KR20110037055A - Method for preparing carbon nanoparticles-polymer composites using magnetic fields and the carbon nanoparticles-polymer composites - Google Patents

Abstract

PURPOSE: A carbon nanoparticles-polymer composite is provided to obtain a polymer film or patterns with different electric and mechanical properties by causing a concentration gradient of carbon nano-particles in the same thin film. CONSTITUTION: A method for preparing a carbon nanoparticles-polymer composite comprises the steps of: mixing a carbon nano-particle dispersion with a polymer solution to prepare a composite formation solution, wherein the carbon nano-particle dispersion includes nano metal with magnetism; arranging or maldistributing the carbon nano-particles by applying magnetic field to the composite formation solution; and polymerizing or drying the composite formation solution.

Description

Method for Preparing Carbon Nanoparticles-Polymer Composites Using Magnetic Fields and The Carbon Nanoparticles-Polymer Composites}

The present invention relates to a method for producing a carbon nanoparticle-polymer composite using a magnetic field and a carbon nanoparticle-polymer composite obtained therefrom. More particularly, the present invention relates to a method of preparing carbon nanoparticle-polymer composites by controlling the dispersion characteristics of magnetic carbon nanoparticles in a polymer liquid phase, and to carbon nanoparticle-polymer composites obtained therefrom.

The present invention is derived from the task performed as part of the Ministry of Knowledge Economy's information and communication R & D project [Task No .: 2006-S-006-04, Task name: Component module for ubiquitous terminal].

Since carbon nanotubes were discovered by Dr. Ijima of NEC in 1991, they have unique properties and applications, including their large surface area and excellent mechanical, electrical and optical properties, and very high aspect ratios at the nanometer level. As sex has become known, researchers in many fields have spent time and effort on the application of carbon nanoparticles.

Until now, dispersion methods in the solution of carbon nanoparticles are mechanically pulverized using ball milling, and chemically, strong acids are used to form defects in the π-resonance structure. A method of dispersing by incorporating a high affinity material through covalent bonding, and adsorbing monomolecular film or polymer through non-covalent bonding to separate hydrophobic carbon nanoparticles from liquid phase Increasing affinity has increased the dispersibility in the final solvent or polymer matrix.

In particular, nanocomposites based on carbon nanoparticle-polymer composite systems are currently attracting attention because they can improve electrical, thermal, and mechanical properties, and control the dispersion of carbon nanotubes in three-dimensional polymer matrix. Research is in full swing.

As an example, an alternating electric field is applied to chemically activate carbon nanotubes in the polymer matrix in the direction of the electrode, or carbon nanotubes (or fullerenes, synthetic graphite, etc.) are chemically activated in an effort to align the carbon nanotubes in the polymer matrix using a magnetic field. One example is the introduction of magnetic particles synthesized separately on the surface of carbon nanotubes. However, these methods require separate electrodes (or electrode arrays) and an external electric field to align the carbon nanotubes in the former example, and in the latter, following magnetic nanoparticle synthesis and chemical pretreatment of the carbon nanoparticles Several steps are required, including the combination of

In addition, a multi-layered polymer thin film manufacturing process must be involved, or a spraying method using a spray or a microelectrode structure is used to electrophoretically apply electric force to carbon nanotubes.

Moreover, the methods exemplified above are not effective in terms of time and cost to obtain a gradual change in carbon nanotube concentration in the polymer matrix in the vertical or horizontal direction.

Therefore, the conditions to be prepared in the carbon nanoparticle-polymer composite manufacturing process are as follows.

First, it should be easy to operate in various processes irrespective of the type and physical properties of the polymer, and should be easily dispersed and controlled in concentration gradient in functional polymers having various characteristics such as liquid crystal or block copolymers, conductive and ionic polymers. .

Second, since it should be easily applicable to various carbon nanoparticle concentrations and film thicknesses, and should have general versatility suitable for manufacturing composite membranes for various uses, the alignment process of carbon nanoparticles should be able to constantly react to external stimuli. .

Therefore, the inventors of the present invention include carbon nanotubes and derivatives thereof in the manufacture of such carbon nanoparticle-polymer composite materials if the most economical method is developed to satisfy the above conditions and control the alignment or concentration gradient of the carbon nanoparticles. We believe that we will be able to explore new application areas for new functional composites, and we will continue to study them, without going through the pretreatment and introduction of magnetic particles required in the latter example. The present invention has been completed by developing an alignment method using magnetic particles contained as a 'pristine carbon nanotube' catalyst.

On the other hand, efforts to localize the carbon nanoparticles in the polymer matrix of the conventional carbon nanoparticles mainly used a method of manufacturing by introducing the carbon nanoparticle composite liquid phase in various ways on one side or both sides to the polymer substrate containing no carbon nanoparticles However, since a lot of trial and error, time and cost are required in this process, a solution to this problem is the formation of a composite film and the concentration gradient of carbon nanoparticles using an external magnetic field in the production of carbon nanoparticle-polymer films. Was adjusted.

An object of the present invention is to provide a method for producing a carbon nanoparticle-polymer composite by dispersing and aligning carbon nanoparticles having magnetic properties in a desired direction in a polymer liquid phase using magnetic force.

Still another object of the present invention is to provide a carbon nanoparticle-polymer composite prepared by dispersing and aligning carbon nanoparticles having magnetic properties in a desired direction in a polymer liquid phase using magnetic force.

In order to achieve the above object, the present invention comprises the steps of preparing a composite manufacturing solution by mixing a carbon nanoparticle dispersion liquid containing a polymer nanoparticles with magnetic and a polymer solution; It provides a method for producing a carbon nanoparticles-polymer composite comprising applying a magnetic field to the composite preparation solution to align or localize the carbon nanoparticles, and polymerizing or drying the composite preparation solution.

In the carbon nanoparticle-polymer composite manufacturing method according to the present invention, the magnetic metal nanoparticles are preferably selected from the group consisting of Ni, Co, Fe, Y, Pd, Pt and Au, the magnetic The size of the prominent metal nanoparticles is preferably 5 nm to 500 nm.

In addition, in the carbon nanoparticle-polymer composite manufacturing method according to the present invention, the carbon nanoparticles are single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, bundled carbon nanotubes, carbon nanoparticles. It is preferably selected from spheres, graphenes and combinations thereof.

In the step of preparing a composite preparation solution of the carbon nanoparticle-polymer composite production method according to the present invention, the content of the carbon nanoparticles is preferably 0.01 to 50 parts by weight based on 100 parts by weight of the total solid content of the composite preparation solution, The content of the solvent in the preparation solution is preferably 5 to 10,000 parts by weight based on 1 part by weight of total solids, and the solvent includes water, ethanol, methanol, isopropanol, 1,2-dichlorobenzene, It is preferably selected from chloroform, dimethylformamide, acetone and combinations thereof.

The polymerization or drying step of the method for preparing a carbon nanoparticle-polymer composite according to the present invention is preferably performed by heating to 40 to 150 ° C., and the magnetic field has a magnetic force of 100 Gauss to 200,000 Gauss. It is preferably applied to contact or in proximity to the composite preparation solution, the magnet is preferably selected from the group consisting of neodymium (NdFeB) magnets, ferrite magnets, samarium (SmCo) magnets, alico magnets. Do.

In order to achieve another object of the present invention, the present invention comprises the steps of preparing a composite preparation solution by mixing a carbon nanoparticle dispersion and a polymer solution containing a magnetic metal nanoparticles; Arranging or omitting carbon nanoparticles by applying a magnetic field to the composite solution; It provides a carbon nanoparticles-polymer composite prepared by the method for producing a carbon nanoparticles-polymer composite comprising a; and polymerizing or drying the complex preparation solution.

The effects of the present invention are as follows.

First, by dispersing the magnetized carbon nanoparticles in the direction of the external magnetic field to induce a concentration gradient of the carbon nanoparticles in the same thin film can be obtained a polymer film or pattern with different electrical and mechanical properties of the surface. The carbon nanoparticle-polymer composite thin film has characteristics suitable for a flexible electrode or an ionic polymer driver.

Second, the dispersion / alignment method using the magnetic field of the present invention is industrially useful because the process is simple, unlike the general method requiring a complicated process of several steps.

Third, the distribution of aligned carbon nanoparticles in various polymer liquid phases can be obtained using magnetic catalysts contained in carbon nanoparticles that can be applied to various fields. It is possible to provide carbon nanoparticle-polymer composite membranes arranged at low cost in a wide range of industrial fields such as medical, and the use of them is of great value toward high-tech industries.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

1 is a flowchart illustrating a method of preparing a carbon nanoparticle-polymer composite according to an embodiment of the present invention.

Referring to Figure 1, the carbon nanoparticle-polymer composite manufacturing method according to the present invention comprises the steps of preparing a composite manufacturing solution by mixing a carbon nanoparticle dispersion and a polymer solution containing a metal nanoparticles having magnetic properties (S11), Applying a magnetic field to the composite preparation solution to align or localize the carbon nanoparticles (S12), and polymerizing or drying the composite preparation solution (S13).

In preparing the composite preparation solution (S11), the magnetic metal nanoparticles may be selected from the group consisting of Ni, Co, Fe, Y, Pd, Pt, and Au, but is not limited thereto. The size of the metal nanoparticles is preferably 5 to 500 nm. The magnetic metal nanoparticles may act as a catalyst.

In addition, the carbon nanoparticles are single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, bundle carbon nanotubes, carbon nanospheres (graph nano), graphene (graphene), graphene oxide and these Can be selected from, but is not limited to.

Examples of carbon nanoparticles including the magnetic metal nanoparticles are schematically illustrated in FIG. 2. That is, the metal nanoparticles 2 having magnetic properties may be attached to the carbon nanotubes 1.

As the solvent of the carbon nanoparticle dispersion and the polymer solution, any solvent capable of dispersing the carbon nanoparticles or the polymer may be used, and any solvent may be used as long as it can be mixed well with each other. More preferably water, ethanol, methanol, isopropanol, 1,2-dichlorobenzene, chloroform, dimethylformamide, acetone and combinations thereof.

In addition, the physical properties of the carbon nanoparticles-polymer membrane may be controlled by controlling the ratio of the polymer and the carbon nanoparticles when preparing the composite preparation solution in which the carbon nanoparticle dispersion and the polymer solution are mixed. For example, it is possible to obtain an electrode having very high conductivity by controlling the ratio of polymer and carbon nanoparticles.

In the preparation step (S11) of the composite preparation solution, the content of carbon nanoparticles is preferably in the range of 0.01 to 50 parts by weight based on 100 parts by weight of the total weight of solids of the solution. When the content of carbon nanotubes is less than 0.01 parts by weight, the effect of the external magnetic field is lowered, and when the content of carbon nanotubes exceeds 50 parts by weight, the alignment phenomenon due to the influence of the magnetic field may not be noticeable, and thus the shape of the final composite may be irregular. . This can be improved by increasing the content of the solvent, but can be carried out in consideration of the drying method and time.

In addition, in the complex preparation solution, the content of the solvent is preferably 5 to 10,000 parts by weight based on 1 part by weight of the total solids.

In the step (S12) of aligning or omitting carbon nanoparticles by applying a magnetic field to the composite preparation solution, the composite preparation solution is contained in a mold. Here, the mold may be a rectangular structure of a Teflon material as a frame for containing the composite preparation solution, and molds of different shapes and materials may be used according to the use.

The magnet for inducing the magnetic field is not particularly limited to only permanent magnets, and may be magnets commonly used in related fields such as electromagnets, various permanent magnets, and magnets by induction magnetic fields. Preferably, the magnetic force is 100 gauss (Gause). ) To 200,000 Gauss (Gause) magnet, and more preferably selected from the group consisting of neodymium (NdFeB) magnet, ferrite magnet, samarium (SmCo) magnet, alico magnet.

The alignment method using the magnetic field may draw carbon nanoparticles having a certain size by using an external magnetic field to form a concentration gradient of particles or align them on one side to obtain a composite structure having different characteristics from the opposite side. have. The external magnetic field can then be applied by placing the magnet described above in a mold containing the composite preparation solution. For example, when a magnetic field is applied in one direction of a rectangular mold, a film having different sheet resistances on the face can be obtained. In essence, modifications and applications are possible with other magnetic nanoparticles.

3 is a flowchart illustrating a process of manufacturing a film having different characteristics according to the position of a magnet. Referring to FIG. 3, the composite preparation solution 10 is placed in a rectangular mold 20, and the membrane 30 formed of only the lower magnet of the mold (or a combination of gravity and magnetic field) and a magnet having an N pole are formed. The film 40 formed when positioned on the upper portion, and the magnet 50 showing the N pole is positioned on the upper portion of the mold, and the film 50 formed when the magnet showing the S pole is positioned below the mold. In the case of the membrane 30 formed only with the lower magnet, a magnetic field acts on the lower portion so that the carbon nanoparticles are concentrated in the lower portion of the membrane, whereas the membrane 40 formed by applying the magnetic field on the upper portion of the mold has a carbon nanostructure on the upper portion of the membrane. Particles are concentrated, and in the film 50 formed by applying a magnetic field to the upper and lower parts of the mold, carbon nanoparticles are concentrated at the upper and lower parts of the film.

In this way, the physical properties of the composite can be controlled by adjusting factors such as the strength of the magnetic field, the position of the magnetic field, and the distance from the mold to the magnet. This is possible.

Polymerizing or drying the complex preparation solution to form a complex (S13) is dried for 10 to 14 hours at room temperature to remove the solvent, after removing the magnetic field after 10 to 14 hours in the range of 40 to 150 ℃ Proceeding to the drying, thereby producing a carbon nanoparticle-polymer composite membrane.

Thereafter, vacuum drying may be further performed for 10 to 14 hours at the same temperature of 40 to 150 ° C.

Such drying conditions should be controlled according to the physical and chemical properties of the composite membrane, its shape and thickness, the degree of temperature and vacuum, and the rate of increase and decrease for efficient evaporation of the solvent used, and also depend on the content of carbon nanoparticles. Can be.

Since the carbon nanoparticle-polymer composite membrane obtained by the above manufacturing method has an ordered distribution of carbon nanoparticles, the carbon nanoparticle-polymer composite film may be provided in various fields, electronic and electrical, mechanical, optical, medical, and the like. It can be preferably applied.

Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited by the following examples.

Example 1

Preparation of Carbon Nanotube-Nafion Composite Membrane Using Magnetic Field

Magnetic metal nanoparticles prepared by arc discharge, mixed solution of 5 g of single-walled carbon nanotubes (SWCNT) containing iron nanoparticles in a volume ratio of 50:50 sulfuric acid and nitric acid (v / v) The treatment was carried out at 60 ° C. for 4 hours. Subsequently, the impurities were purified through dilution, filtering, and neutralization.

The carbon nanotubes thus prepared were dispersed in 0 mg, 5 mg, 10 mg, 30 mg, and 50 mg each in a container containing 1 g of dimethylformamide (DMF), and then 4 g of 20% by weight of Nafion in each container. ™) was added to the solution to prepare a carbon nanotube-nafion mixed solution of various ratios.

Each solution was placed in each mold shown in FIG. 4, and a block type neodymium magnet (about 4000 gauss) was placed on top of the mold to maintain a magnetic field. In this state, the solvent was dried for 12 hours while maintaining a humidity of 20 ± 3% at room temperature. After drying in an oven at room temperature over 140 ℃ 12 hours to prepare a carbon nanotube-nafion composite membrane in which carbon nanotubes are aligned to one side.

An image of the carbon nanotube-nafion composite before and after drying is shown in FIG. 4, and an electron micrograph of the carbon nanotube-nafion composite membrane including 10 mg of carbon nanotubes is shown in FIG. 5.

According to Figure 5, it can be seen that the carbon nanotubes are aligned in one direction.

Example 2

Fabrication of Ionic Polymer-Metal Composite (IPMC) Actuator Using Carbon Nanotube-Nafion Composite Membrane

Platinum was used as an electrode for the preparation of the IPMC, and the complex for forming the platinum electrode was selected from ([Pt (NH ₃ ) ₄ ] Cl ₂ ) or ([Pt (NH ₃ ) ₆ ] Cl ₄ ).

Reduction of the platinum complex consists of primary and secondary reductions, NaBH ₄ is used for the primary reduction, and NH ₂ NH ₂ -1 to 1.5H ₂ O or NH ₂ OH-HCl for the secondary reduction. It became.

Ion exchange (adsorption)

A platinum complex ([Pt (NH ₃ ) ₄ ] Cl ₂ ) solution was prepared to be 2 mg Pt per ml, and, for example, 30 cm 2 to be at least 3 mg of Pt per cm 2 of carbon nanotube-nafion composite membrane. The carbon nanotube-nafion composite membrane of was immersed in 45 ml of Pt solution to sufficiently adsorb the Pt complex, and then was immersed in 1 ml of ammonium hydroxide solution (5%) and neutralized at room temperature for 3 hours.

Metal particle layer formation (primary reduction)

A 5 cm ₂ NaBH ₄ solution and a 30 cm 2 carbon nanotube-nafion composite membrane washed well in deionized water were placed in a water bath containing 180 ml of deionized water in a 40 ° C. water bath, and a sodium borohydride solution (5 wt. 2 ml of% NaBH ₄ aq) was added dropwise at 7 times every 30 minutes and then slowly raised to 60 ° C. Subsequently, an additional 20 ml of reducing agent (5% NaBH ₄ ) solution was injected at 60 ° C., followed by stirring for 1.5 hours. After the reaction was washed with deionized water, soaked in 0.1N hydrochloric acid solution for 1 hour. 0.9 mg / cm 2 of platinum was plated by primary reduction.

Platinum Electrode Formation (Secondary Reduction)

5% Ammonium Hydroxide in 240 ml solution containing 120 mg of platinum compound for additional plating of 2 mg / cm 2 platinum per unit area on the platinum-plated carbon nanotube-nafion composite membrane by primary reduction 5 ml of the side solution was added to prepare a plating solution, and after raising to 40 ° C., a carbon nanotube-nafion composite membrane was added thereto, stirred for 30 minutes, and then, 6 ml of 20% NH ₂ OH-HCl was added every 20 minutes. 3 ml of% hydrazine solution was injected. Thereafter, the solution was slowly heated to 60 ° C. over 4 hours to prepare a film having a gray surface, that is, an ionic polymer metal composite (IPMC) driver.

Test Example

Displacement and driving force measurement

Using carbon nanotube-nafion composite membranes having carbon nanotube contents of 0 wt%, 0.5 wt% and 1.0 wt%, respectively, the displacement and driving force of the polymer actuator manufactured in the same manner as in Example 2 were measured. It is shown in Figure 6 below. The displacement of the 3 x 8 mm ² strip type polymer actuator was measured using a frequency generator at 3 V and 0.1 Hz.

1 is a flow chart showing a manufacturing process of carbon nanoparticles-polymer composite according to an embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating carbon nanotubes including magnetic nano metal nanoparticles used in a carbon nanoparticle-polymer composite manufacturing process according to an embodiment of the present invention.

3 is a diagram illustrating a structure of a carbon nanoparticle-polymer composite membrane manufactured differently according to a direction in which a magnetic field is applied.

Figure 4 is an image showing a comparison of the state before and after drying the carbon nanoparticles-polymer composite membrane produced by the carbon nanoparticles content of 0, 5, 10, 30, 50 mg according to an embodiment of the present invention.

5 is an electron micrograph of a carbon nanoparticle-polymer composite membrane having a carbon nanoparticle content of 10 mg in FIG. 4.

6 is a graph evaluating the displacement and driving force characteristics of the polymer actuator using the carbon nanoparticle-polymer composite membrane.

Claims (10)

Preparing a composite preparation solution by mixing a carbon nanoparticle dispersion liquid containing a magnetic metal nanoparticle and a polymer solution; Arranging or ubiquitous carbon nanoparticles by applying a magnetic field to the composite solution; and Polymerizing or drying the complex preparation solution; Method of producing a carbon nanoparticles-polymer composite comprising a. The method of claim 1, The magnetic metal nanoparticles are selected from the group consisting of Ni, Co, Fe, Y, Pd, Pt and Au, the size of the metal nanoparticles is 5 to 500 nm carbon nanoparticle-polymer composite manufacturing method. The method of claim 1, The carbon nanoparticles include single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, bundled carbon nanotubes, carbon nanospheres, graphene, graphene oxide, and combinations thereof. Method for producing a carbon nanoparticle-polymer composite selected. The method of claim 1, In the preparing of the composite preparation solution, the content of carbon nanoparticles is 0.01 to 50 parts by weight based on 100 parts by weight of the total weight of solids of the composite preparation solution of the carbon nanoparticles-polymer composite. The method of claim 1, In the preparing of the composite preparation solution, the content of the solvent in the composite preparation solution is 5 to 10,000 parts by weight based on 1 part by weight of total solids of the carbon nanoparticle-polymer composite manufacturing method. The method of claim 1, The solvent is a method for producing a carbon nanoparticle-polymer composite selected from water, ethanol, methanol, isopropanol, 1,2-dichlorobenzene, chloroform, dimethylformamide, acetone and combinations thereof. . The method of claim 1, In the polymerization or drying step, the carbon nanoparticles-polymer composite is heated to 40 to 150 ℃. The method of claim 1, The magnetic field is a method of producing a carbon nanoparticles-polymer composite is a magnetic force is applied to contact or close to a magnet of 100 Gauss (Gause) to 200,000 Gauss (Gause) to the composite preparation solution. The method of claim 9, The magnet may be selected from the group consisting of neodymium (NdFeB) magnets, ferrite magnets, samarium (SmCo) magnets, and alico magnets. A carbon nanoparticle-polymer composite prepared by the method according to any one of claims 1 to 9.

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