CN112552681B - A functionalized boron nitride nanosheet/MXene/polybenzimidazole composite film with high thermal conductivity and preparation method - Google Patents

Abstract

The invention belongs to the technical field of composite materials, and provides a functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film and a preparation method. Disperse in a dispersant, mix to obtain a mixed solution, then add polybenzimidazole to the mixed solution to obtain a functionalized boron nitride nanosheet/MXene/polybenzimidazole blend, and filter the blend to obtain a composite film . The invention utilizes the three-dimensional structure of the polybenzimidazole polymer to make the modified boron nitride and the MXene with electronegativity undergo electrostatic self-assembly to form the polybenzimidazole as the skeleton, the functionalized boron nitride nanosheets and the MXene as the Self-supporting films of mixed fillers. The filled network formed by the synergistic effect of boron nitride nanosheets and Ti ₃ C ₂ Tx bridging effectively reduces the interfacial thermal resistance and endows the composite film with excellent thermal conductivity. The method is simple and effective, and the prepared high thermal conductivity film has wide application prospects in the fields of energy, electronics and the like.

Description

A functionalized boron nitride nanosheet/MXene/polybenzimidazole composite film with high thermal conductivity and preparation method

technical field

The invention belongs to the technical field of composite materials, in particular to a functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film and a preparation method.

Background technique

With the rapid development of science and technology, electronic components and their equipment are gradually becoming integrated, miniaturized and light-weight. The concentration of large amounts of heat can have a detrimental effect on the safety and longevity of electronic components. Therefore, in order to ensure that the heat generated by the heat-generating electronic components is discharged in time and the electronic equipment can operate safely and stably for a long time, heat dissipation has become an urgent problem to be solved at present.

Boron nitride has become a widely used thermally conductive hybrid filler due to its ultra-high thermal conductivity, good insulation and mechanical properties. Filling high thermal conductivity mixed fillers to prepare polymer matrix composites is currently the most commonly used method to improve the thermal conductivity of polymer materials. The improvement of the performance of the polymer by the mixed filler mainly comes from the good dispersion of the mixed filler in the polymer and the interaction with the polymer matrix. Unmodified functionalized boron nitride is prone to agglomeration and cannot be better dispersed in solution. Therefore, we need to modify the surface of boron nitride nanosheets to enhance the interaction between them and the polymer matrix.

However, the thermal conductivity of most polymer materials themselves is low, and the intrinsic thermal conductivity does not exceed 0.2W/(mK), which is far from meeting the requirements of the industry. Therefore, we need mixed fillers with high thermal conductivity to fill polymers to obtain composite materials with high thermal conductivity.

SUMMARY OF THE INVENTION

The present invention is carried out in order to solve the above-mentioned problem that the thermal conductivity of the single mixed filler filled polymer is not obvious enough, and the purpose is to provide a functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite with high thermal conductivity The film and the preparation method use 2D mixed fillers to bridge and synergize, so as to better form a good mixed filler-polymer interface, reduce the thermal resistance of the interface, build a good thermal conduction path, and promote heat transfer.

The invention provides a preparation method of functionalized boron nitride nanosheets/MXene/polybenzimidazole high thermal conductivity composite film, which has the characteristics of including the following steps: firstly, the amino-functionalized boron nitride nanosheets and MXene are prepared. The nanosheets are respectively dispersed in the dispersant, mixed to obtain a mixed solution, and then polybenzimidazole is added to the mixed solution to obtain a functionalized boron nitride nanosheet/MXene/polybenzimidazole blend solution, and the blend solution is suction filtered, A functionalized boron nitride nanosheet/MXene/polybenzimidazole composite film with high thermal conductivity with polybenzimidazole as the skeleton and boron nitride nanosheets and MXene nanosheets as mixed fillers is obtained. The mass ratio of imidazole is 0.01-0.30.

In the preparation method of the functionalized boron nitride nanosheets/MXene/polybenzimidazole high thermal conductivity composite film provided by the present invention, it can also have the following characteristics: wherein, the amino functionalized boron nitride nanosheets are dispersed in a dispersed The boron nitride nanosheet dispersion liquid is obtained in the agent, and the specific operation is as follows: step S1-1, the boron nitride powder is calcined in a nitrogen furnace at 800℃～1000℃ for 1h～4h, and the calcined boron nitride powder is mixed with urea The melting reaction was carried out under nitrogen atmosphere for 3h to 6h, then the obtained solid was dispersed in water, ultrasonically stripped and centrifuged, the supernatant was collected, the supernatant was filtered and the filter cake was collected, and then the filter cake was washed and dried to obtain amino Functionalized boron nitride nanosheets; step S1-2, dispersing the amino functionalized boron nitride nanosheets in a dispersant to obtain a boron nitride nanosheet dispersion.

In the preparation method of the functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film provided by the present invention, it can also have the following characteristics: wherein, the MXene nanosheet is dispersed in a dispersant to obtain MXene nanosheets. The specific operation is as follows: step S2-1, adding titanium aluminum carbide into hydrofluoric acid for etching, centrifugal washing until the pH value of the washing solution is neutral, and drying to obtain MXene nanosheets; step S2-2, The MXene nanosheets are dispersed in the dispersant to obtain the MXene nanosheet dispersion.

In the preparation method of the functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film provided by the present invention, it can also have the following characteristics: wherein the boron nitride nanosheet dispersion liquid and the MXene nanosheet are dispersed The liquid is ultrasonically mixed to obtain a mixed liquid, then polybenzimidazole is added to the mixed liquid, and the mixture is stirred at 80° C. to 100° C. for 3 h to 8 h.

In the preparation method of the functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film provided by the present invention, it can also have the following characteristics: wherein, the mass ratio of boron nitride powder to urea is 1:4 ~1:7, the temperature of the melting reaction is 130°C to 140°C.

In the preparation method of the functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film provided by the present invention, it may also have the following characteristics: wherein, in step S2-1, 1 g of titanium aluminum carbide is added to In 20ml of hydrofluoric acid with a concentration of 40%, etch for 45h to 55h under stirring conditions. After the etching, wash with water for 3 times by centrifugation, and then centrifuge and wash with ethanol until the pH value of the washing solution is neutral.

In the preparation method of the functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film provided by the present invention, it can also have the following characteristics: wherein, in step S1-1, during calcination, the temperature is 1°C/ The rate of min～5℃/min is increased to 800℃～1000℃, the gas flow rate of nitrogen is 10cc/min～20cc/min, the time of ultrasonic stripping is 8h～12h; the speed of centrifugation is 2500rpm～4000rpm, the duration of centrifugation is The drying time is 5min～20min, the drying temperature is 60℃～80℃, and the drying time is 12h～48h.

In the preparation method of the functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film provided by the present invention, it can also have the following characteristics: wherein, the functionalized nitride is obtained after the blend solution is vacuum filtered and filtered. Boron nanosheet/MXene/polybenzimidazole high thermal conductivity composite film, and then the functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film was vacuum dried at 80 ℃～100 ℃ for 12h～48h.

In the preparation method of the functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film provided by the present invention, it may also have the following characteristics: wherein, the dispersing agent is dimethyl sulfoxide, dimethyl methyl Either amide or N-methylpyrrolidone.

The present invention also provides a functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film, which has the characteristics of being composed of the functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film prepared by the method of preparation.

The role and effect of the invention

According to the preparation method of the functionalized boron nitride nanosheets/MXene/polybenzimidazole high thermal conductivity composite film provided by the present invention, the amino functionalized boron nitride nanosheets and the MXene nanosheets are first dispersed in a dispersant, and mixed Then, a mixed solution is obtained, and then polybenzimidazole is added to the mixed solution to obtain a functionalized boron nitride nanosheet/MXene/polybenzimidazole blend solution, and the blend solution is suction filtered to obtain a composite film. The invention utilizes the three-dimensional structure of the polybenzimidazole polymer as a binder to make the modified boron nitride containing amino group and the MXene with electronegativity undergo electrostatic self-assembly to form the polybenzimidazole as the skeleton, the functional Boron nitride nanosheets and MXene as self-supporting films of mixed fillers. The filled network formed by the synergistic effect of functionalized boron nitride nanosheets and Ti ₃ C ₂ Tx bridging in this film can effectively reduce the interfacial thermal resistance and ultimately promote heat transfer, eliminating the possibility of mixing directly with boron nitride as a mixed filler The agglomeration of fillers, high filling content makes composite materials low flexibility and other adverse effects. Compared with the prior art, the present invention utilizes functionalized boron nitride nanosheets, exfoliated _MXene and polybenzimidazole as assemblies, functionalized boron nitride nanosheets, _Ti3C2Tx and polybenzimidazole. The synergistic effect of the ternary composite system is beneficial to improve the mechanical properties of the ternary system composites. At the same time, the composite film is given excellent thermal conductivity, the method is simple and effective, and the prepared high thermal conductivity film has wide application prospects in the fields of energy, electronics and the like.

Description of drawings

1 is a photo of commercially available boron nitride and the boron nitride nanosheet dispersion liquid prepared in Example 1;

Figure 2 is a photo of the MXene nanosheet dispersion liquid prepared in Example 1;

3 is a SEM image of the functionalized boron nitride nanosheets prepared in Example 1;

Fig. 4 is the SEM image of the MXene nanosheet prepared in Example 1;

5 is a photo of the functionalized boron nitride nanosheet/MXene/polybenzimidazole composite film prepared in Example 1; and

6 is a graph of thermal conductivity of the functionalized boron nitride nanosheets/MXene/polybenzimidazole composite films prepared in Examples 1-4.

Detailed ways

In order to make the technical means, creative features, goals and effects achieved by the present invention easy to understand, a functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film and The preparation method is described in detail.

In the following examples, if there is no special description of raw materials or processing techniques, it is indicated that they are all conventional commercially available raw materials or conventional processing techniques in the art.

The present invention provides a preparation method of a functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film (hereinafter referred to as a composite film), and the specific operations are as follows:

First, the amino-functionalized boron nitride nanosheets and MXene nanosheets were dispersed in a dispersant, respectively, and mixed to obtain a mixed solution, and then polybenzimidazole was added to the mixed solution to obtain functionalized boron nitride nanosheets/MXene/ Polybenzimidazole blend solution, the blend solution is suction filtered to obtain functionalized boron nitride nanosheets/MXene/polybenzimidazole with polybenzimidazole as skeleton and boron nitride nanosheets and MXene nanosheets as mixed fillers In the high thermal conductivity composite film, the mass ratio of the mixed filler to the polybenzimidazole is 0.01-0.30.

Wherein, the boron nitride nanosheet dispersion is obtained by the following operations:

In step S1-1, the boron nitride powder is placed in a nitrogen furnace, and the temperature is increased to 800°C to 1000°C at a rate of 1°C/min to 5°C/min for 1h to 4h. During calcination, the flow rate of nitrogen gas is maintained at 10cc /min～20cc/min. The calcined boron nitride powder and the urea are melted and reacted in a nitrogen atmosphere for 3 h to 6 h, and the temperature of the melting reaction is 130° C. to 140° C. After the melting reaction is completed, the obtained solid is dispersed in deionized water, ultrasonically stripped for 8h to 12h, and then centrifuged at a speed of 2500rpm to 4000rpm for 5min to 20min to collect the supernatant in which the boron nitride nanosheets are dispersed, and discard the bottom. Thick layers of agglomerated boron nitride powder. The supernatant is filtered to collect the filter cake, then the filter cake is washed, and dried at a temperature of 60° C. to 80° C. for 12 h to 48 h to obtain amino-functionalized boron nitride nanosheets. In this step, the mass ratio of boron nitride powder to urea is 1:4 to 1:7.

In step S1-2, the amino-functionalized boron nitride nanosheets are dispersed in a dispersant to obtain a boron nitride nanosheet dispersion.

MXene nanosheet dispersions were obtained by the following operations:

In step S2-1, in step S2-1, 1 g of titanium aluminum carbide (Ti ₃ AlC ₂ ) was added to 20 ml of hydrofluoric acid with a concentration of 40% and etched for 45 h to 55 h under stirring conditions. After centrifugation and washing for 3 times, the washing solution was centrifuged and washed with ethanol until the pH value of the washing solution was neutral, and the MXene nanosheets were obtained after drying. In this step, the magnetic stirring speed of etching is 450r/min～550r/min, the centrifugal speed using deionized water is 4800r/min～5200r/min, the centrifugation time is 5min～10min, centrifuging 3 times, using ethanol The centrifugation speed is 8000r/min～10000r/min, and the centrifugation time is 5min～10min.

Step S2-2, dispersing the MXene nanosheets in a dispersant to obtain a dispersion liquid of MXene nanosheets.

The specific operation of film forming is as follows:

The boron nitride nanosheet dispersion liquid and the MXene nanosheet dispersion liquid are ultrasonically mixed to obtain a mixed liquid, then polybenzimidazole is added to the mixed liquid, and the mixture is stirred at 80° C. to 100° C. for 3 h to 8 h to obtain a mixed liquid. The blend solution is filtered under reduced pressure to obtain a functionalized boron nitride nanosheet/MXene/polybenzimidazole composite film (ie, a composite film) with high thermal conductivity, and then the composite film is vacuum dried at 80°C to 100°C for 12h to 48h.

The dispersant is any one of dimethylsulfoxide (DMSO), dimethylformamide (DMF) or N-methylpyrrolidone (NMP). In the following embodiments, only DMSO is taken as an example for description, and DMF or NMP can achieve the same effect.

<Example 1>

A preparation method of a composite film containing 1wt% boron nitride nanosheet/MXene mixed filler, the specific steps are as follows:

(1) The boron nitride powder was calcined under nitrogen gas in a tube furnace at 1000°C for 3h.

(2) Take 1 g of calcined boron nitride powder and 5 g of urea and put them in a round-bottomed flask, under nitrogen gas, and heated to 140° C. in an oil bath for melting reaction for 6 hours.

(3) After the reaction is completed, the solid is dispersed in 500ml of deionized water, and ultrasonically stripped for 10h to obtain a dispersion, and then the dispersion is centrifuged at 3000rpm for 10min to obtain a supernatant; the supernatant is filtered and deionized water is used. The filter cake is washed, wherein the filtering method is preferably suction filtration, and the collected solids are dried at 60° C. for 10 h to obtain urea-functionalized boron nitride nanosheets.

(4) 1 g of Ti ₃ AlC ₂ was gradually added to 20 ml of 40 wt% hydrofluoric acid solution, followed by stirring at 500 r/min at room temperature for 48 h, and deionized water and ethanol were used for centrifugal washing to the pH value of the solution. Neutral, and vacuum-dried; centrifugation with deionized water at a speed of 5000 r/min, centrifugation time of 5 min, centrifugation 3 times, and centrifugation with ethanol at a speed of 8000 r/min, and centrifugation time of 5 min.

(5) After taking out the powder, add it into dimethyl sulfoxide, stir at 35° C. for 24 hours, and then centrifuge and wash to remove dimethyl sulfoxide. Then an appropriate amount of deionized water was added, and the cells were crushed for 10 h. Centrifuge for 10 min to take the supernatant and freeze-dry to obtain MXene at a centrifugation rate of 3500 r/min.

(6) Take 2.5 mg of boron nitride nanosheets and MXene nanosheets of the same mass and disperse them in 5 ml of dimethyl sulfoxide solution by ultrasonic respectively, and ultrasonically blend to obtain a mixed solution of boron nitride nanosheets/MXene. 0.5 g of polybenzimidazole powder was added to the mixture, and the mixture was magnetically stirred at 100° C. for 5 hours. After the reaction was completed, vacuum filtration was performed to form a film to obtain a composite film. During vacuum filtration, the filter membrane was an organic nylon filter membrane with a diameter of 50 mm and a pore size of 0.2 μm, and the composite membrane was vacuum-dried at 80 °C for 24 h.

<Example 2>

A preparation method of a composite film containing 5wt% boron nitride nanosheet/MXene mixed filler, the specific steps are as follows:

(1) The boron nitride powder was calcined under nitrogen gas in a tube furnace at 1000°C for 3h.

(2) Take 1 g of calcined boron nitride powder and 5 g of urea and put them in a round-bottomed flask, under nitrogen gas, and heated to 140° C. in an oil bath for melting reaction for 6 hours.

(3) After the reaction is completed, the solid is dispersed in 500ml of deionized water, and ultrasonically stripped for 10h to obtain a dispersion, and then the dispersion is centrifuged at 3000rpm for 10min to obtain a supernatant; the supernatant is filtered and deionized water is used. Washing, wherein the filtration method is preferably suction filtration, and the collected solids are dried at 60° C. for 10 h to obtain urea-functionalized boron nitride nanosheets.

(4) 1 g of Ti ₃ AlC ₂ was gradually added to 20 ml of 40 wt% hydrofluoric acid solution, followed by stirring at 500 r/min at room temperature for 48 h, and deionized water and ethanol were used for centrifugal washing to the pH value of the solution. Neutral, and vacuum-dried; centrifugation with deionized water at a speed of 5000 r/min, centrifugation time of 5 min, and centrifugation 3 times, centrifugation with ethanol at a speed of 8000 r/min, and centrifugation time of 5 min.

(5) After taking out the powder, add it to dimethyl sulfoxide and stir at 35°C for 24h. After the reaction was completed, centrifugation and washing were performed to remove dimethyl sulfoxide. Then an appropriate amount of deionized water was added, and the cells were crushed for 10 h. Centrifuge for 10 min to take the supernatant and freeze-dry to obtain MXene at a centrifugation rate of 3500 r/min.

(6) Take 13.1 mg of boron nitride nanosheets and MXene nanosheets of the same mass and disperse them in 5 ml of dimethyl sulfoxide solution by ultrasonic respectively, and ultrasonically blend to obtain a mixed solution of boron nitride nanosheets/MXene. 0.5 g of polybenzimidazole powder was added to the mixture, and the mixture was magnetically stirred at 100° C. for 5 hours. After the reaction was completed, vacuum filtration was performed to form a film to obtain a composite film. During vacuum filtration, the filter membrane was an organic nylon filter membrane with a diameter of 50 mm and a pore size of 0.2 μm, and the composite membrane was vacuum-dried at 80 °C for 24 h.

<Example 3>

A preparation method of a composite film containing 10wt% boron nitride nanosheet/MXene mixed filler, the specific steps are as follows:

(1) The boron nitride powder was calcined under nitrogen gas in a tube furnace at 1000°C for 3h.

(2) Take 1 g of calcined boron nitride powder and 5 g of urea and put them in a round-bottomed flask, under nitrogen gas, and heated to 140° C. in an oil bath for melting reaction for 6 hours.

(3) After the reaction is completed, the solid is dispersed in 500ml of deionized water, and ultrasonically stripped for 10h to obtain a dispersion, and then the dispersion is centrifuged at 3000rpm for 10min to obtain a supernatant; the supernatant is filtered and deionized water is used. Washing, wherein the filtration method is preferably suction filtration, and the collected solids are dried at 60° C. for 10 h to obtain urea-functionalized boron nitride nanosheets.

(4) 1 g of Ti ₃ AlC ₂ was gradually added to 20 ml of 40 wt% hydrofluoric acid solution, followed by stirring at 500 r/min at room temperature for 48 h, and deionized water and ethanol were used for centrifugal washing to the pH value of the solution. Neutral, and vacuum-dried; centrifugation with deionized water at a speed of 5000 r/min, centrifugation time of 5 min, centrifugation 3 times, and centrifugation with ethanol at a speed of 8000 r/min, and centrifugation time of 5 min.

(5) After taking out the powder, add it to dimethyl sulfoxide and stir at 35°C for 24h. After the reaction was completed, centrifugation and washing were performed to remove dimethyl sulfoxide. Then an appropriate amount of deionized water was added, and the cells were crushed for 10 h. Centrifuge for 10 min to take the supernatant and freeze-dry to obtain MXene at a centrifugation rate of 3500 r/min.

(6) Take 27.8 mg of boron nitride nanosheets and MXene nanosheets of the same mass and disperse them in 5 ml of dimethyl sulfoxide solution by ultrasonic respectively, and ultrasonically blend to obtain a mixed solution of boron nitride nanosheets/MXene. 0.5 g of polybenzimidazole powder was added to the mixture, and the mixture was magnetically stirred at 100° C. for 5 h. After the reaction was completed, vacuum filtration was performed to form a film to obtain a composite film. During vacuum filtration, the filter membrane was an organic nylon filter membrane with a diameter of 50 mm and a pore size of 0.2 μm, and the composite membrane was vacuum-dried at 80 °C for 24 h.

<Example 4>

A preparation method of a composite film containing 20wt% boron nitride nanosheet/MXene mixed filler, the specific steps are as follows:

(1) The boron nitride powder was calcined under nitrogen gas in a tube furnace at 1000°C for 3h.

(2) Take 1 g of calcined boron nitride powder and 5 g of urea and put them in a round-bottomed flask, under nitrogen gas, and heated to 140° C. in an oil bath for melting reaction for 6 hours.

(3) After the reaction is completed, the solid is dispersed in 500ml of deionized water, and ultrasonically stripped for 10h to obtain a dispersion, and then the dispersion is centrifuged at 3000rpm for 10min to obtain a supernatant; the supernatant is filtered and deionized water is used. Washing, wherein the filtration method is preferably suction filtration, and the collected solids are dried at 60° C. for 10 h to obtain urea-functionalized boron nitride nanosheets.

(4) 1 g of Ti ₃ AlC ₂ was gradually added to 20 ml of 40 wt% hydrofluoric acid solution, followed by stirring at 500 r/min at room temperature for 48 h, and deionized water and ethanol were used for centrifugal washing to the pH value of the solution. Neutral, and vacuum-dried; centrifugation with deionized water at a speed of 5000 r/min, centrifugation time of 5 min, and centrifugation 3 times, centrifugation with ethanol at a speed of 8000 r/min, and centrifugation time of 5 min.

(5) After taking out the powder, add it to dimethyl sulfoxide and stir at 35°C for 24h. After the reaction was completed, centrifugation and washing were performed to remove dimethyl sulfoxide. Then an appropriate amount of deionized water was added, and the cells were crushed for 10 h. Centrifuge for 10 min to take the supernatant and freeze-dry to obtain MXene at a centrifugation rate of 3500 r/min.

(6) Take the same mass of 62.5 mg of boron nitride nanosheets and MXene nanosheets to ultrasonically disperse them in 5 ml of dimethyl sulfoxide solution, and ultrasonically blend to obtain a mixed solution of boron nitride nanosheets/MXene. 0.5 g of polybenzimidazole powder was added to the mixture, and the mixture was magnetically stirred at 100° C. for 5 h. After the reaction was completed, vacuum filtration was performed to form a film to obtain a composite film. During vacuum filtration, the filter membrane was an organic nylon filter membrane with a diameter of 50 mm and a pore size of 0.2 μm, and the composite membrane was vacuum-dried at 80 °C for 24 h.

<Comparative Example 1>

A preparation method of pure polybenzimidazole film, the concrete steps are as follows:

Add 0.5g of polybenzimidazole powder to 10ml of dimethyl sulfoxide, stir magnetically in an oil bath at 100°C for 5h, after the reaction is completed, use an organic nylon filter membrane with a diameter of 50mm and a pore size of 0.2μm, and vacuum suction. Filtration to obtain a pure polybenzimidazole film, which was dried at 80°C for 24h.

<Test example>

The dispersibility of the functionalized boron nitride nanosheets, MXene nanosheets and commercially available boron nitride prepared in Examples 1-4 was tested, and the functionalized boron nitride nanosheets, MXene prepared in Examples 1-4 were tested The nanosheets were examined by SEM, and the functionalized boron nitride nanosheets and MXene nanosheets in Examples 1-4 had similar dispersibility and SEM, so only the results in Example 1 were attached for description.

Figure 1 is a comparison photo of the functionalized boron nitride nanosheets prepared in Example 1 and the commercially available boron nitride dispersion. The commercially available boron nitride is stacked and not well dispersed in the solution, while the functionalized The dispersion of boron hydride nanosheets has good dispersibility, and there is no phenomenon of agglomeration and accumulation.

Figure 2 is a photograph of the MXene/dimethyl sulfoxide dispersion prepared in Example 1, and it can be seen that MXene is well dispersed in the dimethyl sulfoxide solution.

FIG. 3 is an SEM image of the boron nitride nanosheets prepared in Example 1. It can be seen from the figure that boron nitride has a good peeling effect.

FIG. 4 is the SEM image of the MXene prepared in Example 1. It can be seen from the figure that the MXene has a good peeling effect.

5 is a photograph of the functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film prepared in Example 1.

The thin films prepared in Examples 1-4 and Comparative Example 1 were tested for thermal conductivity, and the specific operations were as follows:

First cut into a 25mm diameter disc with a thickness of less than 0.5mm, and use the German NETZSCH laser method thermal conductivity analyzer (LFA467) to directly measure the thermal diffusivity (α) of the material by the transient method. The specific heat capacity (c) of the composite was characterized by a differential scanning calorimeter (Netzsch DSC200F3) based on ASTM E1269-2011. Finally, the thermal conductivity (λ) is calculated by the formula λ=αρc, and the result is shown in Figure 6.

Fig. 6 is a graph showing the thermal conductivity of the functionalized boron nitride nanosheets/MXene/polybenzimidazole high thermal conductivity composite films prepared in Examples 1-4. Mixed filling, the thermal conductivity of the composite film is also gradually increased.

Action and effect of the embodiment

According to the preparation method of the functionalized boron nitride nanosheets/MXene/polybenzimidazole high thermal conductivity composite film provided in the above embodiment, the amino-functionalized boron nitride nanosheets and MXene nanosheets are first dispersed in a dispersant, respectively, After mixing, a mixed solution is obtained, and then polybenzimidazole is added to the mixed solution to obtain a blended solution of functionalized boron nitride nanosheets/MXene/polybenzimidazole, and the blended solution is suction filtered to obtain a composite film. The invention utilizes the three-dimensional structure of the polybenzimidazole polymer as a binder to make the modified boron nitride containing amino group and the MXene with electronegativity undergo electrostatic self-assembly to form the polybenzimidazole as the skeleton, the functional Boron nitride nanosheets and MXene as self-supporting films of mixed fillers. The filled network formed by the synergistic effect of functionalized boron nitride nanosheets and Ti ₃ C ₂ Tx bridging in this film can effectively reduce the interfacial thermal resistance and ultimately promote heat transfer, eliminating the possibility of mixing directly with boron nitride as a mixed filler The agglomeration of fillers, high filling content makes composite materials low flexibility and other adverse effects. Compared with the prior art, the present invention utilizes functionalized boron nitride nanosheets, exfoliated _MXene and polybenzimidazole as assemblies, functionalized boron nitride nanosheets, _Ti3C2Tx and polybenzimidazole. The synergistic effect of the ternary composite system is beneficial to improve the mechanical properties of the composite material of the ternary system. At the same time, the composite film is given excellent thermal conductivity, the method is simple and effective, and the obtained high thermal conductivity film has wide application prospects in the fields of energy, electronics and the like.

In the above example, the amino group functionalization of boron nitride is realized by the reaction of boron nitride and urea, and then the functionalized boron nitride nanomaterial is realized by ultrasonic exfoliation; at the same time, MXene nanosheets are prepared by ultrasonic exfoliation, which makes MXene more Uniform dispersion can form a good filler-polymer interface, which is beneficial to reduce the thermal resistance of the interface.

The mass ratio of the mixed filler to the polybenzimidazole is 0.01-0.30, and the filling of the mixed filler improves the thermal conductivity of the composite film.

The mass ratio of boron nitride powder to urea is 1:4～1:7, and the temperature of melting reaction is 130℃～140℃, so that boron nitride and urea can fully react, and the amino group of urea is better grafted on boron nitride. edge, the boron nitride amino edge was successfully functionalized.

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (2)

1. a preparation method of functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film, is characterized in that, comprises the following steps: (1) calcining the boron nitride powder under nitrogen gas in a tube furnace at 1000°C for 3h; (2) Take 1 g of the calcined boron nitride powder and 5 g of urea and place them in a round-bottomed flask, and under nitrogen gas, the oil bath is heated to 140° C. to carry out a melting reaction for 6 hours; (3) After the reaction is completed, the solid is dispersed in 500ml of deionized water, and ultrasonically stripped for 10h to obtain a dispersion, and then the dispersion is centrifuged at 3000rpm for 10min to obtain a supernatant; the supernatant is filtered and deionized water is used. Washing, wherein the filtration method is suction filtration, and the collected solids are dried at 60 °C for 10 h to obtain urea-functionalized boron nitride nanosheets; (4) Gradually and slowly add 1 g of Ti ₃ AlC ₂ to 20 ml of 40 wt% hydrofluoric acid solution, then stir at 500 r/min for 48 h at room temperature, and use deionized water and ethanol to centrifuge and wash to the solution. The pH value is neutral, and vacuum drying is carried out, wherein, the centrifugal speed of deionized water is 5000r/min, the centrifugal time is 5min, and the centrifugation is 3 times, and the centrifugal speed of ethanol is 8000r/min. The time is 5min; (5) After taking out the powder, add it into dimethyl sulfoxide, stir at 35°C for 24 hours, and then centrifuge and wash after the reaction is completed to remove the dimethyl sulfoxide, then add an appropriate amount of deionized water, cell crusher for 10 hours, and centrifuge for 10 minutes. The supernatant was freeze-dried to obtain MXene, and the centrifugation rate was 3500 r/min; (6) Take the same mass of 27.8 mg of boron nitride nanosheets and the MXene nanosheets, respectively, ultrasonically disperse them in 5 ml of dimethyl sulfoxide solution, and ultrasonically blend to obtain a boron nitride nanosheet/MXene mixed solution. Add 0.5g of polybenzimidazole powder to the mixed solution, stir magnetically at 100°C for 5h, after the reaction is completed, vacuum filtration to form a film to obtain a composite film, wherein, during vacuum filtration, the filter membrane is selected with a diameter of 50mm and a pore size of 0.2 μm organic nylon filter membrane, the composite membrane was vacuum dried at 80°C for 24h. 2. a functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity composite film, is characterized in that, by the functionalized boron nitride nanosheet/MXene/polybenzimidazole high thermal conductivity described in claim 1 The preparation method of the composite film is prepared.

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