폴리머-탄소나노튜브 복합체 에어로졸 입자의 생성 및 이를 이용한 하이브리드 복합체 박막 제조

김휘동,안지영,김수형 한국입자에어로졸학회 2010 Particle and Aerosol Research Vol.6 No.2

In this paper, we describe a new method to form polymer thin films, in which carbon nanotubes (CNTs) are homogeneously distributed so that they can strengthen the mechanical property of resulting polymer film. To do so, we first homogeneously mixed CNTs with polymer in a DMF solvent. With the assistance of ultrasonic nebulizer, the polymer/CNT solution was then aerosolized into micro-sized droplets and finally turned into solidified polymer/CNT composite particles by gas-phase drying process. As the results of SEM and TEM analysis, CNTs were found to be homogeneously immobilized in the polymer matrix particles due to rapid drying process in the gas phase. For comparison purpose,(i) the polymer/CNTs composite particles prepared by aerosol processing method and (ii) polymer/CNTs sheets prepared by simple solution-evaporation method were employed to form polymer/CNTs composite thin films using a hot press. As the result, the aerosol processing of composite particles was found to be a much more effective method to form homogeneously distributed-CNTs in the polymer matrix thin film.

Thermal and electrical conductivity of poly(L-lactide)/multiwalled carbon nanotube nanocomposites

김현식,Yun Seok Chae,Byung Hyun Park,윤진산,강민성,진형준 한국물리학회 2008 Current Applied Physics Vol.8 No.6

Multiwalled carbon nanotubes (MWCNTs) are considered to be the ideal reinforcing agent for high-strength polymer composites, because of their fantastic mechanical strength, high electrical and thermal conductivity and high aspect ratio. Polymer/MWCNTs composites are easily molded, and the resulting shaped plastic articles have a perfect surface appearance compared with polymer composites made using usual carbon or glass fibers. Good interfacial adhesion between the MWCNTs and the polymer matrix is essential for efficient load transfer in the composite. The ultrahigh strength polymer composites demand the uniform dispersion of the MWCNTs in the polymer matrix without their aggregation and the good miscibility between MWCNT and polymer matrix. This approach can also be applied to biodegradable synthetic aliphatic polyesters such as poly(L-lactide) (PLLA), which has received a great deal of attention due to environmental concerns. In this study, PLLA was melt-compounded with MWCNTs. A high degree of dispersion of the MWCNTs in the composites was obtained by grafting PLLA onto the MWCNTs (PLLA-g-MWCNTs). After oxidizing the MWCNTs by treating them with strong acids, they were reacted with L-lactide to produce the PLLA-g-MWCNTs. The mechanical properties of the PLLA/ PLLA-g-MWCNT composite were higher than those of the PLLA/MWCNT composite. The electrical conductivity of the composites was determined by measuring the volume resistivity, which is a value of the resistance expressed in a unit volume by two-probe method. The thermal diffusivity and heat capacity of composites was measured by laser flash method, and the effects of modification of the MWCNT in PLLA matrix are discussed. Multiwalled carbon nanotubes (MWCNTs) are considered to be the ideal reinforcing agent for high-strength polymer composites, because of their fantastic mechanical strength, high electrical and thermal conductivity and high aspect ratio. Polymer/MWCNTs composites are easily molded, and the resulting shaped plastic articles have a perfect surface appearance compared with polymer composites made using usual carbon or glass fibers. Good interfacial adhesion between the MWCNTs and the polymer matrix is essential for efficient load transfer in the composite. The ultrahigh strength polymer composites demand the uniform dispersion of the MWCNTs in the polymer matrix without their aggregation and the good miscibility between MWCNT and polymer matrix. This approach can also be applied to biodegradable synthetic aliphatic polyesters such as poly(L-lactide) (PLLA), which has received a great deal of attention due to environmental concerns. In this study, PLLA was melt-compounded with MWCNTs. A high degree of dispersion of the MWCNTs in the composites was obtained by grafting PLLA onto the MWCNTs (PLLA-g-MWCNTs). After oxidizing the MWCNTs by treating them with strong acids, they were reacted with L-lactide to produce the PLLA-g-MWCNTs. The mechanical properties of the PLLA/ PLLA-g-MWCNT composite were higher than those of the PLLA/MWCNT composite. The electrical conductivity of the composites was determined by measuring the volume resistivity, which is a value of the resistance expressed in a unit volume by two-probe method. The thermal diffusivity and heat capacity of composites was measured by laser flash method, and the effects of modification of the MWCNT in PLLA matrix are discussed.

Singlewall carbon nanotubes covered with polystyrene nanoparticles by in-situ miniemulsion polymerization

Ham, Hyeong Taek,Choi, Yeong Suk,Chee, Mu Guen,Chung, In Jae Wiley Subscription Services, Inc., A Wiley Company 2006 Journal of polymer science Part A, Polymer chemist Vol.44 No.1

<P>This work is to make carbon nanotubes dispersible in both water and organic solvents without oxidation and cutting nanotube threads. Polystyrene-singlewall carbon nanotube (PS-SWNT) composites were prepared with three different methods: miniemulsion polymerization, conventional emulsion polymerization, and mixing SWNT with PS latex. The two factors, crosslinking and surface coverage of PS are important factors for the mechanical and electrical properties, including dispersion states of SWNT in various solvents. The PS-SWNT composite prepared via a conventional emulsion polymerization showed SWNT bundles entirely covered with PS, whereas the PS-SWNT composite prepared via a miniemulsion polymerization showed SWNT partially covered with crosslinked PS nanoparticles. The method of mixing SWNTs with PS latex did not show the well dispersed state of carbon nanotubes because PS was not crosslinked and was dissolved in a solvent, and nanotubes separated from PS precipitated. So the PS nanoparticle-SWNT composite had lower electrical resistance, and higher mechanical strength than the other composites made by the latter two methods. As the amount of SWNT increases, the bare surface area of SWNT increases and the electrical conductivity increases in the composite made by the miniemulsion polymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 573–584, 2006</P> <B>Graphic Abstract</B> <P>Singlewall carbon nanotubes covered with polystyrene nanoparticles were prepared via in-situ miniemulsion polymerization. Polystyrene nanoparticles were attached on the surface of singlewall carbon nanotubes. The nanoparticles partially covered the sidewall of carbon nanotubes. The bare surface of singlewall carbon nanotubes and polystyrene nanoparticle attached singlewall carbon nanotubes were coexisted. Polystyrene-singlewall carbon nanotube composites were prepared with three different methods: miniemulsion polymerization, conventional emulsion polymerization, and mixing SWNT with PS latex. Their structural difference and properties were examined. <img src='wiley_img/0887624X-2006-44-1-POLA21185-gra001.gif' alt='wiley_img/0887624X-2006-44-1-POLA21185-gra001'> </P>

Synthesis of MWCNTs-core/thiophene polymer-sheath composite nanocables by a cationic surfactant-assisted chemical oxidative polymerization and their structural properties

Reddy, Kakarla Raghava,Jeong, Han Mo,Lee, Youngil,Raghu, Anjanapura Venkataramanaiah Wiley Subscription Services, Inc., A Wiley Company 2010 Journal of polymer science Part A, Polymer chemist Vol.48 No.7

<P>Multi-walled carbon nanotubes (MWCNTs)-core/thiophene polymer-sheath composite nanocables were synthesized by chemical oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) with oxidant (FeCl<SUB>3</SUB>) in the presence of cationic surfactant, deceyltrimethyl ammonium bromide (DTAB). In the polymerization process, DTAB surfactant molecules were adsorbed on the surface of MWCNTs and forms MWCNTs-DTAB soft template. Upon the addition of EDOT and oxidant, the polymerization take place on the surface of MWCNTs and PEDOT is gradually deposited on the surface of MWCNTs. The resulting MWCNTs-PEDOT nanocomposites have the nanocable structure. Nanocomposites were characterized by HRTEM, FE-SEM, XRD, XPS, TGA, FTIR and PL, respectively. The π-π interactions between PEDOT and MWCNTs enhancing the thermal and electrical properties of the nanocomposites with loading of MWCNTs. The temperature dependence conductivity measurements show that the conductivity of the nanocomposite decrease with a decrease of temperature, and conductivity-temperature relationship is well fit by the quasi-one dimensional variable range hopping mode. The mechanism for the formation of composite nanocables was explained on the basis of self- assembly of micelles. The reported self-assembly strategy for the synthesis of PEDOT-coated MWCNTs in micellar medium is a rapid, versatile, potentially scalable, stable, and making it useful for further exploitation in a varies types of applications. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1477–1484, 2010</P> <B>Graphic Abstract</B> <P>The MWCNTs-thiophene polymer core-sheath composite nanocables were synthesized by chemical oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) with oxidant (FeCl<SUB>3</SUB>) in the presence of cationic surfactant, deceyltrimethyl ammonium bromide (DTAB) that acts as the structure-directing agen. In the polymerization process, DTAB surfactant molecules were adsorbed on the surface of MWCNTs and forms MWCNTs-DTAB soft template. On the addition of EDOT and oxidant, the polymerization takes place on the surface of MWCNTs, and PEDOT is gradually deposited on the surface of MWCNTs. The resulting nanocomposites have the nanocable structure as shown in the scheme. The structural, morphological, thermal, optical, and electrical properties of the synthesized nanocomposites were fully characterized by using various techniques. The mechanism for the formation of composite nanocables was explained on the basis of self-assembly of micelles. The reported self-assembly strategy for the synthesis of PEDOT-coated MWCNTs in micellar medium is a rapid, versatile, potentially scalable, stable, and making it useful for further exploitation in various types of applications. <img src='wiley_img_2010/0887624X-2010-48-7-POLA23883-gra001.gif' alt='wiley_img_2010/0887624X-2010-48-7-POLA23883-gra001'> </P>

Multiwalled Carbon Nanotubes Functionalized with PS via Emulsion Polymerization

Park, In-Cheol,Park, Min,Kim, Jun-Kyung,Lee, Hyun-Jung,Lee, Moo-Sung The Polymer Society of Korea 2007 Macromolecular Research Vol.15 No.6

This study demonstrated the in-situ functionalization with polymers of multi-walled carbon nanotubes (MWNTs) via emulsion polymerization. Polystyrene-functionalized MWNTs were prepared in an aqueous solution containing styrene monomer, non-ionic surfactant and a cationic coupling agent ([2-(methacryloyloxy)ethyl]trime-thylammonium chloride (MATMAC)). This process produced an interesting morphology in which the MWNTs, consisting of bead-string shapes or MWNTs embedded in the beads, when polymer beads were sufficiently large, produced nanohybrid material. This morphology was attributed to the interaction between the cationic coupling agent and the nanotube surface which induced polymerization within the hemimicellar or hemicylindrical structures of surfactant micelles on the surface of the nanotubes. In a solution containing MATMAC alone without surfactant, carbon nanotubes (CNTs) were not well-dispersed, and in a solution containing only surfactant without MATMAC, polymeric beads were synthesized in isolation from CNTs and continued to exist separately. The incorporation of MATMAC and surfactant together enabled large amounts of CNTs (> 0.05 wt%) to be well-dispersed in water and very effectively encapsulated by polymer chains. This method could be applied to other well-dispersed CNT solutions containing amphiphilic molecules, regardless of the type (i.e., anionic, cationic or nonionic). In this way, the solubility and dispersion of nanotubes could be increased in a solvent or polymer matrix. By enhancing the interfacial adhesion, this method might also contribute to the improved dispersion of nanotubes in a polymer matrix and thus the creation of superior polymer nanocomposites.

탄소나노튜브-폴리머 복합체의 기능화와 제조방법

오원춘 ( Won Chun Oh ),고원배 ( Weon Bae Ko ),장봉군 ( Feng Jun Zhang ) 한국고무학회 2010 엘라스토머 및 콤포지트 Vol.45 No.2

탄소나노튜브는 우수한 기계적 특성, 전기적 및 자기적 성질 뿐만 아니라 나노 크기의 직경 및 높은 종횡비를 나타낸다. 이는 고강도 고분자 복합체의 이상적인 보강제로 사용할 수 있다. 기능성이 부과된 탄소나노튜브는 기능성 재료 및 복합재료의 제조와 같은 분야에서 아주 유력한 재료로 믿어진다. 탄소나노튜브-고분자 복합체는 탄소나노튜브의 우수한 기능성과 고분자의 우수한 가공성을 가질 것으로 기대된다. 그러나, 탄소나노튜브는 보통 반 델 바알스 작용에 의한 안정화된 번들을 형성하기 때문에 고분자 기지에 배열이나 분산이 상당히 어렵다. 탄소나노튜브 강화복합체의 제조에서 가장 큰 이슈는 고분자내에 탄소나노튜브의 효과적인 분산이며, 기지내에 탄소나노튜브의 배열과 양의 조절이다. 고분자 기지내에 탄소나노튜브의 분산은 용액혼합, 벌크 혼합, 용융혼합, 즉시 고분자화 반응 및 탄소나노튜브의 화학적 기능화 등과 같은 몇 가지 방법이 있다. 본 논평에서는 이들 방법과 고성능 탄소나노튜브-고분자 복합체의 제조에 대하여 서술하고자 한다. Carbon nanotubes (CNTs) exhibit excellent mechanical, electrical, and magnetic properties as well as nanometer scale diameter and high aspect ratio, which make them an ideal reinforcing agent for high strength polymer composites. The functionalized CNTs are believed to be very promising in the fields such as preparation of functional and composite materials. CNT-Polymer composites are expected to have good processability characteristics of the polymer and excellent functional properties of the CNTs. However, since CNTs usually form stabilized bundles due to Van der Waals interactions, are extremely difficult to disperse and align in a polymer matrix. The biggest issues in the preparation of CNT-reinforced composites reside in efficient dispersion of CNTs into a polymer matrix, and the alignment and control of the CNTs in the matrix. There are several methods for the dispersion of nanotubes in the polymer matrix such as solution mixing, bulk mixing, melt mixing, in-situ polymerization and chemical functionalization of the carbon nanotubes, etc. These methods and preparation of high performance CNT-polymer composites are described in this review.

Polymer nanocomposites reinforced with multi-walled carbon nanotubes for semiconducting layers of high-voltage power cables

Jeong, Kwang-Un,Lim, Jee Young,Lee, Jong-Young,Kang, Seong Lak,Nah, Changwoon John Wiley Sons, Ltd. 2010 Polymer international Vol.59 No.1

<P>Polymer nanocomposites reinforced with multi-walled carbon nanotubes (MWCNTs) have been newly introduced for semiconducting layers of high-voltage electrical power cables. Homogeneity of the MWCNT-reinforced polymer nanocomposites was achieved by solution mixing, and their mechanical, thermal and electrical properties were investigated depending on the type of polymer. By changing the polymer matrix, the volume resistance of the MWCNT-reinforced polymer nanocomposites could be varied by more than four orders of magnitude. Through systematic experiments and analysis, two possible factors affecting the volume resistance were found. One is the degree of crystallinity of the polymer used and the other is the change of MWCNT morphology under strain. By increasing the degree of crystallinity above a certain level, the volume resistance linearly increased. The MWCNTs embedded in the nanocomposites gradually protruded through the surface on stretching the sample and reversibly returned back to the original positions at a relatively small strain (below 20%). Based on the criteria of tensile properties and volume resistance, a poly[ethylene-co-(ethyl acrylate)]/MWCNT nanocomposite was selected as the best candidate for the semiconducting layers of high-voltage electrical power cables. Copyright © 2009 Society of Chemical Industry</P> <B>Graphic Abstract</B> <P>Based on the criteria of tensile properties and volume resistance, poly[ethylene-co-(ethyl acrylate)] (EEA)/MWCNT nanocomposite was selected as the best candidate for a SCL of high electrical power cables. <img src='wiley_img/09598103-2010-59-1-PI2696-gra001.gif' alt='wiley_img/09598103-2010-59-1-PI2696-gra001'> </P>

Effect of Polymer Gate Dielectrics on Charge Transport in Carbon Nanotube Network Transistors: Low-<i>k</i> Insulator for Favorable Active Interface

Lee, Seung-Hoon,Xu, Yong,Khim, Dongyoon,Park, Won-Tae,Kim, Dong-Yu,Noh, Yong-Young American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.47

<P>Charge transport in carbon nanotube network transistors strongly depends on the properties of the gate dielectric that is in direct contact with the semiconducting carbon nanotubes. In this work, we investigate the dielectric effects on charge transport in polymer-sorted semiconducting single-walled carbon nanotube field-effect transistors (s-SWNT-FETs) by using three different polymer insulators: A low-permittivity (epsilon(r)) fluoropolymer (CYTOP, epsilon(r) = 1.8), poly(methyl methacrylate) (PMMA, epsilon(r) = 3.3), and a high-epsilon(r) ferroelectric relaxor [P(VDF-TrFE-CTFE), epsilon(r) = 14.2]. The s-SWNT-FETs with polymer dielectrics show typical ambipolar charge transport with high ON/OFF ratios (up to similar to 10(5)) and mobilities (hole mobility up to 6.77 cm(2) V-1 s(-1) for CYTOP). The s-SWNT-FET with the lowest-k dielectric, CYTOP, exhibits the highest mobility owing to formation of a favorable interface for charge transport, which is confirmed by the lowest activation energies, evaluated by the fluctuation-induced tunneling model (FIT) and the traditional Arrhenius model (E-aFIT = 60.2 meV and E-aArr = 10 meV). The operational stability of the devices showed a good agreement with the activation energies trend (drain current decay similar to 14%, threshold voltage shift similar to 0.26 V in p-type regime of CYTOP devices). The poor performance in high-epsilon(r) devices is accounted for by a large energetic disorder caused by the randomly oriented dipoles in high-k dielectrics. In conclusion, the low-k dielectric forms a favorable interface with s-SWNTs for efficient charge transport in s-SWNT-FETs.</P>

A review of the preparation and properties of carbon nanotubes-reinforced polymer compositess

Fan-Long Jin,Soo-Jin Park 한국탄소학회 2011 Carbon Letters Vol.12 No.2

Carbon nanotubes (CNTs) have high Young's modulus, low density, and excellent electrical and thermal properties, which make them ideal fillers for polymer composites. Homogeneous dispersion of CNTs in a polymer matrix plays a crucial role in the preparation of polymer composites based on interfacial interactions between CNTs and the polymer matrix. The addition of a small amount of CNTs strongly improves the electrical, thermal, and mechanical properties of the composites. This paper aims to review the processing technology and improvement of properties of CNT-reinforced polymer composites.

Dual-Functionalized Polymer Nanotubes as Substrates for Molecular-Probe and DNA-Carrier Applications

Jang, J.,Ko, S.,Kim, Y. WILEY-VCH Verlag 2006 Advanced Functional Materials Vol.16 No.6

<P>Bifunctionalized polymer nanotubes have been fabricated using vapor-deposition polymerization in FeCl<SUB>3</SUB>-adsorbed anodic aluminum oxide membranes followed by attachment of amine-functionalized silica nanoparticles. The prepared bifunctionalized polymer nanotubes are applied as both a molecular probe and a DNA carrier by conjugating pyreneacetic acid with the amine groups and immobilizing DNA with the carboxylic acid groups on the surface. The number of amine functional groups on the nanotubes' surface can be measured by means of the photoluminescence intensity of pyreneacetic acid conjugated with amine groups, and the number of the residual carboxylic acid groups is calculated by titration with sodium hydroxide. Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, and confocal laser scanning microscopy have been performed to confirm the complete polymerization of the monomer and the attachment of photoluminescent molecules and single-stranded DNA.</P> <B>Graphic Abstract</B> <P>Bifunctionalized polymer nanotubes (PNTs) are fabricated using vapor-deposition polymerization followed by the attachment of amine-functionalized silica nanoparticles. The nanotubes are applied as both a molecular probe and a DNA carrier (see figure) by conjugating pyreneacetic acid with amine groups, and by immobilizing DNA with carboxylic acid groups on the surface. <img src='wiley_img/1616301X-2006-16-6-ADFM200500832-content.gif' alt='wiley_img/1616301X-2006-16-6-ADFM200500832-content'> </P>