KR101095874B1 - Method for Dispersing Carbon Nanotubes using Gradient Polymer and the Carbon Nanotubes solution - Google Patents

Abstract

The present invention relates to a method for dispersing carbon nanotubes (CNTs) using gradient polymers and a carbon nanotube dispersion solution prepared by the method, and the solubility and dispersibility of carbon nanotubes in a solvent. It is to improve. According to the present invention, a transition metal complex including a transition metal compound (M _t ^{n +} X _n ) and a ligand (L) with an organic compound containing two different monomers in an solvent is transferred to an atom transfer radical. Gradient polymers are formed using organic radicals formed by Polymerization. Gradient polymers contain aromatics and when dispersed with carbon nanotubes in a solvent, the gradient polymers are non-covalently bonded to the carbon nanotubes to disperse the carbon nanotubes in the solvent.

Gradient polymer, carbon nanotube, dispersion, aqueous solution, non-covalent

Description

Dispersion method of carbon nanotubes using gradient polymers and carbon nanotube dispersion solution prepared by the method {Method for Dispersing Carbon Nanotubes using Gradient Polymer and the Carbon Nanotubes solution}

The present invention relates to a dispersion technique of carbon nanotubes, and more particularly, solubility and dispersibility of carbon nanotubes in a solvent can be improved by non-covalently bonding a gradient polymer containing an aromatic system to the surface of the carbon nanotubes. It relates to a carbon nanotube dispersion method using a gradient polymer and a carbon nanotube dispersion solution prepared by the method.

Since Smalley, a professor at Rice University in 1996, won the Nobel Prize for the discovery of fullerene, carbon has emerged as one of the most noteworthy materials in its nanoscale structure. If the core material of the 20th century was silicon, the core material of the 21st century is expected to be carbon. Of these, carbon nanotubes (CNTs) are materials of great industrial applicability in the fields of electronic information communication, environment, energy, and medicine due to their perfect properties and structure, and are important building blocks to lead nanoscience in the future. Expecting.

Carbon nanotubes have a graphite sheet (cylindrical sheet) in the form of a cylinder of nano size diameter, and has a sp2 bonding structure. The graphite surface exhibits the characteristics of a conductor or a semiconductor depending on the angle and structure at which it is curled. Single-walled carbon nanotubes (SWCNTs) also depend on the number of bonds in the wall. Double-walled carbon nanotubes (DWCNT), multi-walled carbon nanotubes (MWCNT) can be classified into a bundle of carbon nanotubes (rope carbon nanotubes). In particular, SWCNTs have a variety of metallic and semiconducting properties to represent a variety of electrical, chemical, physical and optical properties. These features enable more sophisticated and integrated devices. Applications of carbon nanotubes currently being studied include transparent electrodes, electrostatic dispersion films, field emission devices, surface heating elements, optoelectronic devices, various sensors, and transistors.

However, despite the usefulness of such carbon nanotubes, carbon nanotubes have a problem in that their use is limited due to low solubility and low dispersibility. The reason is that carbon nanotubes do not form a stable dispersion state in aqueous solution due to strong van der Waals attractive forces, and coagulation occurs.

Accordingly, it is an object of the present invention to provide a method for dispersing carbon nanotubes using gradient polymers and carbon nanotube dispersion solutions prepared by the method, which can improve solubility and dispersibility in the solution of carbon nanotubes. .

In order to achieve the above object, the present invention is to prepare an organic compound which can form organic radicals by atomic transfer radical polymerization and comprises two different monomers, the prepared organic compound, transition metal compound (M _t ^{n +} X _n ) a mixing step of mixing a transition metal complex containing a ligand (L) with a solvent, the organic compound and the transition metal complex react with each other by an atomic transfer radical polymerization to form an organic radical, and the organic radical Forming step of polymerizing two different monomers of the mixture by using to form a gradient polymer (gradient polymer), dissolving the gradient polymer in a solvent to put the carbon nanotubes dispersed, the gradient polymer and the carbon nanotubes Gradient polymers comprising a dispersion step of dispersing the carbon nanotubes in the solvent by the non-covalent bond Using the method provides a dispersion of carbon nanotubes.

In the carbon nanotube dispersion method according to the present invention, the organic compound includes an aromatic monomer. The organic compound is a low molecular organic compound or a high molecular organic compound. And the organic compound is a halogen element including Cl, Br and I, alkoxy, SR ¹ , SeR ¹ , OC (= O) R ¹ , OP (= O) R ¹ , OP (= O) (OR ¹ ) ₂ , OP (═O) OR ¹ , ON (R ¹ ) ₂ and SC (= S) N (R ¹ ) ₂ . Wherein R ¹ is aryl or a carbon number of from 1 to 20 linear or branched alkyl, N (R ¹⁾ is two R ¹ eseo ₂ are connected to each other may include a 5, 6, or 7-atoms consisting of heterocyclic .

In the carbon nanotube dispersion method according to the present invention, the carbon nanotubes are single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes. One of the tubes (MWCNT) or multi-walled carbon nanotubes (rope carbon nanotubes).

In the carbon nanotube dispersion method according to the present invention, the transition metal (M _t ^{n +} ) constituting the transition metal compound is Cu ¹⁺ , Cu ²⁺ , Fe ²⁺ , Fe ³⁺ , Ru ²⁺ , Ru ³⁺ , Cr ²⁺ , Cr ³⁺ , Mo ⁰ , Mo ⁺ , Mo ²⁺ , Mo ³⁺ , W ²⁺ , W ³⁺ , Rh ³⁺ , Rh ⁴⁺ , Co ⁺ , Co ²⁺ , Re ²⁺ , From the group consisting of Re ³⁺ , Ni ⁰ , Ni ⁺ , Mn ³⁺ , Mn ⁴⁺ , V ²⁺ , V ³⁺ , Zn ⁺ , Zn ²⁺ , Au ⁺ , Au ²⁺ , Ag ⁺ and Ag ²⁺ It is either chosen. X is halogen, alkoxy having 1 to 6 carbon atoms, (SO ₄ ) _1/2 , (PO ₄ ) _1/3 , (HPO ₄ ) _1/2 , (H ₂ PO ₄ ), triflate, hexafluoro Phosphate, methanesulfonate, arylsulfonate, SeR ¹ , CN and R ² CO ₂ . Wherein R ¹ is aryl or a straight or branched alkyl group having 1 to 20 carbon atoms, R ² is H or a straight or branched alkyl group having 1 to 6 carbon atoms, and n is a formal charge of a transition metal, 0 ≦ n ≦ 7 to be.

In the carbon nanotube dispersion method according to the present invention, a solvent which does not cause a radical transfer reaction may be used as a solvent of the carbon nanotube solution. That is, any solvent selected from the group consisting of aromatics such as benzene, toluene, anisole, dichloro benzene, alcohols, water, THF, acetone and ethyl acetate may be used.

The present invention also provides a carbon nanotube dispersion solution prepared by the carbon nanotube dispersion method described above.

According to the present invention, the gradient polymer comprising an aromatic system is non-covalently bonded to the carbon nanotubes without surface modification of the carbon nanotubes, thereby smoothly dispersing the carbon nanotubes in the solvent, and dissolution and dispersibility of the carbon nanotubes in the solvent. Can improve.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention.

In the method for dispersing carbon nanotubes using the gradient polymer according to the present invention, as shown in FIG. 1, a preparation step of preparing an organic compound which may form organic radicals and includes two different monolayers (S11) , By mixing the prepared organic compound, the transition metal complex (M _t ^{n +} X _n ) and the transition metal complex including the ligand (L) in a solvent (S13), by using an organic radical formed by atom transfer radical polymerization Forming step (S15) of polymerizing two different monomers of the mixture to form a gradient polymer (S15), and dissolving the gradient polymer in a solvent to add carbon nanotubes, the gradient polymer and carbon nanotubes are non-covalently bonded. It comprises a dispersion step (S17) for dispersing the carbon nanotubes in a solvent.

Thus, according to the dispersion method of carbon nanotubes according to the present invention, in the step of dispersing (S17), the gradient polymers are non-covalently bonded to the carbon nanotubes without surface modification of the carbon nanotubes to smoothly disperse the carbon nanotubes in the solvent. To improve the solubility and dispersibility of carbon nanotubes in the interior.

Hereinafter, the carbon nanotube dispersion method using the gradient polymer according to the present invention will be described in detail.

First, the reason for using the gradient polymer in the carbon nanotube dispersion method is as follows. The surface of carbon nanotubes is composed of hexagonal graphite structure, which can interact with π electrons with molecules made of aromatic hydrocarbons such as pyrene, porphyrin and conjugated polymers. Therefore, the gradient polymer containing aromatic system forms non-covalent defects on the surface of the carbon nanotubes by the π-stacking (π-π) interaction with the aromatic ring structure on the surface of the carbon nanotubes, This is because it enhances the dispersion effect of carbon nanotubes without damaging them and obtains a multifunctional effect by forming a composite of carbon nanotubes and a polymer.

That is, in the present invention, the gradient polymer for dispersing the carbon nanotubes sequentially polymerizes the monomers to the polymer chain by using the difference in the initiation rate of the monomers. Gradient polymers have the advantages of block polymers and random polymers. In addition, the gradient polymer has a different composition of the repeating monomers sequentially, so that the repulsive force between the repeating units is less depending on the polymer chain. Therefore, high conversion rate and efficient fusion occur. And even in poorly mixed block polymer composites, gradient polymers are being used as better commercial materials. By using the gradient polymer of this characteristic, it is possible to obtain a result of further enhancing the dispersion effect of carbon nanotubes. In order to improve the dispersion stability, the dispersion stability of carbon nanotubes can be improved by synthesizing gradient polymers having aromatic ring structures that strongly adsorb carbon nanotubes.

In the method for dispersing carbon nanotubes according to the present invention, an organic radical may be formed by atomic transfer radical polymerization, and an organic compound including two different monomers is prepared (S11). Two different monomers of the organic compound include an aromatic monomer represented by the following formula (1).

Here, the organic compound refers to an organic compound capable of forming an organic radical by an atomic transfer reaction with a transition metal complex, and is not particularly limited as long as it has such characteristics, and includes both low molecular organic compounds and high molecular organic compounds. That is, two different monomers of an organic compound may form a gradient polymer by undergoing an atomic transfer reaction with a transition metal complex (S13, S15), and the gradient polymer finally forms a non-covalent bond on the surface of the carbon nanotube. By modifying the surface of the carbon nanotubes serves to improve the solubility and dispersibility of the carbon nanotubes.

The molecular weight and various functional groups of the organic compound may be variously changed depending on the use of carbon nanotubes. That is, it is not particularly limited as long as it can form an organic radical by an atomic transfer reaction. For example, it may be a low molecular organic compound or a high molecular organic compound. In particular, the structure of the organic compound should include a functional group capable of forming a radical by an atomic transfer reaction. Examples of such functional groups include halogen elements such as Cl, Br, I, alkoxy, SR ¹ , SeR ¹ , OC (= O) R ¹ , OP (= O) R ¹ , OP (= O) (OR ¹ ) ₂ , OP (= O) OR ¹ , ON (R ¹ ) ₂ , SC (= S) N (R ¹ ) _2, etc. there, where R ¹ can be an aryl or a carbon number of 1 to 20 linear or branched alkyl, N ^{(R. 1)} both of R ¹ ₂ are connected to each other eseo 5, 6, or 7-atoms consisting of heterocyclic . In addition, the structure of the organic compound may include various functional groups that can improve the solubility and dispersibility of the carbon nanotubes. Such organic compounds may be generally used commercially available products, or may be prepared by various synthetic methods.

Here, in the case of the polymer organic compound, the production method is not limited, and depending on the use, the physical properties such as molecular weight may be appropriately adjusted or selected according to the use, such as atom transfer with a transition metal complex at the end of the polymer chain. The functional group which can form a radical by reaction should just be bonded. Examples of such functional groups are as described above. In addition, such a high molecular compound is not limited to the kind such as homopolymer, copolymer, block copolymer.

When the gradient polymer is prepared, the carbon nanotubes to be dispersed are dispersed together with the solvent using an ultrasonic disperser (S17).
Here, the atomic transfer radical polymerization proceeding in the forming step (S15) may be represented by the following formula (2).

RY + M _t ^{n +} X _n / L → R + Y ^- M _t ^{n + 1} X _n / L

In Formula 2, RY represents an organic compound, and Y represents a functional group capable of forming an organic radical (R) by an atomic transfer reaction with a transition metal complex. In addition, M _t ^{n +} X _n / L represents a transition metal complex, M _t ^{n +} X _n represents a transition metal compound, M _t represents a transition metal, X represents an anion component bonded to the transition metal, n is the transition metal It is a formal charge and L means a ligand.

At this time, the solvent is not limited so long as it is a solvent causing a radical transfer reaction. For example, as the solvent, aromatics such as benzene, toluene, anisole, dichloro benzene, alcohols, water, THF, acetone, ethyl acetate and the like can be used, but are not limited thereto.

Carbon nanotubes are single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs) or bundles. One of the carbon nanotubes (rope carbon nanotube).

The transition metal complex consists of a transition metal compound (M _t ^{n +} X _n ) and a ligand (L). The transition metal complex serves to form organic radicals by atom transport reaction with the organic compound. The transition metal complex is not particularly limited as long as it can undergo an atomic transfer reaction. Examples of the transition metal (M _t ^{n +} ) include Cu ¹⁺ , Cu ²⁺ , Fe ²⁺ , Fe ³⁺ , Ru ²⁺ , and Ru ^3+. , Cr ²⁺ , Cr ³⁺ , Mo ⁰ , Mo ⁺ , Mo ²⁺ , Mo ³⁺ , W ²⁺ , W ³⁺ , Rh ³⁺ , Rh ⁴⁺ , Co ⁺ , Co ²⁺ , Re ²⁺ , Re ³⁺ , Ni ⁰ , Ni ⁺ , Mn ³⁺ , Mn ⁴⁺ , V ²⁺ , V ³⁺ , Zn ⁺ , Zn ²⁺ , Au ⁺ , Au ²⁺ , Ag ⁺ , Ag ^2+, and the like. These may be used by mixing one or more kinds, but are not limited thereto. X which is an anion component bonded with the transition metal is not particularly limited as long as it can be combined with the transition metal within the scope of the present invention. For example halogen, alkoxy having 1 to 6 carbon atoms, (SO ₄ ) _1/2 , (PO ₄ ) _1/3 , (HPO ₄ ) _1/2 , (H ₂ PO ₄ ), triflate, hexafluorophosphate , Methanesulfonate, arylsulfonate, SeR ¹ , CN, R ² CO _{2 and the} like, R ¹ is as described above, R ² is H or a straight or branched alkyl group having 1 to 6 carbon atoms. In the transition metal compound, n is the formal charge of the transition metal, for example, 0 ≦ n ≦ 7.

The ligand (L), which forms a complex with the transition metal compound, is not particularly limited as long as it has an appropriate atomic mobility reaction rate. For example, a ligand containing one or more nitrogen, oxygen, phosphorus and / or sulfur atoms is coordinated with the transition metal via σ bond. In addition, ligands containing two or more carbon atoms are coordinated with the transition metal via π bond. Furthermore, ligands that coordinate with a transition metal via μ or η bond are also included. Such ligand is not particularly limited as long as it is a ligand capable of having an appropriate atomic transfer reaction rate. In such a reaction mixture, further reducing materials may be added as necessary to promote the reaction and regenerate the transition metal complex by reduction, and as a preferred example, a reducing metal powder such as copper powder may be further added. In this case, the transition metal complex may act as a catalyst. In addition, various additives known to those skilled in the art may be further included within the scope of the present invention.

Gradient polymers containing aromatics form non-covalent bonds on the surface of the carbon nanotubes by the cyclic ring interaction with the aromatic ring structure on the surface of the carbon nanotubes, thereby avoiding damage to the surface of the carbon nanotubes. Ensure good dispersion in solvent. In addition, as a characteristic of the gradient polymer structure, it is possible to form an improved composite structure with carbon nanotubes due to less repulsive force of monomer repeating units than random and block polymers. After completion of the reaction, the solid component is filtered, the solid filtered with an appropriate solvent is well washed, and then dried by an appropriate method to obtain a carbon nanotube complex non-covalently bound to an organic compound. In this case, a method of drying under vacuum may also be used.

A method of dispersing carbon nanotubes using gradient polymers according to an embodiment of the present invention will be described with reference to FIGS. 2 to 6. Since the embodiments of the present invention are provided only for the purpose of more fully illustrating the present invention to those skilled in the art, the scope of the present invention is limited to the embodiments described below. It should be clear that it should not be interpreted.

First, in the present embodiment, a gradient molecule of P (PEGMA) -grad-PS is used as the carbon nanotube dispersant.

PEG is a hydrophilic polymer and can be dispersed in water, and is widely used in biodegradable polymers. PEG has a variety of functions in the polymer. As a result of the study on the molecular weight of PEG, as a result of increasing the molecular weight of PEG, the result of the research that the ion conductivity increases is reported, and actually used as an important material in the solar cell field.

Synthesis of P (PEGMA) -grad-PS can be carried out as follows. At this time, the polymerization reaction in which the synthesis of P (PEGMA) -grad-PS can be represented by Chemical Formula 3, and the compounds used are shown in Table 1.

Put PEGMA (Mn: 475, 2ml, 2.55mmol), Styrene (2ml, 17.4mmol), Anisole (2ml) into the dried 15ml Schlenk flask. The oxygen was removed by repeating the Schlenk flask five times in the order of freeze-pump-thaw. After 5 freeze-pump-thaw cycles, nitrogen was added to the Schlenk flask, followed by 3 times of CuCl (22.5mg, 0.227mmol) and 2,2-bipyridine (71.1mg. 0.455mmol), followed by freeze-pump-thaw. do. Place Schlenk flask in an oil bath with a temperature of 130˚C and add initiator, Ethyl 2-bromoisobutylate (33.75ul, 0.227mmol). After sealing the flask, connect the oil pump with a rubber tube and apply vacuum. After 9 hours, the reaction solution was diluted with THF and flown into alumina-filled glass to remove Cu. The solution from which Cu has been removed is removed with THF using an evaporator. And wash with diisopropyl ether several times to remove the remaining monomers. Put the final P (PEGMA) -grad-PS into the vacuum oven for 24 hours and remove the remaining solvent.

Name ratio Quantity mmol mg / mmol g / ml monomer1 PEGMA 20 2ml 4.55 475.0000 1.0800 monomer2 styrene 75 2ml 17.40 104.1500 0.9070 initiator EBiB One 34.44ul 0.23 195.0600 1.3150 catalyst CuCl One 22.5mg 0.23 98.9900 ligand bpy 2 71.1mg 0.46 156.1900 solvent Anisole 2ml

At this time, through the polymerization rate graph of P (PEGMA) -grad-PS shown in Figure 2, it can be seen that the polymerization proceeds faster than PEGMA Styrene. The molecular weight change of the synthesized P (PEGMA) -grad-PS can be confirmed through the illustrated GPC data of FIG. 3. And it can be confirmed through the NMR data shown in Figure 4 that P (PEGMA) -grad-PS was properly synthesized by the present synthesis method.

The CNT dispersion process using gradient polymer (P (PEGMA) -grad-PS) is as follows.

First, carbon nanotubes (SWCNT, MWCNT, Iljin Nanotech, 5mg) are placed in a 40ml vial bottle. P (PEGMA) -grad-PS (5mg) was added to another 40ml vial bottle, and P (PEGMA) -grad-PS was dissolved in a sonicator by adding 10ml of THF and primary distilled water in a 1: 1 ratio. 5 and 6, the dissolved polymer solution is placed in a vial bottle containing carbon nanotubes using a syringe, and then dispersed for 90 minutes using a sonicator. In this case, it can be confirmed through FIG. 5 and FIG. 6 that carbon nanotubes are uniformly dispersed in distilled water. In addition, as shown in Figure 5 and 6, the carbon nanotubes can be confirmed that the dispersion is not agglomerated by non-covalent bond with P (PEGMA) -grad-PS. In FIG. 5 and FIG. 6, SWCNT is used as the carbon nanotube on the left side and MWCNT is used as the carbon nanotube on the right side.

On the other hand, the embodiments of the present invention disclosed in the specification and drawings are merely presented specific examples to aid understanding, and are not intended to limit the scope of the present invention. In addition to the embodiments disclosed herein, it is apparent to those skilled in the art that other modifications based on the technical idea of the present invention may be implemented.

1 is a flowchart showing a method of dispersing carbon nanotubes using a gradient polymer according to an embodiment of the present invention.

2 is a graph showing the polymerization rate according to the synthesis time of the gradient polymer in the dispersion method of FIG.

3 is a graph showing the molecular weight change of the gradient polymer synthesized according to the dispersion method of FIG.

4 is structural analysis (NMR) result data of gradient polymers synthesized according to the dispersion method of FIG. 1.

5 is a photograph showing a carbon nanotube dispersion solution prepared according to the dispersion method of FIG.

6 is a transmission electron microscope (TEM) photograph of carbon nanotubes dispersed in a carbon nanotube dispersion solution prepared according to the dispersion method of FIG. 1.

Claims (8)

Preparing an organic compound which can form organic radicals by atom transfer radical polymerization and comprises two different monomers; A mixing step of mixing the prepared organic compound, a transition metal compound (M _t ^{n +} X _n ) and a ligand (L) with a first solvent to form a mixture; Forming an organic radical by reacting the organic compound with the transition metal complex according to an atomic transfer radical polymerization, and polymerizing two different monomers of the mixture using the organic radical to form a gradient polymer; And dispersing the gradient polymer and carbon nanotubes in a second solvent, wherein the gradient polymer and the carbon nanotubes are non-covalently bonded to disperse the carbon nanotubes in the second solvent. In the preparation step, Two different monomers of the organic compound dispersion method of carbon nanotubes using a gradient polymer, characterized in that it comprises an aromatic monomer represented by the following formula.

delete The method of claim 1, The organic compound is PEGMA and Styrene, the gradient polymer is P (PEGMA) -grad-PS characterized in that the dispersion of carbon nanotubes using a gradient polymer. The method of claim 1, The organic compound may be a halogen element including Cl, Br and I, alkoxy, SR ¹ , SeR ¹ , OC (= 0) R ¹ , OP (= 0) R ¹ , OP (= 0) (OR ¹ ) ₂ , OP (= O) OR ¹ , ON (R ¹ ) _2, and SC (= S) N (R ¹ ) ₂ and any one group selected from the group consisting of: Wherein R ¹ is aryl or a carbon number of from 1 to 20 linear or branched alkyl, N (R ¹⁾ two of R ¹ eseo ₂ are connected to each other; and a heterocyclic ring comprising 5, 6, or 7 atoms Dispersion method of carbon nanotubes using a gradient polymer. 5. The method of claim 4, The carbon nanotubes are single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs) or bundles. Dispersion method of carbon nanotubes using a gradient polymer, characterized in that one of the type carbon nanotubes (rope carbon nanotube). The method of claim 1, The transition metal (M _t ^{n +} ) constituting the transition metal compound is Cu ¹⁺ , Cu ²⁺ , Fe ²⁺ , Fe ³⁺ , Ru ²⁺ , Ru ³⁺ , Cr ²⁺ , Cr ³⁺ , Mo ⁰ , Mo ⁺ , Mo ²⁺ , Mo ³⁺ , W ²⁺ , W ³⁺ , Rh ³⁺ , Rh ⁴⁺ , Co ⁺ , Co ²⁺ , Re ²⁺ , Re ³⁺ , Ni ⁰ , Ni ⁺ , Mn ³⁺ , Mn ⁴⁺ , V ²⁺ , V ³⁺ , Zn ⁺ , Zn ²⁺ , Au ⁺ , Au ²⁺ , Ag ⁺ and Ag ²⁺ , and any one selected from the group consisting of X is halogen, alkoxy having 1 to 6 carbon atoms, (SO ₄ ) _1/2 , (PO ₄ ) _1/3 , (HPO ₄ ) _1/2 , (H ₂ PO ₄ ), triflate, hexafluorophosphate , Methanesulfonate, arylsulfonate, SeR ¹ , CN and R ² CO _{2 It} is any one selected from the group consisting of, R ¹ is aryl or a straight or branched alkyl group having 1 to 20 carbon atoms, R ² is H or a straight or branched alkyl group having 1 to 6 carbon atoms, n is a formal charge of a transition metal, and 0 ≦ n ≦ 7. Dispersion method of carbon nanotubes using a gradient polymer, characterized in that. The method of claim 1, wherein in the dispersing step, The second solvent is a solvent that does not cause a radical transfer reaction, any one selected from the group consisting of aromatics such as benzene, toluene, anisole, dichlorobenzene, alcohols, water, THF, acetone and ethyl acetate Dispersion method of carbon nanotubes using a gradient polymer, characterized in that the. A carbon nanotube dispersion solution prepared by the dispersion method according to claim 1.

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