KR101151737B1 - Method for preparating of chemically treated carbon nanotube/polyvinylidene fluoride nanocomposite - Google Patents

Abstract

The present invention relates to a poly (vinylidene fluoride) nanocomposite filled with carbon nanotubes chemically treated and a method for preparing the same. More specifically, the present invention relates to a polyfilled carbon nanotube surface-treated hydrophilically by chemical treatment. (Vinylidene fluoride) It relates to a nanocomposite and a method for producing the same.

Poly (vinylidene fluoride) nanocomposites filled with carbon nanotubes surface-treated hydrophilically by the chemical treatment of the present invention are conventional poly (vinylidene fluoride) nanoparticles containing carbon nanotubes surface-treated by acid treatment. Compared with the composite material, the electrical conductivity and thermal properties are uniformly increased, and the mechanical properties are greatly improved, thereby enabling the production of carbon nanotubes / polymer nanocomposites having excellent physical properties.

Description

Chemically treated carbon nanotubes / poly (vinylidene fluoride) nanocomposites and methods for preparing the same {Method for preparating of chemically treated carbon nanotube / poly (vinylidene fluoride) nanocomposite}

The present invention relates to a chemically treated carbon nanotube / poly (vinylidene fluoride) nanocomposite and a method for preparing the same, and more particularly, to poly (vinylidene) filled with carbon nanotubes surface-treated hydrophilically by chemical treatment. Fluoride) nanocomposites and methods for their preparation.

Recently, with the advancement of advanced technology, the demand for high functionalization of materials is urgently raised, and accordingly, interest in the existing material industry is continuously increasing.

However, traditional materials already exhibit many problems and limitations in their performance and function. Thus, one of the effective ways to overcome them is to combine different materials, such as organic-inorganic hybrid materials, to function and perform their functions. Efforts are being made to gain synergies from the company. In particular, as an alternative to significantly improve the physical properties of existing materials, research into polymer nanocomposites that combine carbon nanotubes discovered by Iijima in 1991 with existing materials is being actively conducted.

Carbon nanotubes are extremely fine cylindrical materials with aspect ratios ranging from tens to thousands, generally having diameters of several nm to tens of nm and lengths of several to several hundred micrometers. Thermal conductivity close to twice that of diamond and 1,000 times higher current transfer capability compared to copper, making them suitable for all engineering applications, including nanoscale electrical, electronic devices, nanosensors, optoelectronic devices, and high-performance composites This is estimated to be very high. Therefore, attention has been focused on the development of polymer composite materials based on carbon nanotubes using the innovative properties of such carbon nanotubes.

In the production of carbon nanotube / polymer composite materials, uniform dispersion of carbon nanocubes in the polymer matrix, penetration and adhesion between the carbon nanotubes and the polymer matrix are important problems in the manufacturing process of the carbon nanocomposite material. However, impurities such as metal catalyst particles, amorphous carbon, graphite, spheroidal fullerene, etc. are present in carbon nanotubes, which not only deteriorates the dispersing properties but also deteriorates mechanical and electrical properties when polymerized. . In addition, the development of nanocomposites has been delayed because the existing process cannot solve the problem of heterogeneous dispersion and mixing of carbon nanotubes in existing materials due to the strong cohesion of carbon nanotubes.

Accordingly, the present inventors have made diligent efforts to prepare a polymer nanocomposite having significantly improved conductivity, thermal and mechanical properties of the polymer composite material by improving the dispersibility of the carbon nanotubes described above and the adhesion between the polymer matrix and the carbon nanotubes. The nanocomposite was prepared using carbon nanotubes and poly (vinylidene fluoride) surface-treated hydrophilically to complete the present invention.

After all, the present invention has been made to solve the above problems, an object of the present invention is to provide a chemically treated carbon nanotube / poly (vinylidene fluoride) nanocomposite and a method of manufacturing the same.

In order to achieve the above object, the present invention provides a chemically treated carbon nanotube / poly (vinylidene fluoride) nanocomposite and a method of manufacturing the same.

Nanocomposites according to the present invention (1) to produce a carbon nanotube having a hydrophilic functional group by chemical treatment; (2) dispersing the carbon nanotubes in a poly (vinylidene fluoride) solution; And (3) preparing carbon nanotubes / poly (vinylidene fluoride) nanocomposites; It characterized in that the manufacturing process including.

Hereinafter, each component and the preparation method of the nanocomposite of the present invention will be described in detail step by step.

The present invention provides a poly (vinylidene fluoride) nanocomposite filled with carbon nanotubes chemically treated.

In the present invention, the carbon nanotubes are activated carbon, activated carbon fibers, pitch-based nanofibers, graphite, single-walled carbon nanotubes (multi-walled carbon nanotubes) It is preferable to use at least one selected from the above, more preferably a multi-walled carbon nanotube having an average diameter of 10 to 30 nm, length of 10 to 50 ㎛.

In addition, the carbon nanotubes are immersed in an acid solution and stirred at 60 ° C. for 12 to 24 hours to prepare carbon nanotubes having a carboxyl group on the surface thereof, and then washed with distilled water, dried, and completely dried with thionyl chloride. (AcCl ₂ ) is preferably acylated by reacting at 70 ℃ for 24 hours, the acylated carbon nanotubes are washed with tetrahydrofuran (THF) and ethanol and dried in a vacuum oven at room temperature, dried Carbon nanotubes may be added to the surface treatment solution and reacted at 60 ° C. for 12 hours, followed by washing and drying to finally prepare carbon nanotubes that have been hydrophilically surface treated (that is, having a hydrophilic functional group on the surface). In this case, the acid solution is preferably selected from sulfuric acid (H ₂ SO ₄ ), nitric acid (HNO ₃ ), phosphoric acid (H ₃ PO ₄ ), hydrochloric acid (HCl), hydrogen peroxide (H ₂ O ₂ ) and a mixed solution thereof. More preferably, it is preferable to use a mixed solution in which sulfuric acid and nitric acid are mixed at a weight ratio of 3: 1 to 1: 3. In addition, the surface treatment solution may use ethylene glycol, 1,5-pentadiol, 1.6- hexanediol having a hydrophilicity and hydrophobicity at the same time, the surface of the carbon nanotubes chemically treated as described above to the general acid treatment Compared to the surface-treated carbon nanotubes, hydrophilic functional groups are further increased, and compatibility with hydrophobic polymers can be controlled according to the carbon length between both hydroxyl groups.

 The carbon nanotube / poly (vinylidene fluoride) nanocomposite of the present invention is a carbon nanotube treated with a chemical surface treatment as described above in a range of 0.1 to 5 parts by weight based on 100 parts by weight of poly (vinylidene fluoride) as a filler. It can be prepared by mixing. In this case, in order to disperse the carbon nanotubes evenly in poly (vinylidene fluoride), dissolving poly (vinylidene fluoride) in dimethylformamide as a polar solvent and sonicating for 1 to 3 hours to mix the solution desirable.

This is to improve the dispersibility of the hydrophilic surface-treated carbon nanotubes in the polar solvent, the agglomeration of carbon nanotubes reduces the interfacial bonding force between poly (vinylidene fluoride) and carbon nanotubes, eventually affecting the physical properties of the nanocomposite This can have a big impact. In addition, in the present invention, by changing the content of the carbon nanotubes, the conductivity, thermal and mechanical properties of the nanocomposite may be adjusted according to the application. In addition, although poly (vinylidene fluoride) is used as the polymer base in the present invention, the polymer is not limited thereto and has excellent dielectric constant and is soluble in a polar solvent.

In addition, the poly (vinylidene fluoride) nanocomposite filled with the carbon nanotubes chemically treated in the present invention may be manufactured in a film form using a simple film casting method. The carbon nanotube / poly (vinylidene fluoride) film is preferably dried for about two days in a vacuum oven at 60 ℃ to remove the residual solvent.

The carbon nanotubes / poly (vinylidene fluoride) nanocomposites thus prepared are characterized by electrical conductivity of 3 × 10 ⁻³ to 5 × 10 ⁻¹ S / cm and tensile strength of 20 to 50 MPa.

The present invention has an effect of providing a carbon nanotube with an increased hydrophilic functional group on the surface of the carbon nanotube through an additional chemical treatment to the acid treatment method of conventional carbon nanotubes.

In addition, poly (vinylidene fluoride) nanocomposites filled with carbon nanotubes surface-treated hydrophilically by chemical treatment as described above are poly (vinylidene fluorides) containing carbon nanotubes surface-treated by conventional acid treatment. Compared to nanocomposites, the electrical conductivity and thermal properties are increased uniformly, and the mechanical properties are greatly improved, making it possible to manufacture carbon nanotubes / polymer nanocomposites with excellent physical properties.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these examples are for illustrative purposes only and that the scope of the present invention is not construed as being limited by these examples.

Measurement Example 1. Measurement of Surface Properties

Changes in the surface properties of the carbon nanotubes prepared according to the present invention were measured using an X-ray photoelectron spectroscopy (K-Alpha, Thermo Scientific, USA).

Measurement Example 2 Measurement of Electrical Conductivity of Carbon Nanotube / Poly (vinylidene Fluoride) Film

In order to check the conductivity according to the content of carbon nanotubes of the carbon nanotubes / poly (vinylidene fluoride) film prepared according to the present invention, using a digital multi-meter (MCP-T610, Mitsubishi Chem., Japan) at room temperature Electrical conductivity was measured at.

Measurement Example 3 Measurement of Glass Transition Melt Temperature and Heat Capacity of Carbon Nanotube / Poly (vinylidene Fluoride) Film

In order to check the thermal properties according to the content of carbon nanotubes of the carbon nanotubes / poly (vinylidene fluoride) film prepared according to the present invention, using differential scanning calorimetry (DSC200F3, NETZSCH, Germany), The glass transition melting temperature (T _m ) and heat capacity (ΔH _m ) were measured in a temperature range of 30 to 300 ° C. under a nitrogen atmosphere at a temperature rising rate of 10 ° C./min.

Measurement Example 4 Measurement of Tensile Strength of Carbon Nanotube / Poly (vinylidene Fluoride) Film

In order to check the mechanical properties according to the content of carbon nanotubes of the carbon nanotubes / poly (vinylidene fluoride) films prepared according to the present invention, a universal test machine (Lloyd LR5K, LLOYD, UK) was used. Tensile strength was measured.

Example 1.

1-1. Preparation of Chemical Surface Treated Carbon Nanotubes

After multi-walled carbon nanotubes (Nanosolution, average diameter: 10 ~ 20 ㎚ / average length: 50 ㎛) was immersed in a mixed solution mixed with a weight ratio of sulfuric acid and nitric acid 3: 1, and reacted at 60 ℃ for 12 hours Washed with distilled water and dried in an oven for 8 hours. When completely dried, it is added to thionyl chloride (SOCl ₂ ) and reacted at 70 ° C. for 24 hours, followed by washing. After drying in a vacuum oven at room temperature, it is added to ethylene glycol and reacted at 60 ° C. for 12 hours, followed by washing and drying. To prepare a carbon nanotube surface treatment.

1-2. Preparation of Carbon Nanotube / Poly (Vinylidene Fluoride) Nanocomposites

Then, after dissolving poly (vinylidene fluoride) in dimethylformamide, 0.5 parts by weight of the hydrophilic surface-treated carbon nanotubes were added to 100 parts by weight of poly (vinylidene fluoride), and the uniformity of the carbon nanotubes was The carbon nanotube / poly (vinylidene fluoride) mixture was sonicated for about 3 hours for one dispersion. The mixed solution was prepared into a film having a thickness of about 70 μm through film casting and solvent evaporation, and then dried in a vacuum oven at 60 ° C. for about 2 days to remove residual solvent in the film, thereby preparing a final film.

Example 2.

A carbon nanotube / poly (vinylidene fluoride) film was prepared by the same process as in Example 1, but adding 1 part by weight based on 100 parts by weight of the poly (vinylidene fluoride) chemically treated carbon nanotubes. It was.

Example 3.

A carbon nanotube / poly (vinylidene fluoride) film was prepared in the same manner as in Example 1, except that 2 parts by weight of carbon nanotubes having chemical surface treatment were added to 100 parts by weight of poly (vinylidene fluoride). It was.

Example 4.

A carbon nanotube / poly (vinylidene fluoride) film was prepared in the same manner as in Example 1, except that 3 parts by weight of carbon nanotubes having chemical surface treatment were added to 100 parts by weight of poly (vinylidene fluoride). It was.

Comparative Example 1.

After dissolving poly (vinylidene fluoride) in dimethylformamide, it was made into a film having a thickness of about 70 μm through film casting and solvent evaporation without adding chemical surface treated carbon nanotubes, and then in a vacuum oven at 60 ° C. Drying was performed for about 2 days to remove residual solvent in the film to prepare a final film.

Comparative Examples 2-5.

Poly (vinylidene fluoride) was prepared by treating carbon nanotubes surface-treated with a mixed solution in which multi-walled carbon nanotubes (Nanosolution, average diameter: 10-20 nm / average length: 50 µm) were mixed at a weight ratio of sulfuric acid and nitric acid 3: 1. 0.5), 1, 2, and 3 parts by weight of 100 parts by weight of each of the compounds were prepared in the same manner as in Example 1-2 to prepare a carbon nanotube / poly (vinylidene fluoride) film.

The electrical conductivity and thermal properties of the carbon nanotubes / poly (vinylidene fluoride) film prepared as described above are shown in Table 1 and Table 2, respectively.

In addition, Figure 1 is a result of observing the surface characteristics of the carbon nanotubes and acid-treated carbon nanotubes surface-treated by the chemical treatment according to the present invention with an optoelectronic spectrophotometer, as shown above additionally surface treatment after the acid treatment It was confirmed that the oxygen functional group was increased on the surface of the carbon nanotubes.

Conductivity (S / cm) Example 1 3.7 × 10 ^-3 Example 2 3.1 × 10 ^-2 Example 3 7.5 × 10 ^-2 Example 4 1.4 × 10 ^-1 Comparative Example 1 - Comparative Example 2 1.9 × 10 ^-3 Comparative Example 3 6.2 × 10 ^-2 Comparative Example 4 2.8 × 10 ^-1 Comparative Example 5 4.6 × 10 ^-1

Melting temperature (℃) Heat capacity (J / g) Crystallinity (%) Example 1 163.3 35.72 34.02 Example 2 163.8 38.83 37.18 Example 3 164.2 37.56 35.77 Example 4 164.5 36.31 34.58 Comparative Example 1 162.4 25.83 24.60 Comparative Example 2 162.3 35.46 33.77 Comparative Example 3 162.3 43.13 41.07 Comparative Example 4 162.3 34.57 32.93 Comparative Example 5 162.3 34.05 32.43

As described above, specific portions of the contents of the present invention have been described in detail, and for those skilled in the art, these specific techniques are merely preferred embodiments, and the scope of the present invention is not limited thereto. Will be obvious. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Figure 1 shows the surface properties of the carbon nanotubes surface-treated by conventional acid treatment and the chemical surface-treated carbon nanotubes of the present invention.

2A and 2B illustrate carbon nanotubes / poly (vinylidene fluoride) according to the contents of carbon nanotubes (a) surface treated by conventional acid treatment and chemically treated carbon nanotubes (b) of the present invention. It shows the thermal properties of the film.

Figure 3 shows the tensile strength of the carbon nanotube / poly (vinylidene fluoride) film according to the content of the carbon nanotube surface-treated by the conventional acid treatment and the chemical surface-treated carbon nanotube of the present invention.

Claims (8)

A poly (vinylidene fluoride) nanocomposite characterized by being filled with carbon nanotubes having increased hydrophilic functional groups by chemical surface treatment with 1,5-tendidiol or 1,6-hexanediol. The method of claim 1, The chemical surface-treated carbon nanotubes are mixed in a range of 0.1 to 5 parts by weight based on 100 parts by weight of poly (vinylidene fluoride) poly (vinylidene fluoride) nanocomposite. The method of claim 1, The poly (vinylidene fluoride) nanocomposite is a poly (vinylidene fluoride) nanocomposite, characterized in that the electrical conductivity is 3 × 10 ^-3 to 5 × 10 ^-1 S / cm. The method of claim 1, The poly (vinylidene fluoride) nanocomposite is a poly (vinylidene fluoride) nanocomposite, characterized in that the tensile strength of 20 to 50 MPa. (1) chemically surface-treating with 1,5-tentadiol or 1,6-hexanediol to prepare carbon nanotubes having increased hydrophilic functional groups; (2) mixing the carbon nanotubes prepared in step (1) to a solution in which poly (vinylidene fluoride) is dissolved in a polar solvent; And (3) treating the carbon nanotube and the poly (vinylidene fluoride) mixed solution prepared in step (2) by ultrasonic wave; a method of manufacturing a poly (vinylidene fluoride) nanocomposite comprising the . The method of claim 5, wherein step (1) (A) immersing the carbon nanotubes in an acid solution for 12 to 24 hours, stirring at 60 ℃ to prepare a carbon nanotube having a carboxyl group (-COOH); (b) washing the carbon nanotubes prepared in step (a) with distilled water and drying them, and then placing them in thionyl chloride (SOCl ₂ ) for 24 hours at 70 ° C. for acylating; (c) washing and drying the acylated carbon nanotubes in step (b) using tetrahydrofuran (THF) and ethanol; And (d) adding the carbon nanotubes dried in the step (c) to a 1,5-tentadiol or 1,6-hexanediol solution and reacting at 60 ° C. for 12 hours. Vinylidene fluoride) nanocomposites. The method of claim 5, The carbon nanotubes chemically treated in the step (2) is mixed with 0.1 to 5 parts by weight with respect to 100 parts by weight of poly (vinylidene fluoride). The method of claim 5, Method for producing a poly (vinylidene fluoride) nanocomposite, characterized in that the polar solvent used in the step (2) is dimethylformamide.

Images