Photothermal material composition, application thereof and photothermal composite film, preparation method and application thereof

Abstract

The present application relates to the field of photothermal materials, discloses a kind of photothermal coating preparation photothermal material composition and its application and photothermal composite film and its preparation method and application, the photothermal material composition contains chitosan, hydrophilic photothermal component and optional auxiliary, wherein, the content weight ratio of the chitosan, the hydrophilic photothermal component and optional auxiliary is 1:0.1-15:0-5, the photothermal composite film prepared by the photothermal material composition provided by the present application is strong, has higher light absorption rate, photothermal conversion efficiency and driving water evaporation rate.

Description

Technical Field

[0001] This invention relates to the field of photothermal materials, specifically to a photothermal material composition for preparing a photothermal coating and its application, and a photothermal composite film and its preparation method and application. Background Technology

[0002] Faced with the dual pressures of environmental pollution and energy consumption, developing clean energy technologies has become a crucial direction in the development plans of various countries. Under the requirements of energy conservation and environmental protection, solar energy, as an ideal form of clean energy, has received widespread attention. Solar energy is characterized by high total energy output and sustainability. Through the conversion of light energy, it has extremely high application potential in fields such as photothermal, photovoltaic, and photochemical reactions. Among these, the photothermal conversion process has low technical barriers, high energy conversion efficiency, and wide applicability, making it effective for applications in water treatment, building energy conservation, and large-scale power generation. One of the key materials for photothermal conversion applications is photothermal materials capable of efficiently capturing sunlight and converting it into heat energy. The performance of its photothermal coating directly affects the energy input of the application system. Currently, high-performance photothermal materials are developing rapidly, encompassing not only conventional carbon-based and inorganic metal oxides but also emerging polymers, novel two-dimensional materials, and noble metal nanomaterials. In practical applications, it is often necessary to prepare or deposit photothermal materials on the surface of a substrate to form a functional coating. In-situ preparation typically involves selecting specific processing methods for a particular substrate. Deposition, on the other hand, is achieved through methods such as impregnation, coating, and sputtering.

[0003] Currently, the preparation of photothermal films often faces the following problems: (1) Photothermal films prepared by spin coating, filtration, etc. have a small area, making them difficult to apply to the preparation of large-size photothermal films with uniform surfaces; (2) The preparation of some photothermal films involves multiple complex operations, making continuous preparation difficult. These factors greatly limit the production and practical application of photothermal films. At the same time, in order to obtain good wettability, the existing raw material formulations for preparing photothermal composite films usually require the addition of a large number of additives, such as surfactants, propylene glycidyl ethers, and silane modifiers with hydrophilic groups, to promote good wetting between the film surface and water. The addition of a large number of additives not only increases the preparation cost, but also, since the additives are usually organic substances, they are not environmentally friendly and have certain toxic effects on organisms.

[0004] Therefore, there is an urgent need to develop photothermal material compositions that can be prepared at low cost, have high wettability, and are environmentally friendly and non-biotoxic. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned problems existing in the prior art and provide a photothermal material composition that can be produced simply, cheaply, and continuously, and the resulting photothermal composite film has excellent surface wettability and environmental friendliness.

[0006] To achieve the above objectives, the present invention provides a photothermal material composition for preparing a photothermal coating, the photothermal material composition comprising chitosan, a hydrophilic photothermal component and optionally present additives, wherein the weight ratio of the chitosan, the hydrophilic photothermal component and the optionally present additives is 1:0.1-15:0-5.

[0007] The second aspect of the present invention provides the application of the photothermal material composition described in the first aspect above in the preparation of photothermal coatings or photothermal composite films.

[0008] A third aspect of the present invention provides a photothermal composite film comprising a substrate and a photothermal coating covering the surface of the substrate, wherein the photothermal coating contains the photothermal material composition described in the first aspect.

[0009] A fourth aspect of the present invention provides a method for preparing the photothermal composite film described in the third aspect above, comprising:

[0010] (1) In the presence of an acidic solvent, the components in the photothermal material composition described in the first aspect are mixed to obtain a casting slurry;

[0011] (2) The casting slurry is applied to the surface of the substrate and then cured to form a photothermal coating on the substrate surface.

[0012] The fifth aspect of this invention provides the application of the photothermal composite film described in the third aspect above in photothermal conversion.

[0013] Compared with the prior art, the present invention has at least the following advantages:

[0014] The photothermal material composition provided by this invention uses chitosan as the polymer backbone, which is inexpensive and environmentally friendly. The resulting photothermal composite film has strong wettability, as well as high light absorption, photothermal conversion efficiency and stable coating properties.

[0015] Furthermore, the photothermal material composition provided by this invention does not contain any components that are harmful to the environment or have biological toxicity, making it environmentally friendly. Moreover, the film-forming process is simple, easy to scale up for production, suitable for continuous production, and has good application prospects. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the preparation process of a preferred embodiment of the photothermal composite film of the present invention;

[0017] Figure 2 This is a contact angle test diagram of the photothermal composite film prepared in Example 1;

[0018] Figure 3 These are the diffuse reflectance and absorbance data of the photothermal composite film prepared in Example 1; wherein, Figure (a) is the diffuse reflectance test graph and Figure (b) is the absorbance test result graph.

[0019] Figure 4 The photothermal composite film prepared in Example 1 is at 100 mW·cm -2 The water evaporation test curve under simulated sunlight irradiation; Figure (a) is a graph of water quality change under sunlight conditions, and Figure (b) is a graph of water evaporation rate calculated from the water quality change;

[0020] Figure 5 The photothermal composite film samples of different thicknesses obtained in Example 3 were tested at 100 mW·cm⁻¹. -2 Simulate the rate of water evaporation under sunlight. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] As previously stated, a first aspect of the present invention provides a photothermal material composition for preparing a photothermal coating, the photothermal material composition comprising chitosan, a hydrophilic photothermal component and optionally present additives, wherein the weight ratio of the chitosan, the hydrophilic photothermal component and the additives is 1:0.1-15:0-5.

[0023] According to the present invention, the photothermal composition provided by the present invention does not contain components that are environmentally unfriendly or toxic to organisms, such as propylene glycidyl ether, silane modifiers with hydrophilic groups, etc.

[0024] According to a preferred embodiment of the present invention, the viscosity of the chitosan is <200 mPa·s, and the degree of deacetylation is ≥80%. According to the present invention, the viscosity of the chitosan is obtained by measuring the dynamic viscosity of chitosan solutions of different concentrations at 25°C using a rotational viscometer, and then fitting the viscosity value using a fitted curve; the degree of deacetylation is obtained by measuring the amino content of chitosan by acid-base titration at room temperature, and then calculating it according to the formula: Degree of deacetylation = [Amino content (%)] / 9.94% * 100%.

[0025] According to another preferred embodiment of the present invention, the hydrophilic photothermal component is selected from at least one of hydrophilic carbon nanotubes, hydrophilic carbon black, hydrophilic graphite powder, melanin nanomaterials, ferrous metal oxides with spinel structures, polyaniline, polypyrrole, and polythiophene. More preferably, the average particle size of the hydrophilic photothermal component is 10 nm-300 μm; the static water contact angle of the hydrophilic photothermal component is ≤42°, and the solar light absorption rate is ≥85%. According to the present invention, the static water contact angle of the hydrophilic photothermal component is obtained by grinding the hydrophilic photothermal component into a uniform powder, pressing it into tablets, and then testing it using a contact angle measuring instrument at room temperature.

[0026] According to the present invention, the average particle size of the hydrophilic carbon nanotubes, the hydrophilic carbon black, and the hydrophilic graphite powder are each independently selected from 40 nm to 800 nm. In the present invention, the average particle size of tubular materials such as hydrophilic carbon nanotubes is expressed as their diameter.

[0027] Preferably, the melanin nanomaterial is selected from at least one of polydopamine, 2,2,6,6-tetramethylpiperidine oxide-doped dopamine, 3,4-dihydroxyphenylalanine oxide, and tea polyphenol oxide. Preferably, the average particle size of the melanin nanomaterial is 20-300 nm.

[0028] Preferably, the spinel-structured ferrous metal oxide is selected from at least one of CoFe2O4, MnCo2O4, CuCoMnO4 and CuFeMnO4; preferably, the average particle size of the spinel-structured ferrous metal oxide is 50-600 nm.

[0029] According to the present invention, the polyaniline, the polypyrrole, and the polythiophene are all black nanopolymers, and their average particle sizes are each independently selected from 10-60 μm. According to the present invention, the particle size of the polymer is obtained by averaging the particle sizes of multiple particles observed within the field of view of an electron microscope.

[0030] According to a particularly preferred embodiment of the present invention, the hydrophilic photothermal component is a combination of hydrophilic carbon nanotubes and hydrophilic carbon black, and the mass ratio of hydrophilic carbon nanotubes to hydrophilic carbon black is 0.5-2:1. The inventors of the present invention have discovered that the photothermal composite film prepared by specifically selecting the hydrophilic photothermal component with the aforementioned composition has better stability and photothermal conversion efficiency.

[0031] Preferably, the additive is selected from at least one of polyols and ester compounds, more preferably from at least one of glycerol, dibutyl phthalate, acrylate, dodecyl alcohol ester, and citrate.

[0032] According to a more preferred embodiment of the present invention, the photothermal material composition contains an additive, namely, the photothermal material composition contains chitosan, a hydrophilic photothermal component, and the additive; and the weight ratio of the chitosan, the hydrophilic photothermal component B, and the additive is 1:0.2-10:0.1-4. Photothermal composite films prepared from photothermal material compositions having the aforementioned content range exhibit good flexibility and fewer brittle and wrinkle defects in the photothermal coating.

[0033] As previously stated, the second aspect of the present invention provides the application of the photothermal material composition described in the first aspect in the preparation of photothermal coatings or photothermal composite films.

[0034] As previously described, a third aspect of the present invention provides a photothermal composite film comprising a substrate and a photothermal coating covering the surface of the substrate, wherein the photothermal coating contains the photothermal material composition described in the first aspect.

[0035] Preferably, the contact angle of the photothermal composite film is 0-15°, more preferably 0-5°; the solar light absorption rate under dry conditions is 80-96%, more preferably 85-96%; the solar light absorption rate after water immersion is 85-99%, more preferably 88-99%; the photothermal conversion efficiency is 75-90%, more preferably 80-90%; and the film stability is 90-100%, more preferably 95-100%.

[0036] The photothermal composite film provided by this invention has higher solar light absorption rate and photothermal conversion efficiency. Furthermore, the photothermal composite film provided by this invention also exhibits excellent coating stability.

[0037] As described above, a fourth aspect of the present invention provides a method for preparing the photothermal composite film described in the third aspect, comprising:

[0038] (1) In the presence of an acidic solvent, the components in the photothermal material composition described in the first aspect are mixed to obtain a casting slurry;

[0039] (2) The casting slurry is applied to the surface of the substrate and then cured to form a photothermal coating on the substrate surface.

[0040] Preferably, in step (1), the acidic solvent is selected from at least one of acetic acid, hydrochloric acid, sulfuric acid, acetic acid, oxalic acid, lactic acid, succinic acid, malic acid, citric acid, and tartaric acid; according to the present invention, the concentration of the acidic solvent is preferably 0.2-5 wt%.

[0041] Preferably, in step (1), the amount of acidic solvent used is such that the concentration of chitosan in the resulting casting slurry is 0.5-10 wt%, more preferably 0.5-5 wt%.

[0042] Preferably, the mixing conditions include a temperature of 25-90°C; more preferably, a temperature of 40-70°C.

[0043] According to a particularly preferred embodiment of the present invention, such as Figure 1 As shown, in step (1), the mixing operation includes: first, chitosan and optionally present additives are subjected to a first contact mixing in the acidic solvent, and then subjected to a second contact mixing with the hydrophilic photothermal component to obtain the casting slurry. The inventors of the present invention have found that the casting slurry prepared by this preferred stepwise mixing is more uniform, has better dispersibility, and the stability of the photothermal coating formed after coating is better. According to the present invention, there are no particular limitations on the specific operation of the mixing in step (1), as long as the components in the photothermal material composition can be uniformly mixed in the solvent. For example, this can be achieved by stirring, oscillation, etc. There are no particular limitations on the stirring speed and oscillation frequency, which can be selected according to the actual mixing situation.

[0044] Preferably, the conditions for the first contact mixing include: temperature 50-90℃; time 2-8h.

[0045] Preferably, the conditions for the second contact mixing include: a temperature of 50-90°C and a time of 1-4 hours.

[0046] Preferably, in step (2), the base membrane is selected from at least one of nonwoven fabric, dust-free paper, fiber fabric, porous polymer membrane, and polymer mesh. The porous polymer membrane is preferably a hydrophilic polyvinylidene fluoride membrane, a hydrophilic polytetrafluoroethylene membrane, a polycarbonate membrane, a cellulose membrane, etc.; the polymer mesh is preferably a polyethylene mesh, a polypropylene mesh, a polyurethane mesh, a polyamide mesh, etc.

[0047] According to the present invention, in step (2), there is no particular limitation on the specific means of covering the casting liquid onto the surface of the base film. Commonly used coating methods in the art can be employed, such as immersion, manual coating, or automatic processing using a coating machine, coating machine, or casting machine to uniformly disperse the casting liquid onto the surface of the base film to a specific thickness, thereby obtaining a base film covered with the casting liquid. Preferably, the thickness of the casting liquid covering the surface of the base film is 20-65 micrometers, more preferably 35-65 micrometers.

[0048] Preferably, the curing process employs heat curing. Preferably, the heat curing conditions include a curing temperature of 40-150℃, more preferably 50-80℃. The present invention does not impose a particular limitation on the curing time, as long as the casting slurry is cured. Those skilled in the art can make reasonable adjustments and selections based on actual conditions.

[0049] As previously stated, the fifth aspect of the present invention provides the application of the photothermal composite film described in the third aspect in photothermal conversion.

[0050] Preferably, the applications include seawater desalination, photothermal evaporation, building thermal energy collection, and thermoelectric power generation.

[0051] Unless otherwise specified, room temperature in this invention refers to 25±2℃.

[0052] The present invention will be described in detail below through embodiments.

[0053] In the following examples, unless otherwise specified, all raw materials involved are commercially available products.

[0054] Chitosan is a commercially available product from McLean Company, brand name C804726, with a viscosity of 100-200 mPas and a degree of deacetylation of ≥95%.

[0055] The hydrophilic carbon nanotubes are carboxylated multi-walled carbon nanotubes from Chia-Tai Technology Co., Ltd., with a diameter of 40-60nm, a static water contact angle of 37°, and a solar absorption rate of 94.1%.

[0056] The hydrophilic carbon black was purchased from Boyuan Chemical Co., Ltd., with an average particle size of 600 nm, a static water contact angle of 19°, and a solar absorption rate of 91.3%.

[0057] Polydopamine was purchased from Xianfeng Nanotechnology Co., Ltd. under the brand name XFDZ. It has an average particle size of 84 nm, a static water contact angle of 22°, and a solar absorption rate of 87.1%.

[0058] CuFeMnO4 was prepared by calcination of metal nitrate sol-gel, with an average particle size of 400 nm, a static water contact angle of <4°, and a solar absorption rate of 91.3%.

[0059] Polyaniline was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with an average particle size of 35 μm, a static water contact angle of 42°, and a solar absorption rate of 85.8%.

[0060] Example 1

[0061] (1) Add 1.6 parts of chitosan to 97.5 parts of 1wt% acetic acid aqueous solution, then add 0.5 parts of glycerol, and mechanically stir at 60°C for 4 hours at a stirring speed of 400 rpm. Then add 0.4 parts of hydrophilic modified carbon nanotubes and continue stirring at 60°C for 2 hours to obtain casting slurry.

[0062] (2) The casting slurry was coated onto the surface of a dust-free paper by a scraping method. The coating thickness was 65 μm. The coated sample was placed in a 60℃ oven and dried for 12 hours to obtain a photothermal composite film with photothermal coating deposition.

[0063] Example 2A

[0064] (1) Add 2 parts of chitosan to 91 parts of 1wt% acetic acid aqueous solution, then add 2 parts of citrate, and mechanically stir at 60°C for 4 hours at a stirring speed of 400 rpm. Then add 5 parts of hydrophilic modified graphite powder and continue stirring at 60°C for 2 hours to obtain casting slurry.

[0065] (2) The casting slurry was coated onto the surface of a dust-free paper by a scraping method. The coating thickness was 65 μm. The coated sample was placed in a 60℃ oven and dried for 12 hours to obtain a photothermal composite film with photothermal coating deposition.

[0066] Example 2B

[0067] (1) Add 0.5 parts of chitosan to 93 parts of 1wt% acetic acid aqueous solution, then add 1.5 glycerol, and mechanically stir at 60°C for 4 hours at a stirring speed of 400 rpm. Then add 5 parts of polydopamine and continue stirring at 60°C for 2 hours to obtain casting slurry.

[0068] (2) The casting slurry was coated onto the surface of a dust-free paper by a scraping method. The coating thickness was 65 μm. The coated sample was placed in a 60℃ oven and dried for 12 hours to obtain a photothermal composite film with photothermal coating deposition.

[0069] Example 2C

[0070] (1) Add 2 parts of chitosan to 90.8 parts of 1wt% acetic acid aqueous solution, then add 0.2 parts of glycerol, and mechanically stir at 60°C for 4 hours at a stirring speed of 400 rpm. Then add 7 parts of CuFeMnO4 and continue stirring at 60°C for 2 hours to obtain casting slurry.

[0071] (2) The casting slurry was coated onto the surface of a dust-free paper by a scraping method. The coating thickness was 65 μm. The coated sample was placed in a 60℃ oven and dried for 12 hours to obtain a photothermal composite film with photothermal coating deposition.

[0072] Example 2D

[0073] (1) Add 2 parts of chitosan to 96.5 parts of 1wt% acetic acid aqueous solution, then add 1 part of dibutyl phthalate, and mechanically stir at 60°C for 4 hours at a stirring speed of 400 rpm. Then add 0.5 parts of polyaniline and continue stirring at 60°C for 2 hours to obtain casting slurry.

[0074] (2) The casting slurry was coated onto the surface of a dust-free paper by a scraping method. The coating thickness was 65 μm. The coated sample was placed in a 60℃ oven and dried for 12 hours to obtain a photothermal composite film with photothermal coating deposition.

[0075] Examples 3A-3C

[0076] The photothermal composite film was prepared in a similar manner to that in Example 1, except that the coating thicknesses were 20 μm, 35 μm, and 50 μm, respectively, while all other aspects were the same as in Example 1.

[0077] Example 4

[0078] The photothermal composite film was prepared in a similar manner to that in Example 1, except that the same weight parts (0.2 parts hydrophilic carbon nanotubes + 0.2 parts hydrophilic carbon black) were used instead of the hydrophilic modified carbon nanotubes in Example 1. All other aspects were the same as in Example 1.

[0079] Example 5

[0080] The photothermal composite film was prepared in a manner similar to that of Example 1, except that the auxiliary agent glycerol was not added; otherwise, it was the same as that of Example 1.

[0081] Example 6

[0082] The method is similar to that in Example 1, except that step (1) is as follows:

[0083] 1.6 parts of chitosan were added to 97.5 parts of 1 wt% acetic acid aqueous solution, 0.5 parts of glycerol were added, and 0.4 parts of hydrophilic modified carbon nanotubes were added. The mixture was mechanically stirred at 60°C for 6 hours at a stirring speed of 400 rpm to obtain a casting slurry. Step (2) was the same as in Example 1A to obtain a photothermal composite film.

[0084] Example 7

[0085] The photothermal composite film was prepared in a similar manner to that in Example 1, except that the amount of chitosan was 1.8 parts and the amount of carbon nanotubes was 0.2 parts, while the rest were the same as in Example 1.

[0086] Comparative Example 1

[0087] The photothermal composite film was prepared in a similar manner to that in Example 1, except that the chitosan was a commercially available product from Shanghai Aladdin Biochemical Technology Co., Ltd., with the product name C105803, and its viscosity was >400 mPa·s and its degree of deacetylation was ≥75%.

[0088] Comparative Example 2

[0089] The photothermal composite film was prepared in a similar manner to that in Example 1, except that the carbon nanotubes were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. and were commercially available with the product name C139829. The carbon nanotubes had a static water contact angle of 67° and a solar absorption rate of 90.8%.

[0090] Comparative Example 3

[0091] The photothermal composite film was prepared in a similar manner to that in Example 1, except that the amount of chitosan was 0.1 parts and the amount of carbon nanotubes was 1.9 parts, while the rest were the same as in Example 1.

[0092] Test case

[0093] The following properties of the photothermal composite film samples obtained in the above embodiments were tested:

[0094] 1) Wetting properties

[0095] The wettability of the photothermal composite film samples prepared in the above embodiments and comparative examples was tested, and the results are shown in Table 1 below. Specifically, the contact angle of the photothermal composite film surface with water was measured using a contact angle measuring instrument. An exemplary test result diagram of the sample from Example 1 is also provided. Figure 2 As shown, from Figure 2 As can be seen from the data, the initial contact angle of the photothermal composite film provided by the present invention is 24°. As the test water droplets gradually spread, the contact angle in the equilibrium state is <4°, indicating that the photothermal coating provided by the present invention has good hydrophilicity.

[0096] 2) Light absorption

[0097] The diffuse reflectance and light absorptance of the photothermal composite film samples prepared in the above embodiments and comparative examples were tested, and the results are shown in Table 1 below. Specifically, the diffuse reflectance in the wavelength range of 280-2500 nm was measured using a UV-Vis-NIR spectrometer, and the light absorptance (light absorptance = 1 - diffuse reflectance) was calculated. An exemplary graph of the test results for the sample in Example 1 is also provided. Figure 3 ,Depend on Figure 3 The average diffuse reflectance of the dried sample was 13.1%, and the absorbance was 86.9%. Furthermore, the average diffuse reflectance of the sample decreased to 6.6% and the absorbance to 93.4% after water immersion, indicating that the photothermal film exhibits excellent light absorption performance after immersion.

[0098] 3) Photo-driven water evaporation and photothermal conversion efficiency

[0099] The light-driven water evaporation properties of the photothermal composite film samples prepared in the above embodiments and comparative examples were tested, and the results are shown in Table 1 below. Specifically, the samples were tested at 100 mW·cm⁻¹. -2 Its performance in promoting water evaporation rate was tested under light conditions (test temperature 25°C), and the test results of the sample in Example 1 are provided exemplarily. (See attached image for results.) Figure 4 The average evaporation rate of water reached 1.29 ± 0.03 kg·m³. -2 ·h -1 A comparison chart of test results with those of Sample 3A-3D in Example 3 is also provided; the results are shown in [the original text]. Figure 5 .

[0100] Meanwhile, based on the test results of the light-driven water evaporation rate, the photothermal conversion efficiency of the photothermal composite film samples prepared in the above embodiments and comparative examples was calculated using the following formula:

[0101] Photothermal conversion efficiency = Light-driven water evaporation rate × Enthalpy of water vaporization / Light power density × 100%

[0102] In the above formula, the enthalpy of evaporation of water is 2402.8 kJ / kg.

[0103] 4) Stability test of photothermal composite film

[0104] The stability of the photothermal composite film samples prepared in the above embodiments and comparative examples was tested. The specific test process was as follows: the photothermal composite film sample was placed in water and exposed to sunlight in a natural environment. After 6 months, the sample was taken out and its light-driven water evaporation rate was tested in the constructed photothermal evaporation system (the specific test process is as described in (3) above, light-driven water evaporation test). The measured evaporation rate was compared with the original evaporation rate to obtain the performance retention rate, which represents the film stability. The test results are shown in Table 1 below.

[0105] Table 1

[0106]

[0107]

[0108] As can be seen from the above, the photothermal composite film prepared using the photothermal material composition provided by this invention exhibits strong wettability, high light absorption, high photothermal conversion efficiency, and high water evaporation rate, making it highly suitable for applications in seawater desalination, photothermal water evaporation, building thermal collectors, and thermoelectric power generation. Furthermore, the photothermal material composition provided by this invention does not contain any environmentally harmful or biotoxic components, making it environmentally friendly. The film preparation process is simple and allows for continuous production, thus possessing broad application prospects.

[0109] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A photothermal material composition for preparing a photothermal coating, characterized in that, The photothermal material composition contains chitosan, a hydrophilic photothermal component, and an additive, wherein the weight ratio of chitosan, the hydrophilic photothermal component, and the additive is 1:0.1-15:0.1-4; the viscosity of the chitosan is <200 mPa•s; the hydrophilic photothermal component is a combination of hydrophilic carbon nanotubes and hydrophilic carbon black, and the mass ratio of hydrophilic carbon nanotubes to hydrophilic carbon black is 0.5-2:1; the static water contact angle of the hydrophilic photothermal component is ≤42°; and the additive is selected from at least one of glycerol, dibutyl phthalate, acrylate, dodecyl alcohol ester, and citrate.

2. The photothermal material composition according to claim 1, wherein, The degree of deacetylation of the chitosan is ≥80%.

3. The photothermal material composition according to claim 1, wherein, The average particle size of the hydrophilic photothermal component is 10 nm-300 μm; the solar light absorption rate of the hydrophilic photothermal component is ≥85%.

4. The photothermal material composition according to any one of claims 1-3, wherein, The weight ratio of the chitosan, the hydrophilic photothermal component, and the auxiliary agent is 1:0.2-10:0.1-4.

5. The use of the photothermal material composition according to any one of claims 1-4 in the preparation of photothermal coatings or photothermal composite films.

6. A photothermal composite film, characterized in that, It includes a substrate and a photothermal coating covering the surface of the substrate, wherein the photothermal coating contains the photothermal material composition according to any one of claims 1-4.

7. The photothermal composite film according to claim 6, wherein, The contact angle of the photothermal composite film is 0-15°; the solar light absorption rate under dry conditions is 80-96%; the solar light absorption rate after water immersion is 85-99%; the photothermal conversion efficiency is 75-90%; and the film stability is 90-100%.

8. The photothermal composite film according to claim 7, wherein, The contact angle of the photothermal composite film is 0-5°; the solar light absorption rate under dry conditions is 85-96%; the solar light absorption rate after water immersion is 88-99%; the photothermal conversion efficiency is 80-90%; and the film stability is 95-100%.

9. A method for preparing the photothermal composite film according to claim 6, characterized in that, include: (1) In the presence of an acidic solvent, the components of the photothermal material composition according to any one of claims 1-4 are mixed to obtain a casting slurry; (2) The casting slurry is applied to the surface of the substrate and then cured to form a photothermal coating on the surface of the substrate.

10. The method according to claim 9, wherein, In step (1), the mixing operation includes: first, mixing chitosan and additives in the acidic solvent in a first contact, and then mixing them in a second contact with the hydrophilic photothermal component to obtain the casting slurry.

11. The method according to claim 10, wherein, The acidic solvent is selected from at least one of acetic acid, hydrochloric acid, sulfuric acid, oxalic acid, lactic acid, succinic acid, malic acid, citric acid, and tartaric acid.

12. The method according to claim 10, wherein, The conditions for the first contact mixing include: temperature 50-90℃; time 2-8h.

13. The method according to claim 10, wherein, The conditions for the second contact mixing include: temperature 50-90℃; time 1-4h.

14. The method according to claim 9 or 10, wherein, In step (2), the curing process is heat curing.

15. The method according to claim 14, wherein, The conditions for heat curing include a temperature of 40-150℃.

16. The method according to claim 15, wherein, The conditions for heat curing include a temperature of 50-80℃.

17. The application of the photothermal composite film according to any one of claims 6-8 in photothermal conversion.

18. The application of the photothermal composite membrane according to any one of claims 6-8 in the fields of seawater desalination, photothermal evaporation, building heat collection and thermoelectric power generation.

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