Efficient photo-thermal super-hydrophobic anti-icing / deicing coating with sandwich structure and preparation method of efficient photo-thermal super-hydrophobic anti-icing / deicing coating

Abstract

The invention discloses an efficient photo-thermal super-hydrophobic anti-icing / deicing coating of a sandwich structure and a preparation method of the efficient photo-thermal super-hydrophobic anti-icing / deicing coating. The coating is composed of a foam structure aerogel heat insulation layer, a middle bonding layer and a mixed-dimension nano structure photo-thermal super-hydrophobic functional layer from bottom to top. The preparation method comprises the following steps: firstly, mixing aerogel nanoparticles and a low-thermal-conductivity binder, and spraying the mixture on a base material to form a thermal insulation layer; spraying a binder on the surface of the substrate to construct a middle layer; and finally, spraying the zero-dimensional, one-dimensional and two-dimensional photo-thermal nanoparticle composite dispersion liquid modified by fluorosilane on the middle layer, and curing to form the functional layer. In the structure, the heat insulation layer effectively prevents heat from being dissipated to the base material, and efficient deicing under weak light is ensured; the functional layer synergistically improves the photo-thermal conversion efficiency and the Cassie-Baxter state stability of the supercooled liquid drops through a multi-dimensional composite and multi-scale coarse structure, and excellent anti-icing is achieved; the middle bonding layer ensures that the whole structure is firm and durable. The process is simple and convenient, is suitable for various base materials, and comprehensively solves the problem of insufficient anti-icing and deicing performance of the existing coating in a severe environment.

Description

TECHNICAL FIELD

[0001] The present application relates to a photothermal superhydrophobic coating and a preparation method thereof, in particular to a high-efficiency photothermal superhydrophobic anti- / de-icing coating with a "sandwich" structure and a preparation method thereof, and belongs to the technical field of anti- / de-icing materials. BACKGROUND

[0002] Surface icing poses a serious threat to the safe operation and performance maintenance of key equipment in new energy facilities, aerospace, and other fields. The current commonly used methods such as mechanical de-icing and thermal melting have problems such as high energy consumption, low efficiency, and easy damage to the surface of the substrate.

[0003] Inspired by superhydrophobic surfaces in nature, biomimetic superhydrophobic coatings can significantly delay icing and reduce ice adhesion strength due to their high contact angle (> 150°) and low rolling angle (< 10°), thus becoming a research hotspot in the field of passive anti-icing. For example, the prior art introduces fluorinated microparticles and nanoparticles into a low-surface-energy resin to construct a micro-nano composite rough structure, thereby obtaining a superhydrophobic anti-icing coating with certain mechanical stability (see comparative document CN117210071A). However, such a purely passive coating can only delay the formation of ice crystals, and in harsh environments with continuous low temperature and high humidity, ice will still gradually accumulate and eventually affect the function of the equipment, which cannot meet the long-term and reliable anti-icing requirements.

[0004] To overcome the limitations of purely passive technology, researchers have developed photothermal superhydrophobic coatings, which combine the active energy conversion capability of photothermal materials with the passive anti-icing properties of superhydrophobic surfaces. This type of coating aims to use sunlight and other light sources to actively melt the accumulated ice formed through photothermal effect. In the prior art, there is a scheme that uses the strategy of in-situ growing photothermal metal-organic framework (MOF) nanoparticles on the surface of low-thermal-conductivity fibrous clay minerals to construct composite functional particles, and uses a phase separation process to prepare a coating with a micro-nano hierarchical structure (see comparative document CN119614064B). Although this design integrates the functions of photothermal and hydrophobic to some extent, its performance still faces two key bottlenecks in typical icing conditions, especially in low temperature (such as 0°C to -20°C), high humidity (relative humidity > 60%), and weak light (such as less than 0.1 solar intensity): First, in a low-temperature and high-humidity environment, condensation water droplets or supercooled droplets on the surface of the coating are prone to transition from the high-energy Cassie-Baxter non-wetting state to the Wenzel fully wetting state, resulting in a dramatic increase in solid-liquid contact area, rapid decay or even failure of superhydrophobicity and anti-icing performance; Second, under weak light conditions, the limited heat energy generated by the photothermal material is easily conducted through the coating to the underlying low-temperature substrate and quickly dissipated, making it difficult for the surface temperature of the coating to be continuously and effectively raised above the freezing point, and the active de-icing function cannot be reliably triggered.

[0005] Therefore, how to design a coating structure that can maintain a stable non-wetting state of the superhydrophobic surface and efficiently concentrate the heat energy generated by photothermal conversion under extreme environments such as low temperature, high humidity, and low light, thereby achieving the synergy and enhancement of passive anti-icing and active de-icing performance, has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the two major bottlenecks of existing photothermal superhydrophobic coatings—superhydrophobic instability and low photothermal efficiency—under low-temperature, high-humidity, and low-light environments, this invention aims to provide a coating and its preparation method that combine excellent passive anti-icing and efficient active de-icing performance. Specifically, the purpose of this invention is to synergistically improve the overall performance of the coating under harsh icing conditions through an innovative "sandwich" hierarchical structure design.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: I. High-efficiency photothermal superhydrophobic anti-icing / de-icing coating with a "sandwich" structure and its preparation A high-efficiency photothermal superhydrophobic anti-icing / de-icing coating with a "sandwich" structure is composed of a foam-structured aerogel insulation layer, an intermediate adhesive layer, and a mixed-dimensional nanostructured photothermal superhydrophobic functional layer from bottom to top.

[0008] The method for preparing the coating includes the following steps: (1) Preparation of "foam" structure aerogel insulation layer: aerogel nanoparticles are mixed and dispersed with a low thermal conductivity binder to form a first dispersion; the first dispersion is coated on the surface of the substrate to form a heat insulation layer with a porous structure; (2) Preparation of intermediate adhesive layer: A layer of adhesive is coated on the surface of the heat insulation layer obtained in step (1), and after curing, an intermediate adhesive layer is formed; (3) Preparation of the “mixed-dimensional” nanostructure photothermal superhydrophobic functional layer: Zero-dimensional, one-dimensional and two-dimensional photothermal nanoparticles were mixed and dispersed in ethanol at a mass ratio of (0.2~1):(0.5~1):1. Then, ammonia was added to adjust the pH to 8~10, and fluorosilane and silane coupling agent were added. The mixture was reacted at room temperature for 2~6 hours to allow the fluorosilane to undergo hydrolysis and condensation on the surface of the nanoparticles to form a second dispersion. The second dispersion was coated on the surface of the intermediate adhesive layer constructed in step (2), and after curing, the “mixed-dimensional” nanostructure photothermal superhydrophobic functional layer was formed.

[0009] The coating method in the above preparation steps is spraying, and the raw material selection and process parameter control are as follows: The aerogel nanoparticles are selected from at least one of silica aerogel and carbon aerogel; the low thermal conductivity binder is selected from at least one of fluorocarbon resin and polyurethane; the mass fraction of the aerogel nanoparticles in the first dispersion is 3% to 5%.

[0010] The substrate includes, but is not limited to, aluminum alloy, magnesium alloy, glass, stainless steel, etc.

[0011] The adhesive is the same type as the low thermal conductivity adhesive mentioned in step (1); the adhesive is coated in the form of a dispersion with a concentration of 0.1~0.3 g / mL.

[0012] The zero-dimensional photothermal nanoparticles are selected from at least one of carbon black and Fe3O4 nanoparticles; the one-dimensional photothermal nanoparticles are selected from at least one of carbon nanotubes and carbon fiber nanoparticles; the two-dimensional photothermal nanoparticles are selected from at least one of graphene oxide and MXene nanoparticles, and the concentration of the "mixed-dimensional" photothermal nanoparticles formed by mixing the zero-dimensional, one-dimensional and two-dimensional photothermal nanoparticles in the reaction system is 10~20 mg / mL.

[0013] The fluorosilane is selected from at least one of perfluorodecyltrimethoxysilane and perfluorodecyltriethoxysilane; the mass ratio of the fluorosilane to the "mixed-dimensional" photothermal nanoparticles is 1:(0.5~1).

[0014] The silane coupling agent is selected from at least one of methyl orthosilicate and ethyl orthosilicate; the mass ratio of the silane coupling agent to fluorosilane is (0.1~0.3):1.

[0015] II. Performance of the "Sandwich" Structure High-Efficiency Photothermal Superhydrophobic Anti-icing / De-icing Coating (1) Superhydrophobic properties The coating prepared by this invention exhibits excellent superhydrophobicity under both room temperature and low temperature and high humidity conditions.

[0016] At room temperature, the contact angle (CA) of a 10 μL water droplet is >167°, and the roll-off angle (SA) is <1°; for a 0.5 μL water droplet, the CA is >165°, and the SA is <5°. Figure 1 ).

[0017] Under low temperature and high humidity conditions: at -10℃ and 80% relative humidity, the salinity (SA) of a 10μL water droplet is <10°. Figure 2 At -20℃ and 80% relative humidity, the salinity (SA) of a 10μL water droplet is <15°. Figure 2 At -30℃ and 80% relative humidity, the salinity (SA) of a 10μL water droplet is <30°. Figure 2 ).

[0018] (2) Photothermal performance The coating prepared by this invention exhibits excellent photothermal properties under both room temperature and low temperature, high humidity, and extremely weak light conditions.

[0019] Under ambient temperature and 1 sun light intensity, the surface temperature of the coating can rise to over 98°C within 5 minutes. Figure 3 a); Under conditions of -10℃, 80% relative humidity, and 0.05sun light intensity, the temperature of the coating surface can rise to above 6℃ within 8 minutes. Figure 3 b).

[0020] (3) Passive anti-icing performance The coating prepared by this invention exhibits excellent static and dynamic anti-icing performance in low temperature and high humidity environments.

[0021] Static anti-icing performance: At -10℃ and 80% relative humidity, a 60μL water droplet did not freeze after 3 hours on the coating surface; under the same conditions, the ice adhesion strength of the coating was less than 10kPa; at -10℃, 80% relative humidity, and 0.05sun light intensity, a 60μL water droplet could remain unfrozen for 24 hours.

[0022] Dynamic anti-icing performance: Under an environment of -10℃ and 80% relative humidity, when 60 μL of supercooled water is continuously added at a rate of 40-50 drops / minute, no ice accumulation occurs on the coating surface within 5 hours.

[0023] (4) Active de-icing performance At -10°C, 80% relative humidity, and 0.05 solar irradiance, when the coating is tilted at 15°, 60 μL of frozen water droplets on its surface can completely melt and roll off within 4 minutes; under the same conditions, ice with a thickness of 1 mm can melt and fall off within 1 hour.

[0024] In summary, this invention first proposes a "sandwich" structure for a highly efficient photothermal superhydrophobic anti-icing / de-icing coating. The coating structure, from top to bottom, comprises: a top layer of photothermal superhydrophobic functional layer with a "mixed-dimensional" nanostructure; a middle layer of chemically bonded adhesive layer; and a bottom layer of aerogel insulating layer with a "foam" porous structure. Secondly, the specific preparation process of this coating is disclosed, including: ① uniformly dispersing aerogel nanoparticles in a low thermal conductivity adhesive system, and forming an insulating layer on the substrate surface through a spraying process; ② spraying an adhesive dispersion onto the insulating layer surface to construct an intermediate adhesive layer; ③ compositing photothermal nanoparticles of different dimensions (zero-dimensional, one-dimensional, two-dimensional) and modifying them with low surface energy before spraying them onto the adhesive layer to form a "mixed-dimensional" nanostructured photothermal superhydrophobic functional layer. In this "sandwich" structure, the bottom aerogel insulating layer significantly inhibits heat conduction to the substrate, ensuring that the heat energy generated by photothermal conversion is concentrated on the surface, thereby significantly improving de-icing performance under typical icing conditions. The middle adhesive layer achieves a stable bond between the surface functional layer and the bottom insulating layer, ensuring the long-term durability of the coating. The surface "mixed-dimensional" nanostructure not only enhances broadband light absorption and photothermal conversion capabilities but also, through its multi-scale rough structure, keeps supercooled droplets in a stable Cassie-Baxter state on its surface, endowing the coating with excellent anti-icing performance. These three elements work synergistically to improve the coating's anti-icing and photothermal de-icing performance under typical icing conditions of low temperature, high humidity, and weak light. In summary, this invention, through multi-level structural design and material synergy, systematically solves the key problem of insufficient anti-icing and de-icing performance of existing photothermal superhydrophobic coatings under typical icing conditions, possessing significant scientific and engineering application value. Attached Figure Description

[0025] Figure 1 a represents CA of 10 μL and 1 μL water droplets on the photothermal superhydrophobic coating of the present invention; Figure 1 b represents 10 μL and 1 μL water droplets on the photothermal superhydrophobic coating of the present invention.

[0026] Figure 2 SA is a 10μL water droplet placed on the photothermal superhydrophobic coating of this invention under low temperature and 80% relative humidity conditions.

[0027] Figure 3 a represents the temperature change over time of the bare substrate and the surface of the photothermal superhydrophobic coating of the present invention under room temperature and 1 sun light intensity conditions; Figure 3 b represents the temperature change over time of the bare substrate and the surface of the photothermal superhydrophobic coating of the present invention at -10℃, 80% relative humidity, and 0.05sun light intensity. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the embodiments of this invention will be described in detail below with reference to specific examples. It should be understood that the specific embodiments described herein are for illustrative purposes only and do not constitute a limitation on the scope of protection of this invention. Those skilled in the art can make various modifications or adjustments within the spirit and scope defined by the claims, and all such modifications or adjustments should be covered within the scope of protection of this invention.

[0029] This invention provides a method for preparing a highly efficient photothermal superhydrophobic anti-icing / de-icing coating with a "sandwich" structure. The coating consists of a "foam" structure aerogel insulation layer, an intermediate adhesive layer, and a "mixed-dimensional" nanostructure photothermal superhydrophobic functional layer from bottom to top. Specific examples are provided below. Unless otherwise specified, all reagents used in the examples were commercially available.

[0030] Example 1 ① Mix 5g of silica aerogel nanoparticles with 120g of fluorocarbon resin and ball mill for 4 hours to obtain a uniform and stable dispersion. Then spray it onto the surface of an aluminum alloy substrate and dry it at room temperature for 24 hours to form a "foam" structure aerogel insulation layer. ② Dilute the same fluorocarbon resin to 0.15 g / mL and spray it uniformly onto the surface of the insulation layer. Cure it at room temperature for 1 hour to form an intermediate bonding layer. ③ Mix carbon black, carbon nanotubes, and graphene oxide nanoparticles at a mass ratio of 0.3:0.8:1. Take 1g of the total mass and disperse it in 80mL of ethanol. Add 2mL of ammonia water, sonicate for 30 minutes, then add 1.5g of perfluorodecyltriethoxysilane and 0.3g of methyl orthosilicate. Stir and react for 4 hours, then spray it onto the bonding layer and cure it at room temperature for 24 hours to form a "hybrid" photothermal superhydrophobic functional layer. The coating properties are shown in Table 1.

[0031] Table 1 Performance of the coating prepared in Example 1 Example 2 ① Mix 5g of silica aerogel nanoparticles with 120g of fluorocarbon resin and ball mill for 4 hours to obtain a uniform and stable dispersion. Then spray it onto the surface of an aluminum alloy substrate and dry it at room temperature for 24 hours to form a "foam" structure aerogel insulation layer. ② Dilute the same fluorocarbon resin to 0.15 g / mL and spray it uniformly onto the surface of the insulation layer. Cure it at room temperature for 1 hour to form an intermediate bonding layer. ③ Composite Fe3O4, carbon nanofibers, and MXene nanoparticles at a mass ratio of 0.9:0.7:1. Take 1g of the total mass and disperse it in 80mL of ethanol. Add 2mL of ammonia water, sonicate for 30 minutes, then add 1.7g of perfluorodecyltrimethoxysilane and 0.4g of tetraethyl orthosilicate. Stir and react for 6 hours, then spray it onto the bonding layer and cure it at room temperature for 24 hours to form a "hybrid" photothermal superhydrophobic functional layer. The coating properties are shown in Table 2.

[0032] Table 2 Performance of the coating prepared in Example 2 Example 3 ① 4g of carbon aerogel nanoparticles were mixed with 120g of fluorocarbon resin and ball-milled for 4 hours to obtain a uniform and stable dispersion. This dispersion was then sprayed onto the surface of an aluminum alloy substrate and dried at room temperature for 24 hours to form a "foam" structure aerogel insulation layer. ② The same fluorocarbon resin was diluted to 0.15 g / mL and uniformly sprayed onto the surface of the insulation layer. It was cured at room temperature for 1 hour to form an intermediate bonding layer. ③ Carbon black, carbon nanotubes, and graphene oxide nanoparticles were mixed at a mass ratio of 0.4:0.9:1. 1g of the total mixture was dispersed in 80mL of ethanol. 2mL of ammonia was added, and the mixture was sonicated for 30 minutes. Then, 1.5g of perfluorodecyltriethoxysilane and 0.3g of tetraethyl orthosilicate were added. After stirring and reacting for 4 hours, the mixture was sprayed onto the bonding layer and cured at room temperature for 24 hours to form a "hybrid" photothermal superhydrophobic functional layer. The coating properties are shown in Table 3.

[0033] Table 3 Performance of the coating prepared in Example 3 Example 4 ① Mix 5g of silica aerogel nanoparticles with 140g of polyurethane and ball mill for 4 hours to obtain a uniform and stable dispersion. Then spray it onto the surface of an aluminum alloy substrate and dry it at room temperature for 24 hours to form a "foam" structure aerogel insulation layer. ② Dilute the same polyurethane to 0.15 g / mL and spray it uniformly onto the surface of the insulation layer. Cure it at room temperature for 1 hour to form an intermediate bonding layer. ③ Mix carbon black, carbon nanotubes, and graphene oxide nanoparticles at a mass ratio of 0.3:0.8:1. Take 1g of the total mass and disperse it in 80mL of ethanol. Add 2mL of ammonia water, sonicate for 30 minutes, then add 1.5g of perfluorodecyltriethoxysilane and 0.3g of methyl orthosilicate. Stir and react for 4 hours, then spray it onto the bonding layer and cure it at room temperature for 24 hours to form a "hybrid" photothermal superhydrophobic functional layer. The coating properties are shown in Table 4.

[0034] Table 4 Performance of the coating prepared in Example 4 The test results above show that the present invention, through the specialized design and layered construction of "insulation layer-adhesive layer-functional layer", has synergistically solved the core problems of low de-icing efficiency under weak light and unstable superhydrophobic state under low temperature and high humidity. Its comprehensive performance is significantly better than that of traditional double-layer or single-layer composite structures.

[0035] The above description is merely a preferred embodiment of the present invention and does not limit the scope of the patent. Any equivalent structural transformations made based on the inventive concept of the present invention and the content of this specification, or direct / indirect applications in other related technical fields, should be included within the scope of patent protection of the present invention.

Claims

1. A method for preparing a highly efficient photothermal superhydrophobic anti-icing / de-icing coating with a "sandwich" structure, characterized in that, The coating, from bottom to top, consists of a "foam" structure aerogel thermal insulation layer, an intermediate adhesive layer, and a "hybrid" nanostructure photothermal superhydrophobic functional layer. The preparation includes the following steps: (1) Preparation of "foam" structure aerogel insulation layer: aerogel nanoparticles are mixed and dispersed with a low thermal conductivity binder to form a first dispersion; the first dispersion is coated on the surface of the substrate to form a heat insulation layer with a porous structure; (2) Preparation of intermediate adhesive layer: A layer of adhesive is coated on the surface of the heat insulation layer obtained in step (1), and after curing, an intermediate adhesive layer is formed; (3) Preparation of "mixed-dimensional" nanostructure photothermal superhydrophobic functional layer: Zero-dimensional, one-dimensional and two-dimensional photothermal nanoparticles are mixed and dispersed in ethanol at a mass ratio of (0.2~1):(0.5~1):

1. Then, ammonia water is added to adjust the pH to 8~10, and fluorosilane and silane coupling agent are added. The mixture is reacted at room temperature for 2~6 hours to allow the fluorosilane to undergo hydrolysis and condensation reaction on the surface of the nanoparticles to form a second dispersion. The second dispersion is coated on the surface of the intermediate adhesive layer constructed in step (2), and after curing, a "mixed-dimensional" nanostructure photothermal superhydrophobic functional layer is formed.

2. The preparation method according to claim 1, characterized in that: In step (1), the aerogel nanoparticles are selected from at least one of silica aerogel and carbon aerogel; the low thermal conductivity binder is selected from at least one of fluorocarbon resin and polyurethane; and the mass fraction of the aerogel nanoparticles in the first dispersion is 3% to 5%.

3. The preparation method according to claim 2, characterized in that: In step (1), the substrate includes, but is not limited to, aluminum alloy, magnesium alloy, glass, stainless steel, etc.

4. The preparation method according to claim 1, characterized in that: In step (2), the adhesive is the same type as the low thermal conductivity adhesive in step (1); the adhesive is coated in the form of a dispersion with a concentration of 0.1~0.3 g / mL.

5. The preparation method according to claim 1, characterized in that: In step (3), the zero-dimensional photothermal nanoparticles are selected from at least one of carbon black and Fe3O4 nanoparticles; the one-dimensional photothermal nanoparticles are selected from at least one of carbon nanotubes and carbon fiber nanoparticles; the two-dimensional photothermal nanoparticles are selected from at least one of graphene oxide and MXene nanoparticles, and the concentration of the "mixed-dimensional" photothermal nanoparticles formed by mixing the zero-dimensional, one-dimensional and two-dimensional photothermal nanoparticles in the reaction system is 10~20 mg / mL.

6. The preparation method according to claim 1, characterized in that: The fluorosilane is selected from at least one of perfluorodecyltrimethoxysilane and perfluorodecyltriethoxysilane; the mass ratio of the fluorosilane to the "mixed-dimensional" photothermal nanoparticles is 1:(0.5~1).

7. The preparation method according to claim 1, characterized in that: The silane coupling agent is selected from at least one of methyl orthosilicate and ethyl orthosilicate; the mass ratio of the silane coupling agent to fluorosilane is (0.1~0.3):

1.

8. The preparation method according to claim 1, characterized in that: The coating method in steps (1), (2) and (3) is spraying.

9. A high-efficiency photothermal superhydrophobic anti-icing / de-icing coating prepared by the preparation method according to any one of claims 1 to 8.

10. An article characterized in that, Its surface is provided with the high-efficiency photothermal superhydrophobic anti-icing / de-icing coating as described in claim 9.

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