KR101499673B1 - A carbon nanotube-buckypaper and the preparation method thereof - Google Patents

Abstract

The present invention relates to a carbon nanotube-bucky paper in which chitosan is uniformly coated on the surface of carbon nanotubes, and a method for producing the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a carbon nanotube-bucky paper and a method for manufacturing the same. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to a carbon nanotube-bucky paper in which chitosan is uniformly coated on the surface of carbon nanotubes, and a method for producing the same.

Carbon nanotube (CNT) refers to a hexagonal honeycomb-shaped graphite surface in which one carbon atom is bonded to three different carbon atoms and is rounded to a nano-sized diameter, and has a unique physical property depending on its size and shape It is a macromolecule. Depending on the type of coating, it can be divided into single walled nanotubes (SWNTs), multi-walled nanotubes (MWNTs) and rope nanotubes. Carbon nanotubes have the potential to be used as nanoelectronic devices, but numerous tubes must be assembled to take advantage of their exciting properties at large levels such as thin films and membranes.

Such large aggregates are commonly referred to as buckypaper, which is a random arrangement of carbon nanotubes in the form of webs, with optical transparency, mechanical flexibility, good electrical conductivity, uniform size, adjustable electron properties, Smooth surface shape and the like. With these properties, bucky paper embodies the potential as a functional or structural component in a variety of fields such as optoelectronic devices, nanocomposites, chemical separators, biocompatible platforms, energy conversion and storage.

In recent years, studies on composites of carbon nanotubes have been actively carried out in order to effectively exhibit excellent mechanical and electrical properties of carbon nanotubes. For example, Korean Patent Publication No. 2010-0107200 discloses a multi- A polystyrene / carbon nanotube composite having a high bonding ratio is disclosed. However, this technique has a disadvantage in that a long process time and various problems may occur depending on the molecular weight of polystyrene.

In addition, in order to form a carbon nanotube composite in the prior art, there is a drawback in that a pretreatment such as attaching a functional group to the carbon nanotube is required.

In the conventional carbon nanotube composite, electrical percolation occurs even when the carbon nanotubes are filled in a small amount. The amount of the multi-wall carbon nanotubes is 1 to 2 wt%, the single wall carbon nanotubes is 0.05 to 0.1 wt% , Electrical percolation occurs, and the electrical conductivity at this time is a surface resistivity of about 10 ⁶ to 10 ¹² Ω / sq, which is a very large disadvantage.

Korean Patent Publication No. 2010-0107200

The present invention relates to a carbon nanotube-buckypaper having a surface of a carbon nanotube surrounded by a van der Waals attractive force, chitosan molecules surrounding the carbon nanotube are connected to each other through hydrogen bonding to form aggregates, And a method for producing the same.

It is also an object of the present invention to provide a carbon nanotube-bucky paper excellent in tensile strength, elastic modulus and moldability, low in surface resistance value, and excellent in electrical conductivity without deteriorating mechanical and physical properties.

In order to achieve the above object,

The present invention

A carbon nanotube-buckypaper characterized in that chitosan molecules surround the surface of a carbon nanotube with van der Waals attraction and chitosan molecules surrounding the carbon nanotubes are connected to each other through hydrogen bonding to form aggregates. to provide.

Preferably, the carbon nanotubes and the chitosan are formed in a core-shell structure.

Preferably, the carbon nanotube is a multi-walled carbon nanotube (MWNT).

Preferably, the carbon nanotubes are carbon nanotubes characterized by a nonfunctionalized nature.

Preferably, the carbon nanotube is contained in an amount of 10 to 90% by weight based on the total weight of the carbon nanotube-bucky paper.

Preferably, the surface resistance value of the carbon nanotube-bucky paper is 100 Ω / sq or less, more preferably 50 Ω / sq or less.

In addition,

a) dissolving chitosan in an acid solution, adding pure multi-walled carbon nanotubes and stirring;

b) dispersing the stirred solution in step a) in an ultra-high pressure homogenizer for 5 minutes; And

c) treating the dispersed solution in step b) with an alkali solution, and pouring the solution in a Teflon mold to dry the carbon nanotube-bucky paper.

The present invention can simplify the process by enclosing the surface of the carbon nanotubes with a van der Waals force rather than a covalent bond by chemical reaction of the chitosan molecules.

In addition, it is possible to provide a carbon nanotube-bucky paper excellent in tensile strength, elastic modulus and moldability, low in surface resistance value, and excellent in electrical conductivity without deteriorating mechanical and physical properties.

In addition, the carbon nanotube-bucky paper of the present invention can be applied to a conductive composite material, a transparent conductive film, a structural material using lightweight characteristics of high strength, and the like. Specifically, the carbon nanotube- , Various vehicle bulletproof materials, electrostatic dissipation (ESD) materials, transparent conductive films, aerospace and automotive structural materials.

1 is a view illustrating a process of forming a chitosan / CNT hybrid film by bonding carbon nanotubes with chitosan.
2A is a photograph of a chitosan / CNT hybrid film.
FIG. 2B is a SEM image of carbon nanotube cylindrical complexes coated with chitosan forming a network through hydrogen bonding. FIG. At this time, it can be confirmed that there are numerous pores having a size of nano unit between all the strands.
FIG. 3 shows a change in stress when a carbon nanotube-chuckosan-bound carbon nanotube-bucky paper is strained.
4 is data of a thermogravimetric analyzer (TGA) showing the change in weight of chit-CNT 50 in a chitosan-carbon nanotube-chit-CNT 50 sample according to a temperature change.
5 is an FT-IR spectrum of chit-CNT 50 in a chitosan-carbon nanotube-bucky paper sample.

Hereinafter, the present invention will be described in more detail.

The present invention

A carbon nanotube-bucky paper characterized in that chitosan molecules surround the surface of the carbon nanotubes with Van der Waals attraction, and chitosan molecules surrounding the carbon nanotubes are connected to each other through hydrogen bonding to form a thin sheet. Lt; / RTI >

Preferably, the size of the carbon nanotube-bucky paper of the present invention can be varied.

Preferably, the carbon nanotubes and the chitosan are formed in a core-shell structure.

Preferably, the carbon nanotube is a multi-walled carbon nanotube (MWNT).

Hereinafter, each component will be described in more detail.

1. Carbon Nanotube (CNT)

Carbon nanotubes are graphite sheets that are rounded to a nano-sized diameter and exhibit the characteristics of metals or semiconductors depending on the angle and structure of the graphite surface. In addition, depending on the number of bonds forming the wall, single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, It is classified as a Rope Carbon Nanotube.

Preferably, the carbon nanotubes used in the present invention are multi-walled carbon nanotubes (MWNTs).

Preferably, the carbon nanotubes used in the present invention are characterized by being nonfunctionalized.

The carbon nanotubes may include 10 to 90 wt%, preferably 25 to 85 wt%, based on the total weight of the carbon nanotube-bucky paper. When the content of chitosan is less than 10% by weight, the amount of chitosan increases, and the chitosan molecules form agglomerates among them, and the electrical resistance is very high (100? / Sq or more) The bonding force between the chitosan molecules coated on the surface of the CNT may be lowered and the tensile strength of the paper may be very low.

The carbon nanotube-bucky paper of the present invention has a high ratio of carbon nanotubes and thus has an advantage of excellent electrical conductivity and the like.

2. Chitosan

The chitosan used in the present invention has the following structure and can be produced by deacetylation of chitin present in nature such as crab, shell of shrimp, squid bone, mold, mushroom mycelium and microorganism cell wall, It is a kind of biodegradable and biocompatible material. It has been used as a physiologically effective substance which can be applied for medical treatment such as wound treatment agent, artificial skin, blood coagulant, immunity enhancer, antibacterial and antioxidant since 1990s. It has been known. Chitin in nature is usually only partially deacetylated and chitosan is mixed with 10-30% chitin and is also commonly called chitin chitosan.

<Chitosan>

Chitosan is a biocompatible, biodegradable nontoxic natural biopolymer. Chitosan has excellent film formability, high water permeability, good adhesion and sensitivity to chemical modification and provides a convenient polymeric scaffold for enzyme fixation.

Also, since it is dissolved in organic acids such as lactic acid and citric acid, an aqueous solution can be prepared by using it. Unlike most conventional plant fibers (dietary fibers), which have a negative charge (-), chitosan has a unique structure called "natural animal fiber", which is positively charged (+) in the dissolved state. Especially, The strong hydrogen bonds in the liver strengthen the role of waste as a helix structure and adsorb and discharge the anions that are the mainstream of accumulated harmful substances (heavy metals, radioactive substances, pesticides, etc.). Due to the natural component of this specific structure, it is highly versatile for the living body, and it is evaluated as a multifunctional substance not only having all the conditions required as a functional food, but also having a great value in the fields of medicine, industry and agriculture.

1) Types of chitosan

Chitosan has three types of alpha, beta, and gamma. First, alpha-chitin and chitosan are present in the shells of crabs, shrimps, etc., and account for about two-thirds of all chitinol on Earth. Generally known chitin and chitosan have a very strong bonding structure because they are arranged in opposite equilibrium so that the chain directions of the molecules are shifted from each other.

Beta-chitin, chitosan, is a very valuable biological material that lacks species diversity and has a small total biomass. It is extracted from the cartilage of molluscs and squid, which live mainly in the sea. Which has a very loose coupling structure. Because of this, the bioreactivity and binding force are very fast, and the formation of the derivative is very easy, and research is being conducted as a medicine material.

Gamma-chitin and chitosan are mainly found in the carapace of insects (beetle, longevity beetle, etc.), and have a mixed structure of alpha-type crossing and beta-type equilibrium. Commercial production is difficult and the effect is less than that of the beta-type.

The surface resistance value of the carbon nanotube-bucky paper of the present invention is 50 Ω / sq or less.

In the carbon nanotube-bucky paper of the present invention, carbon nanotubes and chitosan are formed in a core-shell structure. That is, the present invention is characterized in that the shell-like chitosan molecule surrounds the hydrogen bonding force between the chitosan molecules and the van der Waals attraction between the chitosan molecules and the carbon nanotubes. The connection between CNT / chitosan hybrid tubes is made by hydrogen bonding between the chitosan molecules on the surface, resulting in huge CNT agglomerates. This was made into a thin sheet-like plain paper.

In the carbon nanotube-bucky paper of the present invention, the chitosan molecules bind to the surface of the carbon nanotubes by van der Waals attractive force to surround the surface of the carbon nanotubes. The combined carbon nanotube-chitosan hybrid tubes are in the form of a core-shell, and each hybrid tube is connected by strong hydrogen bonding between chitosan molecules to form aggregates.

In addition, the carbon nanotube-bucky paper of the present invention can be utilized as next-generation electronic parts, displays, military armor materials, and various vehicle bulletproof materials because of its high electrical conductivity (electric resistance is metal level) from the viewpoint of use.

In addition,

a) dissolving chitosan in an acid solution, adding pure multi-walled carbon nanotubes and stirring;

b) dispersing the stirred solution in step a) in an ultra-high pressure homogenizer for 5 minutes; And

c) treating the dispersed solution in step b) with an alkali solution, and pouring the solution in a Teflon mold to dry the carbon nanotube-bucky paper.

Preferably, the acid solution is acetic acid or hydrochloric acid.

Preferably, the alkali solution is ammonia water.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. These Examples and Experimental Examples are only for illustrating the present invention, and the scope of the present invention is not limited to these Examples and Experimental Examples.

Carbon nanotubes - Of bucky paper  Produce

Example  One

75 mg (75% by weight) of chitosan (Aldrich) was added to 50 mL of a 1% acetic acid solution (purchased from DUKSAN) and the solution was completely dissolved by stirring. 25 mg (25% by weight) of pure multi-walled carbon nanotubes (purchased from EM-POWER, average diameter 15 nm) was added and stirred for 1 hour. After stirring, the mixture was thoroughly dispersed for about 5 minutes using an ultra-high pressure homogenizer (NanoDebee). Thereafter, the mixture was rapidly stirred for about 10 minutes using 5% ammonia water (purchased from OCI Company), and slowly added to pH 8-9. The mixture was continuously stirred and poured into a Teflon mold and dried at room temperature.

The size of the carbon nanotube-bucky paper of the present invention prepared in Example 1 is 6 cm x 6 cm x 0.05 cm.

Example 2

Carbon nanotube-bucky paper was prepared in the same manner as in Example 1 except that 50 mg (50% by weight) of carbon nanotubes and 50 mg (50% by weight) of chitosan were used.

Example 3

Carbon nanotube-bucky paper was prepared in the same manner as in Example 1, except that 75 mg (75% by weight) of carbon nanotubes and 25 mg (25% by weight) of chitosan were used.

Example 4

Carbon nanotube-bucky paper was prepared in the same manner as in Example 1 except that 85 mg (85% by weight) of carbon nanotubes and 15 mg (15% by weight) of chitosan were used.

Comparative Example 1

100 mg (100% by weight) of chitosan without carbon nanotubes was used.

Experimental Example  1: Carbon nanotubes - Of bucky paper  Mechanical properties measurement

The mechanical properties of the carbon nanotube-bucky paper prepared in Examples 1 to 4 and chitosan of Comparative Example 1 were recorded at room temperature using an Instron universal material testing system (Instron 3344). Specimens with dimensions of 25 mm x 10 mm x 2 mm (length x width x thickness) were made at 5 mm / min and the average values of the four specimens were recorded. The elastic modulus (initial slope in the linear portion), tensile strength (maximum stress before breaking) and elongation rate of the sample were measured on the basis of the obtained stress-strain curve The results are shown in Table 1 below.

As shown in Table 1, on the basis of the 100% chitosan sample of Comparative Example 1, the sample containing 25 wt% of the carbon nanotubes of Example 1 showed an increase in the modulus of elasticity of 408% and a tensile strength of 14.9% The samples containing 50 wt% of carbon nanotubes showed a 318% increase in elastic modulus and a 47.4% increase in tensile strength. A sample containing 75 wt% of carbon nanotubes had a modulus of elasticity 373.7%, tensile strength decreased by 8.8%, samples with 85 wt% carbon nanotubes showed a 22% increase in elastic modulus and a 69.3% decrease in tensile strength (see Table 1 pCNT means pure carbon nanotubes).

Experimental Example  2: Carbon nanotubes - Of bucky paper Surface resistance value ( 표면 resistivity ) Measure

A sample containing a carbon nanotube-bucky paper sample containing 80 mg of carbon nanotubes and 20 mg of chitosan and a sample containing 90 mg of carbon nanotubes and 10 mg of chitosan was further prepared. In addition, samples prepared in Examples 1 to 4 The surface resistance value of the carbon nanotube-bucky paper was measured by measuring the resistance value of a 6 cm x 6 cm x 0.05 cm sheet obtained by using a 4-point probe head (JANDE, Test Unit (HM21) Respectively.

Sample (CNT%) The surface resistance value (Rs; Ω / m 2) Chi-CNT (25) 40 Chi-CNT (50) 10 Chi-CNT (75) 6 Chi-CNT (80) 5 Chi-CNT (85) <3 Chi-CNT (90) <3

As shown in Table 2, in the case of the electrical conductivity, a sample containing 25 wt% of carbon nanotubes on the basis of surface resistivity, 40 Ω / sq, and 50 wt% of carbon nanotubes A sample containing 10 Ω / sq, a sample containing 75 wt% of carbon nanotubes containing 6 Ω / sq, a sample containing 80 wt% of carbon nanotubes containing 5 Ω / sq and 85 wt% of carbon nanotubes (Rs;? / M < 2 &gt;) of <3? / Sq.

The results showed that the tensile strength, elastic modulus, and moldability of the film were superior to those of the carbon nanotubes without deteriorating the mechanical and physical properties due to the specificity of the nanomorphology. In addition, as a large amount of carbon nanotubes were charged, they exhibited very low electrical resistance.

Experimental Example  3: Carbon nanotubes - Of bucky paper  Measurement of stress variation due to deformation

The deformation of the carbon nanotube-bucky paper of Examples 1 to 4 was measured, and the change of the stress was measured, and it is shown in Fig. In all of the carbon nanotube-bucky papers of Examples 1 to 4, the stress was increased as the strain was increased, but the stress was not further increased after the specific strain.

Claims (9)

The chitosan molecules surrounding the surface of the carbon nanotubes are surrounded by van der Waals attraction and the chitosan molecules surrounding the carbon nanotubes are connected to each other through hydrogen bonding to form an aggregate.
The carbon nanotubes and chitosan are formed in a core-shell structure,
Wherein the carbon nanotubes are multi-walled carbon nanotubes (MWNTs). delete delete The carbon nanotube-bucky paper of claim 1, wherein the carbon nanotubes are nonfunctionalized. The carbon nanotube-bucky paper according to claim 1, wherein the carbon nanotube-bucky paper comprises 10 to 90% by weight of carbon nanotubes based on the total weight of the carbon nanotube-bucky paper. The carbon nanotube-bucky paper according to claim 1, wherein the surface resistance value of the carbon nanotube-bucky paper is 50 Ω / sq or less. a) dissolving chitosan in an acid solution, adding pure multi-walled carbon nanotubes and stirring;
b) dispersing the stirred solution in step a) in an ultra-high pressure homogenizer for 5 minutes; And
c) treating the dispersed solution in step b) with an alkaline solution, and pouring the solution in a Teflon mold to dry the carbon nanotube-bucky paper. [Claim 7] The method according to claim 7, wherein the acid solution is acetic acid or hydrochloric acid. [Claim 7] The method according to claim 7, wherein the alkali solution is ammonia water.

Images