BNNTs@MXene / ANF heat-conducting composite material and preparation method thereof

Abstract

The application discloses a BNNTs@MXene / ANF heat-conducting composite material and a preparation method thereof, and the preparation method comprises the following steps: firstly, single-layer MXene is treated in a mixed solution of a nitrogen source and a boron source, so that the MXene surface is nitrided and loaded with nitrogen ions and boron ions; then, the treated MXene is subjected to high-temperature pyrolysis, so that boron nitride nanotubes are in-situ grown on the MXene surface, and a BNNTs@MXene filler is obtained; finally, the BNNTs@MXene filler is combined with aramid fiber ANF in a vacuum-assisted suction filtration mode, and a BNNTs@MXene / ANF composite material is obtained. The method can effectively reduce the contact thermal resistance between fillers, build a horizontal heat-conducting path, and significantly improve the heat-conducting performance of the composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of MXene and ANF composite materials, and particularly to a BNNTs@MXene / ANF thermally conductive composite material and a preparation method thereof. Background Art

[0002] With the rapid development of electronic devices towards miniaturization and high frequency, the high integration of electronic devices has led to the generation of large amounts of heat during the operation of electronic components. This leads to the continuous accumulation of heat in electronic devices, resulting in serious overheating. Therefore, it is necessary to use materials with thermal conductivity to dissipate heat. Existing thermally conductive materials are mainly polymer-based composites. Pure polymer-based materials are difficult to use directly due to their low thermal conductivity. Therefore, they need to be doped with inorganic fillers such as high-thermal-conductivity metals, carbon-based materials, or ceramics to improve thermal conductivity. However, in existing polymer-based composite materials, the polymer and filler are simply compounded. For example, the document "Enhanced Electromagnetic Shielding and Thermal Management Properties in MXene / Aramid Nanofiber Films Fabricated by Intermittent Filtration" discloses a layered MXene / aramid nanofiber (ANF) composite film obtained by filtration, which is a simple compounding of the filler and the substrate (Liu, Chenxu, et al. "Enhanced Electromagnetic Shielding and Thermal Management Properties in MXene / Aramid Nanofiber Films Fabricated by Intermittent Filtration." ACS Applied Materials & Interfaces 15.3 (2023): 4516-4526.). However, the polymer-based composite material obtained by simple compounding does not construct an effective filler heat conduction path. There is interfacial thermal resistance between the substrate and the filler, and there is also interfacial thermal resistance between the fillers. Therefore, the thermal conductivity of the material cannot be improved to the ideal level. Summary of the Invention

[0003] Based on the problems existing in the above-mentioned prior art, the present invention provides a BNNTs@MXene / ANF thermal conductive composite material and a preparation method thereof, aiming to connect the MXene sheets through BNNTs grown on the MXene surface, thereby reducing the contact thermal resistance between fillers and improving the thermal conductivity of the composite material.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for preparing a BNNTs@MXene / ANF thermally conductive composite material is characterized by: first, treating a single layer of MXene in a mixture of a nitrogen source and a boron source to nitride the MXene surface and load nitrogen and boron ions; then, pyrolyzing the treated MXene at high temperature to in-situ grow boron nitride nanotubes (BNNTs) on the MXene surface, with the MXene and the BNNTs connected by carbon-nitrogen bonds to obtain a BNNTs@MXene filler; finally, using vacuum-assisted filtration to composite the BNNTs@MXene filler with aramid fiber (ANF) to obtain a BNNTs@MXene / ANF composite material. Specifically, the method comprises the following steps:

[0006] Step 1: Preparation of Nitrided MXene

[0007] 40-60 mg of MXene and 30-40 mL of deionized water were ultrasonically mixed in an ice bath to obtain a MXene suspension.

[0008] Dissolve 30-50 g of CH4N2O in 100 mL of deionized water, add 0.8-1.5 g of H3BO3, and stir at room temperature for 10-14 h to obtain a precursor solution;

[0009] The MXene suspension is added to the precursor solution, and stirred at room temperature for 4 to 6 hours to nitride the MXene surface and load nitrogen ions and boron ions. The precipitate is collected by centrifugation and vacuum dried to obtain the nitrided MXene;

[0010] Step 2: Preparation of BNNTs@MXene filler

[0011] The nitrided MXene is subjected to high-temperature pyrolysis treatment at 800-1000° C. in a nitrogen atmosphere for 8-10 hours to obtain a BNNTs@MXene filler;

[0012] Step 3: Preparation of BNNTs@MXene / ANF composites

[0013] Add 0.75-1.0 g of chopped aramid fiber ANF and 1-1.5 g of KOH to 60-80 mL of DMSO and stir evenly to obtain an ANF dispersion;

[0014] BNNTs@MXene filler was added to the ANF dispersion and stirred evenly. The mixture was then washed with water to remove DMSO. The mixture was then dispersed in 250 mL of deionized water by shearing to obtain a mixed dispersion. The BNNTs@MXene / ANF composite material was obtained by vacuum-assisted filtration and hot pressing.

[0015] As a further preferred technical solution of the present invention, in step 2, the heating rate during the high-temperature pyrolysis treatment is 2°C / min.

[0016] As a further preferred technical solution of the present invention, in step 3, the filter paper for vacuum-assisted filtration is polytetrafluoroethylene hydrophobic filter paper with a pore size of 0.22 μm.

[0017] As a further preferred technical solution of the present invention, in step 3, the pressure of the hot pressing treatment is 5-10 MPa, the temperature is 100-140° C., and the treatment time is 5-10 min.

[0018] As a further preferred technical solution of the present invention, in step 3, the amount of BNNTs@MXene filler added accounts for 10% to 40% of the total mass of the BNNTs@MXene / ANF composite material.

[0019] As a further preferred technical solution of the present invention, in step 3, the shearing rotation speed is 10000-14000 rpm.

[0020] As a further preferred technical solution of the present invention, the monolayer MXene is prepared by in-situ generation of HF by HCl and LiF to etch the MAX phase followed by ultrasonic exfoliation, the specific steps being as follows:

[0021] 1-2 g LiF and 15-25 mL 9 M HCl solution were mixed and stirred in an ice bath, and then 1 g MAX phase powder was added and reacted at 30-40 ° C for 22-26 h. The resulting slurry was repeatedly washed with deionized water and centrifuged to pH ≥ 6 to obtain Ti3C2T x The obtained precipitate was redispersed in deionized water, ultrasonicated in an ice bath for 1 to 3 hours under oxygen isolation conditions, the supernatant was collected by centrifugation, and freeze-dried to obtain a single-layer MXene.

[0022] Compared with the prior art, the beneficial effects of the present invention are embodied in:

[0023] This invention uses MXene with in-situ BNNT growth on its surface as a filler. The BNNTs serve as a one-dimensional material connecting two 2D MXene sheets, creating a thermally conductive network that effectively reduces interfacial thermal resistance between the fillers. Furthermore, the oriented structure formed by vacuum-assisted filtration creates a horizontal heat conduction path, further enhancing the composite's thermal conductivity. Furthermore, the MXene and BNNTs are connected by carbon-nitrogen bonds, creating a strong interaction between them. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] Figure 1 This is the SEM image of the single-layer MXene obtained in Example 1 of the present invention;

[0026] Figure 2 This is the SEM image of BNNTs@MXene obtained in Example 1 of the present invention;

[0027] Figure 3 TEM image of BNNTs@MXene obtained in Example 1 of the present invention;

[0028] Figure 4 FI-IR comparison chart of the single-layer MXene and BNNTs@MXene obtained in Example 1 of the present invention;

[0029] Figure 5 This is the XRD pattern of BNNTs@MXene obtained in Example 1 of the present invention;

[0030] Figure 6 This is the XPS total spectrum of the single-layer MXene and BNNTs@MXene obtained in Example 1 of the present invention;

[0031] Figure 7 The thermal conductivity of the samples obtained in Examples 1, 2, 3, and 4 of the present invention and Comparative Example 1 is compared. DETAILED DESCRIPTION

[0032] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0033] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which this invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are conventional biochemical reagents; the experimental methods described, unless otherwise specified, are conventional methods.

[0034] Example 1

[0035] In this example, the BNNTs@MXene / ANF composite material was prepared according to the following steps.

[0036] Step 1. Preparation of single-layer MXene

[0037] 1.5 g of LiF was added to a polytetrafluoroethylene bottle containing 20 mL of 9 M HCl solution and stirred for 15 min in an ice bath to obtain an etchant. Then 1 g of MAX phase powder (Ti3AlC2) was slowly added to the etchant in batches and reacted at 35 ° C for 24 h. The resulting slurry was repeatedly washed with deionized water and centrifuged at 3500 rpm until the pH was ≥ 6 to obtain Ti3C2T xprecipitate; the obtained precipitate was redispersed in deionized water, and the dispersed liquid was poured into a gas collecting bottle, argon was passed for 5 minutes to isolate oxygen, and then ultrasonicated in an ice bath for 2 hours, centrifuged at 8000 rpm for 10 minutes, and the supernatant was collected and freeze-dried for 24 hours to obtain a single-layer MXene powder.

[0038] Step 2: Preparation of Nitrided MXene

[0039] Add 50 mg of MXene and 35 mL of deionized water to a 100 mL beaker. Place the beaker in an ultrasonicator and sonicate for 30 minutes in an ice bath to obtain a MXene suspension. Dissolve 40 g of CH₄N₂O in 100 mL of deionized water using magnetic stirring. Once dissolved, add 1 g of H₃BO₃ and stir for 12 hours to obtain a precursor solution.

[0040] The prepared MXene suspension was added to the precursor solution, stirred for 5 hours, and then centrifuged at 10,000 rpm for 10 minutes. The supernatant was removed, and the lower sediment was taken out and dried in a vacuum drying oven at 70°C for 24 hours to obtain nitrided MXene.

[0041] Step 3: Preparation of BNNTs@MXene filler

[0042] The nitrided MXene was ground into powder in a mortar and pyrolyzed at 900 °C in a nitrogen atmosphere for 8 h to obtain BNNTs@MXene filler.

[0043] Step 4: Preparation of BNNTs@MXene / ANF composite materials

[0044] Chopped Kevlar 49 (0.75 g) and KOH (1.125 g) were added to 75 mL of DMSO and stirred at 800 rpm for 4 days to prepare a uniform deep red ANF dispersion (concentration of 10 mg / mL).

[0045] 5.5 mg of BNNTs@MXene filler was added to 5 mL of ANF dispersion and stirred thoroughly. The mixture was then washed with water to remove DMSO and dispersed in 250 mL of deionized water by shearing (vigorous stirring at 12,000 rpm for 1 minute) to obtain a uniform mixed dispersion. Vacuum-assisted filtration (using polytetrafluoroethylene hydrophobic filter paper with a pore size of 0.22 μm) and hot pressing (at a pressure of 5 MPa, a temperature of 120°C, and a processing time of 5 minutes) yielded a composite material with a filler content of 10 wt%, designated BNNTs@MXene-10 / ANF.

[0046] Example 2

[0047] In this example, a BNNTs@MXene / ANF composite material was prepared in the same manner as in Example 1, except that 12.5 mg of BNNTs@MXene filler was added in step 4, resulting in a composite material with a filler content of 20 wt%, which was designated as BNNTs@MXene-20 / ANF.

[0048] Example 3

[0049] In this example, a BNNTs@MXene / ANF composite material was prepared in the same manner as in Example 1, with the only difference being that the amount of BNNTs@MXene filler added in step 4 was 21.43 mg, resulting in a composite material with a filler content of 30 wt%, which was recorded as BNNTs@MXene-30 / ANF.

[0050] Example 4

[0051] In this example, a BNNTs@MXene / ANF composite material was prepared in the same manner as in Example 1, except that the amount of BNNTs@MXene filler added in step 4 was 33.33 mg, resulting in a composite material with a filler content of 40 wt%, which was recorded as BNNTs@MXene-40 / ANF.

[0052] Comparative Example 1

[0053] 5 mL of the 10 mg / mL ANF dispersion prepared in Example 1 was weighed into a beaker, washed with water to remove DMSO, and then dispersed in 250 mL of deionized water by shearing (vigorous stirring at 12,000 rpm for 1 minute) to obtain a uniform dispersion. A pure ANF membrane was obtained by vacuum filtration (using hydrophobic polytetrafluoroethylene filter paper with a pore size of 0.22 μm) and autoclaving (autoclaving at a pressure of 5 MPa, a temperature of 120°C, and a processing time of 5 minutes).

[0054] Figure 1 This is the SEM image of the single-layer MXene prepared in Example 1. Figure 2 This SEM image of the BNNTs@MXene filler obtained in Example 1 shows the successful in-situ growth of BNNTs on the MXene surface through high-temperature heat treatment. The BNNTs connect the MXene layers, forming a thermal pathway that effectively reduces the contact thermal resistance between fillers and improves the thermal conductivity of the composite material.

[0055] Figure 3 This is the TEM image of the BNNTs@MXene filler obtained in Example 1. An obvious cavity structure can be seen in the image, indicating that BNNTs have successfully grown on the surface of the MXene layer.

[0056] Figure 4This is the FI-IR comparison chart of the monolayer MXene and BNNTs@MXene obtained in Example 1. Compared with pure MXene, BNNTs@MXene has a -1 BN bond bending vibration appears at 1377 cm -1 The stretching vibration of BN bond appears at , indicating the formation of BNNT.

[0057] Figure 5 This is the XRD pattern of BNNTs@MXene obtained in Example 1. By comparing with pure MXene and pure BNNT, it can be seen that there is an obvious peak shift, indicating that BNNTs have successfully grown on the MXene surface.

[0058] Figure 6 This is the overall XPS spectrum of the single-layer MXene and BNNTs@MXene obtained in Example 1. Compared with MXene, the atomic ratio of B and N in BNNTs@MXene is larger, indicating the successful introduction of BNNT.

[0059] Figure 7 The thermal conductivity of the samples obtained in Examples 1, 2, 3, and 4, as well as Comparative Example 1, is shown. Compared to the pure ANF membrane in Comparative Example 1, the thermal conductivity of the samples obtained in Examples 1 to 4 first increases and then decreases with increasing filler content. This is primarily due to the in-situ growth of BNNTs on the MXene surface, which effectively reduces the contact thermal resistance between MXene sheets, thereby improving thermal conductivity. However, excessive filler concentration can lead to agglomeration, affecting the thermal conductivity of the composite membrane.

[0060] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. A method for preparing a BNNTs@MXene / ANF thermally conductive composite material, characterized by: First, a single layer of MXene is treated in a mixture of nitrogen and boron sources to nitride the MXene surface and load nitrogen and boron ions. The treated MXene is then pyrolyzed at high temperature to in-situ grow boron nitride nanotubes on the MXene surface, and the MXene and boron nitride nanotubes are connected by carbon-nitrogen bonds to obtain BNNTs@MXene filler. Finally, the BNNTs@MXene filler is compounded with aramid fiber (ANF) by vacuum-assisted filtration to obtain a BNNTs@MXene / ANF composite material. The specific steps include: Step 1: Preparation of Nitrided MXene 40-60 mg of MXene and 30-40 mL of deionized water were ultrasonically mixed in an ice bath to obtain a MXene suspension. Dissolve 30-50 g of CH4N2O in 100 mL of deionized water, add 0.8-1.5 g of H3BO3, and stir at room temperature for 10-14 h to obtain a precursor solution. The MXene suspension is added to the precursor solution, and stirred at room temperature for 4 to 6 hours to nitride the MXene surface and load nitrogen ions and boron ions. The precipitate is collected by centrifugation and vacuum dried to obtain the nitrided MXene; Step 2: Preparation of BNNTs@MXene filler The nitrided MXene is subjected to high-temperature pyrolysis treatment at 800-1000° C. in a nitrogen atmosphere for 8-10 h to obtain a BNNTs@MXene filler; Step 3: Preparation of BNNTs@MXene / ANF composites Add 0.75-1.0 g of chopped aramid fiber ANF and 1-1.5 g of KOH to 60-80 mL of DMSO and stir evenly to obtain an ANF dispersion. BNNTs@MXene filler was added to the ANF dispersion and stirred evenly. The mixture was then washed with water to remove DMSO. The mixture was then dispersed in 250 mL of deionized water by shearing to obtain a mixed dispersion. The BNNTs@MXene / ANF composite material was obtained by vacuum-assisted filtration and hot pressing.

2. The preparation method according to claim 1, wherein: In step 3, the filter paper for vacuum-assisted filtration is polytetrafluoroethylene hydrophobic filter paper with a pore size of 0.22 μm.

3. The preparation method according to claim 1, wherein: In step 3, the pressure of the hot pressing treatment is 5-10 MPa, the temperature is 100-140° C., and the treatment time is 5-10 min.

4. The preparation method according to claim 1, wherein: In step 3, the amount of BNNTs@MXene filler added accounts for 10%~40% of the total mass of the BNNTs@MXene / ANF composite material.

5. The preparation method according to claim 1, wherein: The monolayer MXene is prepared by in-situ generation of HF by HCl and LiF to etch the MAX phase followed by ultrasonic exfoliation.

6. The preparation method according to claim 5, characterized in that The monolayer MXene is prepared according to the following steps: 1-2 g LiF and 15-25 mL 9 M HCl solution were mixed and stirred in an ice bath, and then 1 g MAX phase powder was added and reacted at 30-40 °C for 22-26 h. The resulting slurry was repeatedly washed with deionized water and centrifuged to pH ≥ 6 to obtain Ti3C2T x The obtained precipitate was redispersed in deionized water, ultrasonicated in an ice bath for 1 to 3 hours under oxygen isolation conditions, the supernatant was collected by centrifugation, and freeze-dried to obtain a single-layer MXene.

7. A BNNTs@MXene / ANF thermally conductive composite material prepared by the preparation method according to any one of claims 1 to 6.

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