CN112980056A - Composite flexible film with electromagnetic shielding and heat conducting functions and preparation method thereof - Google Patents

Abstract

The invention discloses a flexible film with both electromagnetic shielding and thermal conductivity functions and a preparation method thereof, which can form a two-dimensional heterojunction MXene/BN flexible film. BN nanosheets and two-dimensional Ti ₃ C ₂ T _x MXene nanosheets are constructed into two-dimensional electrical and thermal conductive heterojunctions, and a one-dimensional nanocellulose network structure is used to enhance the mechanical properties of the film. A composite flexible film with both electromagnetic shielding and thermal conductivity functions. The MXene/BN film prepared in this example has a significant shielding effect on electromagnetic waves, and has the characteristics of good thermal conductivity, good bending flexibility, and simple synthesis process, which can meet the practical application of high-performance communication equipment, computers, smart phones, automobiles, etc. Specific requirements for electromagnetic shielding and thermally conductive devices and related industrial applications.

Description

Composite flexible film with electromagnetic shielding and heat conducting functions and preparation method thereof

Technical Field

The invention relates to a composite flexible film and a preparation method thereof, in particular to an electromagnetic shielding composite flexible film and a preparation method thereof, or relates to a heat-conducting composite flexible film and a preparation method thereof, and is applied to the technical field of electromagnetic shielding composite materials or heat-conducting composite materials.

Background

With the rapid development of electronic devices and wireless transmission technologies, the harm of electromagnetic interference and electromagnetic radiation to portable electronics, aerospace and national defense safety and human health is also getting more and more serious. The traditional electromagnetic shielding material represented by metal has the defects of high density, poor flexibility, easy corrosion and the like, so that the development requirement of light portable electronic products is difficult to meet. In recent years, MXene, as a novel two-dimensional layered transition metal carbon/nitride, has excellent metal conductivity (the conductivity is as high as 65000S/m) and ferromagnetism, and becomes an ideal electromagnetic shielding material. Meanwhile, as the 5G era approaches, the power consumption of the device is increasing with the frequent updating of the electronic products, and the heat productivity is rapidly increasing. In order to solve the problem, more and more electromagnetic shielding and heat conducting devices are added to electronic products during design. Therefore, the function of electromagnetic shielding, heat conducting material and device will become more important, and the demand will continue to increase in the future.

Forming a composite material by adding other materials is an effective way to impart more functionality to the material. LeiWang et al, northwest university of industry, prepared Fe with carboxyl groups₃O₄@ Ag core-shell nano-particles, and multi-walled carbon tubes (MWCNT-NH) with amino groups obtained by modifying multi-walled carbon nanotubes (MWCNT) by amination₂) Then grafting the two by amidation reaction of amino and carboxyl to obtain MWCNT-Fe₃O₄@ Ag, and finally preparing a 22.86mm X10.16 mm X2 mm sample by using epoxy resin and an epoxy resin through a mixed casting method, wherein the highest electromagnetic shielding efficiency in an X wave band is 35dB, and the highest heat conductivity coefficient isThe height is 0.46W/mK. RGO @ Fe was prepared by electrostatic self-assembly in alkaline solution followed by co-precipitation by Yingchun Liu et al, Guangzhou chemical institute of Chinese academy₃O₄And (3) nanosheets, and finally, mixing the sample with epoxy resin under the action of a magnetic field and curing to prepare the sample, wherein the electromagnetic shielding is as high as 13.45dB at the X wave band, and the heat conductivity coefficient (in-plane) is as high as 1.213W/mK. Reduced Graphene Oxide (RGO)/nanofiber (CNF) composite membranes are prepared by WeixingYang and the like of Sichuan university through vacuum-assisted filtration and hydroiodic acid (HI) reduction, the electromagnetic shielding efficiency reaches 26.2dB (X wave band, 8.2-12.4GHz) at most, and the in-plane thermal conductivity reaches 7.3W/mK.

Therefore, it is of great significance to select appropriate materials and reasonably design process conditions and develop a heat-conducting, flexible and efficient MXene electromagnetic shielding film to meet the requirement that a flexible device has both electromagnetic shielding and heat-conducting functions, and the technical problem to be solved urgently is formed.

Disclosure of Invention

In order to solve the problems of the prior art, the invention aims to provide a composite flexible film with electromagnetic shielding and heat conducting functions and a preparation method thereof, and particularly relates to a two-dimensional heterojunction MXene/BN film with electromagnetic shielding and heat conducting functions and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

a two-dimensional heterojunction MXene/BN composite flexible film with electromagnetic shielding and heat conducting functions adopts blocky hexagonal boron nitride (h-BN) and blocky multilayer Ti₃C₂T_xAs a raw material, carbon nanocellulose CNF is adopted as an auxiliary addition material; stripping blocky hexagonal boron nitride (h-BN) by using an ultrasonic crusher to obtain a boron nitride nanosheet dispersion liquid; then, the massive multilayer Ti is treated by an ultrasonic method₃C₂T_xThe sheets in the layer are stripped to obtain Ti with less layers not more than 3₃C₂T_xMXene nanosheets; finally through the electrostatic action and hydrogen bond of positive and negative chargesActing to mix the two-dimensional BN nano-sheet with the two-dimensional Ti₃C₂T_xThe MXene nanosheets are constructed into a two-dimensional electric conduction and heat conduction heterojunction, the one-dimensional carbon nanocellulose CNF is added to enhance the mechanical performance of the film, and the film with the structural form of MXene/BN and the electromagnetic shielding and heat conduction functions is assembled in one step through a filter pressing film forming method.

As a preferred technical scheme of the invention, when the one-step method assembly is carried out, the pressure is controlled to be 1.0-2.0MPa, and the film with electromagnetic shielding and heat conducting functions is formed.

As a preferable embodiment of the present invention, Ti is used₃C₂T_xWhen the BN and the carbon nano-cellulose are mixed, the mixture ratio is as follows according to the mass ratio: when Ti is present₃C₂T_xWhen the content of (b) is 8.57-46.67 mg, the BN is at least 20mg, the carbon nano-cellulose is at least 12.5g, and the composite material is formed according to the component ratio.

The invention discloses a preparation method of a two-dimensional heterojunction MXene/BN composite flexible film with electromagnetic shielding and heat conducting functions, which comprises the following steps:

a. dispersing hexagonal boron nitride (h-BN) powder in at least 100mL of ethanol solution with the volume percentage concentration of 10%, and ultrasonically dispersing and throwing for 3 hours to obtain a boron nitride nanosheet suspension, wherein the boron nitride nanosheet suspension contains boron nitride nanosheets with the concentration (w/v%) of 0.08-0.10 g/L;

b. a bulk multi-layer Ti₃C₂T_xDispersing (MXene) powder in at least 100mL ethanol solution with 10% concentration by volume, and ultrasonically dispersing for at least 3 hours to obtain Ti₃C₂T_xNanosheet suspension, wherein Ti₃C₂T_xThe nano-sheet suspension contains Ti₃C₂T_xThe concentration (w/v%) of the nano-sheets is 0.16-0.20 g/L;

c. mixing nano cellulose dispersion liquid with the material-liquid ratio (w/v) of 0.10-0.10 w/v%, boron nitride nanosheet suspension prepared in the step a, and Ti prepared in the step b₃C₂T_xMixing the nano-sheet suspension, and ultrasonic treatingAt least 10min to obtain MXene/BN mixed suspension liquid with uniform dispersion;

d. and (c) pouring the MXene/BN mixed suspension prepared in the step (c) into a high-pressure filter press, adjusting the pressure to be 1.0-2.0MPa, carrying out filter pressing until no filtrate flows out, taking out a filter cake, and carrying out vacuum drying on the filter cake to obtain the two-dimensional heterojunction MXene/BN composite flexible film with electromagnetic shielding and heat conducting functions.

As a preferable technical scheme of the invention, in the step d, the fracture strength of the prepared two-dimensional heterojunction MXene/BN composite flexible film is not lower than 1.51 MPa; in an X wave band within the range of 8.2-12.4GHz, the electromagnetic shielding effectiveness is not lower than 11.38 dB; the thermal conductivity coefficient is not lower than 8.03W/mK at 25 ℃.

As a preferable embodiment of the present invention, in the step c, Ti is performed₃C₂T_xWhen the BN and the carbon nano-cellulose are mixed and proportioned, the mixture ratio is as follows according to the mass ratio: when Ti is present₃C₂T_xWhen the content of (b) is 8.57-46.67 mg, the content of BN is at least 20mg, the content of carbon nano-cellulose is at least 12.5g, and MXene/BN mixed suspension liquid which is uniformly dispersed is prepared.

As a further preferable embodiment of the present invention, in the step c, Ti is carried out₃C₂T_xWhen the BN and the carbon nano-cellulose are mixed and proportioned, the mixture ratio is as follows according to the mass ratio: when Ti is present₃C₂T_xWhen the content of (b) is 13.33-46.67 mg, the content of BN is at least 20mg, the content of carbon nano-cellulose is at least 12.5g, and MXene/BN mixed suspension liquid which is uniformly dispersed is prepared.

Compared with the prior art, the invention has the following obvious and prominent substantive characteristics and remarkable advantages:

1. the invention utilizes the electrostatic action and the hydrogen bond action of positive and negative charges to mix the two-dimensional BN nano-sheet with the two-dimensional Ti₃C₂T_xThe MXene nanosheets are constructed into a two-dimensional electric conduction and heat conduction heterojunction, and the mechanical property of the film is enhanced by adding the one-dimensional nano-cellulose to obtain the film which is in the form of MXene/BN and has the functions of electromagnetic shielding and heat conduction; the invention selects reasonable design process conditions and developsThe MXene electromagnetic shielding film with high strength, flexibility and efficiency has important significance in meeting the performance requirement of a flexible device under bending deformation;

2. the invention carries out one-step assembly to form a film with electromagnetic shielding and heat conducting functions; the breaking strength of the prepared film with electromagnetic shielding and heat conducting functions is not lower than 1.51 MPa; in an X wave band within the range of 8.2-12.4GHz, the electromagnetic shielding effectiveness is not lower than 11.38 dB; the heat conductivity coefficient is not lower than 8.03W/mK at 25 ℃;

3. the invention adopts two-dimensional BN nano-sheet and two-dimensional Ti₃C₂T_xThe MXene nanosheets are constructed into a two-dimensional electric conduction and heat conduction heterojunction, so that the capability of the film for absorbing and internally reflecting electromagnetic waves for many times is enhanced, the heat transfer between layers of the film is enhanced, and the MXene nanosheets have wide practical application prospects.

Drawings

Fig. 1 is a graph comparing the electromagnetic shielding performance of a film having both electromagnetic shielding and heat conducting functions according to an embodiment of the present invention and an MXene film prepared according to a comparative example.

Fig. 2 is a comparison graph of thermal diffusivity and thermal conductivity of a film having both electromagnetic shielding and thermal conductivity functions according to an embodiment of the present invention and an MXene film prepared according to a comparative example.

Fig. 3 is a film photo of the present invention with electromagnetic shielding and heat conduction functions.

Detailed Description

The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

example one

In the embodiment, a two-dimensional heterojunction MXene/BN composite flexible thin film with electromagnetic shielding and heat conducting functions is adopted, referring to FIG. 3, bulk hexagonal boron nitride (h-BN) and bulk multilayer Ti are adopted₃C₂T_xAs a raw material, carbon nanocellulose CNF is adopted as an auxiliary addition material; stripping blocky hexagonal boron nitride (h-BN) by using an ultrasonic crusher to obtain a boron nitride nanosheet dispersion liquid; then, the massive multilayer Ti is treated by an ultrasonic method₃C₂T_xThe sheet layer in the (A) is stripped,obtaining a small layer of Ti with a number of layers not exceeding 3₃C₂T_xMXene nanosheets; finally, the two-dimensional BN nano-sheet and the two-dimensional Ti are subjected to the electrostatic action and the hydrogen bond action of positive and negative charges₃C₂T_xThe MXene nanosheets are constructed into a two-dimensional electric conduction and heat conduction heterojunction, the one-dimensional carbon nanocellulose CNF is added to enhance the mechanical performance of the film, and the film with the structural form of MXene/BN and the electromagnetic shielding and heat conduction functions is assembled in one step through a filter pressing film forming method.

In the embodiment, two-dimensional BN nanosheet and two-dimensional Ti are prepared by utilizing the electrostatic action and the hydrogen bonding action of positive and negative charges₃C₂T_xThe MXene nanosheets are constructed into a two-dimensional electric conduction and heat conduction heterojunction, and the mechanical property of the film is enhanced by adding the one-dimensional nano-cellulose, so that the film which is in the form of MXene/BN and has the functions of electromagnetic shielding and heat conduction is obtained. In this embodiment, a film having electromagnetic shielding and heat conducting functions is formed by performing one-step assembly by a filter pressing method under a pressure of 2.0MPa, as shown in fig. 3. In this example, 46.67mgMXene nanosheets (Ti) were used₃C₂T_x) 20mg BN nano-sheet and 12.5mg nano-cellulose according to the component proportion to form the film with electromagnetic shielding and heat conduction functions. The boron nitride nanosheet is formed by reacting with two-dimensional Ti through the electrostatic action and hydrogen bond action of positive and negative charges₃C₂T_xMXene nano-sheets construct a two-dimensional electric conduction and heat conduction heterojunction.

In this embodiment, the method for preparing a film with electromagnetic shielding and thermal conductivity functions in this embodiment includes the following steps:

a. dispersing hexagonal boron nitride (h-BN) powder in 100mL of ethanol solution with the volume percentage concentration of 10%, and ultrasonically dispersing and throwing for 3 hours to obtain boron nitride nanosheet suspension, wherein the boron nitride nanosheet suspension contains boron nitride nanosheets with the concentration (w/v%) of 0.10 g/L;

b. a bulk multi-layer Ti₃C₂T_x(MXene) powder was dispersed in 100mL of 10 vol% ethanol solution and ultrasonically dispersed for 3 hours to obtain Ti₃C₂T_xA nanosheet suspension, whereinTi₃C₂T_xThe nano-sheet suspension contains Ti₃C₂T_xThe concentration (w/v%) of the nano-sheets is 0.20 g/L;

c. 46.67mgMXene nanosheets (Ti) were used₃C₂T_x) 20mg BN nano-sheet and 12.5mg nano-cellulose, namely mixing nano-cellulose dispersion liquid with the feed liquid ratio (w/v) of 0.10-0.10 w/v%, boron nitride nano-sheet suspension prepared in the step a and Ti nano-sheet suspension prepared in the step b₃C₂T_xMixing the nano sheet suspension liquid, and performing ultrasonic treatment for 10min to obtain uniformly dispersed MXene/BN mixed suspension liquid, wherein the MXene/BN mixed suspension liquid contains Ti₃C₂T_xThe proportion of the nano-sheets is 0.11 g/L;

d. and (c) pouring the MXene/BN mixed suspension prepared in the step (c) into a high-pressure filter press, adjusting the pressure to be 2.0MPa, carrying out filter pressing until no filtrate flows out, taking out a filter cake, and carrying out vacuum drying on the filter cake to obtain the two-dimensional heterojunction MXene/BN composite flexible film with electromagnetic shielding and heat conducting functions.

Experimental test analysis:

the film with electromagnetic shielding and heat conducting functions prepared in this example was subjected to measurement of heat conductivity and electromagnetic shielding performance test, and referring to fig. 1 and 2, the film with electromagnetic shielding and heat conducting functions prepared in this example had a thermal diffusivity of 10.16mm²The thermal conductivity coefficient is 8.03W/mK, and the electromagnetic shielding can reach 37.29dB at the X wave band within the range of 8.2-12.4 GHz. The film with electromagnetic shielding and heat conducting functions and the preparation method thereof enable two-dimensional BN nanosheets and two-dimensional Ti to be formed through the electrostatic effect and the hydrogen bond effect of positive and negative charges₃C₂T_xThe MXene nanosheets are constructed into a two-dimensional electric conduction and heat conduction heterojunction, and the mechanical property of the film is enhanced by adding the one-dimensional nano-cellulose, so that the film which is in the form of MXene/BN and has the functions of electromagnetic shielding and heat conduction is obtained. And finally, performing one-step assembly by a filter pressing method under the condition that the pressure is controlled to be 2.0MPa to form the film with electromagnetic shielding and heat conducting functions. The film with electromagnetic shielding and heat conducting functions prepared by the embodiment has remarkable electromagnetic wave shielding effect, andthe flexible electronic material has the characteristics of good heat-conducting property, good bending flexibility and simple synthesis process, and can meet the specific requirements of flexible electronics in practical application.

Example two

This embodiment is substantially the same as the first embodiment, and is characterized in that:

a two-dimensional heterojunction MXene/BN composite flexible film with electromagnetic shielding and heat conducting functions adopts blocky hexagonal boron nitride (h-BN) and blocky multilayer Ti₃C₂T_xAs a raw material, carbon nanocellulose CNF is adopted as an auxiliary addition material; stripping blocky hexagonal boron nitride (h-BN) by using an ultrasonic crusher to obtain a boron nitride nanosheet dispersion liquid; then, the massive multilayer Ti is treated by an ultrasonic method₃C₂T_xThe sheets in the layer are stripped to obtain Ti with less layers not more than 3₃C₂T_xMXene nanosheets; finally, the two-dimensional BN nano-sheet and the two-dimensional Ti are subjected to the electrostatic action and the hydrogen bond action of positive and negative charges₃C₂T_xThe MXene nanosheets are constructed into a two-dimensional electric conduction and heat conduction heterojunction, the one-dimensional carbon nanocellulose CNF is added to enhance the mechanical performance of the film, and the film with the structural form of MXene/BN and the electromagnetic shielding and heat conduction functions is assembled in one step through a filter pressing film forming method.

In the embodiment, two-dimensional BN nanosheet and two-dimensional Ti are prepared by utilizing the electrostatic action and the hydrogen bonding action of positive and negative charges₃C₂T_xThe MXene nanosheets are constructed into a two-dimensional electric conduction and heat conduction heterojunction, and the mechanical property of the film is enhanced by adding the one-dimensional nano-cellulose, so that the film which is in the form of MXene/BN and has the functions of electromagnetic shielding and heat conduction is obtained. In the embodiment, the film with electromagnetic shielding and heat conducting functions is formed by performing one-step assembly by a filter pressing method under the condition that the pressure is controlled to be 2.0 MPa. In this example, 13.33mgMXene nanosheets (Ti)₃C₂T_x) 20mg BN nano-sheet and 12.5mg nano-cellulose according to the component proportion to form the film with electromagnetic shielding and heat conduction functions. The boron nitride nanosheet is formed by reacting with two-dimensional Ti through the electrostatic action and hydrogen bond action of positive and negative charges₃C₂T_xMXene nano-sheetTwo-dimensional electric conduction and heat conduction heterojunction is constructed.

In this embodiment, the method for preparing a film with electromagnetic shielding and thermal conductivity functions in this embodiment includes the following steps:

a. dispersing hexagonal boron nitride (h-BN) powder in 100mL of ethanol solution with the volume percentage concentration of 10%, and ultrasonically dispersing and throwing for 3 hours to obtain boron nitride nanosheet suspension, wherein the boron nitride nanosheet suspension contains boron nitride nanosheets with the concentration (w/v%) of 0.10 g/L;

b. a bulk multi-layer Ti₃C₂T_x(MXene) powder was dispersed in 100mL of 10 vol% ethanol solution and ultrasonically dispersed for 3 hours to obtain Ti₃C₂T_xNanosheet suspension, wherein Ti₃C₂T_xThe nano-sheet suspension contains Ti₃C₂T_xThe concentration (w/v%) of the nano-sheets is 0.20 g/L;

c. using 13.33mg MXene nanoplate (Ti)₃C₂T_x) 20mg BN nano-sheet and 12.5mg nano-cellulose, namely mixing nano-cellulose dispersion liquid with the feed liquid ratio (w/v) of 0.10-0.10 w/v%, boron nitride nano-sheet suspension prepared in the step a and Ti nano-sheet suspension prepared in the step b₃C₂T_xMixing the nano sheet suspension liquid, and performing ultrasonic treatment for 10min to obtain uniformly dispersed MXene/BN mixed suspension liquid, wherein the MXene/BN mixed suspension liquid contains Ti₃C₂T_xThe proportion of the nano-sheets is 0.05 g/L;

d. and (c) pouring the MXene/BN mixed suspension prepared in the step (c) into a high-pressure filter press, adjusting the pressure to be 2.0MPa, carrying out filter pressing until no filtrate flows out, taking out a filter cake, and carrying out vacuum drying on the filter cake to obtain the two-dimensional heterojunction MXene/BN composite flexible film with electromagnetic shielding and heat conducting functions.

Experimental test analysis:

the film with the electromagnetic shielding and heat conducting functions prepared in the embodiment is used for measuring the heat conductivity coefficient and testing the electromagnetic shielding performance, and the film with the electromagnetic shielding and heat conducting functions prepared in the embodiment has the heat diffusion coefficient of 11.27mm²The thermal conductivity coefficient is 11.02W/mK, and the electromagnetic shielding can reach 11.53dB at the X wave band within the range of 8.2-12.4 GHz. The film with electromagnetic shielding and heat conducting functions and the preparation method thereof enable two-dimensional BN nanosheets and two-dimensional Ti to be formed through the electrostatic effect and the hydrogen bond effect of positive and negative charges₃C₂T_xThe MXene nanosheets are constructed into a two-dimensional electric conduction and heat conduction heterojunction, and the mechanical property of the film is enhanced by adding the one-dimensional nano-cellulose, so that the film which is in the form of MXene/BN and has the functions of electromagnetic shielding and heat conduction is obtained. And finally, performing one-step assembly by a filter pressing method under the condition that the pressure is controlled to be 2.0MPa to form the film with electromagnetic shielding and heat conducting functions. The film with electromagnetic shielding and heat conducting functions prepared by the embodiment has an obvious electromagnetic wave shielding effect, has the characteristics of good heat conducting property, good bending flexibility and simple synthesis process, and can meet the specific requirements of flexible electronics in practical application.

Comparative example

In this comparative example, a method of making an MXene film comprising the steps of:

a. a bulk multi-layer Ti₃C₂T_x(MXene) powder was dispersed in 100mL of 10 vol% ethanol solution and ultrasonically dispersed for 3 hours to obtain Ti₃C₂T_xNanosheet suspension, wherein Ti₃C₂T_xThe nano-sheet suspension contains Ti₃C₂T_xThe concentration (w/v%) of the nano-sheets is 0.20 g/L;

b. ti will be prepared in said step c₃C₂T_xAnd pouring the nanosheet suspension into a high-pressure filter press, adjusting the pressure to be 2.0MPa, performing filter pressing until no filtrate flows out, taking out a filter cake, and performing vacuum drying to obtain the MXene flexible film.

Experimental test analysis:

the MXene film prepared by the comparative example is subjected to experimental test analysis, and the thermal diffusion coefficient of the MXene film prepared by the comparative example is 8.4mm²The thermal conductivity coefficient is 6.9W/mK, and the electromagnetic shielding can reach 35.7dB at the X wave band within the range of 8.2-12.4 GHz. See fig. 1 and 2 for thermal diffusivityObviously, the parameters of the thermal conductivity and the electromagnetic shielding effectiveness are lower than those of the MXene/BN composite flexible thin films prepared in the first embodiment and the second embodiment.

According to the embodiments, the two-dimensional heterojunction MXene/BN composite flexible film with electromagnetic shielding and heat conducting functions and the preparation method thereof enable the two-dimensional BN nanosheet and the two-dimensional Ti to be bonded through the electrostatic action and the hydrogen bonding action of positive and negative charges₃C₂T_xMXene nano-sheets are constructed into a two-dimensional electric conduction and heat conduction heterojunction, a one-dimensional nano-cellulose network structure is adopted to enhance the mechanical property of the film, and finally the composite flexible film with electromagnetic shielding and heat conduction functions is assembled in one step by a filter pressing film forming method. The MXene/BN film prepared by the embodiment has an obvious electromagnetic wave shielding effect, has the characteristics of good heat conducting property, good bending flexibility and simple synthesis process, and can meet the specific requirements of electromagnetic shielding and heat conducting devices and related industrial applications in practical applications of high-performance communication equipment, computers, smart phones, automobiles and the like. The above examples utilize electrostatic interactions and hydrogen bonding using positive and negative charges to convert Ti₃C₂T_xThe nano sheets are combined with the boron nitride nano sheets to obtain an MXene/BN two-dimensional electric conduction and heat conduction heterojunction; the one-dimensional nano-cellulose CNF is added to enhance the mechanical property of the flexible film, the composite construction of the one-dimensional and two-dimensional nano materials and the composite two-dimensional electric conduction and heat conduction heterojunction and mechanical property strengthening structure are realized, reasonable design process conditions are selected, and the MXene electromagnetic shielding film with high strength, flexibility and efficiency is developed to meet the performance requirement of the flexible device under bending deformation, so that the method has important significance.

The embodiments of the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the embodiments, and various changes can be made according to the purpose of the invention, and any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention shall be equivalent substitution ways, so long as the technical principle and the inventive concept of the method for preparing the high strength calcium sulfate whisker reinforced bagasse fiber paper according to the present invention are met, and all fall within the protection scope of the present invention.

Claims (7)

1. A two-dimensional heterojunction MXene/BN composite flexible film with both electromagnetic shielding and thermal conductivity functions is characterized in that: using bulk hexagonal boron nitride (h-BN) and bulk multilayer Ti ₃ C ₂ T _x As the raw material, carbon nanocellulose CNF was used as the auxiliary additive material; the bulk hexagonal boron nitride (h-BN) was peeled off with an ultrasonic pulverizer to obtain a boron nitride nanosheet dispersion; The lamellae in the Ti ₃ C ₂ T _x layer are exfoliated to obtain a few-layer Ti ₃ C ₂ T _x MXene nanosheets with no more than 3 layers; finally, through the electrostatic interaction and hydrogen bonding of positive and negative charges, the two Two-dimensional BN nanosheets and two-dimensional Ti ₃ C ₂ T _x MXene nano sheets were constructed to form a two-dimensional electrical and thermal conductive heterojunction, and then one-dimensional carbon nanocellulose CNF was added to enhance the mechanical properties of the film. Membrane method, one-step assembly into a thin film with both electromagnetic shielding and thermal conductivity in the form of MXene/BN. 2. The two-dimensional heterojunction MXene/BN composite flexible film with both electromagnetic shielding and thermal conductivity functions according to claim 1, characterized in that: during one-step assembly, the control pressure is 1.0-2.0 MPa to form both electromagnetic shielding and thermal conductivity. Shielding and thermally conductive films. 3. The two-dimensional heterojunction MXene/BN composite flexible film having both electromagnetic shielding and thermal conductivity according to claim 1, is characterized in that: when carrying out the ratio of Ti ₃ C ₂ T _x , BN and carbon nanocellulose, The proportioning is carried out according to the following mass ratio: when the content of Ti ₃ C ₂ T _x is 8.57-46.67 mg, the content of BN is at least 20 mg, and the content of carbon nanocellulose is at least 12.5 g, and the composite material is formed according to the component ratio. 4. the preparation method of the two-dimensional heterojunction MXene/BN composite flexible film with both electromagnetic shielding and thermal conductivity according to claim 1, is characterized in that, comprises the following steps: a. Disperse the hexagonal boron nitride (h-BN) powder in at least 100 mL of an ethanol solution with a concentration of 10% by volume, and ultrasonically disperse the sieve for 3 hours to obtain a boron nitride nanosheet suspension, wherein the boron nitride nanosheets The concentration (w/v%) of boron nitride nanosheets in the suspension is 0.08-0.10g/L; b. Disperse the bulk multi-layer Ti ₃ C ₂ T _x (MXene) powder in at least 100 mL of an ethanol solution with a concentration of 10% by volume, and ultrasonically disperse for at least 3 hours to obtain a Ti ₃ C ₂ T _x nanosheet suspension, The concentration (w/v%) of Ti ₃ C ₂ T _x nano flakes contained in the Ti ₃ C ₂ T _x nano flake suspension is 0.16-0.20 g/L; c. The nanocellulose dispersion with a material-to-liquid ratio (w/v) of 0.10-0.10w/v% and the boron nitride nanosheet suspension prepared in step a and the boron nitride nanosheet suspension prepared in step b Mixing the Ti ₃ C ₂ T _x nanosheet suspension and ultrasonicating for at least 10min to obtain a uniformly dispersed MXene/BN mixed suspension; d. Pour the MXene/BN mixed suspension prepared in the step c into a high-pressure filter press, adjust the pressure to 1.0-2.0 MPa, filter by pressure until no more filtrate flows out, and take out the filter cake for vacuum drying, thereby obtaining a combination of Two-dimensional heterojunction MXene/BN composite flexible films with electromagnetic shielding and thermal conductivity. 5. The method for preparing a two-dimensional heterojunction MXene/BN composite flexible film according to claim 4, wherein in the step d, the prepared two-dimensional heterojunction MXene/BN composite flexible film is fractured The strength is not less than 1.51MPa; the electromagnetic shielding efficiency is not less than 11.38dB in the X-band in the range of 8.2-12.4GHz; the thermal conductivity is not less than 8.03W/mK at 25℃. 6. The preparation method of the two-dimensional heterojunction MXene/BN composite flexible film according to claim 4, wherein in the step _c , a mixed preparation of _Ti3C2Tx , BN and carbon nanocellulose _is performed. When the ratio is made, the proportion is carried out according to the following mass ratio: when the content of Ti ₃ C ₂ T _x is 8.57-46.67 mg, the content of BN is at least 20 mg, and the content of carbon nanocellulose is at least 12.5 g, and the uniformly dispersed MXene/ BN mixed suspension. 7. The preparation method of the two-dimensional heterojunction MXene/BN composite flexible film according to claim 6, wherein in the step _c , a mixed preparation of _Ti3C2Tx , BN and carbon nanocellulose _is performed. When the ratio is made, the ratio is carried out according to the following mass ratio: when the content of Ti ₃ C ₂ T _x is 13.33-46.67 mg, the content of BN is at least 20 mg, and the content of carbon nanocellulose is at least 12.5 g, and the uniformly dispersed MXene/ BN mixed suspension.

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