KR101624945B1 - Composite of blockcopolymer/mwnt/metal, and the manufacturing method thereof - Google Patents

Abstract

TECHNICAL FIELD The present invention relates to a thermally conductive, heat-dissipative composite material including a self-assembling block copolymer, MWNT, and metal, and is a composite material that can exhibit a very high thermal conductivity as compared with a composite material that does not include a conventional MWNT, And a manufacturing method thereof.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a block copolymer, a MWNT, a metal complex,

The present invention relates to a high thermal conductivity composite comprising a block copolymer, a multi-walled carbon nanotube (MWNT) and a metal, and a method of manufacturing the same.

The rapid increase in power density required in the fields of information, communication, and energy storage technology is a counterproductive issue for heat transfer or heat dissipation in electronic devices. As electronic devices become more highly integrated, lighter, shorter, and multifunctional, more heat is generated in electronic devices. This heat dissipates the functions of devices, causing malfunction of peripheral devices, substrate deterioration, and the like . Particularly, in the case of LED, the temperature of the junction is continuously increased due to the heat of high temperature, which causes the lifetime of the LED semiconductor to deteriorate. Reducing the operating temperature by effectively dissipating the heat generated from such electronic devices is very important for improving the performance of electronic devices and extending the service life.

As such heat dissipation materials for electronic devices, composite materials in which high thermal conductive fillers such as metals, ceramics, and carbon materials are mixed with polymer materials used as continuous media are mainly used. The high thermal conductive composite material of the polymer / filler can maintain the inherent characteristics of the filler such as metal, ceramic or carbon material, while retaining properties such as light weight, processability, flexibility, Another reason for using these composites is due to the excellent adhesion and corrosion resistance between the two surfaces in the vertical direction where heat is transferred simultaneously with effective heat transfer. In other words, thermally conductive polymer composites provide new possibilities for replacing existing parts of metals or ceramics in electronic devices.

The addition of carbon materials in thermally conductive polymer composites is a simple method commonly used to impart thermal conductivity to existing polymeric materials. Carbon nanotubes exhibit excellent flexibility, large aspect ratio of 1000 or more, and high thermal conductivity. In particular, 6000 W / mK for single wall carbon nanotubes (SWNT) and 3075 W / mK for multi wall carbon nanotubes (MWNT) due to a phonon free path due to a one-dimensional structure characteristic of carbon nanotubes only Respectively.

In the prior art relating to a high thermal conductive composite material using such a carbon nanotube and a polymer, Patent Publication No. 10-1274976 discloses a thermally conductive hollow particle such as carbon nanotubes and graphene, a silicone resin, an epoxy resin, a phenol resin, and a polyethylene Discloses a technique for a thermally conductive composite material of a polymer resin such as a resin. In addition, Japanese Patent Application Laid-Open No. 10-2013-0088251 discloses a thermoconductive composite material composition comprising a thermoplastic resin such as a polyolefin resin and a thermally conductive filler such as expanded graphite, a long fiber and a carbon nanotube.

However, in the case of adding carbon nanotubes in this prior art, the addition of carbon nanotubes to a polymer continuous medium showed a much lower thermal conductivity (about 10 W / mK) than expected, despite the excellent thermal properties of only carbon nanotubes. This is explained by the effect of the high interfacial thermal resistance between the polymer matrix and the carbon nanotubes interface and between the carbon nanotubes. In addition, the dispersion of insufficient carbon nanotubes generates interfacial thermal resistance, It affects.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made in an effort to solve the above problems, and an object of the present invention is to provide a high thermal conductive composite material using a block copolymer polymer as a continuous medium and using multiwalled carbon nanotubes and metal particles as a filler .

According to one embodiment of the present invention, a block copolymer / MWNT / metal composite comprising a block copolymer, a Multi-Walled Carbon Nanotube (MWNT), and a metal may be provided.

The composite may be a mixture of a powder comprising a block copolymer and MWNT and metal particles, and the powder may be mixed with 2 to 10 parts by weight of the block copolymer with respect to 1 part by weight of MWNT.

The powder-metal particles may be mixed in a volume percentage of 30 to 90 vol%: 10 to 70 vol%, and the block copolymer may be a block copolymer forming micelles, Silver, and aluminum.

According to another embodiment of the present invention, there is provided a method for producing a block copolymer, comprising the steps of: (a) preparing a mixed solution comprising a block copolymer, MWNT and a solvent; (b) removing the solvent from the mixed solution; And (c) mixing the metal particles with the powder and then processing the block copolymer / MWNT / metal composite to prepare a block copolymer / MWNT / metal composite. A method for producing the metal complex can be provided.

In step (a), the block copolymer may be mixed in an amount of 2 to 10 parts by weight based on 1 part by weight of the MWNT. The block copolymer may be dissolved in a solvent to prepare a block copolymer solution. And mixing the MWNT with the solution to disperse the MWNT.

In the step (c), the powder-metal particles may be mixed in a volume ratio of 30 to 90% by volume: 10 to 70% by volume, and then heated to form a composite. The block copolymer / MWNT / May be produced by any one of hot-pressing, autoclave-molding, compression-molding, open-mold-molding, and RTM-molding.

The step of dispersing the MWNT may be performed by ultrasonication and horn sonication.

The solvent may be toluene, and the step (b) may be performed by vacuum-filtering the mixed solution to obtain a mat, and vacuum drying the mat .

The metal may be any one of copper, silver and aluminum, the copper particles may be 1 to 2 占 퐉, the silver (Ag) particles may be 2 to 3.5 占 퐉, and the aluminum particles may be 1 to 3 占 퐉.

In the high thermal conductive composite according to an embodiment of the present invention, the MWNT is uniformly dispersed by the block copolymer, and thus the well-dispersed MWNT not only enhances the thermal contact contact between the metal particles, So that the thermal conductivity can be improved.

In addition, the thermally conductive composite of the present invention can exhibit a higher thermal conductivity than a composite material of only a polymer and MWNT or a composite material of a polymer and a metal.

The MWNT highly dispersed by the block copolymer enhances thermal interface contact of the metal particle filler to facilitate heat transfer, and the block copolymer may be used as a continuous medium base as it is.

Further, in one embodiment of the present invention, the cost can be reduced by using MWNTs compared with single-walled carbon nanotubes or double-walled carbon nanotubes.

1 is a schematic representation of a mechanism by which a block copolymer micelle disperses a multi-walled carbon nanotube (MWNT).
2A and 2B are SEM images and TEM images of multi-walled carbon nanotubes dispersed by PS- b- P4VP micelles in a toluene solvent, respectively.
FIG. 3A is an image of PS- b- P4VP / MWNT mat image, and FIG. 3b shows that MWNT redispersed by micelles of PS- b -P4VP when PS- b -P4VP / MWNT powder again dissolved in toluene 3C and 3D are surface and cross-sectional SEM images of the PS- b- P4VP / MWNT mat, respectively, and Figs. 3e and 3f are SEM images of the PS- b -P4VP / MWNT powder.
4a and 4b show the results of measurement of the diffusivity and thermal conductivity of the MWNT / PS- b- P4VP complexes of various content ratios, and Figs. 4c and 4d show the results of PS- b -P4VP / MWNT (Content ratio 5: 1).
Figures 5a and 5b PS- b -P4VP / MWNT (weight ratio 5: 1) PS- b -P4VP / MWNT / Al sample to a powder containing aluminum in different volume ratio (10, 30, 50, 70 vol%) And FIGS. 5C and 5D are SEM images. FIG.
Figure 6a and 6b PS- b -P4VP / MWNT (weight ratio 5: 1) PS- b -P4VP / MWNT / Cu samples containing copper in different volume ratio of the powder (10, 30, 50, 70 vol%) And FIGS. 6C and 6D are SEM images. FIG.
Figures 7a and 7b are PS- b -P4VP / MWNT: PS- containing silver of (content ratio 51) different volume ratio of the powder (10, 20, 30, 40 , 50, 70 vol%) b -P4VP / The thermal diffusivity and thermal conductivity of the MWNT / Ag specimen are plotted, and FIGS. 7C and 7D are SEM images.
FIG. 8A shows the composite of the present invention comprising various volume ratios of aluminum, copper, and silver in a PS- b- P4VP / MWNT (5: 1 ratio by weight) powder and the thermal conductivity of the composite containing epoxy in various volume ratios FIG. 8B is a view for explaining the internal structure of the PS- b- P4VP / MWNT / Ag composite of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like or similar elements are denoted by the same or similar reference numerals, and a duplicate description thereof will be omitted. In the following description of the embodiments of the present invention, a detailed description of related arts will be omitted when it is determined that the gist of the embodiments disclosed herein may be obscured. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. , ≪ / RTI > equivalents, and alternatives.

Terms including ordinals, such as first, second, etc., may be used to describe various elements, but the elements are not limited to these terms. The terms are used only for the purpose of distinguishing one component from another.

The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the present application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

In one embodiment of the present invention, a multiwalled carbon nanotube (hereinafter referred to as MWNT) is used as a carbon nanotube, and the uniform dispersion of the MWNT is controlled to maximize the thermal effect, MWNT was dispersed using a self-assembling block copolymer to increase the thermal coupling of the MWNT.

That is, the MWNT highly dispersed by the block copolymer enhances the thermal interface contact of the metal particle filler to facilitate heat transfer, and has an advantage that the block copolymer is used as a continuous medium base as it is. In contrast to the thermally conductive composite material obtained by merely mixing a polymer and a metal usually having a thermal conductivity of about 10 W / mK, the block copolymer polymer and the metal composite material containing MWNT as in one embodiment of the present invention are very It was confirmed that not only the high thermal conductivity was shown but also the high thermal conductivity (see FIG. 8A) by interacting with various metal particle fillers.

In addition, the production of composite materials by hot pressing has the advantage of not only reducing the pores in the specimen but also enhancing the thermal contact between the MWNT and the interface between the fillers and the heat transfer of the filler. In one embodiment of the present invention, a new thermally conductive nanocomposite using MWNT highly dispersed by a block copolymer together with various metals not only remarkably improves the low thermal conductivity of the existing composite material, It will be used as a material and applicable to various studies.

Particularly, in an embodiment of the present invention, a multi-walled carbon nanotube is used at a price much higher than that of a single-walled or double-walled carbon nanotube without using single-walled carbon nanotubes or double-walled carbon nanotubes It is not only inexpensive, but also because each of the tubes of the multi-walled carbon nanotubes is metallic, a composite exhibiting a higher thermal conductivity can be manufactured by forming a metallic heat conduction network.

Hereinafter, the present invention will be described with reference to specific experiments.

(One) Block copolymer  Solution preparation

In one embodiment of the present invention, a block copolymer is used as a dispersant for dispersing multi-walled carbon nanotubes. The block copolymer does not need to form micelles. For example, PS- b- PPP block copolymer (polystyrene-block-polyparaphenylene) does not form micelles, but it can disperse carbon nanotubes, However, PS- b- PPV block copolymer (PS- b- PPVP) which forms micelles at a relatively low price due to its high price is used in the following experiments Respectively. In the following experiments, PS- b -P4VP block copolymers having molecular weights of PS and P4VP of 20,000 gmol ^-1 and 17,000 gmol ^-1 , respectively, were used.

Toluene was used as a solvent to make a block copolymer solution in which micelle was formed, and the concentration of the block copolymer was maintained at 0.5 wt%. Since the P4VP block did not dissolve well in toluene, the temperature was maintained at 80-90 ° C. and the shape change of the block copolymer micelle was induced while the block copolymer was dissolved in the solvent using a PTFE magnet stir bar for 2 hours .

Because the specific block copolymers and suitable solvents therefor that can be used in one embodiment of the present invention are very diverse, and the selection of such block copolymers and suitable solvents is a well known technique, the scope of the present invention is limited to specific block copolymers and solvents It is not limited.

(2) Block copolymer  by MWNT  Dispersion

In order to investigate the change of the thermal properties depending on the amount of the PS- b -P4VP block copolymer continuous medium, 1 part by weight of the block copolymer PS- b- P4VP was mixed with 1 part by weight of MWNT at a ratio of 1: 2, 1: 3, 1: : 7 and 1:10.

Then, after the solution containing the block copolymer and the multi-walled carbon nanotubes were subjected to ultrasonic destruction (100 W, 40 KHz) for 30 minutes, the block copolymer was effectively adsorbed on the surface of the multi-walled carbon nanotubes, (Horn sonication, VC 750, Sonic & Materials, Inc. 750 W) for 10 minutes to disperse the multi-walled carbon nanotubes. After that, the dispersion of the block copolymer and the MWNT was stabilized by ultrasonic treatment again for 10 minutes. Figure 1 is a schematic representation of the mechanism by which block copolymer micelles disperse MWNTs and shows that block copolymer micelles serve as dispersants to allow MWNTs to be uniformly dispersed throughout the medium without being bundled with MWNTs .

(3) Block copolymer / MWNT  Powder manufacturing

PS- b -P4VP block copolymer In preparation for the preparation of a highly thermally conductive nanocomposite using MWNT dispersed by micelle, vacuum filtering was performed to remove toluene, which is a solvent of a carbon nanotube-dispersed solution . The solvent of the carbon nanotube dispersion solution was filtered using a PTFE membrane filter having a pore size of 200 nm and a diameter of 47 mm. 30 g of the solution is subjected to vacuum filtration for 2 days to obtain a PS- b -P4VP / MWNT mat, which is used as a base for continuous media with metal filler.

After PS- b -P4VP / MWNT mat was obtained by vacuum filtering, vacuum drying was performed for 1 hour to remove residual toluene. The PS- b- P4VP / MWNT mat was pulverized using a mortar bowl until micro-sized fine powder particles were obtained. Through the above process, PS- b- P4VP / MWNT powder was prepared and mixed with metal microparticles as described in the next step to prepare a nanocomposite. That is, a mat (sheet shape means) of a block copolymer / MWNT was first prepared, and then the mat was pulverized to prepare a powder.

(4) Block copolymer / MWNT / Composite of metals

(4-1) Hot Pressing  through Block copolymer / MWNT / Composite of metals

PS- b- P4VP / MWNT / Hot pressing was performed to fabricate the metal specimen. In addition to hot pressing, there are a wide variety of methods for forming polymer composite materials, such as autoclave molding, compression molding, open mold molding, and RTM molding, but in the experiment according to one embodiment of the present invention, hot pressing was used .

The PS- b -P4VP / MWNT 1 ~ 3 ㎛ size with the aluminum powder, 1 ~ 2 ㎛ of copper or a 2 ~ 3.5 ㎛ size of the size of the metallic filler is 10, 20, 30, 40, 50 and 70% by volume Thermally conductive carbon nanotube - metal nanocomposite specimens were prepared at various ratios. The volume percent of PS- b -P4VP / MWNT powder and 100% of the total volume of metal is mixed with 10-70% by volume of metal and the remaining 30-90% by volume of PS- b -P4VP / MWNT powder it means.

Hot pressing was performed for 1 hour at a relatively low pressure of 5 MPa at 160 DEG C using a stainless steel pressing mold having a diameter of 12.7 mm and then cooled at room temperature. Hot-pressing can reduce the pores in the specimen as well as increase the thermal conductivity between the fillers and the interface and between the filler and the MWNT.

 (4-2) Polishing ( Polishing )

The specimens prepared by hot pressing were polished according to the standard for thermal properties measurement using Xenon Flash. The polishing process was performed using a stainless steel polishing mold designed to be 12.7 mm in diameter and 2 mm in thickness. Weights and volumes were measured with specimens that conformed to the specification, and the density was calculated to calculate the thermal conductivity.

The physical properties of the intermediate process sample and final sample block copolymer / MWNT / metal composite prepared through the above steps were tested as follows.

<Experimental Results>

Experimental Example  One : Block copolymer  by MWNT Dispersion confirmation experiment

FIGS. 2A and 2B are SEM images and TEM images of MWNT dispersed by PS- b- P4VP micelles in a toluene solvent, respectively. In the experiment, the content of block copolymer to MWNT in the solution was adjusted to a weight ratio of 5: 1.

2A is a SEM image of a block copolymer spin-coated on a Si substrate at 1000 rpm for 60 seconds in order to examine the dispersibility of carbon nanotubes. MWNT was highly dispersed by PS- b -P4VP micelle, which is a block copolymer, and micelles were adsorbed on the surface of carbon nanotubes and showed dispersibility and stability.

As shown in the TEM image of FIG. 2B, it was confirmed that the block copolymer micelles were adsorbed on the surface while surrounding the MWNTs. This shows that the block copolymers stably disperse MWNT while forming self-assembly behavior and forming micelles and preventing bundling. It was found that the highly dispersed carbon nanotubes are stable as individual tubes rather than bundles, so that they can exhibit the inherent characteristics of carbon nanotubes. Furthermore, the dispersion stability of the block copolymer micelles is superior to those of other surfactants.

Experimental Example  2 : PS - b - P4VP / MWNT  Measurement of physical properties of mat and powder

3A is a photograph of a PS- b- P4VP / MWNT mat, and Fig. 3b shows that MWNT is redispersed by micelles of PS- b -P4VP when PS- b -P4VP / MWNT powder is again dissolved in toluene 3C and 3D are surface and cross-sectional SEM images of the PS- b -P4VP / MWNT mat, respectively, and Figs. 3e and 3f are SEM images of the PS- b -P4VP / MWNT powder.

An image of the PS- b- P4VP / MWNT mat obtained through the vacuum filtering process of the toluene solution mixed with PS- b- P4VP to MWNT in a weight ratio of 5: 1 is shown in Fig. After removing the remaining toluene solvent by vacuum drying, the powder was prepared using a mortar. It is necessary to change enough to obtain micro-sized fine particles, and the size of the powder can be found from FIG. 3E. The size of PS- b- P4VP / MWNT powder was 10 ~ 50 ㎛. 3F shows that the MWNT is present in the form of a separate tube without bundling due to the dispersion stability of the block copolymer in the solution thus prepared. The block copolymer adsorbed on the surface of MWNT not only improves the dispersibility but also can be used as a continuous medium base by the polymer itself. Even if the polymer is redispersed in a toluene solvent after being made into a powder, Figure 3b shows the self-assembling behavior of the coalescence and return to the micellar form. The toluene nonpolar solvent redistributed at the same concentration as 0.5 wt% shows the same phenomenon as the dispersion solution of the carbon nanotubes using the block copolymer for the first time and adsorbed on the MWNT to disperse the tubes individually and stably. there was. FIGS. 3c and 3d are the surface and cross-sectional SEM images of the prepared PS- b -P4VP / MWNT mat, wherein the self-assembled block copolymer and carbon nanotubes generated through the solution process are removed by vacuum filtration It is found that the dispersion and the shape are maintained.

Experimental Example  3: PS - b - P4VP / MWNT  Experiment to measure thermal properties of composite

In Experimental Example 2, the physical properties of the PS- b -P4VP / MWNT powder were tested. In Experimental Example 3, the physical properties of the PS- b -P4VP / MWNT composite prepared by hot pressing the powder were examined.

4a and 4b show the results of measurement of the diffusivity and the thermal conductivity of the PS- b -P4VP / MWNT composite of various content ratios, and Figs. 4c and 4d show the results of PS- b -P4VP / MWNT 5: 1) SEM image of the composite.

After PS- b- P4VP / MWNT powder was prepared, thermally conductive PS- b- P4VP / MWNT nanocomposites were prepared by hot pressing the powder itself without adding metal particles. The specimen size of the thermally conductive nanocomposite was polished to a size of 12.7 mm in diameter and 2 mm in thickness, and the density was measured by weighing. The heat capacity (Cp, Heat Capacity) was derived from the Xenon Flash comparison method. The values obtained are shown in Table 1, and the density tends to decrease as the proportion of the block copolymer increases. On the other hand, the higher the content of PS- b -P4VP, the larger the Cp. As shown in FIG. 4A, the thermal conductivity of each specimen was determined by the product of the measured thermal diffusivity, density and specific heat. As the ratio of the polymer increases, the thermal contact resistance between the polymer matrix and the filler 4B. As shown in FIG. In spite of the inherent high thermal conductivity of carbon nanotubes, the reason why the thermal conductivity is smaller than expected is that the thermal coupling between the interface and the filler is not good and the phonon migration is not free, resulting in a very small value. 4C and 4D, the MWNTs are not bundled at the block copolymer base but are individually dispersed. This is because the interfacial contact of the highly dispersed carbon nanotubes is not increased and the thermal conductivity is lowered. Is interpreted.

MWNT / PS- b -P4VP specimen Density (g / cm ³⁾ Cp (J / gK) 1: 2 1.199 1.041 1: 3 1.176 1.049 1: 5 1.128 1.098 1: 7 1.083 1.125 1:10 1.089 1.118

Experimental Example  4 :. PS - b - P4VP / MWNT / Al  Thermal properties of specimen

Figures 5a and 5b show a PS- b- P4VP / MWNT / Al composite with various volume ratios (10, 30, 50, 70 vol%) aluminum in PS- b -P4VP / MWNT (5: And 5c and 5d are SEM images of PS- b- P4VP / MWNT / Al composite (content of Al is 30% by volume) sample.

As a result of Experimental Example 3, a block copolymer / MWNT / metal nanocomposite was prepared by using aluminum having relatively high thermal conductivity, low cost and low density due to low thermal conductivity of PS- b- P4VP / MWNT complex. The density of aluminum is 2.70 g / cm ³ , which is 1.916 g / cm ³ , which is a low density even though it is a 70 vol% aluminum specimen as shown in Table 2. The MWNT / PS- b -P4VP powder with a ratio of 1: 5 was used as the polymer continuous media base because its process yield was significantly better than that of MWNT / PS- b -P4VP with different ratios, If the ratio of b -P4VP is lower than this, it is deteriorated in dispersibility and stability.

1: 5 MWNT / PS-b-P4VP / Al Density (g / cm ³ ) Cp (J / gK) 10 vol% Al 1.188 1.083 30 vol% Al 1.493 1.016 50 vol% Al 1.800 1.063 70 vol% Al 1.916 1.096

As shown in FIGS. 5A and 5B, the maximum thermal conductivity of the PS- b -P4VP / MWNT / Al specimen is 16.900 W / mK and the PS- b -P4VP / MWNT powder, The number of point thermal contacts was increased to increase the phonon movement path between the aluminum metal particles.

Experimental Example  5: PS - b - P4VP / MWNT / Cu  Thermal properties of specimen

Figures 6a and 6b are PS- b -P4VP / MWNT: the PS- b -P4VP / MWNT / Cu composite material comprising a copper (content ratio 51) different volume ratio of the powder (10, 30, 50, 70 vol%) 6C and 6D are SEM images of PS- b- P4VP / MWNT / Cu composite (content of Cu of 30% by volume) sample.

Due to the low thermal conductivity and mechanical properties of the PS- b -P4VP / MWNT / Al specimens, in Experimental Example 5, copper particles having a high thermal conductivity of 1 ~ 2 탆 among the metal fillers were used and PS- b -P4VP / MWNT powder PS- b- P4VP / MWNT / Cu composite specimens were prepared by hot pressing together. As shown in Table 3, as the volume ratio of copper increased due to the high density of copper, the density increased, while the specific heat tended to decrease gradually. The highly dispersed and stabilized MWNTs by block copolymers effectively adsorbed on the surface of the copper to increase the number of point thermal contacts and also effectively lead to thermal coupling with the copper, resulting in a high thermal conductivity of the polymer / metal composite Respectively. As shown in FIGS. 6A and 6B, the PS- b -P4VP / MWNT / Cu specimen made with copper exhibited a maximum thermal conductivity of 48.901 W / mK. As can be seen from the SEM images of FIGS. 6C and 6D, It was found that the heat transfer efficiency was increased effectively by increasing the travel path of the heat transfer path.

1: 5 MWNT / PS-b-P4VP / Cu Density (g / cm ³ ) Cp (J / gK) 10 vol% Cu 1.907 0.904 30 vol% Cu 3.440 0.531 50 vol% Cu 4.615 0.474 70 vol% Cu 5.438 0.439

Experimental Example  6: PS - b - P4VP / MWNT / Ag  Thermal properties of specimen

Figures 7a and 7b show PS- b- P4VP / MWNTs containing silver in various volume ratios (10, 20, 30, 40, 50, 70 vol%) in PS- b -P4VP / MWNT / Ag composite, and Figs. 7c and 7d are SEM images of PS- b- P4VP / MWNT / Ag composite (Ag content of 30 vol%) samples.

PS- b -P4VP / MWNT Powder and specimen were made with silver which is the highest thermal conductivity metal. As can be seen in Table 4, the higher the volume ratio of silver, the higher the density of the specimen, while the specific heat decreases. Carbon nanotube - silver (2-3.5 ㎛) nanocomposites using self - assembled block copolymers exhibited high thermal conductivity, which was not seen before, with a maximum thermal conductivity of 122.806 W / mK. As shown in FIGS. 7A and 7B, the highly dispersed carbon nanotubes drastically increase the thermal diffusivity and thermal conductivity of the specimen. As can be seen from the SEM image of FIGS. 7C and 7D, Not only the number of thermal contacts of phosphorus is increased but also the thermal coupling is stable and the phonon movement is facilitated and the thermal conductivity is high. It is interpreted that the phonon movement between the silver filler and the carbon nanotube interface occurs not only at the interface of the silver filler but also at the interface between the metal filler and the MWNT dispersed in the polymer matrix, without thermal coupling problems, resulting in a very high thermal conductivity.

1: 5 MWNT / PS-b-P4VP / Ag Density (g / cm ³ ) Cp (J / gK) 10 vol% Ag 2.000 0.714 20 Vol% Ag 2.985 0.525 30 vol% Ag 3.702 0.470 40 vol% Ag 4.236 0.369 50 vol% Ag 5.194 0.354 70 vol% Ag 6.634 0.320

The experimental results of the above-mentioned PS- b- P4VP / MWNT / metal complex are summarized in FIG. 8A. Figure 8a shows the composite of the present invention comprising various volume ratios of aluminum, copper and silver to MWNT: PS- b -P4VP powder with a 1: 5 content ratio, and the thermal conductivity of the material containing silver in various volume ratios .

As shown in FIG. 8A, the MWNT / PS- b- P4VP / Ag specimen showed the highest thermal conductivity, and the micro-sized silver metal filler exhibited better thermal conductivity than the nano-sized silver metal filler. This is because nano-sized metal particles are passivated in air and exhibit less thermal conductivity than micro-sized silver, and the high bulk density of nano-sized silver also results in a higher thermal conductivity due to the probability of large pores in the specimen "

8B is a view for explaining the internal structure of the PS- b- P4VP / MWNT / Ag composite of the present invention. As described above, MWNT not only helps phonon movement between fillers and polymer matrix but also enhances thermal contact between silver metal filler interfaces to promote phonon migration and to enhance phonon migration as a kind of resistance parallel connection phenomenon. The resistance is reduced.

Further, it can be seen that heat conduction by free electrons occurs between silver metal fillers. PS- b -P4VP, which is a block copolymer, assists dispersion of MWNTs and improves stability, so that MWNTs can be individually dispersed and can be a continuous medium base even if only a block copolymer is added without adding another polymer matrix. A polymer composite material can be produced. The dispersion of MWNT using the self-assembled block copolymer and the block copolymer / MWNT / metal nanocomposite of the present invention using the self-assembled block copolymer exhibit excellent thermal conductivity and can be applied to various fields as a heat dissipation material.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

Claims (15)

A block copolymer and a multi-walled carbon nanotube (MWNT); And
Comprising a metal,
Wherein the powder is mixed with 2 to 10 parts by weight of a block copolymer with respect to 1 part by weight of MWNT and the powder to metal particles are mixed with a volume ratio of 30 to 90% by volume and 10 to 70% by volume, / MWNT / metal complex. delete delete delete The method according to claim 1,
The block copolymer / MWNT / metal complex according to claim 1, wherein the block copolymer is a block copolymer forming micelles. The method according to claim 1,
Wherein the metal is one of copper, silver and aluminum. &Lt; RTI ID = 0.0 &gt; 18. &lt; / RTI &gt; (a) preparing a mixed solution comprising a block copolymer, MWNT, and a solvent;
(b) removing the solvent from the mixed solution to prepare a powder containing the block copolymer / MWNT; And
(c) mixing metal particles with the powder and then processing the mixture to prepare a block copolymer / MWNT / metal composite,
In the step (a), 2 to 10 parts by weight of a block copolymer is mixed with 1 part by weight of the MWNT,
In the step (c), the powder-metal particles are mixed in a volume ratio of 30 to 90 vol%: 10 to 70 volume% and then heated to produce a composite. The block copolymer / MWNT / metal complex &Lt; / RTI &gt; delete 8. The method of claim 7,
The step (a)
Dissolving the block copolymer in a solvent to prepare a block copolymer solution; And
And mixing the block copolymer solution with MWNT to disperse the MWNT. The method for producing a block copolymer / MWNT / metal composite according to claim 1, delete 8. The method of claim 7,
In the step (c), the block copolymer / MWNT / metal composite may be prepared by any one of hot pressing, autoclave molding, compression molding, open mold molding and RTM molding / RTI &gt; and / or a block copolymer / MWNT / metal complex. 10. The method of claim 9,
Wherein the step of dispersing the MWNT comprises:
Wherein the mixed solution is subjected to an ultrasonic treatment and a sonication treatment. &Lt; RTI ID = 0.0 &gt; 18. &lt; / RTI &gt; 8. The method of claim 7,
Wherein the solvent is toluene,
The step (b)
Obtaining a mat by vacuum filtering the mixed solution; And
Wherein the matting is carried out by vacuum drying the mat. &Lt; RTI ID = 0.0 &gt; 18. &lt; / RTI &gt; 8. The method of claim 7,
Wherein the metal is one of copper, silver and aluminum. &Lt; RTI ID = 0.0 &gt; 18. &lt; / RTI &gt; 15. The method of claim 14,
Wherein the copper particles have a size of 1 to 2 占 퐉, the silver particles have a size of 2 to 3.5 占 퐉, and the aluminum particles have a size of 1 to 3 占 퐉.

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