Preparation method of in-situ orientation carbon nanotube / boron nitride nanobelt aerogel

Abstract

The invention relates to a preparation method of in-situ oriented carbon nanotube / boron nitride nanobelt aerogel, which comprises the following steps: dissolving melamine and boric acid in a co-solvent of tert-butyl alcohol and hot deionized water, stirring and mixing, carrying out ultrasonic treatment, freeze-drying and the like to obtain an aerogel precursor, placing the precursor in a tubular furnace, and pyrolyzing to obtain boron nitride nanobelt aerogel; under a high-temperature condition, a mixed solution of ethanol, ethylenediamine and ferrocene is injected into a tubular furnace through a floating CVD method, and a carbon nanotube is grown on the boron nitride nano surface, so that the in-situ oriented carbon nanotube / boron nitride nanobelt aerogel is obtained. The in-situ orientation carbon nanotube / boron nitride nanobelt aerogel is low in density and good in flexibility, and has electromagnetic shielding performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of composite material preparation, and particularly relates to a preparation method of in-situ oriented carbon nanotube / boron nitride nanoribbon aerogel. BACKGROUND

[0002] Boron nitride nanoribbon is a one-dimensional material similar to graphene nanoribbon, which has a high aspect ratio and a highly ordered structure. After being assembled into aerogel, it forms a highly porous, ultra-light three-dimensional skeleton structure with extremely low density, high porosity and excellent thermal stability. Since boron nitride itself has excellent high-temperature resistance, chemical inertness and electrical insulation properties, when it is constructed into an aerogel form, it not only retains its intrinsic properties, but also endows the material with good mechanical elasticity and multi-directional structure regulation ability. This kind of aerogel is widely used in high-temperature insulation, electromagnetic shielding, environmental purification, flexible electronic devices and other frontier fields, and shows superior performance and broad application prospects under extreme service conditions. However, due to the electrical insulation of boron nitride itself, its electromagnetic shielding effect is not good, which restricts its further application in the field of electromagnetic shielding.

[0003] At present, boron nitride and carbon nanotubes are combined through physical methods to play the role of electromagnetic shielding. For example, carbon nanotubes and hexagonal boron nitride layers are alternately stacked to realize anisotropic distribution through emulsion assembly; a three-dimensional skeleton of hexagonal boron nitride / multi-walled carbon nanotube is constructed by ice template method, and is filled with epoxy resin after carbonization. The Chinese invention patent with the patent number CN120328497 A, a preparation method of boron nitride / carbon nanotube electromagnetic wave absorbing material, uses the metal-organic coordination network formed by nickel nitrate in the solution to catalyze the formation of carbon nanotubes in the pyrolysis reaction of melamine. Although the composite material prepared by this method has considerable wave absorbing capacity, the performance of the material in mechanics and thermal is not mentioned, and the difference between boron nitride and carbon nanotube cannot be observed obviously in the micro-morphology of the material.

[0004] In summary, the existing boron nitride / carbon nanotube composite material only has single performance or still has some defects, and there is still a blank in preparing a material with mechanical, thermal and electromagnetic shielding properties. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a preparation method of in-situ oriented carbon nanotube / boron nitride nanoribbon aerogel. By introducing in-situ oriented carbon nanotubes, the carbon nanotubes and the boron nitride nanoribbons are face-to-face, so that the interface bonding force between them is stronger, and the carbon nanotubes are not easy to fall off.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is: A method for preparing an in-situ oriented carbon nanotube / boron nitride nanoribbon aerogel, characterized by comprising the following steps: Step 1: Melamine and boric acid are dissolved in a co-solution of tert-butanol and hot deionized water. After stirring, sonication and freeze-drying, melamine-boric acid precursor aerogel is obtained, wherein the mass ratio of melamine, boric acid, tert-butanol and deionized water is 1 : (1~5) : (10~25) : (20~35). Step 2: Place the melamine-boric acid precursor aerogel in a tube furnace and pyrolyze it to obtain boron nitride nanoribbon aerogel. Step 3: Prepare a mixed solution of ethanol, ethylenediamine and ferrocene, and mix the solution evenly by ultrasonic vibration. The mass ratio of the three components in the mixed solution of ethanol, ethylenediamine and ferrocene is (10~50): (5~20): 1. Step 4: Place the boron nitride nanoribbon aerogel in a tube furnace, purge with argon gas, and inject the solution prepared in Step 3 into the tube furnace under high temperature. After injection, remove the needle, seal the pores with vacuum mud, and cool the tube furnace to room temperature. Carbon nanotubes are then grown on the surface of the boron nitride nanoribbons to obtain carbon nanotube / boron nitride nanoribbon aerogel.

[0007] The temperature of the hot deionized water is 60~90 ℃.

[0008] The stirring time is 40-90 min, the ultrasonic time is 5-15 min, and the freeze-drying time is 24-48 h.

[0009] In step 2, the temperature of the pyrolysis reaction is 950~1400 ℃, and the time of the pyrolysis reaction is 2~5 h.

[0010] The atmosphere for the pyrolysis reaction in step 2 is one of argon, nitrogen, or 95% nitrogen + 5% hydrogen.

[0011] In step 4, the carbon nanotubes are grown at a temperature of 700-900 ℃ for 10-60 min.

[0012] In step 4, the carbon nanotubes are one or a mixture of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0013] In step 4, the argon gas washing process lasts for 30 minutes.

[0014] The injection begins when the tubular furnace reaches 850 °C, with the injection rate controlled at 10 mL / h and the gas flow rate controlled at 900 sccm.

[0015] The present invention has the following beneficial effects: This invention provides an in-situ oriented carbon nanotube / boron nitride nanoribbon aerogel and its preparation method. By introducing in-situ oriented carbon nanotubes, the carbon nanotubes and boron nitride nanoribbons are connected face-to-face, resulting in stronger interfacial bonding and making the carbon nanotubes less prone to detachment. Compared with traditional physical methods for preparing carbon nanotube / boron nitride composites, this invention achieves enhanced toughness and improves the electromagnetic shielding performance of the composite material while also making it lighter and more flexible. Attached Figure Description

[0016] Figure 1 SEM image of an in-situ grown carbon nanotube / boron nitride nanoribbon aerogel prepared in Example 1 of the present invention; Figure 2 SEM image of an in-situ grown carbon nanotube / boron nitride nanoribbon aerogel prepared in Example 2 of the present invention. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.

[0018] This invention provides an in-situ oriented carbon nanotube / boron nitride nanoribbon aerogel and its preparation method. Specifically, using boron nitride nanoribbon aerogel as a matrix, carbon nanotubes are grown in an in-situ oriented array on the surface of boron nitride nanoribbons using a floating CVD method.

[0019] Specifically, the present invention provides a method for preparing silica / boron nitride nanoribbon aerogel, comprising the following steps: Step 1) Melamine and boric acid are dissolved in a co-solvent of tert-butanol and hot deionized water, and then stirred, sonicated and freeze-dried to obtain melamine-boric acid precursor aerogel.

[0020] Step 2) Place the melamine-boric acid precursor aerogel in a pyrolysis chamber to obtain boron nitride nanoribbon aerogel.

[0021] Step 3) Prepare a mixed solution of ethanol, ethylenediamine and ferrocene.

[0022] Step 4) Place the boron nitride nanobelt aerogel in a tube furnace, pass argon gas through it, and inject the mixed solution described in Step 3 into the tube furnace using a floating CVD method at high temperature to grow carbon nanotubes on the surface of the boron nitride nanobelts. The specific dosage and process conditions are as follows: In step 1), the mass ratio of melamine, boric acid, tert-butanol and deionized water is 1: (1~5): (10~25): (20~35).

[0023] In step 1), the stirring time is 40-90 min, the ultrasonic time is 5-15 min, and the freeze-drying time is 24-48 h.

[0024] In step 2), the temperature of the pyrolysis reaction is 950~1400 ℃, the time of the pyrolysis reaction is 2~5 h, and the inert gas can be one of argon, nitrogen, or 95% nitrogen + 5% hydrogen.

[0025] In step 3), the mass ratio of ethanol, ethylenediamine and ferrocene in the mixed solution is (10~50): (5~20): 1.

[0026] In step 4), the carbon nanotubes are grown at a temperature of 700-900 ℃ for 10-60 min. The carbon nanotubes are one or a mixture of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes. Example 1

[0027] Step 1) Dissolve 0.4762 g of melamine and 0.4838 g of boric acid in a co-solvent mixture of 28 mL of tert-butanol and 20 mL of deionized water. Stir magnetically in an oil bath at 80 °C for 30 min to obtain a clear precursor solution. Pour the solution into a mold, let it stand at room temperature for 0.5 h, freeze for 24 h, and then freeze-dry at -40 °C for 48 h to obtain a white dry gel precursor.

[0028] Step 2) Place the dry gel obtained in Step 1) in a tube furnace, pass argon gas through it, and heat it at a rate of 10 °C / min to 1000 °C, then at a rate of 5 °C / min to 1400 °C. Pyrolyze for 4 h to obtain boron nitride nanoribbon aerogel.

[0029] Step 3) Weigh 40 mL of ethanol and 10 mL of ethylenediamine using a graduated cylinder, and separately weigh 1 g of ferrocene using an electronic balance. Mix them in a beaker and place the beaker in an ultrasonic oscillator to mix the solution evenly using ultrasonic vibration.

[0030] Step 4) Place the aerogel obtained in step 2) in a tube furnace, purge with argon gas for 30 min, and heat to 850 ℃ at 8 ℃ / min.

[0031] Step 5) Draw the homogeneous mixture obtained in Step 3) into a syringe. Begin injection when the tube furnace reaches 850 °C, controlling the injection rate at 10 mL / h and the gas flow rate at 900 sccm. Inject for 45 min. After injection, remove the needle, seal the pores with vacuum clay, and cool the tube furnace to room temperature.

[0032] Figure 1This is a SEM image of the in-situ grown carbon nanotube / boron nitride nanoribbon aerogel. The vertically aligned in-situ growth of carbon nanotubes on the nanoribbon surface is clearly visible. Example 2

[0033] Step 1) Dissolve 0.4762 g of melamine and 0.4838 g of boric acid in a co-solvent mixture of 28 mL of tert-butanol and 20 mL of deionized water. Stir magnetically in an oil bath at 80 °C for 30 min to obtain a clear precursor solution. Pour the solution into a mold, let it stand at room temperature for 0.5 h, freeze for 24 h, and then freeze-dry at -40 °C for 48 h to obtain a white dry gel precursor.

[0034] Step 2) The boron nitride nanoribbon aerogel obtained in Step 1) is redispersed in a co-solution of deionized water and tert-butanol. Specifically, 35 mL of deionized water and 15 mL of tert-butanol are used, resulting in an aerogel dispersion concentration of 0.02 g / mL. The mixture is stirred magnetically until no obvious particles are visible. The dispersion is then poured into a mold and oriented using the ice template method. Afterward, it is transferred to a freeze dryer and freeze-dried at -40℃ for 48 h to obtain dispersed boron nitride nanoribbon aerogel.

[0035] Step 3) Weigh 40 mL of ethanol and 10 mL of ethylenediamine using a graduated cylinder, and separately weigh 1 g of ferrocene using an electronic balance. Mix them in a beaker and place the beaker in an ultrasonic oscillator to mix the solution evenly using ultrasonic vibration.

[0036] Step 4) Fix the aerogel obtained in Step 2) onto a corundum crucible sheet using tungsten wire, place it in a tube furnace, purge with argon gas at a flow rate controlled at 100 sccm, and purge for half an hour. Increase the temperature to 850 ℃ at 10 ℃ / min.

[0037] Step 5) Draw the homogeneous mixture obtained in Step 3) into a syringe. Begin injection when the tube furnace reaches 850 °C, controlling the injection rate at 10 mL / h and the gas flow rate at 900 sccm. Inject for 60 min. After injection, remove the needle, seal the pores with vacuum clay, and cool the tube furnace to room temperature.

[0038] Figure 2 This is a SEM image of in-situ grown carbon nanotube / boron nitride nanoribbon aerogel. The in-situ oriented, vertically grown carbon nanotubes on the surface of the boron nitride nanoribbons are clearly visible, with lengths reaching up to 40 μm and exhibiting considerable flexibility. Example 3

[0039] Step 1) Dissolve 1 g of melamine and 5 g of boric acid in 25 g of tert-butanol and 35 g of hot deionized water. Stir magnetically in an oil bath at 85 °C for 60 min to obtain a clear precursor solution. Pour the solution into a mold, let it stand at room temperature for 30 min, and then place it on a liquid nitrogen directional freezing device to rapidly freeze the solution using the ice template method. Then freeze-dry at -40 °C for 48 h to obtain a white dry gel precursor.

[0040] Step 2) Place the dry gel obtained in Step 1) in a tube furnace, pass argon gas through it, and heat it at a rate of 10 °C / min to 1000 °C, then at a rate of 5 °C / min to 1400 °C. Pyrolyze for 4 h to obtain oriented boron nitride nanoribbon aerogel.

[0041] Step 3) Weigh 40 mL of ethanol and 10 mL of ethylenediamine using a graduated cylinder, and separately weigh 1 g of ferrocene using an electronic balance. Mix them in a beaker and place the beaker in an ultrasonic oscillator to mix the solution evenly using ultrasonic vibration.

[0042] Step 4) Place the aerogel obtained in step 2) in a tube furnace, purge with argon gas for 30 min, and heat to 850 ℃ at 8 ℃ / min.

[0043] Step 5) Draw the homogeneous mixture obtained in Step 3) into a syringe. Begin injection when the tube furnace reaches 850 °C, controlling the injection rate at 10 mL / h and the gas flow rate at 900 sccm. Inject for 45 min. After injection, remove the needle, seal the pores with vacuum clay, and cool the tube furnace to room temperature.

[0044] Tests and analyses show that the in-situ grown carbon nanotube / boron nitride nanoribbon aerogel obtained by this method has a layered structure and exhibits superior compressive strength in the vertical direction. Example 4

[0045] Step 1) Dissolve 1 g of melamine and 2 g of boric acid in 20 g of tert-butanol and 30 g of hot deionized water. Stir magnetically for 90 min in an oil bath at 90°C to obtain a clear precursor solution. Pour this solution into a mold and place the mold in an ultrasonic oscillator. Sonicate for 8 min until a white gel appears. Allow to stand at room temperature for 30 min, then freeze for at least 24 h. Finally, transfer to a freeze dryer and freeze-dry at -60°C for 48 h to obtain the precursor aerogel.

[0046] Step 2) Place the precursor aerogel described in Step 1) in a tube furnace, pass nitrogen gas through it at a flow rate of 60 sccm, and heat it to 1400 ℃ at a rate of 5 ℃ / min. Pyrolyze for 3 h to obtain boron nitride nanoribbon aerogel.

[0047] Step 3) Prepare a mixed solution of ethanol, ethylenediamine and ferrocene in a mass ratio of 10:5:1. Place the mixture in an ultrasonic oscillator and sonicate for 30 minutes until the solution is clear.

[0048] Step 4) Fix the boron nitride nanoribbon aerogel obtained in Step 2) onto a corundum crucible sheet with molybdenum wire, place it in a tube furnace, pass argon gas through it, and raise the temperature to 800 ℃ at 10 ℃ / min.

[0049] Step 5) Draw the homogeneous mixture obtained in Step 3) into a syringe. Begin injection when the tube furnace reaches 800 °C, controlling the injection rate at 10 mL / h and the gas flow rate at 900 sccm. Inject for 10 min. After injection, remove the needle, seal the pores with vacuum clay, and cool the tube furnace to room temperature.

[0050] The resulting in-situ grown carbon nanotubes are uniformly distributed and relatively short on the surface of boron nitride nanoribbons, with moderate interfacial force bonding, and can retain some thermal insulation properties. Example 5

[0051] Step 1) Melamine and boric acid were added to a co-solution of 15 mL tert-butanol and 35 mL hot deionized water at a molar ratio of 1:5, resulting in a concentration of 35 mg / mL. The solution was magnetically stirred in an oil bath at 85 °C for 60 min to obtain a clear precursor solution. This solution was poured into a mold, which was then placed in an ultrasonic oscillator and ultrasonically vibrated for 12 min, resulting in the formation of a white gel. After standing at room temperature for 30 min, the gel was frozen and stored for at least 24 h. Finally, it was transferred to a freeze dryer and freeze-dried at -60 °C for 48 h to obtain the precursor aerogel.

[0052] Step 2) Place the precursor aerogel described in Step 1) in a tube furnace, pass argon gas at a flow rate of 60 sccm, and heat it to 1400 ℃ at a rate of 5 ℃ / min. Pyrolyze for 3 h to obtain boron nitride nanoribbon aerogel.

[0053] Step 3) Prepare a mixed solution of ethanol, ethylenediamine and ferrocene in a mass ratio of 20:8:1. Place the mixture in an ultrasonic oscillator and sonicate for 30 minutes until the solution is clear.

[0054] Step 4) Place the boron nitride nanoribbon aerogel obtained in Step 2) on a corundum crucible sheet, put it into a tube furnace, pass argon gas through it, and raise the temperature to 750 ℃ ​​at 10 ℃ / min.

[0055] Step 5) Draw the homogeneous mixture obtained in Step 3) into a syringe. Begin injection when the tube furnace reaches 750 °C, controlling the injection rate at 10 mL / h and the gas flow rate at 900 sccm. Inject for 45 min. After injection, remove the needle, seal the pores with vacuum sealant, and cool the tube furnace to room temperature.

[0056] Tests and analysis showed that the in-situ grown carbon nanotubes were densely packed on the surface of boron nitride nanoribbons, forming a certain three-dimensional network structure, which effectively improved the mechanical strength of the aerogel.

Claims

1. A method for preparing an in-situ oriented carbon nanotube / boron nitride nanoribbon aerogel, characterized in that, Includes the following steps: Step 1: Melamine and boric acid are dissolved in a co-solution of tert-butanol and hot deionized water. After stirring, sonication and freeze-drying, melamine-boric acid precursor aerogel is obtained, wherein the mass ratio of melamine, boric acid, tert-butanol and deionized water is 1 : (1~5) : (10~25) : (20~35). Step 2: Place the melamine-boric acid precursor aerogel in a tube furnace and pyrolyze it to obtain boron nitride nanoribbon aerogel. Step 3: Prepare a mixed solution of ethanol, ethylenediamine and ferrocene, and mix the solution evenly by ultrasonic vibration. The mass ratio of the three components in the mixed solution of ethanol, ethylenediamine and ferrocene is (10~50): (5~20):

1. Step 4: Place the boron nitride nanoribbon aerogel in a tube furnace, purge with argon gas, and inject the solution prepared in Step 3 into the tube furnace under high temperature. After injection, remove the needle, seal the pores with vacuum mud, and cool the tube furnace to room temperature. Carbon nanotubes are then grown on the surface of the boron nitride nanoribbons to obtain carbon nanotube / boron nitride nanoribbon aerogel.

2. The method for preparing an in-situ oriented carbon nanotube / boron nitride nanoribbon aerogel according to claim 1, characterized in that, The temperature of the hot deionized water is 60~90 ℃.

3. The method for preparing an in-situ oriented carbon nanotube / boron nitride nanoribbon aerogel according to claim 1, characterized in that, In step 1, the stirring time is 40-90 min, the ultrasonic time is 5-15 min, and the freeze-drying time is 24-48 h.

4. The method for preparing an in-situ oriented carbon nanotube / boron nitride nanoribbon aerogel according to claim 1, characterized in that, In step 2, the temperature of the pyrolysis reaction is 950~1400 ℃, and the time of the pyrolysis reaction is 2~5 h.

5. The method for preparing an in-situ oriented carbon nanotube / boron nitride nanoribbon aerogel according to claim 1, characterized in that, The atmosphere for the pyrolysis reaction in step 2 is one of argon, nitrogen, or 95% nitrogen + 5% hydrogen.

6. The method for preparing an in-situ oriented carbon nanotube / boron nitride nanoribbon aerogel according to claim 1, characterized in that, In step 4, the carbon nanotubes are grown at a temperature of 700-900 ℃ for 10-60 min.

7. The method for preparing an in-situ oriented carbon nanotube / boron nitride nanoribbon aerogel according to claim 1, characterized in that, In step 4, the carbon nanotubes are one or a mixture of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes.

8. The method for preparing an in-situ oriented carbon nanotube / boron nitride nanoribbon aerogel according to claim 1, characterized in that, In step 4, the argon gas washing process lasts for 30 minutes.

9. The method for preparing an in-situ oriented carbon nanotube / boron nitride nanoribbon aerogel according to claim 1, characterized in that, The injection begins when the tubular furnace reaches 850 °C, with the injection rate controlled at 10 mL / h and the gas flow rate controlled at 900 sccm.

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