A polycarbonate / boron nitride nanosheet aerogel film and its preparation method and application

Abstract

The present invention belongs to the technical field of aerogel films, and discloses a polycarbonate / boron nitride nanosheet aerogel film, a preparation method thereof, and an application thereof. The polycarbonate / boron nitride nanosheet aerogel film comprises polycarbonate and two-dimensional boron nitride nanosheets, and the polycarbonate / boron nitride nanosheet aerogel film has a porous structure. The polycarbonate / boron nitride nanosheet aerogel film provided by the present invention can have excellent thermal conductivity while ensuring good mechanical properties and low dielectric constant and dielectric loss. The present invention adopts a phase separation method to prepare the polycarbonate / boron nitride nanosheet aerogel film. Compared with the traditional aerogel film assembly method, the method is easy to operate, has low equipment requirements, and is easy to prepare on a large scale. The polycarbonate / boron nitride nanosheet aerogel film provided by the present invention can be used as a high-quality thermal conductor and insulator, and is widely used in high-frequency electronic equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of aerogel films, and in particular relates to a polycarbonate / boron nitride nanosheet aerogel film and a preparation method and application thereof. Background Art

[0002] Modern electronic devices are rapidly developing towards thinner, more integrated, and higher-performance devices. According to the 10-degree rule, failure rates double for every 10°C increase in temperature. Heat dissipation issues severely impact device reliability and service life. Polycarbonate (PC), with its excellent electrical insulation, mechanical properties, and low dielectric constant, has been widely used in LED lighting, mobile phone housings, radomes, and other fields. However, pure PC suffers from poor thermal conductivity, limiting its application in modern electronic devices. Adding thermally conductive fillers to polymers is currently the mainstream method for preparing thermally conductive composite materials. A variety of fillers, such as graphene, carbon fiber, and alumina, have been added to polymers. However, composites prepared with these fillers suffer from disadvantages such as excessively high electrical conductivity or low thermal conductivity, making them unsuitable for applications in thermal insulation. This is particularly true in the high-frequency 5G communications, where high-frequency signals require polymer materials to possess extremely low dielectric constants and dielectric losses, and to maintain stability. Therefore, improving the thermal conductivity of PC, while maintaining its excellent mechanical properties and low dielectric constant, has attracted considerable attention in both academia and industry.

[0003] Aerogel membranes are materials with a three-dimensional network structure composed of interconnected or closed pores, characterized by low density and high porosity. The incorporation of air allows the composite material to maintain extremely low dielectric properties. Current methods for preparing aerogels include sol-gel, self-assembly, hydrothermal, and 3D printing. However, existing methods have proven difficult to use for the thermoplastic polycarbonate and nanosheet fillers with very low functionalization levels to form aerogel membranes.

[0004] Therefore, there is an urgent need to provide a polycarbonate aerogel film that can improve thermal conductivity while ensuring good mechanical properties and low dielectric constant and dielectric loss. Summary of the Invention

[0005] The present invention aims to address at least one of the technical problems existing in the aforementioned prior art. To this end, the present invention provides a polycarbonate / boron nitride nanosheet aerogel film, its preparation method, and its application. The polycarbonate / boron nitride nanosheet aerogel film prepared by the present invention can improve thermal conductivity while maintaining good mechanical properties and low dielectric constant and dielectric loss.

[0006] A first aspect of the present invention provides a polycarbonate / boron nitride nanosheet aerogel film.

[0007] Specifically, a polycarbonate / boron nitride nanosheet aerogel film comprises polycarbonate and two-dimensional boron nitride nanosheets, and the polycarbonate / boron nitride nanosheet aerogel film has a porous structure.

[0008] Preferably, the two-dimensional boron nitride nanosheets are prepared by at least one of ball milling, sand milling, grinding, mechanical stirring, high-speed shearing, ultrasonic treatment, high-pressure homogenization, chemical exfoliation or microfluidization.

[0009] Preferably, the two-dimensional boron nitride nanosheets have a sheet diameter of 0.4 to 1.0 μm.

[0010] Preferably, the mass of the two-dimensional boron nitride nanosheets accounts for 1% to 40% of the mass of the polycarbonate / boron nitride nanosheet aerogel film; further preferably, the mass of the two-dimensional boron nitride nanosheets accounts for 5% to 35% of the mass of the polycarbonate / boron nitride nanosheet aerogel film; more preferably, the mass of the two-dimensional boron nitride nanosheets accounts for 10% to 30% of the mass of the polycarbonate / boron nitride nanosheet aerogel film.

[0011] A second aspect of the present invention provides a method for preparing a polycarbonate / boron nitride nanosheet aerogel film.

[0012] Specifically, a method for preparing a polycarbonate / boron nitride nanosheet aerogel film comprises the following steps:

[0013] A good solvent and a poor solvent are mixed to obtain a mixed solvent; polycarbonate is then added to the mixed solvent, and after fully dissolved, two-dimensional boron nitride nanosheets are added and dispersed to obtain a mixed dispersion; the mixed dispersion is then blade-coated or cast onto a support, and dried to obtain a polycarbonate / boron nitride nanosheet aerogel film;

[0014] The good solvent can dissolve polycarbonate, and the poor solvent cannot dissolve polycarbonate;

[0015] The boiling point of the poor solvent is 10° C. higher than the boiling point of the good solvent.

[0016] The polycarbonate / boron nitride nanosheet aerogel film is prepared by a phase separation method. In the ternary system of a good solvent, a poor solvent, and a polymer (polycarbonate), polycarbonate is soluble in the good solvent but insoluble in the poor solvent. Initially, the ternary system is completely mutually soluble to form a homogeneous state because there is a boiling point difference between the good solvent and the poor solvent. During the drying process, as the good solvent evaporates first, the poor solvent precipitates to form small droplets and is dispersed in a system containing a large amount of polycarbonate / two-dimensional boron nitride nanosheet phase until the surrounding polycarbonate / boron nitride nanosheets are gelled and solidified, and the poor solvent is completely evaporated to form an aerogel film with a porous structure. In addition, during the preparation, the use of a doctor blade or casting method can prolong the time for the solvent (good solvent and poor solvent) to evaporate, which is beneficial to the formation of a porous structure in the aerogel film.

[0017] Preferably, the boiling point of the poor solvent is 20° C. higher than that of the good solvent; more preferably, the boiling point of the poor solvent is 30° C. higher than that of the good solvent.

[0018] Preferably, the good solvent is selected from one of dichloromethane (39.75°C), chloroform (61.2°C), and tetrahydrofuran (66°C); the poor solvent is selected from one of isopropyl alcohol (82.5°C), ethanol (78.4°C), and butanol (117.6°C). If the good solvent is dichloromethane, the poor solvent is isopropyl alcohol, ethanol, or butanol; if the good solvent is chloroform, the poor solvent is isopropyl alcohol, ethanol, or butanol; if the good solvent is tetrahydrofuran, the poor solvent is isopropyl alcohol, ethanol, or butanol.

[0019] Preferably, the volume ratio of the poor solvent to the good solvent is 1:(2-20); further preferably, the volume ratio of the poor solvent to the good solvent is 1:(5-20); more preferably, the volume ratio of the poor solvent to the good solvent is 1:(8-15). For example, the volume ratio of the poor solvent to the good solvent is 1:5, the volume ratio of the poor solvent to the good solvent is 1:10, the volume ratio of the poor solvent to the good solvent is 1:15, and the volume ratio of the poor solvent to the good solvent is 1:20.

[0020] Preferably, the mass concentration of the polycarbonate in the mixed dispersion is 40 to 80 mg / mL; more preferably, the mass concentration of the polycarbonate in the mixed dispersion is 50 to 80 mg / mL, such as 40, 45, 50, 55, 60, 65, 70, 75, or 80 mg / mL.

[0021] Preferably, the mixing process is carried out by one of manual stirring, magnetic stirring and mechanical stirring.

[0022] Preferably, the support is selected from at least one of a glass plate, a stainless steel plate, a polytetrafluoroethylene film, a polyester film, and a polyethylene film.

[0023] Preferably, when the polycarbonate / boron nitride nanosheet aerogel film is prepared by blade coating, a blade is used for blade coating, and the wet film thickness coated by the blade is 50 to 500 μm, such as 50 μm, 100 μm, 250 μm, or 500 μm.

[0024] Preferably, the drying temperature is 5-40°C, such as 10, 15, 20, 25, 35, 40°C.

[0025] The third aspect of the present invention provides the application of the polycarbonate / boron nitride nanosheet aerogel film.

[0026] Specifically, the application of the polycarbonate / boron nitride nanosheet aerogel film in high-frequency electronic devices.

[0027] Preferably, the high-frequency electronic device is a device requiring low dielectric and high thermal conductivity, such as a 5G base station housing, a mobile phone housing, a computer housing, etc.

[0028] Boron nitride nanosheets have high thermal conductivity (1700-2000Wm -1 K -1 ), high insulation, low dielectric constant, high temperature resistance and excellent chemical stability, and the addition of boron nitride can improve the thermal conductivity of the polymer. Current methods for preparing aerogel films include sol-gel method, self-assembly method, hydrothermal method and 3D printing, however, for thermoplastic material polycarbonate and two-dimensional boron nitride nanosheets with extremely low degree of functionalization, these methods are unable to prepare composite aerogel films. The present invention adopts a phase separation method, utilizing the fact that polycarbonate is soluble in good solvents but insoluble in poor solvents, and there is a boiling point difference between the good solvent and the poor solvent; when the two-dimensional boron nitride nanosheets are dispersed in the above system, an aerogel film with a porous structure can be obtained as the time difference between the volatilization of the good solvent and the poor solvent occurs.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The polycarbonate / boron nitride nanosheet aerogel film provided by the present invention comprises polycarbonate and two-dimensional boron nitride nanosheets, and has a porous structure. The aerogel film not only retains the excellent mechanical properties of polycarbonate, but also has an extremely low dielectric constant due to its porous structure. The continuous phase of polycarbonate doped with boron nitride nanosheets forms a thermal conduction path, which greatly improves its thermal conductivity. Therefore, the polycarbonate / boron nitride nanosheet aerogel film provided by the present invention can achieve excellent thermal conductivity while ensuring good mechanical properties and low dielectric constant and dielectric loss.

[0031] (2) Compared with the traditional aerogel membrane assembly method, the preparation method of the polycarbonate / boron nitride nanosheet aerogel membrane provided by the present invention is easy to operate, has low equipment requirements, and is easy to prepare on a large scale.

[0032] (3) The polycarbonate / boron nitride nanosheet aerogel film provided by the present invention can be used as a high-quality thermal conductor and insulator and is widely used in electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a cross-sectional scanning electron microscope image of the polycarbonate / boron nitride nanosheet aerogel film prepared in Example 1;

[0034] Figure 2 This is a cross-sectional scanning electron microscope image of the polycarbonate / boron nitride nanosheet aerogel film prepared in Example 2;

[0035] Figure 3 This is a cross-sectional scanning electron microscope image of the polycarbonate / boron nitride nanosheet aerogel film prepared in Example 3;

[0036] Figure 4 This is a scanning electron microscope image of a cross section of the polycarbonate aerogel film prepared in Comparative Example 1;

[0037] Figure 5 This is a comparison chart of the thermal conductivity of aerogel films prepared in Examples 1-3 and Comparative Example 1;

[0038] Figure 6 A comparison chart of the dielectric constants of the aerogel films prepared in Examples 1-3 and Comparative Example 1;

[0039] Figure 7 A comparison chart of the dielectric loss of aerogel films prepared in Examples 1-3 and Comparative Example 1;

[0040] Figure 8 Comparison of mechanical curves of aerogel films prepared in Examples 1-3 and Comparative Example 1. DETAILED DESCRIPTION

[0041] In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the following examples are given for illustration. It should be noted that the following examples do not limit the scope of protection claimed by the present invention.

[0042] Unless otherwise specified, the raw materials, reagents, or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0043] Example 1

[0044] A method for preparing a polycarbonate / boron nitride nanosheet aerogel film comprises the following steps:

[0045] (1) The bulk boron nitride is exfoliated into two-dimensional boron nitride nanosheets (sheet diameter is 0.4-1.0 μm) by ball milling and set aside.

[0046] (2) 1 mL of isopropyl alcohol and 10 mL of dichloromethane were measured and mixed to obtain a mixed solvent; 0.75 g of polycarbonate particles were weighed and added to the mixed solvent while stirring continuously, and stirred until fully dissolved to obtain a mixed solution. The isopropyl alcohol and dichloromethane are mutually soluble, and the polycarbonate is dissolved in the dichloromethane. The concentration of the polycarbonate in the mixed solution is approximately 68 mg / mL.

[0047] (3) Weighing 0.08 g of boron nitride nanosheets, adding them to the mixed solution obtained in step (2), and stirring them ultrasonically to obtain a mixed dispersion after mixing evenly, wherein the mass proportion of the boron nitride nanosheets is about 10 wt %.

[0048] (4) Place a glass plate on a doctor blade, pour the mixed dispersion obtained in step (3) on the glass plate, use a 250 μm doctor blade to doctor blade at room temperature (about 30°C), place at room temperature (about 30°C), and wait for drying to obtain a porous structure polycarbonate / boron nitride nanosheet aerogel film. The mechanism of forming a porous structure polycarbonate / boron nitride nanosheet aerogel film is that polycarbonate is soluble in dichloromethane but not in isopropanol, and the boiling point of dichloromethane is lower than that of isopropanol. During the drying process, as dichloromethane evaporates, isopropanol precipitates to form small droplets and disperses in the system containing a large amount of polycarbonate / boron nitride nanosheet phase until the surrounding polycarbonate / boron nitride nanosheets are gelled and solidified, and the isopropanol is completely evaporated to form an aerogel film with a porous structure.

[0049] Scanning electron microscopy (SEM) was used to observe the microstructure of the aerogel membrane cross section. Figure 1 This is a cross-sectional scanning electron microscope image of the polycarbonate / boron nitride nanosheet aerogel film prepared in Example 1. Figure 1 The cross-section of the aerogel membrane exhibits a uniformly distributed pore structure with pore sizes ranging from 2 to 5 μm. The pore size is related to the volume content of the poor solvent. Boron nitride nanosheets are found on the pore walls and are distributed throughout the polycarbonate system, improving the thermal conductivity of the polycarbonate.

[0050] Example 2

[0051] A method for preparing a polycarbonate / boron nitride nanosheet aerogel film comprises the following steps:

[0052] (1) The bulk boron nitride is exfoliated into two-dimensional boron nitride nanosheets (sheet diameter is 0.4-1.0 μm) by ball milling and set aside.

[0053] (2) 1 mL of isopropyl alcohol and 10 mL of dichloromethane were measured and mixed to obtain a mixed solvent; 0.75 g of polycarbonate particles were weighed and added to the mixed solvent while stirring continuously, and stirred until fully dissolved to obtain a mixed solution. The isopropyl alcohol and dichloromethane are mutually soluble, and the polycarbonate is dissolved in the dichloromethane. The concentration of the polycarbonate in the mixed solution is approximately 68 mg / mL.

[0054] (3) Weighing 0.19 g of boron nitride nanosheets, adding them to the mixed solution obtained in step (2), and stirring them ultrasonically to obtain a mixed dispersion after mixing evenly, wherein the mass proportion of the boron nitride nanosheets is about 20 wt%.

[0055] (4) Place a glass plate on a doctor blade, pour the mixed dispersion obtained in step (3) onto the glass plate, and use a 250 μm doctor blade to doctor the plate at room temperature (about 30° C.). Leave the plate at room temperature (about 30° C.) and wait for it to dry to obtain a porous polycarbonate / boron nitride nanosheet aerogel film. The microscopic morphology of the cross section of the aerogel film was observed using a scanning electron microscope (SEM). Figure 2 This is a cross-sectional scanning electron microscope image of the polycarbonate / boron nitride nanosheet aerogel film prepared in Example 2. Figure 2 The cross-section of the aerogel membrane exhibits a relatively uniform pore structure, with pore sizes ranging from 2 to 5 μm. As the amount of boron nitride nanosheets increases, the pore wall thickness increases, and the thermal conductivity of the composite membrane improves accordingly.

[0056] Example 3

[0057] A method for preparing a polycarbonate / boron nitride nanosheet aerogel film comprises the following steps:

[0058] (1) The bulk boron nitride is exfoliated into two-dimensional boron nitride nanosheets (sheet diameter is 0.4-1.0 μm) by ball milling and set aside.

[0059] (2) 1 mL of isopropyl alcohol and 10 mL of dichloromethane were measured and mixed to obtain a mixed solvent; 0.75 g of polycarbonate particles were weighed and added to the mixed solvent while stirring continuously, and stirred until fully dissolved to obtain a mixed solution. The isopropyl alcohol and dichloromethane are mutually soluble, and the polycarbonate is dissolved in the dichloromethane. The concentration of the polycarbonate in the mixed solution is approximately 68 mg / mL.

[0060] (3) Weighing 0.32 g of boron nitride nanosheets, adding them to the mixed solution obtained in step (2), and stirring them ultrasonically to obtain a mixed dispersion after mixing evenly, wherein the mass proportion of the boron nitride nanosheets is about 30 wt%.

[0061] (4) Place a glass plate on a doctor blade, pour the mixed dispersion obtained in step (3) onto the glass plate, and use a 250 μm doctor blade to doctor the plate at room temperature (about 30° C.). Leave the plate at room temperature (about 30° C.) and wait for it to dry to obtain a porous polycarbonate / boron nitride nanosheet aerogel film. The microscopic morphology of the cross section of the aerogel film was observed using a scanning electron microscope (SEM). Figure 3 This is a cross-sectional scanning electron microscope image of the polycarbonate / boron nitride nanosheet aerogel film prepared in Example 3. Figure 3 The cross-section of the aerogel membrane exhibits a uniformly distributed pore structure with pore sizes ranging from 2 to 5 μm. As the amount of boron nitride nanosheets increases, the pore walls thicken significantly, forming continuous heat conduction pathways along the pore walls.

[0062] Comparative Example 1

[0063] A method for preparing a polycarbonate aerogel film comprises the following steps:

[0064] (1) 1 mL of isopropyl alcohol and 10 mL of dichloromethane were measured and mixed to obtain a mixed solvent; 0.75 g of polycarbonate particles were weighed and added to the mixed solvent while stirring continuously, and stirred until fully dissolved to obtain a mixed solution. The isopropyl alcohol and dichloromethane are mutually soluble, and the polycarbonate is dissolved in the dichloromethane. The concentration of the polycarbonate in the mixed solution is approximately 68 mg / mL.

[0065] (2) Place a glass plate on a doctor blade, pour the mixed solution obtained in step (1) directly onto the glass plate, and use a 250 μm doctor blade to doctor the glass plate at room temperature (about 30° C.). Place the glass plate at room temperature (about 30° C.) and wait for it to dry to obtain a porous polycarbonate aerogel film. The microscopic morphology of the cross section of the aerogel film is observed using a scanning electron microscope (SEM). Figure 4 This is a cross-sectional scanning electron microscope image of the polycarbonate aerogel film prepared in Example 4. Figure 4 It can be seen that the cross-section of the aerogel membrane presents a uniformly distributed pore structure with a pore size distribution between 2-5 μm, and the pore wall is formed by polycarbonate dispersed in dichloromethane.

[0066] Product effect testing

[0067] The thermal diffusivities of the aerogel films prepared in Examples 1-3 and Comparative Example 1 were measured using a flash thermal diffusivity analyzer (LFA-467), and the corresponding horizontal and vertical thermal conductivities were calculated. The dielectric constants and dielectric losses of the aerogel films prepared in Examples 1-3 and Comparative Example 1 were measured using a vector network analyzer, and the mechanical properties of the aerogel films prepared in Examples 1-3 and Comparative Example 1 were measured using a universal testing machine. The test results are shown in Table 1.

[0068] Table 1 Performance test results of aerogel films prepared in Comparative Example 1 and Examples 1 to 3

[0069]

[0070] As can be seen from Table 1, the horizontal and vertical thermal conductivities of the polycarbonate / boron nitride nanosheet aerogel films prepared in Examples 1 to 3 are greatly improved as the proportion of boron nitride nanosheets increases. The highest vertical thermal conductivity is 0.128 W / (m·K) and the highest horizontal thermal conductivity is 0.974 W / (m·K). The specific thermal conductivity comparison is shown in the figure below. Figure 5 In addition, the presence of pores in the aerogel allows the aerogel film to maintain an extremely low dielectric constant. The dielectric constants of the polycarbonate / boron nitride nanosheet aerogel films prepared in Examples 1 to 3 are between 1.2 and 1.5. When the addition amount of boron nitride nanosheets is 20wt% and 30wt%, the polycarbonate / boron nitride nanosheet aerogel film may have a higher porosity due to the presence of small pores, and its dielectric constant is lower. The specific dielectric constant comparison is shown in the figure below. Figure 6 As shown in the figure, the dielectric loss gradually increases with the increase of the amount of boron nitride nanosheets added, but the dielectric loss of the polycarbonate / boron nitride nanosheet aerogel films prepared in Examples 1 to 3 are all lower than 0.009. The specific dielectric loss comparison is shown in the figure. Figure 7 As shown. In addition, with the increase in the addition amount of boron nitride nanosheets, the mechanical properties of the composite film gradually decreased, the tensile stress decreased from 19.57MPa of pure polycarbonate aerogel film to 10.81MPa when the filling amount was 30wt%, and the tensile strain also gradually decreased. However, the aerogel film still maintained good mechanical properties and could meet general industrial needs. The specific mechanical curve comparison is shown in the figure below. Figure 8 As shown, in Figure 8 In the equation, the horizontal axis is the tensile strain (ε), and the vertical axis is the tensile stress (σ). Figure 8 The small and medium pictures are enlarged pictures with tensile strain of 0-5%.

[0071] The polycarbonate / boron nitride nanosheet aerogel film prepared in Example 1 has a vertical thermal conductivity of 0.030 W / (m·K) and a horizontal thermal conductivity of 0.817 W / (m·K) when the tensile stress is greater than 15 MPa, the dielectric constant is less than 1.42, and the dielectric loss is less than 0.0065, which is significantly improved based on the comparative document 1.

[0072] It should be noted that the combination of other qualified good solvents and poor solvents can also achieve similar effects and prepare polycarbonate / boron nitride nanosheet aerogel membranes with porous structures.

[0073] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present invention may be made without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A polycarbonate / boron nitride nanosheet aerogel film, characterized in that: The polycarbonate / boron nitride nanosheet aerogel film comprises polycarbonate and two-dimensional boron nitride nanosheets, wherein the polycarbonate / boron nitride nanosheet aerogel film has a porous structure; The polycarbonate / boron nitride nanosheet aerogel film is prepared by a preparation method comprising the following steps: A good solvent and a poor solvent are mixed to obtain a mixed solvent; polycarbonate is then added to the mixed solvent, and after fully dissolved, two-dimensional boron nitride nanosheets are added and dispersed to obtain a mixed dispersion; the mixed dispersion is then blade-coated or cast onto a support, and dried to obtain a polycarbonate / boron nitride nanosheet aerogel film; The good solvent can dissolve polycarbonate, and the poor solvent cannot dissolve polycarbonate; The melting point of the poor solvent is 10° C. higher than the boiling point of the good solvent.

2. The polycarbonate / boron nitride nanosheet aerogel film according to claim 1, characterized in that The two-dimensional boron nitride nanosheet has a sheet diameter of 0.4 to 1.0 μm.

3. The polycarbonate / boron nitride nanosheet aerogel film according to claim 1 or 2, characterized in that: The mass of the two-dimensional boron nitride nanosheets accounts for 1% to 40% of the mass of the polycarbonate / boron nitride nanosheet aerogel film.

4. The polycarbonate / boron nitride nanosheet aerogel film according to claim 3, characterized in that The mass of the two-dimensional boron nitride nanosheets accounts for 5% to 35% of the mass of the polycarbonate / boron nitride nanosheet aerogel film.

5. The method for preparing the polycarbonate / boron nitride nanosheet aerogel film according to any one of claims 1 to 4, characterized in that: The following steps are involved: A good solvent and a poor solvent are mixed to obtain a mixed solvent; polycarbonate is then added to the mixed solvent, and after fully dissolved, two-dimensional boron nitride nanosheets are added and dispersed to obtain a mixed dispersion; the mixed dispersion is then blade-coated or cast onto a support, and dried to obtain a polycarbonate / boron nitride nanosheet aerogel film; The good solvent can dissolve polycarbonate, and the poor solvent cannot dissolve polycarbonate; The melting point of the poor solvent is 10° C. higher than the boiling point of the good solvent.

6. The preparation method according to claim 5, characterized in that The melting point of the poor solvent is 20° C. higher than the boiling point of the good solvent.

7. The preparation method according to claim 6, characterized in that The melting point of the poor solvent is 30° C. higher than the boiling point of the good solvent.

8. The preparation method according to claim 7, characterized in that The good solvent is selected from one of dichloromethane, chloroform and tetrahydrofuran; the poor solvent is selected from one of isopropanol, ethanol and butanol.

9. The preparation method according to claim 5 or 6, characterized in that: The volume ratio of the poor solvent to the good solvent is 1:(2-20).

10. The preparation method according to claim 5 or 6, characterized in that: The volume ratio of the poor solvent to the good solvent is 1:(5-20).

11. The preparation method according to claim 5, characterized in that In the mixed dispersion, the mass concentration of the polycarbonate is 40 to 80 mg / mL.

12. The preparation method according to claim 5, characterized in that The support is selected from at least one of a glass plate, a stainless steel plate, a polytetrafluoroethylene film, a polyester film, and a polyethylene film.

13. Use of the polycarbonate / boron nitride nanosheet aerogel film according to any one of claims 1 to 4 in high-frequency electronic devices.

Images