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 Nano Tube (BNNT) has a structural similarity to Carbon Nano Tube (CNT), but has a hexagonal crystal structure in which boron atoms and nitrogen atoms are substituted for the carbon atoms of CNT which is a carbon single-atom hexagonal system. BNNT has excellent mechanical strength and high thermal conductivity due to a structure similar to CNT, and also has a wide band gap due to the alternating bonds of boron and nitrogen, and has insulating properties, high oxidation resistance and chemical resistance.

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

[0006] Also, another embodiment of the present invention includes 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, 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, and a method for surface-treating boron nitride nanotubes is disclosed.

Advantages of the Invention

[0007] According to the embodiment of the present invention, the boron nitride nanotubes are surface-treated to have hydrophilicity or hydrophobicity and can be dispersed in various solvents, so the usability of the boron nitride nanotubes can be improved.

[0008] Also, when surface-treating the boron nitride nanotubes to have hydrophobicity, water is used as the dispersion medium, so environmental pollution can be prevented without using organic solvents.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0010] 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 forms a π bond with the boron nitride nanotube, and the first layer discloses a surface-treated boron nitride nanotube containing a hydroxyphenyl group.

[0011] In the present embodiment, the first layer may be a polyphenol group and may contain at least any 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 nanotube can be hydrophilic.

[0013] In this embodiment, a second layer is further included 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 nanotube can have hydrophobicity.

[0017] Another embodiment of the present invention discloses a method for surface-treating 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 to 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 this 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 this 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 this 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 this 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 apparent 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 and second are not used in a limiting sense and are used for the purpose of distinguishing one component from another. In the following embodiments, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0023] In the following embodiments, terms such as "comprising" or "having" mean that the features or components described in this specification exist, and do not preclude the possibility that one or more other features or components may be added.

[0024] In the following embodiments, if a part such as a film, region, component, etc. is above or over another part, it includes not only the case where it is directly above the other part, but also the case where other films, regions, components, etc. are interposed in between.

[0025] In the figures, for convenience of explanation, the components can be exaggerated or reduced in size. For example, since the size and thickness of each configuration shown in the figures are arbitrarily shown for convenience of explanation, the present invention is not necessarily limited to what is shown.

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. When describing with reference to the drawings, the same or corresponding components shall be given the same drawing reference numerals.

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

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

[0029] The boron nitride nanotube 110 is a hexagonal nanotube in which nitrogen and carbon are alternately arranged, as shown in FIG. 2. It has excellent thermal conductivity characteristics, but has a wide bandgap and has insulating properties similar to those of ceramics electrically. Therefore, although the boron nitride nanotube 110 is an electrical insulator, it can be applied as a high thermal conductivity composite.

[0030] Furthermore, the boron nitride nanotube 110 is known to have excellent mechanical properties, chemical resistance and oxidation resistance, absorb thermal neutrons, and be harmless to the human body, and can be applied to various industrial fields such as the electronics industry, energy, space, nuclear power, and biomedicine.

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

[0032] For this purpose, the present invention forms a first layer 120 on at least a part of the surface of the boron nitride nanotube 110, so that the boron nitride nanotube 110 has hydrophilicity, and the boron nitride nanotube 110 can be dispersed in a polar solvent.

[0033] The first layer 120 forms a π bond with the boron nitride nanotube 110 and can contain a hydroxyphenyl group. As an example, the first layer 120 is a polyphenol group and can contain at least any 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 by highly reactive quinone oligomers and adhere to the surface of the boron nitride nanotubes 110. Due to the strong interaction between the catechol molecules of the polyphenol groups and the boron nitride nanotubes 110 through van der Waals bonds and π-π stacking, the first layer 120 can be formed on the boron nitride nanotubes 110.

[0035] Thus, by forming the first layer 120 on at least a part of the surface of the boron nitride nanotubes 110, hydroxyl groups will exist on the surface of the boron nitride nanotubes 110. Therefore, the surface-treated boron nitride nanotubes 100 can have hydrophilicity.

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

[0037] Figure 3 is a flowchart schematically showing an example of the method for surface-treating the boron nitride nanotubes of Figure 1.

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

[0039] The first surface treatment agent is a substance capable of forming a first layer and can contain a hydroxyphenyl group. As an example, the first surface treatment agent is a polyphenol group and can contain at least any one of tannic acid, Gallic acid, catechol, epigallocatechin, pyrogallol, Hexahydroxydiphenic acid, ellagic acid, and chlorogenic acid.

[0040] The first surface treatment agent may be contained in an amount of 0.1 wt% to 0.2 wt% based on 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 the 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 of the boron nitride nanotubes does not continuously increase. Therefore, the content of the first surface treatment agent is preferably 0.1 wt% to 0.2 wt% based on the entire mixture.

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

[0042] At this time, the dispersion can have a weak alkaline property. Due to the dispersion having a weak alkaline property, the polyphenol group can be oxidized by the dissolved oxygen in the dispersion into a highly reactive quinone oligomer, and as a result, it can adhere to the surface of the boron nitride nanotubes 110 to form the first layer.

[0043] The pH of the dispersion can be adjusted with a base such as sodium hydroxide. As an example, the pH of the dispersion can be 8 - 9. If the pH of the dispersion is less than 8 or greater than 9, the formation of the quinone oligomer is less likely to occur. Therefore, the pH of the dispersion is preferably 8 - 9.

[0044] The mixing ratio of the boron nitride nanotubes dispersed in the dispersion and the first surface treatment agent can be 1:1 to 1:0.1 in wt%. When the content of the boron nitride nanotubes dispersed in the dispersion exceeds 10 times that of the first surface treatment agent, it may be difficult to effectively form the first layer on the surface of the boron nitride nanotubes. On the other hand, when the content of the 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 rapidly.

[0045] After dispersing boron nitride nanotubes in the mixed solution to form a dispersion, the boron nitride nanotubes with the first layer formed are washed and dried (S130).

[0046] In the washing step, the boron nitride nanotubes are washed with water to remove the remaining polyphenol groups. Then, only the boron nitride nanotubes are taken out by centrifugation or filtration, and after drying, a powder of the surface-treated boron nitride nanotubes having hydrophilicity can be obtained.

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

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

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

[0050] The boron nitride nanotube 110 is a hexagonal nanotube in which nitrogen and carbon are alternately arranged, and the first layer 120 forms a π bond with the boron nitride nanotube 110 and can contain a hydroxyphenyl group. As an example, the first layer 120 is a polyphenol group and can contain at least any 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 and can contain an amine group or a thiol group. For example, the second layer 130 can contain at least any one of alkyl amine, alkyl thiol, aryl amine, aryl thiol, benzyl amine, and benzyl thiol.

[0052] On the other hand, the polyphenol group of the first layer 120 can be oxidized to a highly reactive quinone oligomer and adhere to the surface of the boron nitride nanotube 110, and the quinone structure thus adhered can anchor the primary amine group of the second layer 130 by the 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 can form the second layer 130 on the first layer 120 by a reaction in which the amine or thiol of the second layer 130 undergoes Michael addition to the hydroxyl group of the first layer 120.

[0053] When further including such a second layer 130, the surface-treated boron nitride nanotube 102 will have hydrophobicity and the dispersibility in an organic solvent such as toluene can be improved.

[0054] FIG. 6 is a flowchart schematically showing an example of a method for surface-treating boron nitride nanotubes in FIG. 4.

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

[0056] Since the step (S210) of forming the first mixed solution and the step (S220) of forming the dispersion are the same as the step (S110 in FIG. 3) of forming the mixed solution in FIG. 3 and the step (S120 in FIG. 3) of forming the dispersion, the description will not be repeated, and only the differences from FIG. 3 will be described.

[0057] Referring to FIG. 6, after forming the dispersion, a 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 boron nitride nanotubes, and is a hydrocarbon group capable of performing Michael addition to the hydroxyl group of the first layer 120, and may include an amine group or a thiol group.

[0058] As an example, the second surface treatment agent may include at least any one of alkyl amine, alkyl thiol, aryl amine, aryl thiol, benzyl amine, and benzyl thiol.

[0059] The mixing amount of the second surface treatment agent can be 0.5 times to 2 times the mixing amount of the boron nitride nanotubes. If the mixing amount of the second surface treatment agent is less than 0.5 times the mixing amount of the boron nitride nanotubes, it is difficult to effectively form the second layer, so it is difficult for the boron nitride nanotubes to change to hydrophobicity. If the mixing amount of the second surface treatment agent is more than 2 times the mixing amount of the 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 mixed solution to form a dispersion, the boron nitride nanotubes with the second layer formed are washed and dried (S240).

[0061] In the washing step, the boron nitride nanotubes are sequentially washed with water and ethanol to remove the remaining polyphenol groups and hydrocarbon groups. Then, only the boron nitride nanotubes are taken out by centrifugation or filtration, and after drying, a powder of the surface-treated boron nitride nanotubes having hydrophobicity can be obtained.

[0062] On the other hand, different from the above method, when the second surface treatment agent was mixed with an organic solvent such as toluene and the boron nitride nanotubes were dispersed, no second layer was formed on the surface of the boron nitride nanotubes, and hydrophobicity could not be imparted to the boron nitride nanotubes. That is, in order to form the second layer, the first layer must be formed on the surface of the boron nitride nanotubes in advance by the first surface treatment agent.

[0063] The above method can be carried out at room temperature and in the atmosphere. Therefore, according to the present invention, without creating a specific environment, after dispersing boron nitride nanotubes in a mixed solution of a first surface treatment agent and water, the second surface treatment agent can be further mixed to make the boron nitride nanotubes hydrophobic by a simple method. Further, according to this method, by using water as a dispersion medium in the process of surface-treating the boron nitride nanotubes so that they have hydrophobicity, the problem of environmental pollution caused by using organic solvents does not occur. Also, as shown in FIG. 4, the second layer can be formed without damaging the boron nitride nanotubes.

[0064] FIG. 7 is a diagram showing the results of measuring the composition of boron nitride nanotubes according to Examples and Comparative Examples.

[0065] FIG. 7(1) is the composition analysis result of boron nitride nanotubes that have not been surface-treated (hereinafter referred to as "Comparative Example"), FIG. 7(2) is the composition analysis result when a first layer is formed on the surface of boron nitride nanotubes (hereinafter referred to as "Example 1"), and FIG. 7(3) is the composition analysis result 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, bath sonication was performed for 10 minutes to form a mixed solution, then 1 g of boron nitride nanotube powder was added to the mixed solution, and tip sonication was performed for 60 minutes to form a dispersion. At this time, sodium hydroxide was mixed into the mixed solution to adjust the pH to 8. The boron nitride nanotubes surface-treated with the dispersion were washed with water, then taken out 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 sonicated for 10 minutes to form a mixed solution. Then, 1 g of boron nitride nanotube powder was added to the mixed solution, and tip sonication was performed for 60 minutes to form a dispersion. At this time, sodium hydroxide was mixed into the mixed solution to adjust the pH to 8. 2 g of alkylamine was added to the dispersion, and tip sonication was performed for 60 minutes. Subsequently, the surface-treated boron nitride nanotubes were washed with water and ethanol, then taken out by filtration or centrifugation, and dried at a temperature of 80 °C for 8 hours.

[0068] The surface of the boron nitride nanotubes is mostly composed of boron (B), nitrogen (N), carbon (C), and oxygen (O). Referring to Figure 7, in the comparative example of Figure 7(1), the surface of the boron nitride nanotubes 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 the case of Example 1 in Figure 7(2), the surface of the surface-treated boron nitride nanotubes is composed of 45.74% (atomic weight) of boron (B), 37.41% (atomic weight) of nitrogen (N), 12.51% (atomic weight) of carbon (C), and 4.35% (atomic weight) of oxygen (O).

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

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

[0072] Fig. 8 is a diagram showing the contact angles of the boron nitride nanotubes according to the examples and the comparative example.

[0073] In Fig. 8, the contact angle was measured by dropping a water droplet after coating the boron nitride nanotubes on a glass substrate. (1) in Fig. 8 shows the contact angle of the comparative example, (2) in Fig. 8 shows the contact angle of Example 1, and (3) in Fig. 8 shows the contact angle of Example 2.

[0074] As a result, in the case of the boron nitride nanotubes without surface treatment (comparative example), the contact angle was 140° as shown in Fig. 8(1), but in the case of forming the first layer on the surface of the boron nitride nanotubes (Example 1), as shown in Fig. 8(2), it can be seen that the contact angle decreased to 105°. This is the result of surface treatment so that the boron nitride nanotubes have hydrophilicity due to the first layer.

[0075] Also, in the case of forming up to the second layer on the surface of the boron nitride nanotubes (Example 2), as shown in Fig. 8(3), the contact angle increased to 151° again. This is because the surface was treated to have hydrophobicity by the alkyl chain of the second layer.

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

[0077] (A) of Fig. 9 shows the case where the surface-treated boron nitride nanotubes of Example 1 in Fig. 7(2) are dispersed in water, but the content of the dispersed boron nitride nanotubes is varied. (B) of Fig. 9 shows the results of dispersing 1 wt% of the surface-treated boron nitride nanotubes in water, ethanol, IPA, and methanol, respectively.

[0078] As can be seen from Fig. 9, as a result of forming the first layer on the surface of the boron nitride nanotubes to make them hydrophilic by surface treatment, as can be seen from (A) and (B) of Fig. 9, it can be understood that good dispersion can be achieved in polar solvents.

[0079] Fig. 10 is a diagram showing the dispersion states of the boron nitride nanotubes in Fig. 3 in various solvents. Fig. 10 shows the dispersion states of the surface-treated boron nitride nanotubes according to Example 2 in Fig. 7(3).

[0080] (A) of Fig. 10 shows the results of dispersing 1 wt% of the surface-treated boron nitride nanotubes of Example 2 in Fig. 7(3) in NMP, DMP, MEK, and toluene, respectively. (B) of Fig. 10 shows the case where the surface-treated boron nitride nanotubes are dispersed in toluene, but the content of the boron nitride nanotubes dispersed in each solvent is varied.

[0081] As can be seen from Fig. 10, in the case of Example 2 where the second layer is further formed and the boron nitride nanotubes are surface-treated to be hydrophobic, it can be understood that good dispersion can be achieved in non-polar solvents.

[0082] Fig. 11 is a diagram showing the dispersion states of the boron nitride nanotubes according to the comparative example without surface treatment with water, ethanol, and toluene.

[0083] FIG. 11 shows the results of dispersing the comparative example of FIG. 7 in water, ethanol, and toluene, respectively. (A) in FIG. 11 shows the results immediately after dispersing the boron nitride nanotubes of the comparative example in water, ethanol, and toluene, and (B) in FIG. 11 shows the case where one hour has passed after dispersing the boron nitride nanotubes of the comparative example of FIG. 7(1) in water, ethanol, and toluene.

[0084] In the case of the comparative example of FIG. 7(1), it can be confirmed that the boron nitride nanotubes without surface treatment have very poor dispersibility in organic and water-soluble solvents.

[0085] As can be seen from the above, according to the present invention, the surface of the boron nitride nanotubes can be treated to disperse the boron nitride nanotubes in polar or non-polar solvents. Further, by using water as a dispersion medium during the surface treatment of the boron nitride nanotubes, organic solvents can be not used, and the dispersibility of the boron nitride nanotubes in various solvents can be ensured by a simple method without causing environmental pollution, and the usability of the boron nitride nanotubes in various fields can be improved.

[0086] Thus, the present invention has been described with reference to one embodiment shown in the figures, which is merely exemplary, and it will be understood that those having ordinary knowledge in the art will be able to make various modifications and variations of the embodiments from now on. Therefore, the true technical protection scope of the present invention should be determined by the technical idea of the appended claims.

Claims

1. Boron nitride nanotubes, and including a first layer located on at least a part of the surface of the boron nitride nanotubes, the first layer forms a π bond with the boron nitride nanotubes, the first layer is a surface-treated boron nitride nanotube containing a hydroxyphenyl group.

2. The surface-treated boron nitride nanotubes according to claim 1, wherein the first layer contains at least one of polyphenol groups, tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxydiphenic acid, ellagic acid, and chlorogenic acid.

3. The surface-treated boron nitride nanotubes according to claim 1, wherein the surface-treated boron nitride nanotubes are hydrophilic.

4. further including a second layer on the first layer, the second layer is a hydrocarbon group containing an amine group or a thiol group, and the surface-treated boron nitride nanotubes according to claim 1.

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

6. The surface-treated boron nitride nanotubes according to claim 4, wherein the second layer contains at least one of alkylamine, alkylthiol, arylamine, arylthiol, benzylamine, and benzylthiol.

7. The surface-treated boron nitride nanotube according to claim 4, wherein the surface-treated boron nitride nanotube has hydrophobicity due to the second layer.

8. A step of mixing a first surface treatment agent with water to form a mixed solution, A step of dispersing boron nitride nanotubes in the mixed solution to form a dispersion, and A step of washing and drying the boron nitride nanotubes from the dispersion, wherein the pH of the dispersion is 8 to 9, A method for surface-treating boron nitride nanotubes, wherein a first layer containing a hydroxyphenyl group is formed on at least a part of the surface of the dried boron nitride nanotubes.

9. The first surface treatment agent is a polyphenol group and contains at least any one of tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxydiphenic acid, ellagic acid, and chlorogenic acid. The method for surface-treating boron nitride nanotubes according to claim 8.

10. Before the step of washing and drying, Further comprising a step of mixing a second surface treatment agent into the dispersion, 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 contains an amine group or a thiol group. The method for surface-treating boron nitride nanotubes according to claim 8.

11. The surface treatment method of the boron nitride nanotube according to claim 10, wherein the second surface treatment agent contains at least any one of alkyl amine, alkyl thiol, aryl amine, aryl thiol, benzyl amine and benzyl thiol.

12. The surface treatment method of the boron nitride nanotube according to claim 10, wherein the second layer changes the boron nitride nanotube from hydrophilic to hydrophobic.

Images