A thermally conductive and wave-absorbing film based on a MXene quantum dot / boron nitride nanosheet heterostructure, and its preparation method and application

Abstract

The present invention belongs to the field of functional material technology, and specifically relates to a thermally conductive and wave-absorbing film based on a MXene quantum dot / boron nitride nanosheet heterostructure, as well as its preparation method and application. The thermally conductive and wave-absorbing film comprises the following components: MXene quantum dots, boron nitride nanosheets, and nanofibers. By cutting MXene nanosheets into MXene quantum dots, the present invention can avoid the impedance mismatch problem caused by the excessive electrical conductivity of MXene nanosheets. Further combining with boron nitride nanosheets and constructing a MXene quantum dot / boron nitride nanosheet heterostructure, it can achieve the synergistic and complementary advantages of high thermal conductivity boron nitride and excellent wave-absorbing performance MXene, thereby simultaneously improving the thermal conductivity and wave-absorbing performance of the film material. By introducing nanofibers, the film material can have good mechanical flexibility to meet the needs of practical applications. The preparation process of the present invention is simple and controllable, has good universality, and is easy to industrialize.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials, and specifically relates to a thermal conductive and wave-absorbing film based on a MXene quantum dot / boron nitride nanosheet heterostructure, and a preparation method and application thereof. Background Art

[0002] In recent years, the booming development of 5G communications, consumer electronics, new energy vehicles, the Internet of Things, and big data centers has driven the development of electronic devices toward high integration, miniaturization, high frequency, and high performance. As electronic components shrink in size, packaging density increases, and operating frequencies and speeds accelerate, this translates to a surge in heat generation, severe electromagnetic interference, and radiation. This can lead to reduced performance and reliability, and even security issues such as thermal failure or information leakage. To address these issues, electronic product designs generally incorporate extensive use of thermally conductive and absorbing materials. However, as electronic products continue to pursue miniaturization and thinness, the space available for these materials is shrinking dramatically, and traditional materials are no longer able to meet the increasingly stringent application requirements. Therefore, there is an urgent need to develop ultra-thin, thermally conductive and absorbing materials with dual functional properties.

[0003] Hexagonal boron nitride (h-BN), also known as "white graphene", has nitrogen atoms and boron atoms arranged alternately with each other, and there is a strong sp 2 Covalent bonding is widely used in many fields due to its excellent thermal conductivity, electrical insulation, optical properties, thermal stability, and corrosion resistance. However, boron nitride has a low dielectric constant (3.29-3.76) and poor attenuation of electromagnetic waves. Therefore, in order to achieve integrated thermal conductivity and absorption, new methods are currently needed to enhance the absorption properties of boron nitride. Two-dimensional transition metal carbon / nitride (MXene) is a class of two-dimensional layered nanomaterials with a graphene-like structure. It was first discovered by Professor Yury Gogosti's team at Drexel University in 2011 while etching MAX phase ceramics. MXene has attracted considerable attention in the field of absorbing materials due to its excellent electrical conductivity, unique surface activity, and ease of forming heterostructures. However, compared with its absorption properties, MXene's thermal conductivity is less than satisfactory.

[0004] Therefore, how to prepare thermal conductive and wave absorbing dual-functional materials by combining high thermal conductivity boron nitride and excellent wave absorbing properties of MXene through reasonable structural design remains a huge challenge. Summary of the Invention

[0005] In response to the problems existing in the prior art, the purpose of the present invention is to provide a thermally conductive and wave-absorbing film based on a MXene quantum dot / boron nitride nanosheet heterostructure, as well as a preparation method and application thereof. The prepared film has both efficient thermal conductivity and excellent wave-absorbing ability.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is:

[0007] The present invention provides a method for preparing a thermally conductive and wave-absorbing film based on a MXene quantum dot / boron nitride nanosheet heterostructure, comprising the following steps:

[0008] SS1. MAX phase ceramics were etched using a mixed solution of hydrochloric acid and lithium fluoride, followed by ultrasonic exfoliation under inert gas protection. MXene nanosheets were obtained by centrifugation and freeze-drying.

[0009] SS2. Dispersing the MXene nanosheets obtained in step SS1 into an organic solvent, and cutting the MXene nanosheets into MXene quantum dots by a solvothermal method;

[0010] SS3. Hexagonal boron nitride was dispersed in a mixed solvent of isopropyl alcohol and deionized water and then ultrasonically exfoliated to obtain boron nitride nanosheets.

[0011] SS4. The MXene quantum dots obtained in step SS2 and the boron nitride nanosheets obtained in step SS3 are uniformly dispersed in an organic solvent to obtain a MXene quantum dot / boron nitride nanosheet heterostructure after self-assembly;

[0012] SS5. The MXene quantum dot / boron nitride nanosheet heterostructure and nanofibers obtained in step SS4 are uniformly dispersed in an aqueous solution, and a thermally conductive and wave-absorbing film based on the MXene quantum dot / boron nitride nanosheet heterostructure is obtained by vacuum-assisted filtration.

[0013] In the preparation method of the above-mentioned thermally conductive and wave-absorbing film provided by the present invention, by constructing a MXene quantum dot / boron nitride nanosheet heterostructure, it is possible to effectively avoid the structural design contradictions in the thermal conductivity and wave-absorbing properties of boron nitride and MXene, as well as the performance trade-off problem caused by traditional blending methods. This allows the two materials to simultaneously exert an enhancing effect on the thermal conductivity and wave-absorbing properties. At the same time, the introduction of nanofibers can enhance the mechanical properties of the thermally conductive and wave-absorbing film and make the film have good flexibility.

[0014] Preferably, in the above step SS1, the concentration of hydrochloric acid is 3 to 12 M, the mass ratio of HCl to the lithium fluoride is 1:0.01 to 1:0.1; the mass ratio of the lithium fluoride to the MAX phase ceramic is 1:0.2 to 1:2; the etching temperature is 25 to 50° C., and the etching time is 12 to 60 h.

[0015] Preferably, the MAX phase ceramic is selected from one or more of Ti2AlC, Ti3AlC2, Ti3SiC2, Ti3AlCN, V2AlC, V4AlC3, Nb2AlC, Nb4AlC3, Ta4AlC3, Ta2AlC, Sc2AlC and Mo2Ga2C.

[0016] Preferably, in the above step SS2, the operation of the solvothermal method is: dispersing the MXene nanosheets in an organic solvent, the concentration of the MXene nanosheets is 0.5 to 10 g / L, the reaction temperature is 80 to 180° C., and the reaction time is 6 to 24 h.

[0017] Preferably, in step SS3, the concentration of hexagonal boron nitride dispersed in the mixed solvent is 1 to 20 g / L; the volume ratio of isopropyl alcohol to deionized water in the mixed solvent is 1:0.5 to 1:2; and the ultrasonication time is 1 to 12 h.

[0018] Preferably, in the above step SS4, the mass ratio of the MXene quantum dots to the boron nitride nanosheets is 1:1 to 1:10; and the concentration of the MXene quantum dots in the organic solvent is 0.5 to 10 g / L.

[0019] Preferably, in the above step SS5, the mass ratio of the MXene quantum dot / boron nitride nanosheet heterostructure to the nanofiber is 1:0.05 to 1:1, and the nanofiber is selected from one or more of carbon nanofiber, aramid nanofiber, nanocellulose, and carbon nanotube fiber; the concentration of the MXene quantum dot / boron nitride nanosheet heterostructure in water is 0.5 to 10 g / L.

[0020] Preferably, the organic solvent in steps SS2 and SS4 is selected from one or more of ethanol, ethylene glycol, tetrahydrofuran, dimethylformamide and dimethyl sulfoxide.

[0021] In a second aspect, the present invention provides a thermally conductive and absorbing film based on a MXene quantum dot / boron nitride nanosheet heterostructure obtained according to the preparation method described in the first aspect, wherein the thermally conductive and absorbing film comprises the following components: MXene quantum dots, boron nitride nanosheets and nanofibers.

[0022] In a third aspect, the present invention provides an application of a thermally conductive and absorbing film based on a MXene quantum dot / boron nitride nanosheet heterostructure obtained according to the above preparation method in thermal management and electromagnetic wave shielding and absorption.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) In the present invention, MXene nanosheets are cut into MXene quantum dots, which have the advantages of unique nanosize effect, abundant active edge sites and quantum confinement effect. In addition, the semiconductor properties of MXene quantum dots can solve the impedance mismatch problem caused by the excessive conductivity of MXene nanosheets.

[0025] (2) The present invention constructs a MXene quantum dot / boron nitride nanosheet heterostructure to achieve the synergistic and complementary advantages of high thermal conductivity boron nitride and excellent wave absorbing performance of MXene, effectively solving the problem that thermal conductivity and wave absorbing performance are mutually exclusive and difficult to improve at the same time.

[0026] (3) The thermally conductive and wave-absorbing film prepared by the present invention not only has high thermal conductivity and strong wave-absorbing properties, but also has good mechanical flexibility by introducing nanofibers, which can meet the practical application needs in fields such as wearable electronic devices and flexible devices.

[0027] (4) The preparation process of the present invention is simple and controllable, has good universality, is easy to industrialize, and has high practical value and promotion value in the field of functional material technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart for preparing the thermally conductive and wave-absorbing film based on the MXene quantum dot / boron nitride nanosheet heterostructure of the present invention.

[0029] Figure 2 The absorbing performance of the thermally conductive and absorbing film based on the MXene quantum dot / boron nitride nanosheet heterostructure of the present invention. DETAILED DESCRIPTION

[0030] The following examples further illustrate the specific embodiments of the present invention, but the scope of protection of the present invention is not limited to the following examples. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0031] Figure 1 The following is a flow chart for preparing a thermally conductive and wave-absorbing film based on a MXene quantum dot / boron nitride nanosheet heterostructure.

[0032] Example 1

[0033] Prepare 400ml of a mixed solution containing 10g of lithium fluoride and 6M hydrochloric acid, add 10g of Ti3AlC2 to the mixed solution, etch at 30°C for 36h, filter and wash, and perform ultrasonic exfoliation under inert gas protection. MXene nanosheets are obtained by centrifugation and freeze-drying; 8g of MXene nanosheets are dispersed in 2000mL of tetrahydrofuran, and the MXene nanosheets are cut into MXene quantum dots by a solvent thermal method with a reaction temperature of 100°C and a reaction time of 12h; 10g of hexagonal boron nitride is dispersed in 1000mL of a mixed solvent of isopropanol and deionized water (1:1, v / v), and boron nitride nanosheets are obtained by ultrasonic exfoliation for 6h; 5g of MXene quantum dots and 6g of boron nitride nanosheets are evenly dispersed in 2000mL of tetrahydrofuran, and a MXene quantum dot / boron nitride nanosheet heterostructure is obtained after self-assembly; 10g The MXene quantum dot / boron nitride nanosheet heterostructure and 1 g of nanocellulose were evenly dispersed in 2000 mL of aqueous solution, and a thermal conductive and wave-absorbing film sample based on the MXene quantum dot / boron nitride nanosheet heterostructure was obtained by vacuum-assisted filtration.

[0034] Example 2

[0035] Prepare 400ml of a mixed solution containing 10g of lithium fluoride and 9M hydrochloric acid, add 10g of Ti2AlC to the mixed solution, etch at 35°C for 24h, filter and wash, and perform ultrasonic exfoliation under inert gas protection. MXene nanosheets are obtained by centrifugation and freeze-drying; 8g of MXene nanosheets are dispersed in 2000mL of dimethyl sulfoxide, and the MXene nanosheets are cut into MXene quantum dots by a solvent thermal method with a reaction temperature of 140°C and a reaction time of 8h; 15g of hexagonal boron nitride is dispersed in 1500mL of a mixed solvent of isopropanol and deionized water (1:1, v / v), and boron nitride nanosheets are obtained by ultrasonic exfoliation for 6h; 5g MXene quantum dots and 10g of boron nitride nanosheets were evenly dispersed in 2000mL of dimethyl sulfoxide, and MXene quantum dot / boron nitride nanosheet heterostructures were obtained after self-assembly; 10g of MXene quantum dot / boron nitride nanosheet heterostructures and 2g of carbon nanofibers were evenly dispersed in 2000mL of aqueous solution, and a thermal conductive and wave-absorbing film sample based on the MXene quantum dot / boron nitride nanosheet heterostructure was obtained by vacuum-assisted filtration.

[0036] Example 3

[0037] Prepare 500ml of a mixed solution containing 10g of lithium fluoride and 10M hydrochloric acid, add 10g of Ti3AlCN into the mixed solution, etch at 40℃ for 18h, filter and wash, and perform ultrasonic exfoliation under inert gas protection, and obtain MXene nanosheets by centrifugation and freeze drying; MXene nanosheets were dispersed in 2000mL of dimethylformamide, and the MXene nanosheets were cut into MXene quantum dots by a solvothermal method with a reaction temperature of 120°C and a reaction time of 8h. 20g of hexagonal boron nitride was dispersed in 2000mL of a mixed solvent of isopropanol and deionized water (1:1, v / v), and boron nitride nanosheets were obtained by ultrasonic exfoliation for 6h. 5g of MXene quantum dots and 15g of boron nitride nanosheets were evenly dispersed in 2000mL of dimethylformamide, and a MXene quantum dot / boron nitride nanosheet heterostructure was obtained after self-assembly. 10g of MXene quantum dot / boron nitride nanosheet heterostructure and 4g of aramid nanofibers were evenly dispersed in 2000mL of aqueous solution, and a thermal conductive and wave-absorbing film sample based on the MXene quantum dot / boron nitride nanosheet heterostructure was obtained by vacuum-assisted filtration.

[0038] Example 4

[0039] Prepare 500ml of a mixed solution containing 10g of lithium fluoride and 12M hydrochloric acid, add 10g of V2AlC to the mixed solution, etch at 40°C for 12h, filter and wash, and perform ultrasonic exfoliation under inert gas protection. MXene nanosheets are obtained by centrifugation and freeze-drying; 8g of MXene nanosheets are dispersed in 2000mL of ethylene glycol, and the MXene nanosheets are cut into MXene quantum dots by a solvent thermal method with a reaction temperature of 140°C and a reaction time of 8h; 25g of hexagonal boron nitride is dispersed in 2500mL of a mixed solvent of isopropanol and deionized water (1:1, v / v), and boron nitride nanosheets are obtained by ultrasonic exfoliation for 6h; 5g of MXene quantum dots and 20g of boron nitride nanosheets are evenly dispersed in 2000mL of ethylene glycol, and a MXene quantum dot / boron nitride nanosheet heterostructure is obtained after self-assembly; 10g The MXene quantum dot / boron nitride nanosheet heterostructure and 6 g of nanocellulose were evenly dispersed in 2000 mL of aqueous solution, and a thermal conductive and wave-absorbing film sample based on the MXene quantum dot / boron nitride nanosheet heterostructure was obtained by vacuum-assisted filtration.

[0040] Example 5

[0041] Prepare 500ml of a mixed solution containing 10g of lithium fluoride and 9M hydrochloric acid, add 10g of Nb2AlC to the mixed solution, etch at 35°C for 30h, filter and wash, and perform ultrasonic exfoliation under inert gas protection. MXene nanosheets are obtained by centrifugation and freeze-drying; 8g of MXene nanosheets are dispersed in 2000mL of tetrahydrofuran, and the MXene nanosheets are cut into MXene quantum dots by a solvent thermal method with a reaction temperature of 160°C and a reaction time of 6h; 30g of hexagonal boron nitride is dispersed in 3000mL of a mixed solvent of isopropanol and deionized water (1:1, v / v), and ultrasonic exfoliation is performed for 6h to obtain boron nitride nanosheets; 5g of MXene quantum dots and 25g of boron nitride nanosheets are uniformly dispersed in 2000mL of tetrahydrofuran, and a MXene quantum dot / boron nitride nanosheet heterostructure is obtained after self-assembly; 10g The MXene quantum dot / boron nitride nanosheet heterostructure and 8 g of aramid nanofibers were evenly dispersed in 2000 mL of aqueous solution, and a thermal conductive and wave-absorbing film sample based on the MXene quantum dot / boron nitride nanosheet heterostructure was obtained by vacuum-assisted filtration.

[0042] The thermal conductive wave absorbing film samples prepared in Examples 1 to 5 were subjected to performance tests. The test results are shown in Tables 1 and Figure 2 shown.

[0043] Table 1 Thermal conductivity and absorption properties of thermal conductive and absorbing films

[0044]

[0045] The above embodiments fully and effectively achieve the objectives of the present invention. Those skilled in the art will appreciate that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the above specific embodiments. Although the present invention has been described with reference to the embodiments currently considered to be the most practical and preferred, it should be understood that the present invention is not limited to the disclosed embodiments, and any modifications that do not deviate from the functional and structural principles of the present invention are intended to be included within the scope of the claims.

[0046] Some parts of the present invention are well known to those skilled in the art and are not described in detail.

Claims

1. A method for preparing a thermally conductive and wave-absorbing film based on a MXene quantum dot / boron nitride nanosheet heterostructure, characterized in that: The following steps are involved: SS1. MAX phase ceramics were etched using a mixed solution of hydrochloric acid and lithium fluoride, followed by ultrasonic exfoliation under inert gas protection. MXene nanosheets were obtained by centrifugation and freeze-drying. The MAX phase ceramic is selected from one or more of Ti2AlC, Ti3AlC2, Ti3AlCN, V2AlC, and V4AlC3; SS2. The MXene nanosheets obtained in step SS1 are dispersed in an organic solvent and the MXene nanosheets are cut into MXene quantum dots by a solvothermal method; SS3. Hexagonal boron nitride was dispersed in a mixed solvent of isopropyl alcohol and deionized water and then ultrasonically exfoliated to obtain boron nitride nanosheets. SS4. The MXene quantum dots obtained in step SS2 and the boron nitride nanosheets obtained in step SS3 are uniformly dispersed in an organic solvent to obtain a MXene quantum dot / boron nitride nanosheet heterostructure after self-assembly; The mass ratio of the MXene quantum dots to the boron nitride nanosheets is 1:1 to 1:10; the concentration of the MXene quantum dots in the organic solvent is 0.5 to 10 g / L; SS5. The MXene quantum dot / boron nitride nanosheet heterostructure and nanofibers obtained in step SS4 are uniformly dispersed in an aqueous solution, and vacuum-assisted filtration is performed to obtain a thermally conductive and wave-absorbing film based on the MXene quantum dot / boron nitride nanosheet heterostructure. The mass ratio of the MXene quantum dot / boron nitride nanosheet heterostructure to the nanofiber is 1:0.05~1:1, and the nanofiber is selected from one or more of carbon nanofiber, aramid nanofiber, nanocellulose, and carbon nanotube fiber; the concentration of the MXene quantum dot / boron nitride nanosheet heterostructure in water is 0.5~10g / L.

2. The method for preparing a thermally conductive and wave-absorbing film based on a MXene quantum dot / boron nitride nanosheet heterostructure according to claim 1, characterized in that: In the above step SS1, the concentration of the hydrochloric acid is 3 to 12 M, the mass ratio of HCl to the lithium fluoride is 1:0.01 to 1:0.1; the mass ratio of the lithium fluoride to the MAX phase ceramic is 1:0.2 to 1:2; The etching temperature is 25~50℃, and the etching time is 12~60h.

3. The method for preparing a thermally conductive and wave-absorbing film based on a MXene quantum dot / boron nitride nanosheet heterostructure according to claim 1, characterized in that: In the above step SS2, the solvothermal method is as follows: dispersing MXene nanosheets in an organic solvent, the concentration of MXene nanosheets is 0.5-10 g / L, the reaction temperature is 80-180°C, and the reaction time is 6-24 h.

4. The method for preparing a thermally conductive and wave-absorbing film based on a MXene quantum dot / boron nitride nanosheet heterostructure according to claim 1, characterized in that: In step SS3, the concentration of hexagonal boron nitride dispersed in the mixed solvent is 1-20 g / L; the volume ratio of isopropyl alcohol to deionized water in the mixed solvent is 1:0.5-1:2; and the ultrasonication time is 1-12 hours.

5. The method for preparing a thermally conductive and wave-absorbing film based on a MXene quantum dot / boron nitride nanosheet heterostructure according to claim 1, characterized in that: The organic solvent in steps SS2 and SS4 is selected from one or more of ethanol, ethylene glycol, tetrahydrofuran, dimethylformamide and dimethyl sulfoxide.

6. A thermally conductive and wave-absorbing film based on a MXene quantum dot / boron nitride nanosheet heterostructure obtained according to the preparation method according to any one of claims 1 to 5.

7. Application of the thermally conductive and absorbing film based on the MXene quantum dot / boron nitride nanosheet heterostructure according to claim 6 in thermal management and electromagnetic wave shielding and absorption.

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