Surface-treated boron nitride nanotubes and method for surface-treating boron nitride nanotubes

Abstract

One embodiment of the present invention includes a boron nitride nanotube and a first layer disposed on at least a part of the surface of the boron nitride nanotube, the first layer forming a π bond with the boron nitride nanotube, and the first layer discloses a surface-treated boron nitride nanotube containing a hydroxyphenyl group.

Description

Technical Field

[0001] The present invention relates to a surface-treated boron nitride nanotube and a method for surface-treating a boron nitride nanotube.

Background Art

[0002] Boron nitride nanotubes (BNNTs) have a structural similarity to carbon nanotubes (CNTs), but have a hexagonal structure in which boron atoms and nitrogen atoms are substituted for the carbon atoms of the carbon single-atom hexagonal CNT. Due to a structure similar to that of CNTs, BNNTs have excellent mechanical strength and high thermal conductivity, and also have a wide bandgap due to the alternating bonds of boron and nitrogen, and have insulating properties, high oxidation resistance, and chemical resistance.

[0003] In order to apply such excellent properties of BNNTs to various fields, it is a very important requirement to ensure the dispersion quality of BNNTs in a dispersion medium. However, BNNTs have low dispersibility in organic and water-soluble solvents, and there are limitations in the practical application of BNNTs. Therefore, in order to practically apply BNNTs in various fields, it is necessary to disperse BNNTs in various solvents.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Embodiments of the present invention provide a surface-treated boron nitride nanotube excellent in dispersibility in a hydrophilic or hydrophobic solvent and a method for surface-treating a boron nitride nanotube.

Means for Solving the Problems

[0005] One embodiment of the present invention discloses a surface-treated boron nitride nanotube comprising a boron nitride nanotube and a first layer located on at least a portion of the surface of the boron nitride nanotube, wherein the first layer forms a π bond with the boron nitride nanotube, and the first layer contains a hydroxyphenyl group.

[0006] Furthermore, another embodiment of the present invention discloses a surface treatment method for boron nitride nanotubes, comprising the steps of mixing a first surface treatment agent with water to form a mixture, dispersing boron nitride nanotubes in the mixture to form a dispersion, and washing and drying the boron nitride nanotubes from the dispersion, wherein the pH of the dispersion is 8 to 9, and a first layer containing hydroxyphenyl groups is formed on at least a portion of the surface of the dried boron nitride nanotubes. [Effects of the Invention]

[0007] According to embodiments of the present invention, since boron nitride nanotubes are surface-treated to be hydrophilic or hydrophobic and can be dispersed in various solvents, the usability of boron nitride nanotubes can be improved.

[0008] Furthermore, since water is used as a dispersion medium during the surface treatment to make the boron nitride nanotubes hydrophobic, environmental pollution can be prevented by not using organic solvents. [Brief explanation of the drawing]

[0009] [Figure 1] This figure schematically shows an example of a boron nitride nanotube according to one embodiment of the present invention. [Figure 2] Figure 1 shows the structural formula of a boron nitride nanotube. [Figure 3] Figure 1 is a flowchart illustrating a schematic example of a surface treatment method for boron nitride nanotubes. [Figure 4] This figure schematically shows an example of a BNNT according to another embodiment of the present invention. [Figure 5]Figure 4 shows the structural formula of a boron nitride nanotube. [Figure 6] Figure 4 is a flowchart illustrating a schematic example of a surface treatment method for boron nitride nanotubes. [Figure 7] This figure shows the results of measuring the composition of boron nitride nanotubes in the examples and comparative examples. [Figure 8] This figure shows the contact angles of boron nitride nanotubes in the examples and comparative examples. [Figure 9] This figure shows the dispersion states of boron nitride nanotubes in various solvents. [Figure 10] This figure shows the dispersion state of boron nitride nanotubes in various solvents. [Figure 11] This figure shows the dispersion state of boron nitride nanotubes in a comparative example that has not been surface-treated with water, ethanol, and toluene. [Modes for carrying out the invention]

[0010] One embodiment of the present invention discloses a boron nitride nanotube and a first layer disposed on at least a portion of the surface of the boron nitride nanotube, wherein the first layer forms a π bond with the boron nitride nanotube, and the first layer is a surface-treated boron nitride nanotube containing a hydroxyphenyl group.

[0011] In this embodiment, the first layer is a polyphenol group and may include at least one of tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxydiphenic acid, ellagic acid, and chlorogenic acid.

[0012] In this embodiment, the surface-treated boron nitride nanotubes can be hydrophilic.

[0013] In this embodiment, it further includes a second layer on the first layer, and the second layer is a hydrocarbon group and can contain an amine group or a thiol group.

[0014] In this embodiment, the amine group or the thiol group can be Michael-added to the hydroxyl group of the first layer.

[0015] In this embodiment, the second layer can contain at least any one of alkyl amine, alkyl thiol, aryl amine, aryl thiol, benzyl amine and benzyl thiol.

[0016] In this embodiment, due to the second layer, the surface-treated boron nitride nanotubes can have hydrophobicity.

[0017] Another embodiment of the present invention discloses a method for surface treatment of boron nitride nanotubes, which includes the steps of mixing a first surface treatment agent with water to form a mixed solution, dispersing boron nitride nanotubes in the mixed solution to form a dispersion, and washing and drying the boron nitride nanotubes from the dispersion. The pH of the dispersion is 8-9, and a first layer containing a hydroxyphenyl group is formed on at least a part of the surface of the dried boron nitride nanotubes.

[0018] In the present embodiment, the first surface treatment agent can contain at least any one of tannic acid, Gallic acid, catechol, epigallocatechin, pyrogallol, Hexahydroxydiphenic acid, ellagic acid, and chlorogenic acid.

[0019] In the present embodiment, before the step of washing and drying, the step of mixing a second surface treatment agent into the dispersion is further included. By mixing the second surface treatment agent, a second layer is further formed on the first layer. The second layer is a hydrocarbon group Michael - added to the hydroxyl group of the first layer and can contain an amine group or a thiol group.

[0020] In the present embodiment, the second surface treatment agent can contain at least any one of alkyl amine, alkyl thiol, aryl amine, aryl thiol, benzyl amine, and benzyl thiol.

[0021] In the present embodiment, the second layer can change the boron nitride nanotube from hydrophilic to hydrophobic.

[0022] Since the present invention can be subjected to various transformations and can have various embodiments, specific embodiments are shown in the figures and will be described in detail in the detailed description. The effects and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described in detail below together with the figures. However, the present invention is not limited to the embodiments disclosed below and can be implemented in various forms. In the following embodiments, terms such as "first," "second," etc., are not limited in meaning but are used to distinguish one component from another. In the following embodiments, a singular expression includes plural expressions unless the context clearly indicates otherwise.

[0023] In the following embodiments, terms such as "includes" or "has" mean that the features or components described herein are present, and do not preclude the possibility of the addition of one or more other features or components.

[0024] In the following embodiments, if a part such as a membrane, region, or component is located above or above another part, this includes not only cases where it is directly above the other part, but also cases where another membrane, region, component, etc. is interposed between them.

[0025] In the diagrams, the size of the components may be exaggerated or reduced for illustrative purposes. For example, the size and thickness of each component shown in the diagrams are arbitrarily shown for illustrative purposes, and the present invention is not necessarily limited to those shown.

[0026] The embodiments of the present invention will be described in detail below with reference to the attached figures. When describing with reference to the figures, the same or corresponding components will be given the same reference numerals.

[0027] Figure 1 is a schematic perspective view showing an example of a surface-treated boron nitride nanotube according to one embodiment of the present invention, and Figure 2 is the structural formula of the surface-treated boron nitride nanotube shown in Figure 1. Figure 1 is a transmission electron microscope (TEM) image.

[0028] Referring to Figures 1 and 2, a surface-treated boron nitride nanotube 100 according to one embodiment may include a boron nitride nanotube 110 and a first layer 120 on the surface of the boron nitride nanotube 110.

[0029] As shown in Figure 2, boron nitride nanotube 110 is a hexagonal nanotube in which nitrogen and carbon atoms are arranged alternately. It has excellent thermal conductivity but a wide band gap and electrical insulation properties similar to ceramics. Therefore, although boron nitride nanotube 110 is an electrically insulating material, it can be applied as a highly thermally conductive composite.

[0030] Furthermore, boron nitride nanotubes 110 possess excellent mechanical properties, chemical resistance, and oxidation resistance, absorb thermal neutrons, and are known to be harmless to the human body, making them applicable to various industrial fields such as the electronics industry, energy, space, nuclear power, and biomedical industries.

[0031] However, since such boron nitride nanotubes 110 are generally not dispersed in organic and aqueous solvents, in order to actually apply boron nitride nanotubes 110 industrially, it is necessary to make the boron nitride nanotubes 110 hydrophilic or hydrophobic.

[0032] To this end, the present invention makes it possible to disperse the boron nitride nanotubes 110 in a polar solvent by forming a first layer 120 on at least a portion of the surface of the boron nitride nanotubes 110, thereby making the boron nitride nanotubes 110 hydrophilic.

[0033] The first layer 120 can form a π bond with the boron nitride nanotube 110 and may contain a hydroxyphenyl group. For example, the first layer 120 may contain a polyphenol group, which may include at least one of tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxydiphenic acid, ellagic acid, and chlorogenic acid.

[0034] The polyphenol groups of the first layer 120 can be oxidized with a highly reactive quinone oligomer and attached to the surface of the boron nitride nanotube 110. Through strong interactions between the catechol molecules of the polyphenol groups and the boron nitride nanotube 110 via van der Waals bonds and π-π stacking, the first layer 120 can be formed on the boron nitride nanotube 110.

[0035] Thus, by forming the first layer 120 on at least a portion of the surface of the boron nitride nanotube 110, hydroxyl groups become present on the surface of the boron nitride nanotube 110, and the surface-treated boron nitride nanotube 100 can become hydrophilic.

[0036] On the other hand, the tannic acid and other substances contained in the first layer 120 are naturally derived and environmentally friendly, and the surface-treated boron nitride nanotubes 100 can avoid causing environmental pollution.

[0037] Figure 3 is a flowchart illustrating a schematic example of a surface treatment method for the boron nitride nanotubes shown in Figure 1.

[0038] Referring to Figure 3, a surface treatment method for boron nitride nanotubes according to one embodiment of the present invention may include the steps of: mixing a first surface treatment agent with water to form a mixed solution (S110); dispersing boron nitride nanotubes in the mixed solution to form a dispersion (S120); and washing and drying the boron nitride nanotubes from the dispersion (S130).

[0039] The first surface treatment agent is a substance capable of forming the first layer and may contain a hydroxyphenyl group. For example, the first surface treatment agent may contain a polyphenol group and may contain at least one of tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxydiphenic acid, ellagic acid, and chlorogenic acid.

[0040] The first surface treatment agent may be present in an amount of 0.1 wt% to 0.2 wt% relative to the entire mixture. If the content of the first surface treatment agent in the mixture is less than 0.1 wt%, it is difficult to form a first layer that can impart hydrophilicity to the boron nitride nanotubes. On the other hand, even if the content of the first surface treatment agent is greater than 0.2 wt%, the surface treatment effect on the boron nitride nanotubes does not continuously increase. Therefore, it is preferable that the content of the first surface treatment agent be 0.1 wt% to 0.2 wt% relative to the entire mixture.

[0041] Next, boron nitride nanotubes are dispersed in the mixture (S120). Dispersion is carried out by ultrasonic dispersion, stirring, etc.

[0042] In this case, the dispersion can be weakly alkaline. Because the dispersion is weakly alkaline, the polyphenol groups can be oxidized to highly reactive quinone oligomers by the dissolved oxygen in the dispersion, and as a result, they can adhere to the surface of the boron nitride nanotubes 110, forming the first layer.

[0043] The pH of the dispersion can be adjusted with a base such as sodium hydroxide. For example, the pH of the dispersion may be between 8 and 9. If the pH of the dispersion is less than 8 or greater than 9, quinone oligomer formation is less likely to occur, so it is preferable that the pH of the dispersion be between 8 and 9.

[0044] The mixing ratio of boron nitride nanotubes dispersed in the dispersion to the first surface treatment agent can be 1:1 to 1:0.1 in wt%. If the content of boron nitride nanotubes dispersed in the dispersion exceeds 10 times that of the first surface treatment agent, the first layer may not be effectively formed on the surface of the boron nitride nanotubes. On the other hand, if the content of boron nitride nanotubes dispersed in the dispersion is less than 1 time that of the first surface treatment agent, the amount of the first surface treatment agent discarded in the next washing process will increase sharply.

[0045] After dispersing boron nitride nanotubes in the mixture to form a dispersion, the boron nitride nanotubes on which the first layer has been formed are washed and dried (S130).

[0046] In the washing step, the boron nitride nanotubes are washed with water to remove any remaining polyphenol groups. Then, after separating only the boron nitride nanotubes by centrifugation or filtration, a powder of boron nitride nanotubes that has been dried and surface-treated to be hydrophilic can be obtained.

[0047] The above method can be carried out at room temperature and in atmospheric conditions. Therefore, according to the present invention, boron nitride nanotubes can be made hydrophilic by a simple method of dispersing them in a mixture of the first surface treatment agent and water, without creating a specific environment. Furthermore, as shown in Figure 1, the first layer can be formed without damaging the boron nitride nanotubes.

[0048] Figure 4 is a schematic diagram showing an example of a boron nitride nanotube according to another embodiment of the present invention, and Figure 5 is a structural formula showing the boron nitride nanotube of Figure 4.

[0049] Referring to Figures 4 and 5, a surface-treated boron nitride nanotube 102 according to one embodiment may include a boron nitride nanotube 110, a first layer 120 on the surface of the boron nitride nanotube 110, and a second layer 130 on the first layer 120.

[0050] Boron nitride nanotube 110 is a hexagonal nanotube in which nitrogen and carbon atoms are arranged alternately, and the first layer 120 can form a π bond with boron nitride nanotube 110 and contain hydroxyphenyl groups. For example, the first layer 120 may contain polyphenol groups, and may contain at least one of tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxydiphenic acid, ellagic acid, and chlorogenic acid.

[0051] The second layer 130 is a layer for imparting hydrophobicity to the boron nitride nanotube 110 and is a hydrocarbon group that may include an amine group or a thiol group. For example, the second layer 130 may include at least one of alkylamine, alkylthiol, arylamine, arylthiol, benzylamine, and benzylthiol.

[0052] On the other hand, the polyphenol groups of the first layer 120 can be oxidized to highly reactive quinone oligomers and attached to the surface of the boron nitride nanotubes 110. These attached quinone structures can anchor the primary amine groups of the second layer 130 via a Michael addition mechanism. More specifically, the reaction between the amine or thiol of the second layer 130 and the hydroxyl group of the first layer 120 involves a Michael addition reaction in which the amine or thiol of the second layer 130 is added to the hydroxyl group of the first layer 120, thereby forming the second layer 130 on the first layer 120.

[0053] Further inclusion of such a second layer 130 makes the surface-treated boron nitride nanotubes 102 hydrophobic, thereby improving their dispersibility in organic solvents such as toluene.

[0054] Figure 6 is a flowchart illustrating a schematic example of a surface treatment method for the boron nitride nanotubes shown in Figure 4.

[0055] Referring to Figure 6, a surface treatment method for boron nitride nanotubes according to one embodiment of the present invention may include the steps of: mixing a first surface treatment agent with water to form a first mixed solution (S210); dispersing boron nitride nanotubes in the first mixed solution to form a dispersion (S220); mixing a second surface treatment agent with the dispersion to form a second mixed solution (S230); and washing and drying the boron nitride nanotubes from the second mixed solution (S240).

[0056] The steps of forming the first mixture (S210) and forming the dispersion (S220) are the same as the steps of forming the mixture (S110 in Figure 3) and forming the dispersion (S120 in Figure 3) in Figure 3. Therefore, we will not repeat the explanations and will only explain the differences from Figure 3.

[0057] Referring to Figure 6, after forming the dispersion, the second surface treatment agent is further mixed with the dispersion to form a second mixed solution (S230). The second surface treatment agent is a substance for imparting hydrophobicity to the boron nitride nanotubes, and is a hydrocarbon group that can be Michael added to the hydroxyl groups of the first layer 120, and may include amine groups or thiol groups.

[0058] As an example, the second surface treatment agent may include at least one of alkylamines, alkylthiols, arylamines, arylthiols, benzylamines, and benzylthiols.

[0059] The amount of the second surface treatment agent mixed in can be 0.5 to 2 times the amount of boron nitride nanotubes mixed in. If the amount of the second surface treatment agent is less than 0.5 times the amount of boron nitride nanotubes, the second layer is not easily formed, and the boron nitride nanotubes do not easily become hydrophobic. If the amount of the second surface treatment agent is greater than 2 times the amount of boron nitride nanotubes, the amount of the second surface treatment agent discarded in the next washing process will increase sharply.

[0060] After dispersing boron nitride nanotubes in the second mixture to form a dispersion, the boron nitride nanotubes with the second layer formed on them are washed and dried (S240).

[0061] In the washing step, the boron nitride nanotubes are sequentially washed with water and ethanol to remove any remaining polyphenol and hydrocarbon groups. Then, after separating only the boron nitride nanotubes by centrifugation or filtration, a powder of boron nitride nanotubes that has been dried and surface-treated to be hydrophobic can be obtained.

[0062] On the other hand, unlike the method described above, when the second surface treatment agent was mixed with an organic solvent such as toluene and boron nitride nanotubes were dispersed, the second layer was not formed on the surface of the boron nitride nanotubes, and hydrophobicity could not be imparted to the boron nitride nanotubes. In other words, in order to form the second layer, the first layer must be formed first on the surface of the boron nitride nanotubes using the first surface treatment agent.

[0063] The above method can be carried out at room temperature and in atmospheric conditions. Therefore, according to the present invention, boron nitride nanotubes can be made hydrophobic by a simple method that does not require the creation of a specific environment, by dispersing boron nitride nanotubes in a mixture of a first surface treatment agent and water, and then further mixing in a second surface treatment agent. Furthermore, according to this method, by using water as the dispersion medium in the process of surface treating the boron nitride nanotubes to make them hydrophobic, the problem of environmental pollution caused by the use of organic solvents does not occur. In addition, as shown in Figure 4, the second layer can be formed without damaging the boron nitride nanotubes.

[0064] Figure 7 shows the results of measuring the composition of boron nitride nanotubes in the examples and comparative examples.

[0065] Figure 7(1) shows the compositional analysis results of an untreated boron nitride nanotube (hereinafter referred to as "Comparative Example"), Figure 7(2) shows the compositional analysis results when a first layer is formed on the surface of the boron nitride nanotube (hereinafter referred to as "Example 1"), and Figure 7(3) shows the compositional analysis results when a second layer is further formed on the first layer (hereinafter referred to as "Example 2"). In Example 1, the first layer was formed by the following method.

[0066] - 0.1 g of tannic acid was mixed with 100 mL of water, and bath sonication was performed for 10 minutes to form a mixture. Then, 1 g of boron nitride nanotube powder was added to the mixture, and tip sonication was performed for 60 minutes to form a dispersion. At this time, sodium hydroxide was added to the mixture to adjust the pH to 8. The boron nitride nanotubes surface-treated with the dispersion were washed with water, then removed by filtration or centrifugation, and dried at a temperature of 80°C for 8 hours.

[0067] In Example 2, the second layer was formed by the following method. - 0.1 g of tannic acid was mixed with 100 mL of water, and bath sonication was performed for 10 minutes to form a mixture. Then, 1 g of boron nitride nanotube powder was added to the mixture, and tip sonication was performed for 60 minutes to form a dispersion. At this time, sodium hydroxide was added to the mixture to adjust the pH to 8. 2 g of alkylamine was added to the dispersion, and tip sonication was performed for 60 minutes. Next, the surface-treated boron nitride nanotubes were washed with water and ethanol, then removed by filtration or centrifugation, and dried at 80°C for 8 hours.

[0068] The surface of boron nitride nanotubes is mostly composed of boron (B), nitrogen (N), carbon (C), and oxygen (O). However, referring to Figure 7, in the comparative example in Figure 7(1), the surface of the boron nitride nanotube is composed of 50.07% (atomic weight) of boron (B), 41.17% (atomic weight) of nitrogen (N), 6.37% (atomic weight) of carbon (C), and 2.4% (atomic weight) of oxygen (O).

[0069] In Example 1 shown in Figure 7(2), the surface of the surface-treated boron nitride nanotube is composed of 45.74% (atomic weight) boron (B), 37.41% (atomic weight) nitrogen (N), 12.51% (atomic weight) carbon (C), and 4.35% (atomic weight) oxygen (O).

[0070] In Example 2 shown in Figure 7(3), the surface of the surface-treated boron nitride nanotube is composed of 17.42% (atomic weight) boron (B), 15.04% (atomic weight) nitrogen (N), 62.79% (atomic weight) carbon (C), and 4.12% (atomic weight) oxygen (O).

[0071] When comparing Example 1 in Figure 7(2) and Example 2 in Figure 7(3) with the comparative example in Figure 7(1), the carbon (C) and oxygen (O) content increased, while the boron (B) and nitrogen (N) content decreased relatively. This is a result of the formation of a first and second layer on the surface of the boron nitride nanotube.

[0072] Figure 8 shows the contact angles of boron nitride nanotubes in the examples and comparative examples.

[0073] In Figure 8, the contact angle was measured by dropping a water droplet onto a glass substrate coated with boron nitride nanotubes. Figure 8(1) shows the contact angle of the comparative example, Figure 8(2) shows the contact angle of Example 1, and Figure 8(3) shows the contact angle of Example 2.

[0074] As a result, in the case of boron nitride nanotubes without surface treatment (comparative example), the contact angle was 140° as shown in Figure 8(1), but when the first layer was formed on the surface of the boron nitride nanotubes (Example 1), the contact angle decreased to 105° as shown in Figure 8(2). This is a result of the first layer surface-treating the boron nitride nanotubes to make them hydrophilic.

[0075] Furthermore, when a second layer is formed on the surface of the boron nitride nanotube (Example 2), the contact angle increases again to 151°, as shown in Figure 8 (3). This is because the surface is treated to be hydrophobic by the alkyl chain of the second layer.

[0076] Figure 9 shows the dispersion state of the boron nitride nanotubes in Figure 1 in various solvents. Figure 9 shows the dispersion state of the surface-treated boron nitride nanotubes according to Example 1 in Figure 7(2).

[0077] Figure 9(A) shows the results of dispersing the surface-treated boron nitride nanotubes from Example 1 in Figure 7(2) in water, but with different concentrations of dispersed boron nitride nanotubes, while Figure 9(B) shows the results of dispersing 1 wt% of surface-treated boron nitride nanotubes in water, ethanol, IPA, and methanol, respectively.

[0078] As can be seen from Figure 9, when a first layer is formed on the surface of the boron nitride nanotube to give it hydrophilic properties, it can be seen from Figures 9(A) and (B) that it disperses well in polar solvents.

[0079] Figure 10 shows the dispersion state of the boron nitride nanotubes in Figure 3 in various solvents. Figure 10 shows the dispersion state of the surface-treated boron nitride nanotubes according to Example 2 of Figure 7(3).

[0080] Figure 10(A) shows the results of dispersing 1 wt% of surface-treated boron nitride nanotubes from Example 2 of Figure 7(3) in NMP, DMP, MEK, and toluene, respectively, while Figure 10(B) shows the results of dispersing surface-treated boron nitride nanotubes in toluene, but with different amounts of boron nitride nanotubes dispersed in each solvent.

[0081] As can be seen from Figure 10, in Example 2, where a second layer is further formed and the boron nitride nanotubes are surface-treated to be hydrophobic, it can be seen that dispersion in a nonpolar solvent is well achieved.

[0082] Figure 11 shows the dispersion state of boron nitride nanotubes in comparative examples that have not been surface-treated with water, ethanol, and toluene.

[0083] Figure 11 shows the results of dispersing the comparative example from Figure 7 in water, ethanol, and toluene, respectively. Figure 11(A) shows the results immediately after dispersing the boron nitride nanotubes of the comparative example in water, ethanol, and toluene, while Figure 11(B) shows the results after 1 hour has elapsed since dispersing the boron nitride nanotubes of the comparative example from Figure 7(1) in water, ethanol, and toluene.

[0084] In the comparative example shown in Figure 7(1), it can be confirmed that untreated boron nitride nanotubes exhibit very poor dispersibility in organic and water-soluble solvents.

[0085] As can be seen from the above, according to the present invention, the boron nitride nanotubes can be dispersed in polar or nonpolar solvents by treating the surface of the boron nitride nanotubes. Furthermore, by using water as the dispersion medium during the surface treatment of the boron nitride nanotubes, organic solvents can be avoided, ensuring the dispersibility of boron nitride nanotubes in various solvents in a simple manner without causing environmental pollution, and improving the usability of boron nitride nanotubes in various fields.

[0086] Thus, the present invention has been described with reference to one embodiment shown in the figures, but this is merely illustrative, and a person with ordinary skill in the art will understand that various modifications and variations of embodiments are possible therefrom. Therefore, the true scope of technical protection of the present invention should be determined by the technical idea of ​​the appended claims.

Claims

1. Boron nitride nanotubes, and The first layer is located on at least a portion of the surface of the boron nitride nanotube, The first layer forms a π bond with the boron nitride nanotube, The first layer contains a hydroxyphenyl group, The first layer contains at least one polyphenol compound selected from the group consisting of tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxydiphenic acid, ellagic acid, and chlorogenic acid. Surface-treated boron nitride nanotubes.

2. The surface-treated boron nitride nanotube according to claim 1, wherein the surface-treated boron nitride nanotube is hydrophilic.

3. The first layer further includes a second layer, The surface-treated boron nitride nanotube according to claim 1, wherein the second layer comprises hydrocarbon groups, including amine groups or thiol groups.

4. The surface-treated boron nitride nanotube according to claim 3, wherein the amine group or thiol group is Michael-added to the hydroxyl group of the first layer.

5. The surface-treated boron nitride nanotube according to claim 3, wherein the second layer comprises at least one of alkylamine, alkylthiol, arylamine, arylthiol, benzylamine, and benzylthiol.

6. The surface-treated boron nitride nanotube according to claim 3, wherein the surface-treated boron nitride nanotube is hydrophobic due to the second layer.

7. A step of mixing a first surface treatment agent with water to form a mixed solution. The steps of dispersing boron nitride nanotubes in the aforementioned mixture to form a dispersion, and The process includes the step of washing and drying the boron nitride nanotubes on which the first layer has been formed after the dispersion has been formed, The pH of the dispersion is 8 to 9. The first layer containing hydroxyphenyl groups is formed on at least a portion of the surface of the dried boron nitride nanotube. The first surface treatment agent comprises at least one polyphenol compound selected from the group consisting of tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxydiphenic acid, ellagic acid, and chlorogenic acid. A method for surface treatment of boron nitride nanotubes.

8. Before the washing and drying step, The method further includes the step of mixing a second surface treatment agent into the dispersion, A second layer is further formed on the first layer by mixing the second surface treatment agent. The method for surface treatment of boron nitride nanotubes according to claim 7, wherein the second layer is a hydrocarbon group Michael-added to the hydroxyl group of the first layer, and includes an amine group or a thiol group.

9. The method for surface treatment of boron nitride nanotubes according to claim 8, wherein the second surface treatment agent comprises at least one of alkylamine, alkylthiol, arylamine, arylthiol, benzylamine, and benzylthiol.

10. The method for surface treatment of boron nitride nanotubes according to claim 8, wherein the boron nitride nanotubes change from hydrophilic to hydrophobic due to the second layer.

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