Method for preparing aminated hexagonal boron nitride by one-pot method

Abstract

The invention relates to a method for preparing aminated hexagonal boron nitride by a one-pot process, which comprises the following steps: 1) mixing urea and choline chloride according to a molar ratio of 1: (1-3), adding water until the water content of the system is 30%, and heating in a water bath until the mixture is completely molten to obtain a clear and transparent urea / choline chloride eutectic solvent; (2) hexagonal boron nitride powder is added into the eutectic solvent obtained in the step (1) according to the molar ratio of 1: (180-220), ultrasonic treatment is conducted to enable the hexagonal boron nitride powder to be evenly dispersed, and hexagonal boron nitride suspension liquid is obtained; 3) carrying out heating reaction on the suspension obtained in the step 2); and 4) after the reaction is finished, cooling the mixed solution obtained in the step 3) to room temperature, adding distilled water for dilution, centrifuging, filtering, collecting a solid product, and carrying out vacuum drying to obtain the aminated hexagonal boron nitride. The method provided by the invention has the characteristics of simple process, mild conditions and environmental friendliness, and does not need pre-carboxylation or use of expensive modifiers.

Description

Technical Field

[0001] This invention belongs to the field of two-dimensional nanomaterial modification, and particularly relates to a one-pot method for preparing aminated hexagonal boron nitride. Background Technology

[0002] Hexagonal boron nitride (h-BN) belongs to group III-V compounds and has a typical layered crystal structure, in which B and N atoms are separated by sp atoms in the plane. 2 Hybridization forms strong σ bonds, resulting in excellent thermal conductivity (approximately 1700–2000 W / (m·K)) and high chemical stability in the planar direction. Aminated boron nitride (BN-(NH)n) is a functionalized material obtained by introducing amino functional groups onto the surface of h-BN through surface modification. While retaining the excellent properties of h-BN, BN-(NH)n improves the material's hydrophilicity and enhances its interfacial bonding with various polymer matrices. It has broad application prospects in electronic packaging, thermal management, and biomedicine.

[0003] Currently, the preparation methods for aminated boron nitride mainly refer to graphene modification and mechanical exfoliation modification. These methods typically require hydroxylation of h-BN before introducing an amino group. Furthermore, the surface modifiers used in these processes cause environmental pollution and increase production costs, making them unsuitable for large-scale application. Referring to the invention patent "A High-Yield Preparation Method for Aminated Boron Nitride Nanosheets (CN120004225A)," 2,2-bis(trifluoromethyl)diaminobiphenyl is used as a modifying agent. The amino group is introduced through ball milling in an inert gas atmosphere. However, the surface modifier used in this method is a toxic and irritating chemical reagent, exhibiting extremely high toxicity to aquatic organisms. Simultaneously, the mechanical exfoliation of h-BN using ball milling requires 7-9 hours at a speed of 200-400 rpm, generating high energy during the process and further increasing the safety risks of production operations. Referring to the invention patent "A Method and Application for the Preparation of Aminated Hexagonal Boron Nitride (CN109810544A)," this patent uses a two-step method to prepare aminated boron nitride. First, h-BN is calcined in a tube furnace under a steam atmosphere to obtain hydroxylated boron nitride. Then, it is reacted with excess toluene diisocyanate to obtain the target product BN-(NH)n. This two-step method reduces the production efficiency of BN-(NH)n, and heating to 850-1000℃ in a water atmosphere under inert gas protection and holding for 2-4 hours may damage the crystal structure of h-BN. Furthermore, this method uses the toxic reagent toluene diisocyanate as a surface modifier in the reaction, which can cause environmental pollution. Therefore, there is a need to develop a simple, mild, environmentally friendly process for the preparation of aminated boron nitride suitable for large-scale production. Summary of the Invention

[0004] To address the problems of high energy consumption, low production efficiency, and severe environmental pollution in the prior art, this invention provides a one-pot method for preparing aminated boron nitride, which features simple process, mild conditions, and environmental friendliness, and eliminates the need for pre-carboxylation or the use of expensive modifiers.

[0005] The technical solution of this invention is: This invention is a one-pot method for preparing aminated hexagonal boron nitride, characterized in that: the method includes the following steps:

[0006] 1) Mix urea and choline chloride in a molar ratio of 1:1-3, add water, the water content of the system is 30%, heat in a water bath until completely melted, and obtain a clear and transparent urea / choline chloride eutectic solvent;

[0007] This step adjusts the molar ratio to regulate the content of amino groups and the amount of hydrogen bond network introduced by the reaction, ensuring that h-BN has good dispersibility and sufficient contact with the nitrogen source during subsequent heating.

[0008] 2) Add hexagonal boron nitride powder to the eutectic solvent obtained in step 1) at a molar ratio of 1:180-220, and then sonicate it to disperse it evenly to obtain a hexagonal boron nitride suspension;

[0009] This step involves uniformly dispersing hexagonal boron nitride in a eutectic solvent to ensure sufficient contact between the nitrogen source and the reaction substrate in subsequent reactions.

[0010] 3) The suspension obtained in step 2) is heated to react;

[0011] This step employs a solvothermal reaction method to ensure uniform temperature in the reaction environment and to decompose urea into highly reactive nitrogen sources such as ammonia and isocyanate. Adjusting the heating time ensures the reaction proceeds fully.

[0012] 4) After the reaction is complete, the mixture obtained in step 3) is cooled to room temperature, diluted with distilled water, and the solid product is collected by centrifugation and filtration. Then, it is dried under vacuum to obtain aminated hexagonal boron nitride.

[0013] A eutectic solvent acts as a modifier in the amination reaction to produce chloride salts. This step involves adding a large amount of distilled water to wash away residual chloride salts from the reaction substrate, ensuring the purity of the target product.

[0014] Furthermore, the water bath heating conditions in step 1) are: reaction at 70°C for 30 minutes.

[0015] Furthermore, the conditions for ultrasonic treatment in step 2) are: ultrasonic dispersion for 30 minutes and power of 300W.

[0016] Furthermore, in step 3), the heating reaction involves placing the suspension obtained in step 2) in a corundum crucible, heating it to 180°C in a muffle furnace, and holding it at that temperature for 16 hours.

[0017] Furthermore, the specific steps in step 4) are as follows:

[0018] 4.1) Cool the mixture obtained in step 3) to room temperature, add distilled water, centrifuge and filter at high speed for 30 minutes at 10,000 rpm; after centrifugation 5-6 times, obtain the precipitate;

[0019] 4.2) Vacuum drying at 60℃ for 24h yields aminated boron nitride.

[0020] This invention provides a one-pot method for preparing aminated hexagonal boron nitride, using a green and pollution-free urea / choline chloride eutectic solvent as a surface modifier. During heating, urea decomposes and transforms into highly reactive nitrogen sources such as ammonia and isocyanate, which can form BN bonds with boron atoms on the h-BN surface. Simultaneously, the hydroxyl groups and nitrogen atoms in choline chloride form a strong hydrogen bond network with urea, which can replace dispersants, improving the dispersibility of h-BN in the reaction system and ensuring sufficient contact between the reaction substrate and the nitrogen source. Therefore, this invention features a simple process, mild conditions, and environmental friendliness, and eliminates the need for pre-carboxylation or the use of expensive modifiers. Attached Figure Description

[0021] Figure 1 This is a synthetic route diagram of the aminated boron nitride of the present invention;

[0022] Figure 2 This is the Fourier spectrum of the aminated boron nitride of the present invention;

[0023] Figure 3 This is the X-ray photoelectron spectrum of the aminated boron nitride of the present invention. Detailed Implementation

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

[0025] See Figure 1 The method of a specific embodiment of the present invention is as follows:

[0026] 1) Mix urea and choline chloride in a molar ratio of 1:1-3, add water, and heat in a water bath until completely melted to obtain a clear and transparent urea / choline chloride eutectic solvent; the water bath heating conditions are: reaction at 70°C for 30 min.

[0027] 2) Add hexagonal boron nitride powder to the eutectic solvent obtained in step 1) at a molar ratio of 1:180-220, and then sonicate it to disperse it evenly to obtain a hexagonal boron nitride suspension. The conditions for sonication are: sonication for 30 min and power of 300 W.

[0028] 3) The suspension obtained in step 2) is subjected to a heating reaction; the heating reaction is carried out by placing the suspension obtained in step 2) in a corundum crucible, heating it to 180°C in a muffle furnace, and holding it at that temperature for 16 hours.

[0029] 4) After the reaction is complete, cool the mixture obtained in step 3) to room temperature, dilute it with distilled water, collect the solid product by centrifugation and filtration, and then dry it under vacuum to obtain aminated hexagonal boron nitride. The specific steps are as follows:

[0030] 4.1) Cool the mixture obtained in step 3) to room temperature, add 300 ml of distilled water to dilute, centrifuge and filter at high speed for 30 min at 10000 rpm; after centrifugation 5-6 times, obtain the precipitate;

[0031] 4.2) Vacuum drying at 60℃ for 24h yields aminated boron nitride.

[0032] The following are specific application examples of the present invention.

[0033] Example 1

[0034] 1) Add 69.92g of choline chloride and 30.03g of urea to a beaker and react at 70℃ for 30min until the mixture is clear and transparent to obtain a eutectic solvent;

[0035] 2) Add 0.5g of hexagonal boron nitride powder to 100ml of eutectic solvent, and ultrasonically disperse for 30min at 300W to obtain a uniformly mixed suspension;

[0036] 3) Place the suspension obtained in step 2) in a corundum crucible, heat it to 180°C in a muffle furnace, and keep it at that temperature for 24 hours;

[0037] 4) Cool the mixture obtained in step 3) to room temperature, add 300 ml of distilled water, centrifuge and filter at high speed for 30 min at 10000 rpm; after centrifugation 5 times, obtain the precipitate, and dry it under vacuum at 60℃ for 24 h to obtain aminated boron nitride.

[0038] Example 2

[0039] 1) Add 53.75g of choline chloride and 46.24g of urea to a beaker and react at 70℃ for 30min until the mixture is clear and transparent to obtain a eutectic solvent;

[0040] 2) Add 0.5g of hexagonal boron nitride powder to 100ml of eutectic solvent, and ultrasonically disperse for 30min at 300W to obtain a uniformly mixed suspension;

[0041] 3) Place the suspension obtained in step 2) in a corundum crucible, heat it to 180°C in a muffle furnace, and keep it at that temperature for 16 hours.

[0042] 4) Cool the mixture obtained in step 3) to room temperature, add 300 ml of distilled water, centrifuge and filter at high speed for 30 min at 10000 rpm; after centrifugation 6 times, obtain the precipitate, and dry it under vacuum at 60℃ for 24 h to obtain aminated boron nitride.

[0043] Example 3

[0044] 1) Add 43.66g of choline chloride and 56.34g of urea to a beaker and react at 70°C for 30 minutes until the mixture is clear and transparent to obtain a eutectic solvent;

[0045] 2) Add 0.5g of hexagonal boron nitride powder to 100ml of eutectic solvent, and ultrasonically disperse for 30min at 300W to obtain a uniformly mixed suspension;

[0046] 3) Place the suspension obtained in step 2) in a corundum crucible, heat it to 180°C in a muffle furnace, and keep it at that temperature for 24 hours;

[0047] 4) Cool the mixture obtained in step 3) to room temperature, add 300 ml of distilled water, centrifuge and filter at high speed for 30 min at 10000 rpm; after centrifugation 5 times, obtain the precipitate, and dry it under vacuum at 60℃ for 24 h to obtain aminated boron nitride.

[0048] Example 4

[0049] 1) Add 48.95g of choline chloride and 21.05g of urea to a beaker, add 30ml of water, react at 70℃ for 30min until the mixture is clear and transparent, and obtain a eutectic solvent;

[0050] 2) Add 0.5g of hexagonal boron nitride powder to 100ml of eutectic solvent, and ultrasonically disperse for 30min at 300W to obtain a uniformly mixed suspension;

[0051] 3) Place the suspension obtained in step 2) in a corundum crucible, heat it to 180°C in a muffle furnace, and keep it at that temperature for 12 hours;

[0052] 4) Cool the mixture obtained in step 3) to room temperature, add 300 ml of distilled water, centrifuge and filter at high speed for 30 min at 10000 rpm; after centrifugation 6 times, obtain the precipitate, and dry it under vacuum at 60℃ for 24 h to obtain aminated boron nitride.

[0053] Example 5

[0054] 1) Add 37.62g of choline chloride and 32.37g of urea to a beaker, add 30ml of water, react at 70℃ for 30min until the mixture is clear and transparent to obtain a eutectic solvent;

[0055] 2) Add 0.5g of hexagonal boron nitride powder to 100ml of eutectic solvent, and ultrasonically disperse for 30min at 300W to obtain a uniformly mixed suspension;

[0056] 3) Place the suspension obtained in step 2) in a corundum crucible, heat it to 180°C in a muffle furnace, and keep it at that temperature for 24 hours;

[0057] 4) Cool the mixture obtained in step 3) to room temperature, add 300 ml of distilled water, centrifuge and filter at high speed for 30 min at 10000 rpm; after centrifugation 5 times, obtain the precipitate, and dry it under vacuum at 60℃ for 24 h to obtain aminated boron nitride.

[0058] Example 6

[0059] 1) Add 30.56g of choline chloride and 39.4g of urea to a beaker, add 30ml of water, react at 70℃ for 30min until the mixture is clear and transparent to obtain a eutectic solvent;

[0060] 2) Add 0.5g of hexagonal boron nitride powder to 100ml of eutectic solvent, and ultrasonically disperse for 30min at 300W to obtain a uniformly mixed suspension;

[0061] 3) Place the suspension obtained in step 2) in a corundum crucible, heat it to 180°C in a muffle furnace, and keep it at that temperature for 16 hours;

[0062] 4) Cool the mixture obtained in step 3) to room temperature, add 300 ml of distilled water, centrifuge and filter at high speed for 30 min at 10000 rpm; after centrifugation 6 times, obtain the precipitate, and dry it under vacuum at 60℃ for 24 h to obtain aminated boron nitride.

[0063] The aminated boron nitride obtained in the preparation method of the examples was analyzed by Fourier transform infrared spectroscopy and X-ray diffraction. Figure 2 , 3 As shown, the reaction product of this invention exhibits obvious NH stretching and bending vibration peaks, and the amino peak area accounts for 56.47%, significantly higher than the conventional success threshold (>30%), indicating that the amination efficiency of this method is high. Referring to invention patent CN109810544A, Figure 2Infrared comparison images of hexagonal boron nitride before and after amination modification show that the amination-modified hexagonal boron nitride prepared in this invention exhibits more pronounced NH characteristic peaks at 3360 cm⁻¹ and 1650 cm⁻¹, indicating a high content of introduced -NH₂. Referring to the invention patent CN120004225A, the B1s spectrum of its BN-(NH)n product shows two fitting peaks corresponding to BO and BN bonds, indicating that the method performed hydroxylation modification on h-BN, and the amino group introduction was incomplete. In the B1s spectrum of this invention (… Figure 3 (Right) The main peak position shows a negative chemical shift of -0.5 eV compared to the h-BN main peak. This is because the grafting of amino groups onto nitrogen atoms increases the electron cloud density around boron atoms, making them more easily excited by photoelectrons, thus lowering the binding energy. Simultaneously, in the N1s spectrum of this invention ( Figure 3 (Left) The area of ​​the amino peak is significantly higher than that of the amino peak in invention patent CN 109810544 A.

[0064] The above are merely specific embodiments disclosed in this invention, but the scope of protection disclosed in this invention is not limited thereto. The scope of protection disclosed in this invention should be determined by the scope of the claims.

[0065] The technical contents of this invention and those not specifically described in the above embodiments are the same as those in the prior art.

[0066] The present invention is not limited to the above embodiments; all embodiments described herein can be implemented and have the aforementioned good effects.

Claims

1. A method for the one-pot preparation of aminated hexagonal boron nitride, characterized in that: The method comprises the following steps: 1) mixing urea and choline chloride at a molar ratio of 1:1-3, adding water, and heating the system to complete melting in a water bath to obtain a clear and transparent urea / choline chloride eutectic solvent; 2) adding hexagonal boron nitride powder at a molar ratio of 1:180-220 to the eutectic solvent obtained in step 1), and uniformly dispersing the powder by ultrasonic treatment to obtain a hexagonal boron nitride suspension; 3) heating the suspension obtained in step 2) for reaction; 4) after the reaction is completed, cooling the mixture obtained in step 3) to room temperature, diluting with distilled water, collecting the solid product by centrifugation and filtration, and then vacuum drying to obtain aminated hexagonal boron nitride.

2. The method of claim 1, wherein the one-pot preparation of aminated hexagonal boron nitride is characterized by: The water bath heating condition in step 1) is 70°C for 30 min.

3. The method of claim 2, wherein the one-pot preparation of aminated hexagonal boron nitride is characterized by: The ultrasonic treatment condition in step 2) is ultrasonic dispersion for 30 min at a power of 300 W.

4. The method of claim 3, wherein the one-pot preparation of aminated hexagonal boron nitride is characterized by: The heating reaction in step 3) is to place the suspension obtained in step 2) in a corundum crucible, heat the crucible to 180°C in a muffle furnace, and keep the temperature for 16 h.

5. The method of claim 4, wherein the one-pot preparation of aminated hexagonal boron nitride is characterized by: The specific steps in step 4) are as follows: 4.1) cooling the mixture obtained in step 3) to room temperature, adding distilled water, and centrifuging and filtering at a high speed for 30 min at a speed of 10,000 rpm; after centrifuging 5-6 times, a precipitate is obtained; 4.2) vacuum drying at 60°C for 24 h to obtain aminated boron nitride.

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