Preparation method of flexible heat-conducting film with high surface emission

Abstract

The invention relates to a preparation method of a flexible heat-conducting film with high surface emission, which comprises the following steps: (1) dispersing raw material powder in a solvent, and stirring and performing ultrasonic treatment to obtain precursor slurry; (2) taking a thermal shrinkage film as a substrate, coating the precursor slurry on the substrate, and drying to form a thin film on the substrate; (3) transferring the film with the substrate in the step (2) to a drying oven for high-temperature treatment, so that the film forms a wrinkle structure; (4) continuously coating precursor slurry on the thin film with the wrinkle structure in the step (3) to form a planar heat-conducting layer; and (5) removing the substrate from the film obtained in the step (4) through an organic solvent, thereby obtaining the flexible heat-conducting film. The method disclosed by the invention is simple and effective, and the prepared flexible heat-conducting film with the wrinkle structure has high emissivity and high thermal diffusion coefficient, and can meet the heat dissipation requirement of an electronic device.

Description

Technical Field

[0001] This invention belongs to the field of functional thin film materials, and specifically relates to a method for preparing a flexible thermally conductive thin film with high surface emissivity. Background Technology

[0002] As aerospace electronic devices become increasingly smaller, more integrated, and more powerful, they generate significant amounts of heat during operation. High temperatures are a major cause of electronic device failures, and system reliability decreases with increasing temperature. Therefore, precise temperature control is crucial for electronic devices. On one hand, the vacuum environment and direct sunlight create highly variable thermal environments on spacecraft, with surface temperatures typically ranging from -150°C to 150°C – a significant temperature difference. On the other hand, electronic devices continuously generate heat that accumulates within them, potentially leading to excessively high temperatures and malfunctions. Therefore, an efficient thermal management system is needed to ensure proper device operation.

[0003] Traditional thermal control systems currently have fixed heat dissipation capabilities, are heavy, consume a lot of energy, and are difficult to cope with rapidly changing thermal boundary environments; moreover, the heat transfer path is singular, making it difficult to meet the heat dissipation requirements of electronic devices.

[0004] Common two-dimensional thermally conductive materials, such as graphene, molybdenum disulfide (MoS2), titanium carbide (Mxene), boron nitride nanosheets (BNNS), and silver nanosheets (AgNS), exhibit significant anisotropic heat transfer characteristics due to their unique layered structure. Furthermore, when fabricated into thin films, their unique two-dimensional properties endow them with excellent mechanical properties and flatness, thus leading to their widespread application in the thermal management of electronic devices. However, these two-dimensional thin films currently face the following problems in application: (1) a single heat transfer path is insufficient to meet the heat dissipation requirements of electronic devices; (2) traditional two-dimensional materials have simple structures, making it impossible to couple multiple heat transfer methods. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a flexible thermally conductive thin film with high surface emissivity, so as to overcome the problem of limited heat dissipation capability of aerospace electronic devices in the prior art.

[0006] This invention provides a method for preparing a flexible thermally conductive thin film with high surface emissivity, comprising the following steps:

[0007] (1) The raw material powder is dispersed in a solvent and the precursor slurry is obtained by stirring and ultrasonic treatment;

[0008] (2) Using heat-shrinkable film as a substrate, the precursor slurry is coated onto the substrate and dried to form a thin film on the substrate.

[0009] (3) The film with substrate from step (2) is transferred to an oven for high-temperature treatment. The heat shrink film shrinks when heated, and the stress causes the film to form a wrinkled structure.

[0010] (4) Continue to coat the precursor slurry onto the thin film with the wrinkled structure in step (3) to form a planar thermally conductive layer;

[0011] (5) Remove the substrate from the film in step (4) with an organic solvent to obtain a flexible thermally conductive film.

[0012] Preferably, the precursor slurry in step (1) includes at least one of graphene oxide dispersion, titanium carbide dispersion, molybdenum disulfide dispersion, boron nitride nanosheet dispersion, and silver nanosheet dispersion.

[0013] Preferably, the concentration of the precursor slurry in step (1) is 1 to 20 mg / mL.

[0014] Preferably, the solvent in step (1) includes, but is not limited to, ethanol.

[0015] Furthermore, the concentration of the graphene oxide dispersion is 1-20 mg / mL, the concentration of the titanium carbide dispersion is 1-20 mg / mL, the concentration of the molybdenum disulfide dispersion is 1-20 mg / mL, the concentration of the boron nitride nanosheet dispersion is 1-15 mg / mL, and the concentration of the silver nanosheet dispersion is 1-10 mg / mL.

[0016] Preferably, the graphene oxide sheet has a diameter of 300–500 nm; the titanium carbide sheet has a diameter of 150–200 nm; the molybdenum disulfide sheet has a diameter of 150–200 nm; the boron nitride nanosheet has a diameter of 50–100 nm; and the silver nanosheet has a diameter of 500–1000 nm.

[0017] Preferably, the coating method in step (2) is spraying or scraping, and the operation is carried out on a hot table at 50-70°C.

[0018] Preferably, in step (2), the loading amount of the precursor slurry on the substrate is 0.25–2.5 mg / cm³. 2 .

[0019] Preferably, the high-temperature treatment in step (3) is at a temperature of 120-150°C and the treatment time is 10-30 minutes.

[0020] Preferably, the coating method in step (4) is spraying or scraping, and the operation is carried out on a hot table at 50-70°C.

[0021] Preferably, the organic solvent in step (5) includes, but is not limited to, dichloromethane.

[0022] Preferably, when the film in step (5) is a graphene oxide film, it is necessary to repair defects through reduction treatment to optimize its mechanical and thermal properties.

[0023] Furthermore, the reduction method includes high-temperature reduction, or reduction using hydroiodic acid or ascorbic acid solution.

[0024] More preferably, the high-temperature reduction is carried out at a temperature of 600–1000°C for 4–8 hours.

[0025] The present invention provides a flexible thermally conductive thin film with high surface emissivity prepared according to the above preparation method.

[0026] The present invention also provides an application of the above-mentioned highly emissive flexible thermally conductive thin film in the field of thermal management of aerospace electronic devices.

[0027] This invention involves processing raw material powders (graphene oxide, titanium carbide, molybdenum disulfide, boron nitride nanosheets, or silver nanosheets) through stirring and ultrasonication to obtain a precursor slurry. A heat-shrinkable film is used as a substrate, and the precursor slurry is sprayed or coated onto the substrate. The film with the substrate is then subjected to high-temperature treatment; the stress generated during the heat shrinkage of the film causes it to deform, forming a wrinkled structure. Further precursor slurry is coated onto the wrinkled film to form a planar thermally conductive layer. The substrate is dissolved using dichloromethane to obtain a flexible thermally conductive film with a wrinkled surface, such as… Figure 1 As shown.

[0028] Beneficial effects

[0029] (1) The preparation method of the present invention is simple and effective, and can produce a flexible thermally conductive film with high surface emission. The wrinkled structure of the film generates plasma resonance, thereby confining infrared light to the wrinkled surface and causing enhanced infrared emission.

[0030] (2) The present invention also solves the problem of delamination of graphene films during reduction and use. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the flexible thermally conductive thin film with high surface emissivity in this invention.

[0032] Figure 2 These are scanning electron microscope (SEM) images of the surface-wrinkled graphene flexible thermally conductive films under different loading conditions in Examples 1, 2, 3, and 5.

[0033] Figure 3 Mid-infrared emissivity tests were conducted on the surface-wrinkled graphene flexible thermally conductive films under different loading conditions in Examples 1, 2, 3, and 5.

[0034] Figure 4These are infrared thermal images of the flexible graphene thermally conductive films with surface wrinkles under different loading conditions in Examples 1, 2, 3, and 5, taken at the same temperature.

[0035] Figure 5 Thermal diffusion tests were conducted on the surface-wrinkled graphene flexible thermal conductive film in Example 2, the surface-wrinkled Mxene flexible thermal conductive film in Example 7, and the surface-wrinkled molybdenum disulfide flexible thermal conductive film in Example 10. Detailed Implementation

[0036] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0037] In this invention, the thermal diffusivity test method follows the national standard GB22588, and the thermal diffusivity at 30℃, 40℃, 50℃, and 60℃ is tested using a Netzsch LFA467 laser flare thermal conductivity meter. In this invention, the film density is obtained by weighing the film mass and determining the film volume, and then calculated. The specific heat capacity of the film is directly measured using a gas chromatography-mass spectrometry (GC-MS) instrument. The in-plane thermal conductivity of the film is calculated by multiplying the thermal diffusivity by the density and the specific heat capacity.

[0038] The raw materials and solvents used in the embodiments of this invention are all commercially available products.

[0039] Example 1

[0040] (1) At room temperature, 0.1 g of graphene oxide powder (500 nm in diameter) was weighed into 100 ml of ethanol and stirred for 1 h and then sonicated with a probe for 0.5 h to obtain a 1 mg / mL graphene oxide dispersion as a precursor slurry.

[0041] (2) On a 60℃ hot surface, select a 9×9cm... 2 Using polystyrene heat-shrinkable film as a substrate, 20 mL of graphene oxide dispersion was uniformly sprayed onto the substrate using a spray gun. After drying on a hot table, a graphene oxide film was formed on the substrate, with the two-dimensional film supported by the substrate and a loading of 0.25 mg / cm². 2 ;

[0042] (3) Take the graphene oxide film supported by the substrate in step (2) and clamp it with a stainless steel plate to ensure that the heat shrink film only shrinks in two dimensions; put it in a 120°C oven for high temperature treatment for 10 minutes, take it out and let it cool naturally to form a wrinkled graphene oxide film.

[0043] (4) On a hot plate at 60°C, a graphene oxide dispersion is coated onto the wrinkled graphene oxide film obtained in step (3) with a thickness of 1 mm. After drying, a planar thermally conductive layer of the film is formed.

[0044] (5) Take the substrate-supported pleated graphene oxide film from step (4) and put it into 50 mL of dichloromethane. Replace 50 mL of dichloromethane every 1 h until the polymer substrate is completely dissolved to obtain a surface-pleated graphene oxide film.

[0045] (6) The surface wrinkled graphene oxide film was reduced at high temperature. Argon was used in the atmosphere, the temperature was 800℃, the heating rate was 5℃ / min, and the time was 6h. Finally, a surface wrinkled graphene flexible thermal conductive film was obtained.

[0046] The surface-wrinkled graphene flexible thermally conductive film prepared above has a thermal diffusivity of 1257 mm² in the medium temperature range. 2 / s, in-plane thermal conductivity is 734W / (mK), and mid-infrared emissivity of the surface is 85%.

[0047] Example 2

[0048] (1) At room temperature, 2g of graphene oxide powder (500nm in diameter) was weighed into 200ml of ethanol and stirred for 1h and sonicated with a probe for 0.5h to obtain a 10mg / mL graphene oxide dispersion as a precursor slurry.

[0049] (2) On a 60℃ hot surface, select a 9×9cm... 2 Using polystyrene heat-shrinkable film as a substrate, 4 mL of graphene oxide dispersion was uniformly sprayed onto the substrate using a spray gun. After drying on a hot table, a graphene oxide film was formed on the substrate, with the two-dimensional film supported by the substrate and a loading of 0.5 mg / cm². 2 ;

[0050] (3) Take the graphene oxide film supported by the substrate in step (2) and fix it with a stainless steel plate. Place it in a 150°C oven for high temperature treatment for 30 minutes. Take it out and let it cool naturally to form a wrinkled graphene oxide film.

[0051] (4) On a hot plate at 60°C, a graphene oxide dispersion is coated onto the wrinkled graphene oxide film obtained in step (3) with a thickness of 2 mm. After drying, a planar thermally conductive layer of the film is formed.

[0052] (5) Take the substrate-supported pleated graphene oxide film from step (4) and put it into 50 mL of dichloromethane. Replace 50 mL of dichloromethane every 1 h until the polymer substrate is completely dissolved to obtain a surface-pleated graphene oxide film.

[0053] (6) The graphene oxide film from step (5) was placed in 20 mL of hydroiodic acid for reduction treatment for 6 h to obtain a flexible thermally conductive graphene film with surface wrinkles.

[0054] The surface-wrinkled graphene flexible thermally conductive film prepared above has a thermal diffusivity of 1471 mm² in the medium temperature range. 2 / s, in-plane thermal conductivity is 690W / (mK), and mid-infrared emissivity of the surface is 92%.

[0055] Example 3

[0056] (1) At room temperature, 2g of graphene oxide powder (400nm in diameter) was weighed into 200ml of ethanol and stirred for 1h and sonicated with a probe for 1h to obtain a 10mg / mL graphene oxide dispersion as a precursor slurry.

[0057] (2) On a 60℃ hot surface, select a 9×9cm... 2 Using polystyrene heat-shrinkable film as a substrate, 8 mL of graphene oxide dispersion was uniformly sprayed onto the substrate using a spray gun. After drying on a hot table, a graphene oxide film was formed on the substrate, with the two-dimensional film supported by the substrate and a loading of 1 mg / cm². 2 ;

[0058] (3) Take the graphene oxide film supported by the substrate in step (2) and fix it with a stainless steel plate. Place it in a 140°C oven for high temperature treatment for 15 minutes. Take it out and let it cool naturally to form a wrinkled graphene oxide film.

[0059] (4) On a hot plate at 60°C, a graphene oxide dispersion is coated onto the wrinkled graphene oxide film obtained in step (3) with a thickness of 1 mm. After drying, a planar thermally conductive layer of the film is formed.

[0060] (5) Take the substrate-supported pleated graphene oxide film from step (4) and put it into 50 mL of dichloromethane. Replace 50 mL of dichloromethane every 1 h until the polymer substrate is completely dissolved to obtain a surface-pleated graphene oxide film.

[0061] (6) Dissolve 0.5g of ascorbic acid in 50mL of deionized water and heat to 80℃ until completely dissolved. Place the graphene oxide film from step (5) into the ascorbic acid solution for reduction treatment for 12h to obtain a surface-wrinkled graphene flexible thermal conductive film.

[0062] The surface-wrinkled graphene flexible thermally conductive film prepared above has a thermal diffusivity of 1448 mm² in the medium temperature range. 2 / s, in-plane thermal conductivity is 767W / (mK), and mid-infrared emissivity of the surface is 79%.

[0063] Example 4

[0064] (1) At room temperature, 2g of graphene oxide powder (300nm in diameter) was weighed into 200ml of ethanol and stirred for 1h and sonicated with a probe for 1h to obtain a 10mg / mL graphene oxide dispersion as a precursor slurry.

[0065] (2) On a 60℃ hot surface, select a 9×9cm... 2 Using polystyrene heat-shrinkable film as a substrate, 8 mL of graphene oxide dispersion was uniformly sprayed onto the substrate using a spray gun. After drying on a hot table, a graphene oxide film was formed on the substrate, with the two-dimensional film supported by the substrate and a loading of 1 mg / cm². 2 ;

[0066] (3) Take the graphene oxide film supported by the substrate in step (2) and fix it with a stainless steel plate. Place it in a 140°C oven for high temperature treatment for 15 minutes. Take it out and let it cool naturally to form a wrinkled graphene oxide film.

[0067] (4) On a hot plate at 60°C, a graphene oxide dispersion is coated onto the wrinkled graphene oxide film obtained in step (3) with a thickness of 1 mm. After drying, a planar thermally conductive layer of the film is formed.

[0068] (5) Take the substrate-supported pleated graphene oxide film from step (4) and put it into 50 mL of dichloromethane. Replace 50 mL of dichloromethane every 1 h until the polymer substrate is completely dissolved to obtain a surface-pleated graphene oxide film.

[0069] (6) Dissolve 0.5g of ascorbic acid in 50mL of deionized water and heat to 80℃ until completely dissolved. Place the graphene oxide film from step (5) into the ascorbic acid solution for reduction treatment for 12h to obtain a surface-wrinkled graphene flexible thermal conductive film.

[0070] The surface-wrinkled graphene flexible thermally conductive film prepared above has a thermal diffusivity of 1421 mm² in the medium temperature range. 2 / s, in-plane thermal conductivity is 715W / (mK), and mid-infrared emissivity of the surface is 76%.

[0071] Example 5

[0072] The preparation method of the surface-wrinkled graphene flexible thermally conductive film in this embodiment is the same as in Embodiment 2, except that:

[0073] In step (2), 16 mL of graphene oxide dispersion was coated onto a polystyrene heat-shrinkable film substrate with a loading of 2 mg / cm³. 2 ;

[0074] In step (3), the high-temperature treatment temperature is 150℃ and the time is 15min.

[0075] The graphene flexible thermally conductive film prepared above has a thermal diffusivity of 1560 mm² in the mid-temperature range. 2 / s, in-plane thermal conductivity is 685W / (mK), and mid-infrared emissivity of the surface is 77%.

[0076] Different loading amounts of surface-wrinkled graphene flexible thermally conductive films prepared in Examples 1, 2, 3, and 5 (Examples 1, 2, 3, and 5 correspond to 0.25 mg / cm³, respectively) were compared. 2 0.5 mg / cm 2 1mg / cm 2 2mg / cm 2 Morphological characterization was performed, and its scanning electron microscope images are as follows: Figure 2 As shown in the figure, the results show that the prepared flexible thermally conductive film has a distinct wrinkled structure.

[0077] Mid-infrared emissivity tests were conducted on the surface-wrinkled flexible thermally conductive graphene films and planar graphene films with different loadings prepared in Examples 1, 2, 3, and 5. The results are as follows: Figure 3 As shown, the loading rate is 0.25 mg / cm³. 2 Its emissivity is 85%, and its loading is 0.5 mg / cm³. 2 Its emissivity is 92%, and its loading is 1 mg / cm³. 2 Its emissivity is 79%, and its loading is 2 mg / cm³. 2 The emissivity of the graphene film is 77%, while that of the planar graphene film is 36%. This demonstrates that the mid-infrared emissivity of the flexible thermally conductive graphene film with a wrinkled structure is significantly higher than that of the planar graphene film. Furthermore, a suitable graphene loading further enhances the emissivity of the thermally conductive film.

[0078] Figure 4 Infrared thermal imaging images of surface-wrinkled graphene flexible thermally conductive films and planar graphene films with different loadings prepared in Examples 1, 2, 3, and 5, under the same temperature conditions, showing different infrared images due to their different emissivity.

[0079] Example 6

[0080] The preparation method of the surface-wrinkled graphene flexible thermally conductive film in this embodiment is the same as in Embodiment 2, except that:

[0081] Step (1) Weigh 4g of graphene oxide powder (500nm in diameter) into 200mL of ethanol. The concentration of the graphene oxide dispersion is 20mg / mL.

[0082] Step (2) Take 2 mL of graphene oxide dispersion with a loading of 0.5 mg / mL.

[0083] The graphene flexible thermally conductive film prepared above has a thermal diffusivity of 1468 mmHg in the mid-temperature range. 2 / s, in-plane thermal conductivity is 642W / (mK), and mid-infrared emissivity of the surface is 77%.

[0084] Example 7

[0085] (1) At room temperature, 0.1 g of titanium carbide (MXene) powder (200 nm in diameter) was weighed into 100 ml of ethanol and stirred for 2 h and then sonicated with a probe for 1 h to obtain a 1 mg / mL MXene dispersion, which was used as the precursor slurry.

[0086] (2) On a 60℃ hot surface, select a 9×9cm... 2 Using polystyrene heat-shrinkable film as a substrate, 40 mL of MXene dispersion was uniformly sprayed onto the substrate using a spray gun. After drying on a hot table, an MXene film was formed on the substrate with a loading of 0.5 mg / cm³. 2 ;

[0087] (3) Take the MXene film supported by the substrate in step (2) and fix it with a stainless steel plate. Place it in a 150℃ oven for high temperature treatment for 20 minutes. After taking it out, let it cool naturally to obtain a wrinkled MXene film.

[0088] (4) On a hot plate at 60°C, MXene dispersion is coated onto the wrinkled MXene film prepared in step (3) with a thickness of 1 mm. After drying, a planar thermally conductive layer of the film is formed.

[0089] (5) Take the pleated MXene film supported by the substrate in step (4) and put it into 50 mL of dichloromethane solution. Replace 50 mL of dichloromethane every 1 h until the polymer substrate is completely dissolved to obtain a flexible MXene film with pleated surface.

[0090] The MXene flexible thermally conductive film prepared above has a thermal diffusivity of 498 mmHg in the mid-temperature range. 2 / s, in-plane thermal conductivity is 78W / (mK), and mid-infrared emissivity of the surface is 94%.

[0091] Example 8

[0092] (1) At room temperature, 0.1 g of titanium carbide (MXene) powder (150 nm in diameter) was weighed into 100 ml of ethanol and stirred for 2 h and sonicated with a probe for 1 h to obtain a 1 mg / mL MXene dispersion, which was used as a precursor slurry.

[0093] (2) On a 60℃ hot surface, select a 9×9cm... 2 Using polystyrene heat-shrinkable film as a substrate, 40 mL of MXene dispersion was uniformly sprayed onto the substrate using a spray gun. After drying on a hot table, an MXene film was formed on the substrate with a loading of 0.5 mg / cm³. 2 ;

[0094] (3) Take the MXene film supported by the substrate in step (2) and fix it with a stainless steel plate. Place it in a 150°C oven for high temperature treatment for 15 minutes. Take it out and let it cool naturally to obtain a wrinkled MXene film.

[0095] (4) On a hot plate at 60°C, MXene dispersion is coated onto the wrinkled MXene film prepared in step (3) with a thickness of 1 mm. After drying, a planar thermally conductive layer of the film is formed.

[0096] (5) Take the pleated MXene film supported by the substrate in step (4) and put it into 50 mL of dichloromethane solution. Replace 50 mL of dichloromethane every 1 h until the polymer substrate is completely dissolved to obtain a flexible MXene film with pleated surface.

[0097] The MXene flexible thermally conductive film prepared above has a thermal diffusivity of 475 mmHg in the mid-temperature range. 2 / s, in-plane thermal conductivity is 65W / (mK), and mid-infrared emissivity of the surface is 93%.

[0098] Example 9

[0099] (1) At room temperature, 4g of titanium carbide (MXene) powder (150nm in diameter) was weighed into 200ml of ethanol and stirred for 1h and sonicated with a probe for 0.5h to obtain a 20mg / mL MXene dispersion as a precursor slurry.

[0100] (2) On a 60℃ hot surface, select a 9×9cm... 2 Using polystyrene heat-shrinkable film as a substrate, 40 mL of MXene dispersion was uniformly sprayed onto the substrate using a spray gun. After drying on a hot table, an MXene film was formed on the substrate with a loading of 10 mg / cm³. 2 ;

[0101] (3) Take the MXene film supported by the substrate in step (2) and fix it with a stainless steel plate. Place it in a 120℃ oven for high temperature treatment for 15 minutes. After taking it out, let it cool naturally to obtain a wrinkled MXene film.

[0102] (4) On a hot plate at 60°C, MXene dispersion is coated onto the wrinkled MXene film prepared in step (3) with a thickness of 1 mm. After drying, a planar thermally conductive layer of the film is formed.

[0103] (5) Take the pleated MXene film supported by the substrate in step (4) and put it into 50 mL of dichloromethane solution. Replace 50 mL of dichloromethane every 1 h until the polymer substrate is completely dissolved to obtain a pleated MXene film.

[0104] The MXene flexible thermally conductive film prepared above has a thermal diffusivity of 638 mmHg in the mid-temperature range. 2 / s, in-plane thermal conductivity is 82W / (mK), and mid-infrared emissivity of the surface is 68%.

[0105] Example 10

[0106] (1) At room temperature, 1g of molybdenum disulfide powder (200nm in diameter) was weighed into 100ml of ethanol and stirred for 2h and then sonicated with a probe for 1h to obtain a 10mg / mL molybdenum disulfide dispersion as a precursor slurry.

[0107] (2) On a 60℃ hot surface, select a 9×9cm... 2 Using polystyrene heat-shrinkable film as a substrate, 4 mL of molybdenum disulfide dispersion was uniformly sprayed onto the substrate using a spray gun. After drying on a hot table, a molybdenum disulfide film was formed on the substrate with a loading of 0.5 mg / cm³. 2 ;

[0108] (3) Take the molybdenum disulfide film supported by the substrate in step (2), clamp it with a stainless steel plate, put it in a 140℃ oven for high temperature treatment for 15 minutes, and then take it out and let it cool naturally.

[0109] (4) On a hot plate at 60°C, a molybdenum disulfide dispersion is scraped onto the wrinkled molybdenum disulfide film prepared in step (3) with a thickness of 1 mm. After drying, a planar thermally conductive layer of the film is formed.

[0110] (5) Take the pleated molybdenum disulfide film supported by the substrate in step (4) and put it into 50 mL of dichloromethane solution. Replace 50 mL of dichloromethane every 1 h until the polymer substrate is completely dissolved to obtain a flexible molybdenum disulfide film with pleated surface.

[0111] The prepared molybdenum disulfide flexible thermally conductive film has a thermal diffusivity of 1679 mmHg in the medium temperature range. 2 / s, in-plane thermal conductivity is 546W / (mK), and mid-infrared emissivity of the surface is 86%.

[0112] Figure 5Thermal diffusivity tests were conducted on the wrinkled graphene flexible thermal conductive film in Example 2, the wrinkled Mxene flexible thermal conductive film in Example 7, and the wrinkled molybdenum disulfide flexible thermal conductive film in Example 10. The thermal diffusivity of the wrinkled graphene flexible thermal conductive film in Example 2 was 1526 mm² at 30°C, 40°C, 50°C, and 60°C. 2 / s, 1459mm 2 / s, 1476mm 2 / s, 1424mm 2 / s; In Example 7, the thermal diffusivity of the wrinkled Mxene flexible thermally conductive film at 30℃, 40℃, 50℃, and 60℃ was 528 mm / s. 2 / s, 567mm 2 / s, 504mm 2 / s, 575mm 2 / s; In Example 10, the thermal diffusivity of the wrinkled molybdenum disulfide flexible thermally conductive film at 30℃, 40℃, 50℃, and 60℃ was 1786 mm / s. 2 / s, 1598mm 2 / s, 1721mm 2 / s, 1704mm 2 / s.

[0113] Example 11

[0114] The preparation method of the flexible thermally conductive film in this embodiment is the same as that in Embodiment 10, except that:

[0115] In step (1), the amount of molybdenum disulfide powder weighed is 2g, and the concentration of molybdenum disulfide dispersion is 20mg / mL;

[0116] In step (2), 20 mL of molybdenum disulfide dispersion is sprayed onto a polystyrene heat-shrinkable film substrate, with a loading of 5 mg / cm³. 2 .

[0117] The prepared molybdenum disulfide flexible thermally conductive film has a thermal diffusivity of 1745 mm² in the medium temperature range. 2 / s, in-plane thermal conductivity is 593W / (mK), and mid-infrared emissivity of the surface is 65%.

[0118] Example 12

[0119] The preparation method of the flexible thermally conductive film in this embodiment is the same as that in Embodiment 10, except that:

[0120] In step (1), the particle size of the molybdenum disulfide powder weighed is 150 nm;

[0121] The prepared molybdenum disulfide flexible thermally conductive film has a thermal diffusivity of 1734 mm² in the medium temperature range. 2 / s, in-plane thermal conductivity is 576W / (mK), and mid-infrared emissivity of the surface is 67%.

[0122] Example 13

[0123] (1) At room temperature, 0.1 g of boron nitride nanosheets (100 nm in diameter) were weighed into 100 ml of ethanol and stirred for 2 h and then sonicated with a probe for 1 h to obtain a 1 mg / mL molybdenum disulfide dispersion as a precursor slurry.

[0124] (2) On a 60℃ hot surface, select a 9×9cm... 2 Using polystyrene heat-shrinkable film as a substrate, 80 mL of boron nitride nanosheet dispersion was uniformly sprayed onto the substrate using a spray gun. After drying on a hot table, a boron nitride film was formed on the substrate with a loading of 1 mg / cm³. 2 ;

[0125] (3) Take the boron nitride film supported by the substrate in step (2) and fix it with a stainless steel plate. Place it in a 140℃ oven for high temperature treatment for 15 minutes, and then take it out and let it cool naturally.

[0126] (4) On a hot plate at 60°C, a boron nitride dispersion is coated onto the wrinkled boron nitride film prepared in step (3) with a thickness of 1 mm. After drying, a planar thermally conductive layer of the film is formed.

[0127] (5) Take the pleated boron nitride film supported by the substrate in step (4) and put it into 50 mL of dichloromethane solution. Replace 50 mL of dichloromethane every 1 h until the polymer substrate is completely dissolved to obtain a flexible boron nitride film with pleated surface.

[0128] The prepared boron nitride flexible thermally conductive film has a thermal diffusivity of 1679 mmHg in the mid-temperature range. 2 / s, in-plane thermal conductivity is 760W / (mK), and mid-infrared emissivity of the surface is 80%.

[0129] Example 14

[0130] The preparation method of the flexible thermally conductive film in this embodiment is the same as that in Embodiment 13, except that:

[0131] In step (1), the boron nitride nanosheets have a diameter of 50 nm, the amount weighed is 1.5 g, and the concentration of the dispersion is 15 mg / mL;

[0132] In step (2), 50 mL of boron nitride dispersion is sprayed onto a polystyrene heat-shrinkable film substrate, with a loading of 10 mg / cm³. 2 .

[0133] The prepared boron nitride flexible thermally conductive film has a thermal diffusivity of 1890 mmHg in the medium temperature range. 2 / s, in-plane thermal conductivity is 715W / (mK), and mid-infrared emissivity of the surface is 66%.

[0134] Example 15

[0135] (1) At room temperature, 1g of silver nanosheets (1000nm in diameter) were weighed into 100ml of ethanol and stirred for 2h and sonicated with a probe for 1h to obtain a 10mg / mL silver nanosheet dispersion, which was used as a precursor slurry.

[0136] (2) On a 60℃ hot surface, select a 9×9cm... 2 Using polystyrene heat-shrinkable film as a substrate, 40 mL of silver nanosheet dispersion was uniformly sprayed onto the substrate using a spray gun. After drying on a hot table, a silver nanosheet film was formed on the substrate with a loading of 5 mg / cm³. 2 ;

[0137] (3) Take the silver nanosheet film supported by the substrate in step (2), clamp it with a stainless steel plate, put it in a 140℃ oven for high temperature treatment for 15 minutes, and then take it out and cool it naturally.

[0138] (4) On a hot plate at 60°C, a silver nanosheet dispersion is coated onto the wrinkled silver nanosheet film prepared in step (3) with a thickness of 1 mm. After drying, a planar thermally conductive layer of the film is formed.

[0139] (5) Take the wrinkled silver nanosheet film supported by the substrate in step (4) and put it into 50 mL of dichloromethane solution. Replace 50 mL of dichloromethane every 1 h until the polymer substrate is completely dissolved to obtain a flexible silver thermally conductive film with wrinkled surface.

[0140] The silver flexible thermally conductive film prepared above has a thermal diffusivity of 1148 mmHg in the medium temperature range. 2 / s, in-plane thermal conductivity is 362W / (mK), and mid-infrared emissivity of the surface is 70%.

[0141] Example 16

[0142] The preparation method of the flexible thermally conductive film in this embodiment is the same as that in Embodiment 15, except that:

[0143] In step (1), the silver nanosheets have a diameter of 500 nm, and the amount weighed is 0.1 g, with a dispersion concentration of 1 mg / mL;

[0144] In step (2), 80 mL of silver nanosheet dispersion was sprayed onto a polystyrene heat-shrinkable film substrate, with a loading of 1 mg / cm³. 2 ;

[0145] The surface-wrinkled silver thermally conductive film prepared above has a thermal diffusivity of 1266 mm² in the medium temperature range. 2 / s, in-plane thermal conductivity is 368W / (mK), and mid-infrared emissivity of the surface is 69%.

Claims

1. A method for preparing a flexible thermally conductive thin film with high surface emissivity, comprising the following steps: (1) The raw material powder is dispersed in a solvent and the precursor slurry is obtained by stirring and ultrasonic treatment; (2) Using heat-shrinkable film as a substrate, the precursor slurry is coated onto the substrate and dried to form a thin film on the substrate. (3) Transfer the film with substrate from step (2) to an oven for high-temperature treatment to form a wrinkled structure in the film; (4) Continue to coat the precursor slurry onto the thin film with the wrinkled structure in step (3) to form a planar thermally conductive layer; (5) Remove the substrate from the film in step (4) with an organic solvent to obtain a flexible thermally conductive film.

2. The preparation method according to claim 1, characterized in that, In step (1), the precursor slurry includes at least one of graphene oxide dispersion, titanium carbide dispersion, molybdenum disulfide dispersion, boron nitride nanosheet dispersion, and silver nanosheet dispersion; the concentration of the precursor slurry is 1-20 mg / mL; and the solvent includes ethanol.

3. The preparation method according to claim 2, characterized in that, The concentration of the graphene oxide dispersion is 1–20 mg / mL; the concentration of the titanium carbide dispersion is 1–20 mg / mL; the concentration of the molybdenum disulfide dispersion is 1–20 mg / mL; the concentration of the boron nitride nanosheet dispersion is 1–15 mg / mL; and the concentration of the silver nanosheet dispersion is 1–10 mg / mL.

4. The preparation method according to claim 2, characterized in that, The graphene oxide sheets have a diameter of 300–500 nm; the titanium carbide sheets have a diameter of 150–200 nm; the molybdenum disulfide sheets have a diameter of 150–200 nm; the boron nitride nanosheets have a diameter of 50–100 nm; and the silver nanosheets have a diameter of 500–1000 nm.

5. The preparation method according to claim 1, characterized in that, The coating methods in steps (2) and (4) are spraying or scraping, and the operation is carried out on a hot table at 50-70°C.

6. The preparation method according to claim 1, characterized in that, In step (2), the loading amount of the precursor slurry on the substrate is 0.25–2.5 mg / cm³. 2 .

7. The preparation method according to claim 1, characterized in that, The high-temperature treatment in step (3) is at a temperature of 120-150°C and a treatment time of 10-30 minutes.

8. The preparation method according to claim 1, characterized in that, The organic solvent in step (5) includes dichloromethane.

9. A flexible thermally conductive thin film with high surface emissivity prepared by the preparation method according to claim 1.

10. The application of a flexible thermally conductive thin film with high surface emissivity as described in claim 9 in the field of thermal management of aerospace electronic devices.

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