Surface-treated boron nitride nanotube and surface treatment method for boron nitride nanotube

Abstract

One embodiment of the invention discloses a boron nitride nanotube subjected to surface treatment. The boron nitride nanotube subjected to surface treatment comprises a boron nitride nanotube and a boron nitride layer, and a first layer on at least a portion of a surface of the boron nitride nanotube, the first layer forming a pi bond with the boron nitride nanotube, the first layer including a hydroxyphenyl group.

Description

Technical Field

[0001] The invention relates to a surface-treated boron nitride nanotube and a surface treatment method of the boron nitride nanotube. Background Art

[0002] Although boron nitride nanotubes (BNNT) and carbon nanotubes (CNT) have structural similarities, boron nitride nanotubes have a hexagonal structure in which boron atoms and nitrogen atoms replace carbon atoms of CNT, which is a single carbon atom hexagonal structure. BNNT has excellent mechanical strength and high thermal conductivity due to its similar structure to CNT, and also has a wide band gap due to the alternating bonds of boron and nitrogen, so the BNNT has insulating properties, high oxidation resistance and chemical resistance.

[0003] In order to apply the excellent properties of BNNT to various fields, it is very important to ensure the dispersion quality of BNNT in the dispersion medium. However, the dispersibility of BNNT in organic and water-soluble solvents is low, which limits the practical application of BNNT. Therefore, in order to actually apply BNNT in various fields, BNNT needs to be dispersed in a variety of solvents. Summary of the invention

[0004] Technical issues

[0005] Embodiments of the present invention provide a surface-treated boron nitride nanotube having excellent dispersibility in a hydrophilic or hydrophobic solvent and a surface treatment method for the boron nitride nanotube.

[0006] Technical solution

[0007] An embodiment of the present invention discloses a surface-treated boron nitride nanotube, which comprises: 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 hydroxyphenyl groups.

[0008] Another embodiment of the present invention discloses a method for surface treatment of boron nitride nanotubes, the method comprising: a step of mixing a first surface treatment agent in 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 the boron nitride nanotubes from the dispersion and drying 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.

[0009] Effects of the Invention

[0010] According to the embodiments of the present invention, the boron nitride nanotubes may be surface treated to have hydrophilicity or hydrophobicity, and thus may be dispersed in a variety of solvents, thereby improving the usability of the boron nitride nanotubes.

[0011] In addition, when the surface of the boron nitride nanotubes is treated to be hydrophobic, water can be used as a dispersion medium, thereby preventing environmental pollution without using an organic solvent. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a diagram schematically showing an example of a boron nitride nanotube according to an embodiment of the present invention.

[0013] Figure 2 It is shown Figure 1 The structural formula of boron nitride nanotubes.

[0014] Figure 3 It is schematically shown Figure 1 A flow chart of an example of a method for treating the surface of a boron nitride nanotube.

[0015] Figure 4 This is a diagram schematically showing an example of a BNNT according to another embodiment of the present invention.

[0016] Figure 5 It is shown Figure 4 The structural formula of boron nitride nanotubes.

[0017] Figure 6 It is schematically shown Figure 4 A flow chart of an example of a method for treating the surface of a boron nitride nanotube.

[0018] Figure 7 This is a diagram showing the results of measuring the compositions of boron nitride nanotubes in Examples and Comparative Examples.

[0019] Figure 8 This is a graph showing the contact angles of boron nitride nanotubes in Examples and Comparative Examples.

[0020] Fig. 9 It shows the various solvents Figure 1 Figure 2 shows the dispersion state of boron nitride nanotubes.

[0021] Fig.10 It shows the various solvents Figure 3 Figure 2 shows the dispersion state of boron nitride nanotubes.

[0022] Fig.11 : is a diagram showing the dispersion state of boron nitride nanotubes without surface treatment in water and toluene. DETAILED DESCRIPTION

[0023] An embodiment of the present invention discloses a surface-treated boron nitride nanotube, which comprises: 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 hydroxyphenyl groups.

[0024] In this embodiment, the first layer may include at least any one of tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxydiphenic acid, ellagic acid and chlorogenic acid as polyphenol groups.

[0025] In this embodiment, the surface-treated boron nitride nanotubes may be hydrophilic.

[0026] In this embodiment, a second layer may be further included on the first layer, and the second layer may include an amine group or a thiol group based on a hydrocarbon group.

[0027] In this embodiment, the amine group or the thiol group can undergo a Michael addition reaction with the hydroxide group of the first layer.

[0028] In the present embodiment, the second layer may include at least any one of alkyl amine, alkylthiol, aryl amine, aryl thiol, benzyl amine and benzyl thiol.

[0029] In this embodiment, the surface-treated boron nitride nanotubes may have hydrophobicity through the second layer.

[0030] Another embodiment of the present invention discloses a surface treatment method for boron nitride nanotubes, the method comprising: a step of mixing a first surface treatment agent in 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 the boron nitride nanotubes from the dispersion and drying 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.

[0031] In this embodiment, the first surface treatment agent may include at least any one of tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxydiphenic acid, ellagic acid and chlorogenic acid.

[0032] In this embodiment, before the washing and drying steps, the step of mixing a second surface treatment agent in the dispersion is also included. By mixing the second surface treatment agent, a second layer is further formed on the first layer. The second layer may contain an amine group or a thiol group based on a hydrocarbon group that undergoes a Michael addition reaction with the hydroxide group of the first layer.

[0033] In this embodiment, 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.

[0034] In this embodiment, the boron nitride nanotubes can be transformed from hydrophilic to hydrophobic by the second layer.

[0035] Implementation

[0036] The present invention can be modified in many ways and has many embodiments, so specific embodiments are schematically shown in the drawings and described in detail in the detailed description. The effects, features and methods of achieving the same can be seen by referring to the attached drawings. Figure 1 However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms.

[0037] In the following embodiments, the terms “first” and “second” are not used in a limiting sense but are used for the purpose of distinguishing one component from other components.

[0038] In the following embodiments, unless otherwise clearly stated herein, a singular expression includes a plural expression.

[0039] In the following embodiments, terms such as “including” or “having” refer to the presence of features or constituent elements described in the specification, and do not preclude the possibility of adding one or more other features or constituent elements.

[0040] In the following embodiments, when it is mentioned that a part of a film, a region, a component, etc. is located on or above another part, it includes not only the case where it is directly located on the other part, but also the case where other films, regions, components, etc. are interposed therebetween.

[0041] In the drawings, the size of the components may be exaggerated or reduced for the convenience of explanation. For example, the size and thickness of each component shown in the drawings are arbitrarily shown for the convenience of explanation, and the present invention is not necessarily limited to the contents shown in the drawings.

[0042] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description with reference to the accompanying drawings, the same reference numerals are given to the same or corresponding components.

[0043] Figure 1 is a perspective view schematically showing an example of a boron nitride nanotube according to an embodiment of the present invention. Figure 2 It is shown Figure 1 The structural formula of surface-treated boron nitride nanotubes. Figure 1 is a transmission electron microscope (TEM) image.

[0044] Reference Figure 1 and Figure 2 According to an embodiment, the surface-treated boron nitride nanotube 100 may include a boron nitride nanotube 110 and a first layer 120 on the surface of the boron nitride nanotube 110 .

[0045] like Figure 2 As shown, the boron nitride nanotube 110 is a hexagonal nanotube in which nitrogen and carbon are alternately arranged, and has excellent thermal conductivity, but has a wide band gap, so it has electrical insulation properties similar to ceramics. Therefore, the boron nitride nanotube 110 is an insulator electrically, but can be used as a high thermal conductivity composite material.

[0046] Furthermore, it is known that boron nitride nanotubes 110 have excellent mechanical properties, chemical resistance and oxidation resistance, absorb thermal neutrons, and are harmless to the human body, and therefore can be applied to multiple industrial fields such as the electronics industry, energy, aerospace, nuclear power, and biomedicine.

[0047] However, such boron nitride nanotubes 110 are generally not dispersed in organic solvents and aqueous solvents. Therefore, in order to practically apply the boron nitride nanotubes 110 in industry, the boron nitride nanotubes 110 need to have hydrophilic or hydrophobic properties.

[0048] To this end, the present invention forms the first layer 120 on at least a portion of the surface of the boron nitride nanotube 110, so that the boron nitride nanotube 110 has hydrophilicity and the boron nitride nanotube 110 is dispersed in a polar solvent.

[0049] The first layer 120 may form a π bond with the boron nitride nanotube 110 and may include a hydroxyphenyl group. As an example, the first layer 120 may include at least one of tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxydiphenic acid, ellagic acid, and chlorogenic acid as a polyphenol group.

[0050] The polyphenol groups of the first layer 110 can be oxidized into quinone oligomers with good reactivity and attached to the surface of the boron nitride nanotubes 110, and the first layer 120 can be formed on the boron nitride nanotubes 110 through 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.

[0051] As described above, the first layer 120 may be formed on at least a portion of the surface of the boron nitride nanotube 110 so that hydroxyl groups exist on the surface of the boron nitride nanotube 110, and thus the surface-treated boron nitride nanotube 110 has hydrophilicity.

[0052] On the other hand, the tannic acid and the like contained in the first layer 120 are environmentally friendly materials derived from nature, and the surface-treated boron nitride nanotubes 110 do not cause environmental pollution.

[0053] Figure 3 It is schematically shown Figure 1 A flow chart of an example of a method for treating the surface of a boron nitride nanotube.

[0054] Reference Figure 3 A surface treatment method for boron nitride nanotubes according to an embodiment of the present invention may include: a step S110 of mixing a first surface treatment agent in water to form a mixed solution; a step S120 of dispersing boron nitride nanotubes in the mixed solution to form a dispersion; and a step S130 of washing the boron nitride nanotubes from the dispersion and drying the dispersion.

[0055] The first surface treatment agent may include hydroxyphenyl groups as a substance that can form the first layer. As an example, the first surface treatment agent may include at least one of tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxydiphenic acid, ellagic acid, and chlorogenic acid as polyphenol groups.

[0056] Based on the overall mixed solution, the first surface treatment agent may contain 0.1wt% to 0.2wt%. If the content of the first surface treatment agent in the mixed solution is less than 0.1wt%, it is difficult to form a first layer that can impart hydrophilicity to the boron nitride nanotubes. On the contrary, even if the content of the first surface treatment agent is greater than 0.2wt%, the surface treatment effect of the boron nitride nanotubes will not continue to increase. Therefore, based on the overall mixed solution, the content of the first surface treatment agent is preferably 0.1wt% to 0.2wt%.

[0057] Next, in step S120, the boron nitride nanotubes are dispersed in the mixed solution. The dispersion can be performed by ultrasonic dispersion, stirring, or the like.

[0058] At this time, the dispersion may be weakly alkaline. Since the dispersion is weakly alkaline, the polyphenol groups may be oxidized into highly reactive quinone oligomers by dissolved oxygen in the dispersion, and as a result, the polyphenol groups may be attached to the surface of the boron nitride nanotubes 110 to form the first layer.

[0059] The pH of the dispersion can be adjusted by alkali (sodium hydroxide, etc.). As an example, the pH of the dispersion can be 8 to 9. If the pH of the dispersion is less than 8 or greater than 9, it is difficult to form quinone oligomers, so the pH of the dispersion is preferably 8 to 9.

[0060] The mixing ratio (wt%) of the boron nitride nanotubes dispersed in the dispersion to the first surface treatment agent may be 1:1 to 1:0.1. If the content of the boron nitride nanotubes dispersed in the dispersion exceeds 10 times relative to 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 contrary, if the content of the boron nitride nanotubes dispersed in the dispersion is less than 1 time relative to the first surface treatment agent, the amount of the first surface treatment agent discarded in the subsequent washing process increases dramatically.

[0061] After the boron nitride nanotubes are dispersed in the mixed solution to form a dispersion, the boron nitride nanotubes having the first layer formed thereon are washed and dried ( S130 ).

[0062] In the washing step, the boron nitride nanotubes are washed with water and residual polyphenol groups are removed. Next, only the boron nitride nanotubes can be collected by centrifugal separation or filtration and then dried to obtain a powder of the boron nitride nanotubes surface-treated to be hydrophilic.

[0063] The method can be carried out at room temperature and under atmospheric conditions. 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 of the first surface treatment agent and water without forming a specific environment. Figure 1 As shown, the first layer can be formed without damaging the boron nitride nanotubes.

[0064] Figure 4 FIG. 1 is a diagram schematically showing an example of a boron nitride nanotube according to another embodiment of the present invention. Figure 5 It is shown Figure 4 The structural formula of boron nitride nanotubes.

[0065] Reference Figure 4 and Figure 5 According to an embodiment, the surface-treated boron nitride nanotube 102 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 .

[0066] The boron nitride nanotube 110 is a hexagonal nanotube in which nitrogen and carbon are alternately arranged, and the first layer 120 may form a π bond with the boron nitride nanotube 110 and may include a hydroxyphenyl group. As an example, the first layer 120 may include at least one of tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxydiphenic acid, ellagic acid, and chlorogenic acid as a polyphenol group.

[0067] The second layer 130 is a layer for imparting hydrophobicity to the boron nitride nanotubes 110, and may include an amine group or a thiol group based on a hydrocarbon group. For example, the second layer 130 may include at least any one of alkyl amine, alkyl thiol, aryl amine, aryl thiol, benzyl amine, and benzyl thiol.

[0068] On the other hand, the polyphenol groups of the first layer 120 can be oxidized into quinone oligomers with good reactivity and attached to the surface of the boron nitride nanotubes 110, and the attached quinone structure can anchor the primary amine groups of the second layer 130 through the Michael addition mechanism. More specifically, the reaction of the amine or thiol of the second layer 130 with the hydroxide groups of the first layer 120 can be a Michael addition reaction of the amine or thiol of the second layer 130 with the hydroxide groups of the first layer 120, thereby forming the second layer 130 on the first layer 120.

[0069] When such a second layer 130 is further included, the surface-treated boron nitride nanotubes 102 may have hydrophobicity, thereby improving dispersibility in an organic solvent (such as toluene, etc.).

[0070] Figure 6 It is schematically shown Figure 4 A flow chart of an example of a method for treating the surface of a boron nitride nanotube.

[0071] Reference Figure 6 According to an embodiment of the present invention, a surface treatment method for boron nitride nanotubes may include: a step S210 of mixing a first surface treatment agent in 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 in the dispersion to form a second mixed solution; and a step S240 of washing the boron nitride nanotubes from the second mixed solution and drying them.

[0072] The step S210 of forming the first mixed solution and the step S220 of forming the dispersion are Figure 3 The step of forming a mixed solution ( Figure 3 S110) and the step of forming a dispersion ( Figure 3 The same as S120 of FIG. 1 is omitted here and only the same as S120 of FIG. Figure 3 The difference.

[0073] Reference Figure 6 After the dispersion is formed, a second surface treatment agent is additionally mixed in the dispersion to form a second mixed solution S230. The second surface treatment agent may be a substance for imparting hydrophobicity to the boron nitride nanotubes, and may include an amine group or a thiol group based on a hydrocarbon group that undergoes a Michael addition reaction with the hydroxide group of the first layer 120.

[0074] 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.

[0075] The mixing amount of the second surface treatment agent may be 0.5 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, and thus 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 subsequent washing process increases dramatically.

[0076] After the boron nitride nanotubes are dispersed in the second mixed solution to form a dispersion, the boron nitride nanotubes having the second layer formed thereon are washed and dried ( S240 ).

[0077] In the washing step, the boron nitride nanotubes are repeatedly washed with water and ethanol to remove the residual polyphenol groups and hydrocarbon groups. Next, only the boron nitride nanotubes can be collected by centrifugal separation or filtration, and then dried to obtain a powder of the boron nitride nanotubes that have been surface-treated to be hydrophobic.

[0078] On the other hand, unlike the above method, mixing the second surface treatment agent in an organic solvent (such as toluene) and dispersing the boron nitride nanotubes results in no second layer being formed on the surface of the boron nitride nanotubes, thereby failing to impart hydrophobicity to the boron nitride nanotubes. In other words, in order to form the second layer, the first layer should be preliminarily formed on the surface of the boron nitride nanotubes by the first surface treatment agent.

[0079] The method can be carried out at room temperature and under atmospheric conditions. Therefore, according to the present invention, the boron nitride nanotubes can be made hydrophobic by a simple method of dispersing the boron nitride nanotubes in a mixed solution of a first surface treatment agent and water and then additionally mixing a second surface treatment agent, without the need to form a specific environment. In addition, according to the present method, water is used as a dispersion medium in the process of surface treating the boron nitride nanotubes to make them hydrophobic, so that the environmental pollution problem caused by the use of organic solvents does not occur. In addition, from Figure 4 It can be seen that the second layer can be formed without damaging the boron nitride nanotubes.

[0080] Figure 7 This is a diagram showing the results of measuring the compositions of boron nitride nanotubes in Examples and Comparative Examples.

[0081] Figure 7(1) is the composition analysis result of the boron nitride nanotubes without surface treatment (hereinafter referred to as "comparative example"). Figure 7 (2) is the composition analysis result when the first layer is formed on the surface of the boron nitride nanotube (hereinafter referred to as 'Example 1'), Figure 7 (3) is a composition analysis result when a second layer is further formed on the first layer (hereinafter referred to as "Example 2").

[0082] In Example 1, the first layer was formed by the following method.

[0083] - 0.1 g of tannic acid was mixed in 100 mL of water and subjected to bath sonication for 10 minutes to form a mixed solution, and then 1 g of boron nitride nanotube powder was added to the mixed solution and subjected to tip sonication for 60 minutes to form a dispersion. At this time, sodium hydroxide was mixed in the mixed solution to adjust the pH to 8. The surface-treated boron nitride nanotubes in the dispersion were washed with water and dried at 80° C. for 8 hours.

[0084] In Example 2, the second layer was formed by the following method.

[0085] - 0.1 g of tannic acid was mixed in 100 mL of water and subjected to bath sonication for 10 minutes to form a mixed solution, and then 1 g of boron nitride nanotube powder was added to the mixed solution and subjected to tip sonication for 60 minutes to form a dispersion. At this time, sodium hydroxide was mixed in the mixed solution to a pH of 8. 2 g of alkylamine was added to the dispersion and subjected to tip sonication for 60 minutes. Next, the surface-treated boron nitride nanotubes were washed with water and ethanol and dried at 80°C for 8 hours.

[0086] The surface of boron nitride nanotubes is mainly composed of boron (B), nitrogen (N), carbon (C) and oxygen (O). Figure 7 In comparative example (1), the surface of the boron nitride nanotube is composed of 50.07% (atomic weight) boron (B), 41.17% (atomic weight) nitrogen (N), 6.37% (atomic weight) carbon (C) and 2.4% (atomic weight) oxygen (O).

[0087] In Example 1(2), the surface of the surface-treated boron nitride nanotubes 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).

[0088] In Example 2(3), the surface of the surface-treated boron nitride nanotubes 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).

[0089] Comparing Example 1 (2) and Example 2 (3) with Comparative Example (1), the contents of carbon (C) and oxygen (O) increased, and the contents of boron (B) and nitrogen (N) decreased relatively. This is the result of forming the first layer and the second layer on the surface of the boron nitride nanotube.

[0090] Figure 8 This is a graph showing the contact angles of boron nitride nanotubes in Examples and Comparative Examples.

[0091] exist Figure 8 In the present invention, after coating boron nitride nanotubes on a glass substrate, a water droplet is dropped on the glass substrate to measure the contact angle. Figure 8 (1) shows the contact angle of the comparative example, Figure 8 (2) shows the contact angle of Example 1, Figure 8 (3) shows the contact angle of Example 2.

[0092] As a result, for the boron nitride nanotubes without surface treatment (comparative example), Figure 8 As shown in (1), the contact angle is not 140°, and when the first layer is formed on the surface of the boron nitride nanotube (Example 1), as Figure 8 As shown in (2), the contact angle is reduced to 105°. This is the result of the surface treatment of the boron nitride nanotubes to make them hydrophilic based on the first layer.

[0093] In addition, when a second layer is further formed on the surface of the boron nitride nanotube (Example 2), as Figure 8 As shown in (3), the contact angle increases again to 151°. This is because the surface treatment based on the alkyl chain of the second layer makes it hydrophobic.

[0094] Fig. 9 It shows the various solvents Figure 1 Figure 2 shows the dispersion state of boron nitride nanotubes. Fig. 9 The dispersion state of the surface-treated boron nitride nanotubes according to Example 1(2) is shown.

[0095] Fig. 9 (A) is to Figure 7 In the case where the boron nitride nanotubes of Example 1 are dispersed in water and the content of the dispersed boron nitride nanotubes is varied, Fig. 9(B) is the result of dispersing 1 wt % of surface-treated boron nitride nanotubes in water, ethanol, IPA and methanol respectively.

[0096] from Fig. 9 As can be seen from the results, the surface treatment forms a first layer on the surface of the boron nitride nanotubes, which makes them hydrophilic. Fig. 9 It can be seen from (A) and (B) that it is well dispersed in the polar solvent.

[0097] Fig.10 It shows the various solvents Figure 3 Figure 2 shows the dispersion state of boron nitride nanotubes. Fig.10 The dispersion state of the surface-treated boron nitride nanotubes according to Example 2(3) is shown.

[0098] Fig.10 (C) is 1wt% Figure 7 The results of boron nitride nanotubes of Example 2 (3) being dispersed in NMP, DMP, MEK and toluene, respectively, Fig.10 (D) is a case where the boron nitride nanotubes are dispersed in toluene and the content of the boron nitride nanotubes dispersed in each solvent is varied.

[0099] from Fig.10 It can be seen that in the case of Example 2 in which the surface treatment was performed to further form a second layer to make it hydrophobic, it was found that it was well dispersed in the non-polar solvent.

[0100] Fig.11 : is a diagram showing the dispersion state of boron nitride nanotubes without surface treatment in water and toluene.

[0101] Fig.11 Yes Figure 7 The comparative examples were dispersed in water, ethanol and toluene respectively. Fig.11 (E) is the result after dispersing boron nitride nanotubes in water, ethanol and toluene. Fig.11 (F) is the case where the boron nitride nanotubes were dispersed in water, ethanol and toluene and then 1 hour passed.

[0102] In the comparative examples, it was confirmed that the dispersibility of the boron nitride nanotubes without surface treatment in organic solvents and water-soluble solvents was very poor.

[0103] As described above, according to the present invention, the surface of the boron nitride nanotubes can be treated so that the boron nitride nanotubes are dispersed in a polar solvent or a non-polar solvent. In addition, when the surface of the boron nitride nanotubes is treated, water is used as a dispersion medium, so that no organic solvent is used, thus no environmental pollution is caused, and the dispersibility of the boron nitride nanotubes in various solvents is ensured by a simple method, so that the usability of the boron nitride nanotubes in various fields is improved.

[0104] As described above, the present invention has been described with reference to an embodiment shown in the accompanying drawings, but this is only exemplary, and a person skilled in the art will understand that various modifications and variations of the embodiment can be made therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical ideas in the attached claims.

Claims

1. A surface-treated boron nitride nanotube, characterized in that: include: Boron nitride nanotubes; and a first layer located on at least a portion of the surface of the boron nitride nanotubes, The first layer forms a π bond with the boron nitride nanotube, The first layer comprises hydroxyphenyl groups.

2. The surface-treated boron nitride nanotube according to claim 1, characterized in that: The first layer contains at least any one of tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxybiphenyl acid, ellagic acid, and chlorogenic acid as a polyphenol group.

3. The surface-treated boron nitride nanotube according to claim 1, characterized in that: The surface-treated boron nitride nanotubes are hydrophilic.

4. The surface-treated boron nitride nanotube according to claim 1, characterized in that: Also comprising a second layer on the first layer, The second layer includes an amine group or a thiol group based on a hydrocarbon group.

5. The surface-treated boron nitride nanotube according to claim 4, characterized in that: The amine group or thiol group undergoes a Michael addition reaction with the hydroxide group of the first layer.

6. The surface-treated boron nitride nanotube according to claim 4, characterized in that: The second layer includes at least any one of alkylamine, alkylthiol, arylamine, arylthiol, benzylamine, and benzylthiol.

7. The surface-treated boron nitride nanotube according to claim 4, characterized in that: Based on the second layer, the surface-treated boron nitride nanotubes have hydrophobicity.

8. A method for surface treatment of boron nitride nanotubes, characterized in that: include: A step of mixing a first surface treatment agent in water to form a mixed solution; A step of dispersing boron nitride nanotubes in the mixed solution to form a dispersion; and washing the boron nitride nanotubes from the dispersion and drying them, The pH of the dispersion is 8 to 9, A first layer including hydroxyphenyl groups is formed on at least a portion of the surface of the dried boron nitride nanotubes.

9. The surface treatment method of boron nitride nanotubes according to claim 8, characterized in that: The first surface treatment agent includes at least any one of tannic acid, gallic acid, catechol, epigallocatechin, pyrogallol, hexahydroxybiphenyl acid, ellagic acid and chlorogenic acid as a polyphenol group.

10. The surface treatment method of boron nitride nanotubes according to claim 8, characterized in that: The washing and drying steps also include: 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 includes an amine group or a thiol group based on a hydrocarbon group Michael-added to a hydroxide group of the first layer.

11. The surface treatment method of boron nitride nanotubes according to claim 10, characterized in that: The second surface treatment agent includes at least any one of alkylamine, alkylthiol, arylamine, arylthiol, benzylamine and benzylthiol.

12. The surface treatment method of boron nitride nanotubes according to claim 10, characterized in that: Based on the second layer, the boron nitride nanotubes are transformed from hydrophilic to hydrophobic.

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