KR102145538B1 - Method for preparation of functionalized carbon nanotube - Google Patents

Abstract

In the method of manufacturing a functionalized carbon nanotube according to the present invention, a functionalization of the carbon nanotube is possible in a simple and effective method, and the functionalization of the carbon nanotube is possible while maintaining excellent properties without structural changes of the carbon nanotube.

Description

Method for preparation of functionalized carbon nanotube {Method for preparation of functionalized carbon nanotube}

The present invention relates to a method for producing functionalized carbon nanotubes.

Carbon nanotube (CNT) is a material in which a sheet of graphite in which carbon atoms are arranged in a hexagonal shape is rolled into a cylindrical shape to form a hollow tube. These materials are several nanometers (nm) in diameter and tens of micrometers (µm) long. Due to this unique structure, carbon nanotubes exhibit excellent properties such as high strength, elastic modulus, electrical conductivity, thermal conductivity, specific surface area, and aspect ratio. Due to these characteristics, high strength/ultra-light composite materials, field effect transistors , Electrodes, secondary batteries, and ultra-high-capacity capacitors, etc., are expected to have excellent application power, so many studies are being conducted as next-generation future materials.

On the other hand, carbon nanotubes in the form of powder are chemically very stable, and are difficult to disperse because they maintain an agglomerated state by van der Waals attraction caused by a high long-contrast ratio. For this reason, in order to apply carbon nanotubes to a solution process or the like, surface modification through functionalization is required.

Conventionally, carbon nanotubes have been functionalized through a method of chemically treating carbon nanotubes in a strong acid atmosphere or adsorbing single molecules through mechanical milling. However, these functionalization methods are very complicated in the process, and in particular, since they induce defects on the surface of the carbon nanotubes, there is a disadvantage that the inherent characteristics of the carbon nanotubes are greatly degraded. Therefore, it is essential to study a simple and effective functionalization method while maintaining excellent properties without structural changes of carbon nanotubes.

The present invention is to provide a method of manufacturing functionalized carbon nanotubes by a simple and effective functionalization method.

In addition, the present invention is to provide a functionalized carbon nanotube manufactured by the above manufacturing method.

In order to solve the above problems, the present invention provides a method of manufacturing a functionalized carbon nanotube comprising the following steps:

1) preparing a mixture by mixing a carbon nanotube and a salt containing a double bond between carbons; And

2) heat-treating the mixture at 200 to 700°C

In the method of manufacturing a functionalized carbon nanotube of the present invention, when a salt containing a double bond between carbons is activated by breaking a double bond between carbons through heat treatment, the double bond between carbons on the surface of the carbon nanotubes reacts with the adjacent carbon nanotubes. It was conceived that a salt containing a can be functionalized.

Accordingly, the salt containing the double bond between the carbon nanotube and the carbon reacts directly without any other substance, such as a reaction initiator, and thus functionalization can be performed in a simpler method than the conventional carbon nanotube functionalization method. In addition, as a salt including a double bond between carbons is functionalized in the carbon nanotubes, hydrophilic properties are imparted, and the water dispersibility of the carbon nanotubes may be improved.

Therefore, unlike the conventionally known functionalization method of carbon nanotubes, there is an effect that it is possible to functionalize carbon nanotubes while being simple and without impairing the inherent characteristics of carbon nanotubes.

Hereinafter, the present invention will be described in detail for each step.

Carbon nanotubes, and Between carbon Mixing a salt containing a double bond to prepare a mixture (Step 1)

Step 1 is a step of preparing the functionalization of the carbon nanotubes, and is a step of preparing a mixture by mixing the carbon nanotubes and a salt containing a double bond between carbons.

The salt containing a double bond between carbons is a material that enables the functionalization of carbon nanotubes by reacting with carbon nanotubes by activating radicals by the heat treatment in step 2 described later. In addition, the salt containing a double bond between carbons may be functionalized on the carbon nanotubes to impart hydrophilic properties to the carbon nanotubes, thereby improving the water dispersibility of the functionalized carbon nanotubes.

Preferably, as the salt containing a double bond between carbons, a compound represented by the following formula 1 or 2 may be used:

[Formula 1]

In Formula 1,

R ¹ is a single bond; Substituted or unsubstituted C1 to C60 alkylene; Or a substituted or unsubstituted arylene having 6 to 60 carbon atoms,

X ¹ is CO, or SO ₂ ,

M ¹ is an alkali metal,

[Formula 2]

In Formula 2,

R ² is a substituted or unsubstituted alkenylene having 2 to 60 carbon atoms,

X ² is CO, or SO ₂ ,

M ² is an alkali metal.

The compound represented by Formula 1 contains a vinyl group at the terminal, and by the heat treatment in step 2, which will be described later, the radical of the vinyl group is activated to react with the carbon nanotubes to enable the functionalization of the carbon nanotubes. to be.

Preferably, R ¹ is a single bond; Or phenylene.

Preferably, M ¹ is Na or K.

Representative examples of the compound represented by Formula 1 include vinylsulfonic acid sodium salt, sodium acrylate, or 4-styrenesulfonic acid sodium salt. .

In addition, the compound represented by Chemical Formula 2 contains a double bond between carbons in R ² , and the radical of the double bond between carbons is activated by the heat treatment in step 2 to be described later and reacts with the carbon nanotubes to It is a material that enables the functionalization of the tube.

Preferably, R ² is ethenylene (-CH=CH-).

Preferably, M ¹ is Na or K.

Representative examples of the compound represented by Formula 2 include maleic acid sodium salt.

Meanwhile, the salt containing a double bond between carbons is mixed in an amount of 0.1 to 10 parts by weight, or 0.1 to 5 parts by weight, based on 1 part by weight of the carbon nanotubes. When the content is less than 0.1 parts by weight, the degree of functionalization of the carbon nanotubes is insignificant, and when the content exceeds 10 parts by weight, the degree of functionalization of the carbon nanotubes does not substantially increase.

On the other hand, for uniform mixing of the carbon nanotubes and the salt containing a double bond between carbon, a solvent may be used. Since the solvent must be all removed by the heat treatment in step 2, which will be described later, water is preferably used. In addition, after mixing the carbon nanotubes and the salt containing the double bond between carbon using the solvent, it may further include removing the solvent before performing step 2 to be described later.

Heat-treating the mixture (Step 2)

Step 2 is a step of functionalizing carbon nanotubes by heat-treating the mixture prepared in step 1 described above.

In the heat treatment, the heat treatment is performed at a temperature in the range of 200 to 700°C so that the double bond between carbons of the salt including the double bond between carbons is activated and reacts directly with the carbon nanotubes. Preferably, heat treatment is performed in a temperature range of 300 to 650°C, more preferably heat treatment in a temperature range of 400 to 600°C.

In addition, the heat treatment is preferably performed for 1 minute to 5 hours so that the double bonds between carbons of the salt containing the double bonds between carbons are activated to react directly with the carbon nanotubes. More preferably, heat treatment is performed for 5 minutes to 1 hour, or 10 minutes to 30 minutes.

In addition, in the present invention, since the inter-carbon double bond of the salt containing the inter-carbon double bond is activated and reacts directly with the carbon nanotube, the use of a separate reaction initiator is unnecessary. That is, the mixture prepared in step 1 is composed only of a salt containing a double bond between carbon nanotubes and carbon, and does not contain other substances.

On the other hand, after step 2, it may include the step of separating the functionalized carbon nanotubes. The separation may include washing or filtering to remove the remaining material except for the functionalized carbon nanotubes.

Functionalized carbon nanotube

In the functionalized carbon nanotube prepared according to the present invention, a salt containing the double bond between carbons is chemically bonded, for example, covalently bonded to the surface of the carbon nanotube, and thus the functionalized carbon nanotube Increases hydrophilicity. That is, hydrophilic properties are imparted to the carbon nanotubes, thereby increasing dispersibility in a polar solvent.

In addition, since the functionalized carbon nanotubes according to the present invention do not use any other material other than a salt containing a double bond between carbon nanotubes and carbon in the manufacturing process, materials that may impair the properties of carbon nanotubes This is practically not included. Therefore, there is an effect of imparting hydrophilic properties while expressing the unique properties of carbon nanotubes.

Further, unlike the conventional carbon nanotube functionalization method, the present invention enables the functionalization of the carbon nanotube by a simple method, so that the characteristics of the carbon nanotube can be more easily improved.

As described above, in the method of manufacturing functionalized carbon nanotubes according to the present invention, the functionalization of carbon nanotubes is possible in a simple and effective method, and excellent properties are maintained without structural changes of carbon nanotubes. Functionalization is possible.

1 shows TGA and DSC data of sodium vinylsulfonic acid salt used in an example of the present invention.
2 shows TGA and DSC data of a mixture of sodium vinylsulfonic acid and carbon nanotubes used in an example of the present invention.
3 shows the dispersibility of functionalized carbon nanotubes according to an embodiment of the present invention.
4 is a scanning microscope photograph of a functionalized carbon nanotube according to an embodiment of the present invention.
5 shows TGA data of 4-styrene sulfonic acid sodium salt used in an example of the present invention.
6 shows the dispersibility of functionalized carbon nanotubes according to an embodiment of the present invention.

Hereinafter, preferred embodiments are presented to aid understanding of the invention. However, the following examples are only for illustrating the present invention, and the present invention is not limited thereto.

Example One: Vinyl sulfonic acid Sodium salt Functionalization of used carbon nanotubes

(One) Vinyl sulfonic acid Sodium salt TGA And DSC analysis

TGA (Thermo Gravimetric Analyzer) and DSC (Differential Analysis) when the temperature of vinyl sulfonic acid sodium salt (hereinafter referred to as'VS') is raised from room temperature to 800°C at a heating rate of 10°C/min in a nitrogen atmosphere. Scanning Calorimeter) data was measured and shown in FIG. 1.

According to FIG. 1, an exothermic reaction was observed at temperatures of approximately 200°C, 400°C, and 500°C, of which it was confirmed that the thermal decomposition of VS occurred as a mass reduction appeared in the exothermic reactions at 400°C and 500°C. On the other hand, since the exothermic reaction at a temperature of 200°C without mass change is due to an activation reaction induced by breaking a double bond between carbons, it was confirmed that a functionalization reaction occurred in the corresponding temperature range.

(2) Mixing and drying carbon nanotubes and VS

80 g of a solution in which 20 g of VS was dissolved in water was mixed with 2 g of carbon nanotubes in a sonic bath for 20 minutes. Thereafter, the mixture was dried in a vacuum oven at 75° C. to remove water.

(3) Carbon nanotubes and VS TGA And DSC analysis

The TGA and DSC data of the carbon nanotubes and VS mixed and dried in the previous step (2) when the temperature was raised from room temperature to 800° C. at a heating rate of 10° C./min in a nitrogen atmosphere was measured and shown in FIG. .

According to Figure 2, similar to the TGA and DSC results of VS, an exothermic reaction is observed at temperatures of about 200°C, 400°C, and 500°C, of which the exothermic reaction at 200°C is induced by breaking the double bond between carbons. Since it was due to an activation reaction, it was confirmed that the functionalization reaction of CNTs occurred in the corresponding temperature range.

(4) Method for producing functionalized carbon nanotubes

The carbon nanotubes and VS mixed and dried in the previous step (2) were heat-treated at 600° C. for 10 minutes in a tube furnace under an argon gas atmosphere. Thereafter, the product was dispersed in distilled water and vacuum filtered to remove the remaining materials except for the functionalized carbon nanotubes.

(5) Dispersion evaluation

For comparison, carbon nanotubes without functionalization were prepared.

The functionalized carbon nanotubes prepared in the preceding (4) process and the non-functionalized carbon nanotubes were dispersed in distilled water at a concentration of 2 mg/ml, respectively, and the results are shown in FIG. 3.

As shown in FIG. 3, the functionalized carbon nanotubes had excellent water dispersibility, but all of the carbon nanotubes that were not functionalized had precipitation.

In addition, functionalized carbon nanotubes (a) and non-functionalized carbon nanotubes (b) dispersed in distilled water were respectively photographed with a scanning microscope, and the results are shown in FIG. 4.

As shown in FIG. 4, it was confirmed that the functionalized carbon nanotubes had excellent water dispersibility, but the carbon nanotubes that were not functionalized were kept in an agglomerated state.

Example 2: 4 -Styrene sulfonic acid Sodium salt Functionalization of used carbon nanotubes

(1) 4-styrenesulfonic acid Sodium salt TGA analysis

Figure 5 by measuring the TGA data when the temperature of 4-styrenesulfonic acid sodium salt (hereinafter referred to as'SS') was raised from room temperature to 800°C at a heating rate of 10°C/min in a nitrogen atmosphere. Shown in.

(2) Method for producing functionalized carbon nanotubes

2 g of SS and 1 g of carbon nanotubes were mixed with 20 ml of water in a sonic bath for 20 minutes. Thereafter, the mixture was dried in a vacuum oven at 75° C. to remove water. Thereafter, the mixed and dried carbon nanotubes and SS were heat-treated at 400° C. for 10 minutes in a tube electric furnace under an argon gas atmosphere. Thereafter, the product was dispersed in distilled water and vacuum filtered to prepare functionalized carbon nanotubes.

(3) Dispersion evaluation

For comparison, carbon nanotubes without functionalization were prepared.

The functionalized carbon nanotubes prepared above and the carbon nanotubes not functionalized were dispersed in distilled water at a concentration of 2 mg/ml, respectively, and the results are shown in FIG. 6.

As shown in FIG. 6, the functionalized carbon nanotubes (b) had excellent water dispersibility, but all of the carbon nanotubes (a) that were not functionalized had precipitation.

Claims (8)

1) preparing a mixture by mixing a carbon nanotube and a salt containing a double bond between carbons; And
2) The mixture is heat-treated at a temperature of 200 to 700°C to activate the radicals of the double bonds between carbons contained in the salt containing the double bonds between carbons, and the double bonds between carbons in which the radicals are activated are carbon nanotubes. Comprising the step of preparing a functionalized carbon nanotube by reacting with the surface of,
Method for producing functionalized carbon nanotubes.
The method of claim 1,
The salt containing a double bond between carbons is a compound represented by the following formula 1 or 2,
Method for producing functionalized carbon nanotubes:
[Formula 1]

In Formula 1,
R ¹ is a single bond; Substituted or unsubstituted C1 to C60 alkylene; Or a substituted or unsubstituted arylene having 6 to 60 carbon atoms,
X ¹ is CO, or SO ₂ ,
M ¹ is an alkali metal,
[Formula 2]

In Chemical Formula 2,
R ² is a substituted or unsubstituted alkenylene having 2 to 60 carbon atoms,
X ² is CO, or SO ₂ ,
M ² is an alkali metal.
The method of claim 2,
R ¹ is a single bond; Or phenylene,
Method for producing functionalized carbon nanotubes.
The method of claim 2,
Wherein R ² is ethenylene (-CH=CH-),
Method for producing functionalized carbon nanotubes.
The method of claim 1,
The salt containing a double bond between carbons is 4-styrenesulfonic acid sodium salt, sodium acrylate, maleic acid sodium salt, or vinylsulfonic acid sodium salt,
Method for producing functionalized carbon nanotubes.
The method of claim 1,
Mixing the salt containing a double bond between carbons in an amount of 0.1 to 10 parts by weight based on 1 part by weight of the carbon nanotubes,
Method for producing functionalized carbon nanotubes.
The method of claim 1,
The heat treatment of step 2 is performed at a temperature of 300 to 650°C,
Method for producing functionalized carbon nanotubes.
The method of claim 1,
The heat treatment of step 2 is performed for 1 minute to 5 hours,
Method for producing functionalized carbon nanotubes.

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