 5 g of perfluorodecyltrimethoxysilane were added. The mixture was stirred at room temperature for 2 hours. After centrifugation, the nanosheets were washed three times with ethyl acetate and dried under vacuum at 60 °C for 12 hours to obtain hydrophobic modified boron nitride nanosheets with a high aspect ratio.

[0066] S3. Preparation of photothermal self-healing microcapsules

[0067] Same preparation method as in Example 1.

[0068] S4. Preparation of primer layer

[0069] Same preparation method as in Example 1.

[0070] S5, Configured with photothermal self-healing functional layer

[0071] Same preparation method as in Example 1.

[0072] S6. Prepare a superhydrophobic surface layer: Mix 5g of the modified boron nitride nanosheets prepared in step S2 with 10g of silicone resin, 1g of curing agent and 10g of ethyl acetate to obtain a superhydrophobic surface slurry. Spray the slurry onto the photothermal self-healing functional layer in S5 at a distance of 20cm, a spraying angle of 70° and a spraying pressure of 0.3bar. After curing, a photothermal self-healing superhydrophobic coating is obtained.

[0073] In the coating obtained in embodiment 2, the thickness ratio of the photothermal self-healing functional layer to the superhydrophobic surface layer is 1:(1~2).

[0074] Example 3

[0075] Preparation of S1 and MXene nanosheets

[0076] 2g of multilayer MXene powder was dispersed in 200mL of ethanol, ultrasonically exfoliated at 600W for 6h under ice bath conditions, centrifuged, and dried at 60℃ to obtain few-layer MXene nanosheets. Figure 9 As shown.

[0077] S2, Preparation of hydrophobically modified MXene nanosheets

[0078] 10 g of the MXene nanosheets obtained in step S1 were dispersed in 100 g of ethyl acetate, and 5 g of perfluorodecyltrimethoxysilane were added. The mixture was stirred at room temperature for 2 hours. After centrifugation, the nanosheets were washed three times with ethyl acetate and dried under vacuum at 60 °C for 12 hours to obtain hydrophobic modified MXene nanosheets with a high aspect ratio.

[0079] S3. Preparation of photothermal self-healing microcapsules

[0080] Same preparation method as in Example 1.

[0081] S4. Preparation of primer layer

[0082] Same preparation method as in Example 1.

[0083] S5, Configured with photothermal self-healing functional layer

[0084] Same preparation method as in Example 1.

[0085] S6. Prepare a superhydrophobic surface layer: Mix 5g of the modified MXene nanosheets prepared in step S2 with 10g of silicone resin, 1g of curing agent and 10g of ethyl acetate to obtain a superhydrophobic surface slurry. Spray the slurry onto the photothermal self-healing functional layer in S5 at a distance of 20cm, a spraying angle of 70° and a spraying pressure of 0.3bar. After curing, a photothermal self-healing superhydrophobic coating is obtained.

[0086] In the coating of Example 3, the thickness ratio of the photothermal self-healing functional layer to the superhydrophobic surface layer is 1:(1~2).

[0087] Example 4

[0088] Preparation of S1, graphene oxide nanosheets

[0089] Same as S1 in Example 2, but the raw material for the two-dimensional nanosheets is graphene oxide powder.

[0090] S2. Preparation of hydrophobically modified graphene oxide nanosheets

[0091] Same as S2 in Example 1.

[0092] S3. Preparation of photothermal self-healing microcapsules

[0093] Same as S3 in Example 1, but the low surface energy repair agent is perfluorodecyltriethoxysilane.

[0094] S4. Preparation of primer layer

[0095] Same as S4 in Example 1.

[0096] S5, Configured with photothermal self-healing functional layer

[0097] Same as S5 in Example 1, but the mass ratio of photothermal self-healing microcapsules, silicone resin, curing agent and solvent is 10:10:1:10.

[0098] S6, with superhydrophobic surface layer

[0099] Same as S6 in Example 1, but the mass ratio of modified two-dimensional nanosheets, silicone resin, curing agent and solvent is 10:10:1:10.

[0100] In the coating of Example 4, the thickness ratio of the photothermal self-healing functional layer to the superhydrophobic surface layer is 1:(1~2).

[0101] Example 5

[0102] Preparation of S1, molybdenum disulfide nanosheets

[0103] Same as S1 in Example 2, but the raw material for the two-dimensional nanosheets is molybdenum disulfide powder.

[0104] S2, Preparation of hydrophobically modified molybdenum disulfide

[0105] Same as S2 in Example 1.

[0106] S3. Preparation of photothermal self-healing microcapsules

[0107] Same as S3 in Example 1, but the low surface energy repair agent is tridecafluorooctyltriethoxysilane.

[0108] S4. Preparation of primer layer

[0109] Same as S4 in Example 1.

[0110] S5, Configured with photothermal self-healing functional layer

[0111] Same as S5 in Example 1.

[0112] S6, with superhydrophobic surface layer

[0113] Same as S6 in Example 1.

[0114] In the coating of Example 5, the thickness ratio of the photothermal self-healing functional layer to the superhydrophobic surface layer is 1:(1~2).

[0115] Example 6

[0116] Preparation of S1, molybdenum disulfide nanosheets

[0117] Same as S1 in Example 2, but the raw material for the two-dimensional nanosheets is molybdenum disulfide powder.

[0118] Preparation of S2 hydrophobically modified molybdenum disulfide nanosheets

[0119] Same as S2 in Example 1.

[0120] S3. Preparation of photothermal self-healing microcapsules

[0121] Same as S3 in Example 1, but the low surface energy repair agent is dodecyltrimethylsilane.

[0122] S4. Preparation of primer layer

[0123] Same as S4 in Example 1.

[0124] S5, Configured with photothermal self-healing functional layer

[0125] Same as S5 in Example 1.

[0126] S6, with superhydrophobic surface layer

[0127] Same as S6 in Example 1.

[0128] In the coating of Example 6, the thickness ratio of the photothermal self-healing functional layer to the superhydrophobic surface layer is 1:(1~2).

[0129] Comparative Example 1

[0130] S3. Preparation of photothermal self-healing microcapsules

[0131] Same preparation method as in Example 1.

[0132] S4. Preparation of primer layer

[0133] Same preparation method as in Example 1.

[0134] S5, Configured with photothermal self-healing functional layer

[0135] The same preparation method as in Example 1 was used to cure and form a coating without a superhydrophobic layer as in Comparative Example 1.

[0136] Comparative Example 2

[0137] Preparation of S1 and two-dimensional ZIF-67 leaf-like nanosheets

[0138] Same preparation method as in Example 1.

[0139] S2, Preparation of hydrophobically modified ZIF-67 two-dimensional nanosheets

[0140] Same preparation method as in Example 1.

[0141] S4. Preparation of primer layer

[0142] Same preparation method as in Example 1.

[0143] S6, with superhydrophobic surface layer

[0144] 5g of the hydrophobic modified ZIF-67 two-dimensional nanosheets prepared in step S2 were mixed with 10g of silicone resin, 1g of curing agent and 10g of ethyl acetate to obtain a superhydrophobic surface slurry. The slurry was sprayed onto the primer in step S4 at a distance of 20cm, a spraying angle of 70° and a spraying pressure of 0.3bar. After curing, the coating without photothermal self-healing functional layer of Comparative Example 2 was obtained.

[0145] Comparative Example 3

[0146] Preparation of S1 and two-dimensional ZIF-67 leaf-like nanosheets

[0147] Same preparation method as in Example 1.

[0148] S2, Preparation of hydrophobically modified ZIF-67 two-dimensional nanosheets

[0149] Same preparation method as in Example 1.

[0150] S3. Preparation of photothermal self-healing microcapsules

[0151] Same preparation method as in Example 1.

[0152] S4. Preparation of primer layer

[0153] Same preparation method as in Example 1.

[0154] S5. Preparation of photothermal self-healing superhydrophobic hybrid coating: Take 5g of photothermal self-healing microcapsules prepared in step S3, 5g of hydrophobic modified ZIF-67 two-dimensional nanosheets prepared in step S2, 10g of organosilicon resin, 1g of curing agent and 10g of ethyl acetate and mix them. After uniform stirring, functional surface layer slurry is obtained. The slurry is sprayed onto the semi-cured primer layer in step S4 at a spraying distance of 20cm, a spraying angle of 70° and a spraying pressure of 0.3bar. After curing, the photothermal self-healing superhydrophobic hybrid coating of Comparative Example 3 is obtained.

[0155] The performance of each of the above embodiments and comparative examples was tested, and the results are shown in the table below. The specific testing methods adopted were conventional testing methods in the art. For example, the contact angle was obtained by testing with a contact angle measuring instrument and the contact angle resin was obtained by a five-point fitting method; the delayed freezing time was determined by testing the temperature change of the droplet during the freezing process with a temperature sensor, and the delayed freezing time was defined as the time it takes for the droplet to go from supercooled (0°C) to completely frozen; the ice adhesion strength was calculated by pushing an ice block of 1cm×1cm on the surface of the coating with a thrust gauge and using the formula τ=F / A; the surface damage of the superhydrophobic coating was determined by sputtering the coating in an oxygen plasma sputtering instrument for 5 minutes to make the surface hydrophilic; the surface repair of the superhydrophobic coating was determined by irradiating the coating under a xenon lamp of sunlight intensity for 10 minutes to allow the photothermal self-healing microcapsules to release a repair agent and repair the surface hydrophobicity.

[0156] Performance summary of examples and comparative examples

[0157]

[0158] Based on the above performance data, the photothermal self-healing superhydrophobic coating provided in this application has superior anti-icing performance, and its anti-icing performance remains excellent even after multiple repairs.

Claims

1. A photothermal self-healing superhydrophobic coating, characterized in that, The coating includes a primer layer disposed on the surface of the substrate, and a photothermal self-healing functional layer and a superhydrophobic surface layer disposed sequentially on the primer layer; The photothermal self-healing functional layer includes photothermal self-healing microcapsules, silicone resin and curing agent; the mass ratio of the photothermal self-healing microcapsules, silicone resin and curing agent is (5~10):10:1; the photothermal self-healing microcapsules are mesoporous polydopamine microspheres, and low surface energy repair agents are loaded in their mesopores. The superhydrophobic surface layer comprises hydrophobic modified two-dimensional nanosheets with a high aspect ratio obtained by hydrophobic modification with fluorosilane, silicone resin, and curing agent; the mass ratio of the modified two-dimensional nanosheets, silicone resin, and curing agent is (5~10):10:1; the modified two-dimensional nanosheets are loosely stacked in the surface layer to form a stable micro-nano porous structure, enabling the coating to stably maintain the Cassie-Baxter wetting state under low temperature conditions. The thickness ratio of the photothermal self-healing functional layer to the superhydrophobic surface layer is 1:(1~2).

2. The coating of claim 1, wherein, The two-dimensional nanosheets are selected from one or more of ZIF-67 two-dimensional leaf-shaped nanosheets, graphene oxide, boron nitride nanosheets, MXene nanosheets, and molybdenum disulfide nanosheets.

3. The coating of claim 1, wherein, The photothermal self-healing microcapsules have a particle size of 200~800nm; the modified two-dimensional nanosheets have a thickness of 10~50nm and a length / width of 500~2000nm; the modified two-dimensional nanosheets have an aspect ratio ≥10.

4. The coating of claim 1, wherein, The low surface energy repair agent is one or more of perfluorodecyltrimethoxysilane, perfluorodecyltriethoxysilane, tridecafluorooctyltriethoxysilane, octadecyltrichlorosilane, and dodecyltrimethylsilane; the loading amount of the low surface energy repair agent in the photothermal microcapsule is 20~40 wt.%.

5. The coating of claim 1, wherein, The silicone resin is a dual-mechanism silicone resin that is photocurable and moisture-curable, and contains acrylic photocurable groups.

6. A method for producing the coating according to any one of claims 1 to 5, characterized in that Includes the following steps: S1. Preparation of two-dimensional nanosheets: Two-dimensional nanosheets with high aspect ratio are prepared by solvent regulation method or ultrasonic method. S2. Prepare hydrophobically modified two-dimensional nanosheets. Disperse the two-dimensional nanosheets obtained in step S1 in an organic solvent, add fluorosilane for hydrophobic modification, and after separation and drying, obtain hydrophobic modified two-dimensional nanosheets with a high aspect ratio. S3. Photothermal self-healing microcapsules were prepared by self-assembling dopamine into mesoporous polydopamine microspheres in the presence of a template agent under alkaline conditions. After removing the template agent, the mesoporous polydopamine microspheres were immersed in a low surface energy repair agent solution, vacuum loaded, dried and separated to obtain photothermal self-healing microcapsules. S4. Apply the primer layer to the substrate surface and allow it to semi-cur. S5. Configure the photothermal self-healing functional layer: The photothermal self-healing microcapsules, silicone resin, curing agent and organic solvent prepared in step S3 are mixed and stirred evenly to obtain the functional surface layer slurry. The slurry is sprayed onto the semi-cured primer layer in S4 and semi-cured to form the photothermal self-healing functional layer. S6. Configure the superhydrophobic surface layer: Mix the modified two-dimensional nanosheets prepared in step S2 with silicone resin, curing agent and organic solvent to obtain a superhydrophobic surface slurry. Spray the slurry onto the photothermal self-healing functional layer in S5 and cure to obtain a photothermal self-healing superhydrophobic coating.

7. The preparation method according to claim 6, characterized in that, In step S6, the directional arrangement of the modified two-dimensional nanosheets is achieved by controlling the spraying parameters: the spraying distance is 15~25cm, the spraying angle is 45~60°, and the spraying pressure is 0.2~0.5bar.

8. The preparation method according to claim 6, characterized in that, The curing method for steps S5 and S6 is as follows: after spraying, irradiate with ultraviolet light for 1 to 5 minutes to achieve rapid shaping, and then place at room temperature for 12 to 24 hours to complete complete curing.

9. The application of the coating according to any one of claims 1 to 5, characterized in that, The coating is used for anti-icing, de-icing, self-repairing or self-cleaning of machinery and materials. By adjusting the intensity and time of light, it can achieve full-cycle closed protection of low-temperature passive anti-icing, photothermal active de-icing and photothermal triggered repair.

10. The application according to claim 9, characterized in that, The coating has a delayed freezing time of >600s for water droplets at -15℃, an ice adhesion strength of <12kPa, and under irradiation of 1 solar intensity, the surface temperature of the coating rises to 60℃ and the surface ice can be melted within 300s. After 10 photothermal self-repairs, the water contact angle of the coating still remains above 150°, and the low-temperature superhydrophobic performance retention rate is >90%.

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