A gradient composite material with photothermal and superhydrophobic properties and a preparation method and application thereof

Abstract

The application belongs to the technical field of new materials, and relates to a gradient composite material with photothermal and super-hydrophobic properties as well as a preparation method and application thereof. The gradient composite material comprises two or more layers of carbon fiber composite materials, each layer of the carbon fiber composite material comprising: a carbon fiber fabric; a photothermal coating layer coated on the surface of the carbon fiber fabric, the photothermal coating layer comprising nano-carbon powder; and a hydrophobic coating layer coated on the surface of the photothermal coating layer, the hydrophobic coating layer comprising polydimethylsiloxane and nano-silicon dioxide; wherein the content of the nano-carbon powder in the photothermal coating layer of each layer of the carbon fiber composite material is different and decreases layer by layer from top to bottom along the thickness direction of the gradient composite material. The gradient composite material formed by the gradient distribution of the content of the nano-carbon powder has excellent photothermal and super-hydrophobic properties, and while the photothermal performance is maintained, the impact resistance and energy absorption are significantly improved, and the problem of poor toughness caused by high content of carbon powder is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials and relates to a gradient composite material with photothermal and superhydrophobic properties, a preparation method and an application thereof. Background Art

[0002] Due to their unique surface wettability, superhydrophobic materials have shown great application potential in areas such as self-cleaning, anti-icing, defogging, and corrosion prevention. However, traditional superhydrophobic materials often focus solely on surface coatings, suffering from problems such as poor erosion resistance and limited mechanical properties, which limit their practical application. In recent years, combining photothermal materials with superhydrophobic materials to develop superhydrophobic composite materials with photothermal properties has become a research hotspot. These materials not only possess superhydrophobic properties but can also convert light energy into heat energy, showing broad application prospects in areas such as solar interface evaporation, photothermal defogging, and deicing.

[0003] Currently, there are several research reports on photothermal super-hydrophobic composite materials. The existing technologies CN 117304728 A, CN 118791915 A, CN 115584656 B, and CN 117463994 A respectively use surface spraying of composite solutions and surface etching of micro-nanostructures to prepare photothermal super-hydrophobic materials. However, these methods suffer from complex preparation processes, high costs, poor wear resistance, and poor erosion resistance. In addition, the surface spraying method of photothermal super-hydrophobic materials also suffers from poor interfacial bonding between the surface sprayed layer and the substrate material, resulting in a decrease in the overall mechanical properties of the material. Summary of the Invention

[0004] In order to solve the above problems existing in the prior art, the purpose of the present invention is to provide a gradient composite material with photothermal and superhydrophobic properties and its preparation method and application, so as to overcome the shortcomings of the prior art.

[0005] One object of the present invention is achieved by the following technical solutions:

[0006] A gradient composite material with photothermal and superhydrophobic properties, comprising two or more layers of carbon fiber composite materials, each layer of carbon fiber composite material comprising:

[0007] carbon fiber fabric;

[0008] A photothermal coating coated on the surface of the carbon fiber fabric, wherein the photothermal coating includes nano-carbon powder;

[0009] A hydrophobic coating coated on the surface of the photothermal coating, wherein the hydrophobic coating comprises polydimethylsiloxane and nano-silicon dioxide;

[0010] Among them, the content of nano-carbon powder in the photothermal coating in each layer of carbon fiber composite material is different, and decreases layer by layer from top to bottom along the thickness direction of the gradient composite material.

[0011] Preferably, the carbon fiber composite material has 2 to 10 layers, and more preferably 3 to 6 layers.

[0012] Preferably, the photothermal coating is formed on the surface of the carbon fiber fabric by impregnation and pre-curing of a mixed solution A comprising nano-carbon powder, a curing agent and a resin.

[0013] Preferably, the hydrophobic coating is formed on the surface of the photothermal coating by dipping and curing a mixed solution B comprising polydimethylsiloxane, nano-silicon dioxide and an organic solvent.

[0014] The second object of the present invention is achieved through the following technical solutions:

[0015] A method for preparing a gradient composite material with photothermal and superhydrophobic properties comprises the following steps:

[0016] S1, dispersing nano-carbon powder in a curing agent, and then adding resin to obtain a mixed solution A;

[0017] S2, adding polydimethylsiloxane and nano-silica into an organic solvent to obtain a mixed solution B;

[0018] S3, immersing the carbon fiber fabric in the mixed solution A, taking it out, and pre-curing it to obtain a carbon fiber prepreg;

[0019] S4, impregnating the carbon fiber prepreg into the mixed solution B, and taking it out to obtain a layer of carbon fiber composite material;

[0020] S5, repeating steps S1-S4 at least once, wherein the content of nano-carbon powder in the mixed solution A in step S1 is different each time, to obtain at least two layers of carbon fiber composite materials with different nano-carbon powder contents;

[0021] S6. The carbon fiber composite materials with different nano-carbon powder contents are laid layer by layer in the order of the nano-carbon powder content from low to high, and are cured and molded by a vacuum bagging method to form a gradient composite material.

[0022] In step S1, the nanocarbon powder is dispersed in the curing agent using ultrasound for 5 to 30 minutes. After the resin is added, ultrasound is also used for dispersion for 5 to 30 minutes. In step S2, polydimethylsiloxane and nanosilica are added to an organic solvent and dispersed using ultrasound for 5 to 30 minutes. Ultrasonic cleaning is performed in an ultrasonic cleaning machine at a frequency of 20 to 80 kHz and a power of 50 to 500 W.

[0023] In step S1:

[0024] Preferably, the nano-carbon powder comprises one or more of nano-graphene, carbon nanotubes, nano-carbon black, and nano-activated carbon, and more preferably nano-graphene, wherein the graphene has a thickness of 0.34-10 nm and a sheet diameter of 100-999 nm.

[0025] Preferably, the resin is one or more of epoxy resin, polyurethane resin, phenolic resin, and acrylic resin. More preferably, the resin is epoxy resin.

[0026] Preferably, the mass ratio of the nano-carbon powder to the curing agent is 0.1-10:100, more preferably 0.5-6:100.

[0027] Preferably, the mass ratio of the resin to the curing agent is 2 to 4:1.

[0028] Preferably, the content of the nano-carbon powder in the mixed solution A is 0.1-2 wt %.

[0029] Preferably, the nano-carbon powder content in the mixed solution A used in two adjacent layers of carbon fiber composite materials differs by 0.1-1 wt %. More preferably, the nano-carbon powder content in the mixed solution A used in two adjacent layers of carbon fiber composite materials differs by 0.3-0.8 wt %.

[0030] In step S2:

[0031] The organic solvent is a solvent that is volatile at the curing temperature and can dissolve polydimethylsiloxane, and can be one or more of ethyl acetate, methyl acetate, propyl acetate, dimethyl carbonate, n-hexane, and tetrahydrofuran.

[0032] Preferably, the mass ratio of polydimethylsiloxane to nano-silica is 6:1 to 1:1, and the mass of the organic solvent is 1 to 10 times the total mass of the polydimethylsiloxane and nano-silica.

[0033] There is no particular order between steps S1 and S2, and the order can be adjusted at will.

[0034] In step S3:

[0035] Preferably, the impregnation time of the carbon fiber fabric is 5 to 20 minutes.

[0036] Preferably, the pre-curing temperature is 60-90° C., and the pre-curing time is 0.5-2 h.

[0037] The immersion time in step S4 is 10 to 40 minutes.

[0038] In step S6, the curing temperature is 100-150° C., and the curing time is 1-5 hours.

[0039] The third object of the present invention is achieved through the following technical solutions:

[0040] Application of a gradient composite material with photothermal and superhydrophobic properties in any of the following:

[0041] a. Solar interfacial evaporation system, used for seawater desalination or sewage treatment, achieves efficient solar-driven water evaporation through the photothermal properties and surface superhydrophobicity of the material;

[0042] b. Solar thermal deicing devices, used for anti-icing and de-icing of surfaces such as aircraft windows and wind turbine blades, accelerate ice melting and water droplet evaporation by converting solar energy into heat;

[0043] c. Self-cleaning surface construction, used in building exterior walls, solar panels and other fields, through its surface super-hydrophobicity to effectively repel and remove pollutants such as dust and oil, achieving surface self-cleaning.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. The gradient composite material provided by the present invention has excellent photothermal properties and superhydrophobic properties, and has good durability and can withstand long-term rain erosion and ultraviolet radiation.

[0046] 2. The present invention forms a gradient composite material through the gradient distribution of nano-carbon powder content, which significantly improves the impact resistance and energy absorption while maintaining the light and thermal properties, and solves the problem of poor toughness caused by high content of carbon powder.

[0047] 3. Compared with the uniform structure, the gradient composite material provided by the present invention can significantly improve the photothermal performance and impact resistance when the graphene content is equivalent.

[0048] 4. The preparation process of the present invention does not require complex equipment, and the raw materials are easily available. Conventional processes such as impregnation, ultrasonic dispersion, and hot pressing solidification are adopted, which makes it easy to achieve large-scale production and reduce the preparation cost.

[0049] 5. The composite material prepared by the present invention can be applied to multiple fields such as solar interface evaporation, photothermal deicing and defogging, and self-cleaning surfaces, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is the contact angle of Examples 1-4 and Comparative Examples 1-3;

[0051] Figure 2 is the contact angle of Example 1-4 after being treated with rain and UV irradiation for 1 hour;

[0052] Figure 3 The force-displacement curves in the impact tests of Examples 1-4 and Comparative Examples 1-2;

[0053] Figure 4 The force-displacement curves in the impact tests of Comparative Examples 3-6 are shown. DETAILED DESCRIPTION

[0054] Below by specific embodiment and accompanying drawing, technical scheme of the present invention is further described explanation, it should be understood that specific embodiment described herein is only for helping to understand the present invention, is not used for specific limitation of the present invention.And accompanying drawing used herein, is only for better illustrating the disclosure of the present invention, does not have limiting effect on protection scope.If no special instructions, the raw materials adopted in the embodiment of the present invention are all raw materials commonly used in this area, and the method adopted in the embodiment is all conventional method in this area.

[0055] In the description of the present invention, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any combination of real numbers between a and b, and includes a and b.

[0056] Graphene: purchased from Shanghai MacLean Biochemical Technology Co., Ltd., CAS number 1034343-98-0, thickness ~5 nm, conductivity ≥1600 S / cm.

[0057] Epoxy resin AB glue: Yituo composite material YT-CC302, E-51 low viscosity epoxy resin, the epoxy resin in the examples and comparative examples refers to component A in the epoxy resin AB glue, and the curing agent is component B in the epoxy resin AB glue.

[0058] Carbon fiber fabric: purchased from Shandong Dingsheng Composite Materials Co., Ltd., model domestic T300, width 1000 mm.

[0059] Average particle size of nano-silica: 7~40nm.

[0060] PDMS: purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd., model SYLGARD (R) 184.

[0061] In the following examples and comparative examples, an ultrasonic cleaning machine was used to assist dispersion, with a power of 100 W and a frequency of 40 KHz.

[0062] Example 1

[0063] The composite material of this embodiment is prepared by the following steps:

[0064] (1) Add 0.1 g of graphene powder to 10 g of curing agent and disperse it ultrasonically for 20 min. Then add 30 g of epoxy resin and disperse it ultrasonically for 30 min to obtain a uniformly dispersed mixed solution A.

[0065] (2) 5 g of PDMS, 2 g of nano-SiO2, and 20 g of ethyl acetate were mixed and ultrasonically dispersed for 10 min to obtain a uniformly dispersed mixed solution B;

[0066] (3) The carbon fiber fabric was placed in the mixed solution A and fully immersed for 10 minutes, then taken out, flattened and placed in a vacuum oven for pre-curing treatment at a temperature of 70°C for 1 hour to obtain a carbon fiber prepreg;

[0067] (4) The carbon fiber prepreg is immersed in the mixed solution B for 10 minutes and then taken out to obtain a layer of carbon fiber composite material;

[0068] (5) Repeat steps (1) to (4) twice, with step (1) being the same each time, to obtain three layers of carbon fiber composite materials with the same nano-carbon powder content;

[0069] (6) Three layers of carbon fiber composite materials with the same nano-carbon powder content were laid layer by layer, and a vacuum bagging process was used for molding. The composite materials were then placed in an oven for curing at 120°C for 2 hours to obtain the composite materials.

[0070] Example 2

[0071] The composite material of this embodiment is prepared by the following steps:

[0072] (1) Add 0.3 g of graphene powder to 10 g of curing agent and disperse it ultrasonically for 20 min. Then add 30 g of epoxy resin and disperse it ultrasonically for 30 min to obtain a uniformly dispersed mixed solution A.

[0073] (2) 5 g of PDMS, 2 g of nano-SiO2, and 20 g of ethyl acetate were mixed and ultrasonically dispersed for 10 min to obtain a uniformly dispersed mixed solution B;

[0074] (3) The carbon fiber fabric was placed in the mixed solution A and fully immersed for 10 minutes, then taken out, flattened and placed in a vacuum oven for pre-curing treatment at a temperature of 70°C for 1 hour to obtain a carbon fiber prepreg;

[0075] (4) The carbon fiber prepreg is immersed in the mixed solution B for 10 minutes and then taken out to obtain a layer of carbon fiber composite material;

[0076] (5) Repeat steps (1) to (4) twice, with step (1) being the same each time, to obtain three layers of carbon fiber composite materials with the same nano-carbon powder content;

[0077] (6) Three layers of carbon fiber composite materials with the same nano-carbon powder content were laid layer by layer, and a vacuum bagging process was used for molding. The composite materials were then placed in an oven for curing at 120°C for 2 hours to obtain the composite materials.

[0078] Example 3

[0079] The composite material of this embodiment is prepared by the following steps:

[0080] (1) Add 0.5 g of graphene powder to 10 g of curing agent and ultrasonically disperse for 20 min. Then add 30 g of epoxy resin and ultrasonically disperse for 30 min to obtain a uniformly dispersed mixed solution A.

[0081] (2) 5 g of PDMS, 2 g of nano-SiO2, and 20 g of ethyl acetate were mixed and ultrasonically dispersed for 10 min to obtain a uniformly dispersed mixed solution B;

[0082] (3) The carbon fiber fabric was placed in the mixed solution A and fully immersed for 10 minutes, then taken out, flattened and placed in a vacuum oven for pre-curing treatment at a temperature of 70°C for 1 hour to obtain a carbon fiber prepreg;

[0083] (4) The carbon fiber prepreg is immersed in the mixed solution B for 10 minutes and then taken out to obtain a layer of carbon fiber composite material;

[0084] (5) Repeat steps (1) to (4) twice, with step (1) being the same each time, to obtain three layers of carbon fiber composite materials with the same nano-carbon powder content;

[0085] (6) Three layers of carbon fiber composite materials with the same nano-carbon powder content were laid layer by layer, and a vacuum bagging process was used for molding. The composite materials were then placed in an oven for curing at 120°C for 2 hours to obtain the composite materials.

[0086] Example 4

[0087] The gradient composite material of this embodiment is prepared by the following steps:

[0088] According to steps (1) to (4) of Example 1, a first layer of carbon fiber composite material with a low graphene content is obtained;

[0089] A second layer of carbon fiber composite material with a medium graphene content was obtained according to steps (1) to (4) of Example 2;

[0090] According to steps (1) to (4) of Example 3, a third layer of carbon fiber composite material with a high graphene content is obtained;

[0091] First, lay the first layer of carbon fiber composite material, then lay the second layer of carbon fiber composite material on top, and then lay the third layer of carbon fiber composite material on the second layer of carbon fiber composite material, so that the content of nano-carbon powder in the composite material decreases layer by layer from top to bottom. The vacuum bag molding process is adopted, and then it is placed in an oven at 120°C for curing for 2 hours to obtain a gradient composite material.

[0092] Comparative Example 1

[0093] The composite material of Comparative Example 1 was prepared by the following steps:

[0094] (1) Mix 10 g of curing agent and 30 g of epoxy resin and disperse them by ultrasonic for 30 min to obtain a uniformly dispersed mixed solution C;

[0095] (2) The carbon fiber fabric was placed in the mixed solution C and fully immersed for 10 minutes, then taken out, flattened and placed in a vacuum oven for pre-curing treatment at a temperature of 70°C for 1 hour to obtain a carbon fiber prepreg;

[0096] (3) Repeat steps (1)-(2) twice to obtain a three-layer carbon fiber prepreg;

[0097] (4) Three layers of carbon fiber prepreg are laid layer by layer, and a vacuum bagging process is adopted. Then, the prepreg is placed in an oven and cured at 120°C for 2 hours to obtain a conventional carbon fiber composite material.

[0098] Comparative Example 2

[0099] The composite material of Comparative Example 2 was prepared by the following steps:

[0100] (1) Mix 10 g of curing agent and 30 g of epoxy resin and disperse them by ultrasonic for 30 min to obtain a uniformly dispersed mixed solution C;

[0101] (2) Mix 5 g of PDMS and 20 g of ethyl acetate and disperse them by ultrasonication for 10 min to obtain a uniformly dispersed mixed solution D;

[0102] (3) The carbon fiber fabric was placed in the mixed solution C and fully immersed for 10 minutes, then taken out, flattened and placed in a vacuum oven for pre-curing treatment at a temperature of 70°C for 1 hour to obtain a carbon fiber prepreg;

[0103] (4) The carbon fiber prepreg is placed in the mixed solution D and immersed for 10 minutes, and then taken out to obtain a layer of carbon fiber composite material;

[0104] (5) Repeat steps (1) to (4) twice to obtain a three-layer carbon fiber composite material;

[0105] (6) The three layers of carbon fiber composite material were laid layer by layer, and the vacuum bagging process was adopted. Then, the composite material was cured in an oven at 120°C for 2 hours to obtain the composite material.

[0106] Comparative Example 3

[0107] The composite material of Comparative Example 3 was prepared by the following steps:

[0108] (1) Mix 10 g of curing agent and 30 g of epoxy resin and disperse them by ultrasonic for 30 min to obtain a uniformly dispersed mixed solution C;

[0109] (2) 5 g of PDMS, 2 g of nano-SiO2, and 20 g of ethyl acetate were mixed and ultrasonically dispersed for 10 min to obtain a uniformly dispersed mixed solution B;

[0110] (3) The carbon fiber fabric was placed in the mixed solution C and fully immersed for 10 minutes, then taken out, flattened and placed in a vacuum oven for pre-curing treatment at a temperature of 70°C for 1 hour to obtain a carbon fiber prepreg;

[0111] (4) The carbon fiber prepreg is immersed in the mixed solution B for 10 minutes and then taken out to obtain a layer of carbon fiber composite material;

[0112] (5) Repeat steps (1) to (4) twice to obtain a three-layer carbon fiber composite material;

[0113] (6) The three layers of carbon fiber composite material were laid layer by layer, and the vacuum bagging process was adopted. Then, the composite material was cured in an oven at 120°C for 2 hours to obtain the composite material.

[0114] Comparative Example 4

[0115] The composite material of Comparative Example 4 was prepared by the following steps:

[0116] (1) Add 0.5 g of graphene powder to 10 g of curing agent and ultrasonically disperse for 20 min. Then add 30 g of epoxy resin and ultrasonically disperse for 30 min to obtain a uniformly dispersed mixed solution A.

[0117] (2) 5 g of PDMS, 2 g of nano-SiO2, and 20 g of ethyl acetate were mixed and ultrasonically dispersed for 10 min to obtain a uniformly dispersed mixed solution B;

[0118] (3) The carbon fiber fabric was placed in the mixed solution A and fully immersed for 10 minutes, then taken out, flattened and placed in a vacuum oven for pre-curing treatment at a temperature of 70°C for 1 hour to obtain a carbon fiber prepreg;

[0119] (4) The carbon fiber prepreg is immersed in the mixed solution B for 10 minutes and then taken out to obtain a layer of carbon fiber composite material;

[0120] (5) A layer of carbon fiber composite material was formed using a vacuum bagging process and placed in an oven for curing at 120°C for 2 hours to obtain a composite material.

[0121] Comparative Example 5

[0122] The gradient composite material of Comparative Example 5 was prepared by the following steps:

[0123] According to steps (1) to (4) of Example 1, a first layer of carbon fiber composite material with a low graphene content is obtained;

[0124] A second layer of carbon fiber composite material with a medium graphene content was obtained according to steps (1) to (4) of Example 2;

[0125] According to steps (1) to (4) of Example 3, a third layer of carbon fiber composite material with a high graphene content is obtained;

[0126] The first layer of carbon fiber composite material, the third layer of carbon fiber composite material, and the second layer of carbon fiber composite material were laid in sequence, and a vacuum bagging process was adopted. After that, the composite material was placed in an oven for curing at 120° C. for 2 hours to obtain a gradient composite material.

[0127] Comparative Example 6

[0128] The gradient composite material of Comparative Example 6 was prepared by the following steps:

[0129] According to steps (1) to (4) of Example 1, a first layer of carbon fiber composite material with a low graphene content is obtained;

[0130] A second layer of carbon fiber composite material with a medium graphene content was obtained according to steps (1) to (4) of Example 2;

[0131] According to steps (1) to (4) of Example 3, a third layer of carbon fiber composite material with a high graphene content is obtained;

[0132] The third layer of carbon fiber composite material, the first layer of carbon fiber composite material, and the second layer of carbon fiber composite material were laid in sequence, and a vacuum bagging process was adopted. After that, the composite material was placed in an oven for curing at 120° C. for 2 hours to obtain a gradient composite material.

[0133] Performance Testing

[0134] Contact angle test: The contact angle of the composite material was measured quickly and accurately using the sessile drop method using the contact angle meter OCA25.

[0135] Photothermal conversion performance test: The composite material was irradiated with a solar simulator at a radiation intensity of 600W / m 2 After 5 minutes of natural sunlight exposure at room temperature of 9°C, the surface temperature changes were recorded using an infrared thermal imager.

[0136] Erosion resistance test: An environmental test chamber was used to simulate a hot and humid environment. The composite material was washed with rain and irradiated with ultraviolet light for 1 hour. The water pressure was 0.12 MPa, the nozzle hole diameter was 0.8 mm, the temperature was 38°C, and the humidity was 64%. The contact angle of the composite material was then tested again.

[0137] Impact performance test: The sample was subjected to an impact test using a drop hammer impact tester. The hammer head was hemispherical, with a mass of 0.5 kg and an impact speed of 6 m / s. The sample boundaries were fixed on four sides.

[0138] Table 1 Properties of the composite materials of Examples and Comparative Examples

[0139]

[0140] From Table 1 and Figure 1 It can be seen that the contact angles of Examples 1-4 are greater than 150°, indicating that the materials have super hydrophobic properties. The contact angle of Example 3 is the largest, which is attributed to the high graphene content. The composite materials of Examples 1-4 were subjected to rainwater erosion and ultraviolet irradiation tests. Table 1 and Figure 2 The material still maintains good super-hydrophobic properties, indicating that the material has excellent erosion resistance. Comparing Examples 1-4, it can be seen that Example 3 has a higher surface temperature in the photothermal conversion test. This is because the graphene content in Example 3 is the highest. High graphene content is conducive to improving the photothermal conversion performance of the material. Although Example 3 has good photothermal performance, the high content of graphene will lead to poor toughness of the composite material, easy to break, and poor impact resistance. The impact performance is only 1642.5J. Through gradient design (Example 4), the impact resistance of the material is greatly improved to 2342.9J (as shown in Figure 2). Figure 3 ). The graphene content in Example 4 is comparable to that in Example 2, but Example 4 adopts a gradient structure, which is beneficial to improving the photothermal performance, resulting in Example 4 having a higher surface temperature in the photothermal conversion test.

[0141] The material of Comparative Example 4 is a single-layer structure, and its contact angle, photothermal conversion performance, and impact resistance are all very poor, especially it directly breaks and fails in the impact resistance test; by comparing Example 4 and Comparative Examples 5-6, it can be seen that laying the layers in order of graphene content is more conducive to performance improvement.

[0142] The various aspects, embodiments, and features of the present invention should be considered in all respects as illustrative and not limiting, the scope of which is defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0143] In the preparation method of the present invention, the order of the steps is not limited to the order listed. Persons skilled in the art will appreciate that variations in the order of the steps are within the scope of the present invention without inventive effort. Furthermore, two or more steps or actions may be performed simultaneously.

[0144] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit its implementation. Persons skilled in the art may make various modifications, additions, or substitute similar methods for the described specific embodiments. It is not necessary and impossible to provide comprehensive examples of all implementations here. However, obvious variations or modifications arising from the essential spirit of the present invention remain within the scope of protection of the present invention, and interpreting them as any additional limitations would be contrary to the spirit of the present invention.

Claims

1. A method for preparing a gradient composite material with photothermal and superhydrophobic properties, characterized in that: The following steps are involved: S1. Dispersing nano-carbon powder in a curing agent, and then adding resin to obtain a mixed solution A, wherein the content of the nano-carbon powder in the mixed solution A is 0.1-2 wt %; S2, adding polydimethylsiloxane and nano-silica to an organic solvent to obtain a mixed solution B, wherein the mass ratio of polydimethylsiloxane to nano-silica is 6:1 to 1:1; S3, immersing the carbon fiber fabric in the mixed solution A for 5-20 minutes, taking it out, and pre-curing it at 60-90° C. for 0.5-2 hours to obtain a carbon fiber prepreg; S4, immersing the carbon fiber prepreg in the mixed solution B for 10 to 40 minutes, taking it out, and obtaining a layer of carbon fiber composite material; S5. Repeat steps S1-S4 at least once, wherein the content of nano-carbon powder in the mixed solution A in step S1 is different each time, and the nano-carbon powder content in the mixed solution A used in two adjacent layers of carbon fiber composite materials differs by 0.1-1 wt %, to obtain at least two layers of carbon fiber composite materials with different nano-carbon powder contents; S6. Lay the carbon fiber composite materials with different nano-carbon powder contents layer by layer in the order of nano-carbon powder content from low to high, and use a vacuum bagging method to cure them at 100-150° C. for 1-5 hours to form a gradient composite material.

2. The preparation method according to claim 1, characterized in that The nano-carbon powder is one or more of nano-graphene, carbon nanotube, nano-carbon black and nano-activated carbon.

3. The preparation method according to claim 1, characterized in that The resin is one or more of epoxy resin, polyurethane resin, phenolic resin and acrylic resin.

4. The preparation method according to claim 1, characterized in that The mass ratio of the nano-carbon powder to the curing agent is 0.1-10:

100.

5. The preparation method according to claim 1, characterized in that The mass ratio of the resin to the curing agent is 2-4:

1.

6. The preparation method according to claim 1, characterized in that The mass of the organic solvent is 1 to 10 times the total mass of the polydimethylsiloxane and the nano-silica.

7. A gradient composite material with photothermal and superhydrophobic properties prepared by the preparation method according to claim 1, characterized in that: The gradient composite material comprises two or more layers of carbon fiber composite materials, each layer of carbon fiber composite material comprising: carbon fiber fabric; A photothermal coating coated on the surface of the carbon fiber fabric, wherein the photothermal coating includes nano-carbon powder; A hydrophobic coating coated on the surface of the photothermal coating, wherein the hydrophobic coating comprises polydimethylsiloxane and nano-silicon dioxide; Among them, the content of nano-carbon powder in the photothermal coating in each layer of carbon fiber composite material is different, and decreases layer by layer from top to bottom along the thickness direction of the gradient composite material.

8. The gradient composite material according to claim 7, characterized in that The carbon fiber composite material has 2 to 10 layers.

9. Use of the gradient composite material according to claim 7 or the gradient composite material prepared by the preparation method according to claim 1 in any of the following: a. Solar interface evaporation system; b. Solar thermal deicing device; c. Self-cleaning surface construction.

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