• Carbon letters
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• v.11 no.4
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• pp.298-303
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• 2010

A method of functionalization of multi-walled carbon nanotube (MWNT) at room temperature using dry ozone gas is described. The resulting MWNT were characterized by Fourier transform infrared, x-ray photoelectron spectroscopy, and scanning electron microscopy. Combined to these analyses and solubility in liquids, it could be concluded that the dry ozone gas exposure introduces polar functional groups such as carboxylic groups to MWNT similar to acidic modification of MWNT. Particularly, the stable dispersion of MWNT in water after ozone treatment above a critical level could be obtained, implying potential bio-application. The hydrophilic functional groups on the MWNT introduced by ozone oxidation were helpful in improving the interaction with functional groups in PA6 such as $-NH_2$ and -CONH- resulting in improved mechanical properties.

• Korean journal of food and cookery science
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• v.25 no.2
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• pp.252-259
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• 2009

Ergosterol is the significant component of the cell wall of fungi. Its presence is regarded as evidence of fungi contamination in grain and other foods. Many studies on ergosterol detection have been carried out using chemical methods, but those methods required complicated pre-treatments and long analysis times. In this study, an amperometric biosensor was developed for fast and precise ergosterol detection. The biosensor system used the electron transfer of hydrogen peroxide produced from the reaction of ergosterol with cholesterol oxidase. The biosensor system consisted of a peristaltic pump, a syringe loading sample injector, an enzyme reactor, a fabricated flow-through cell containing a working electrode, a reference electrode and a counter electrode, and a potentiostat/recorder. The working electrode was prepared by coating modified multi-wall carbon nanotube (MWNT) on glassy carbon electrode. The $MWNT-NH_2$ coated glassy carbon electrode linearly responded to hydrogen peroxide in the range of $1{\times}10^{-5}{\sim}8{\times}10^{-5}$ M with a detection limit of $10^{-7}$ M in the basic performance test. The currents produced from the ergosterol biosensor showed the linearity in a range from $1.0{\times}10^{-6}$ M to $1.0{\times}10^{-5}$ M ergosterol.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.25.2-25.2
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• 2010

CNT(Carbon Nanotube)는 특이한 구조 및 뛰어난 물성을 갖고 있어, 여러가지 분야에 응용 가능한 신소재로서 연구되어 왔다. 또한 모양 및 구조에 따라 기계, 전기, 화학적인 특성이 달라 다양한 분야에서 활용이 가능하다. 외국에서는 FED tip, TR, 디스플레이 소자, 수소저장체, 고강도 복합체 및 대 표면적 전극 등 CNT의 다양한 특성을 이용한 응용이 연구되고 있는 반면, 국내에서는 이론연구와 합성연구에 편중되어 있다. 본 연구에서는 열 화학 기상법 (Thermal CVD)을 이용하여 MWNT(Multi-wall nano tube)를 성장시켜 촉매두께, 온도, gas변수에 따른 CNT의 양상을 분석하였다. Ni catalyst는 DC magnetron sputter를 이용하여 5~50nm 두께로 증착하였으며, 성장온도는 $800^{\circ}C$에서 $950^{\circ}C$까지 변화시켰다. 기판의 pre-treatment 로 ammonia($NH_3$) gas를 주입한 후, carbon precursor인 methane($CH_4$) gas와 $H_2$ dilute gas를 1:4의 비율로 주입하여 CNT를 성장시켰다. FE-SEM과 TEM, 그리고 XRD를 이용해 성장된 CNT의 형상 및 구조를 분석한 결과, 낮은 온도에서는 100nm이상의 두께를 갖는 수직형상의 MWNT가 성장되었으며, $900^{\circ}C$이상의 높은 온도에서는 20nm이하의 amorphous carbon nano rod가 성장되었다. 각각의 MWNT, carbon nano rod는 온도가 높을수록 직경이 증가하는 추세를 나타냈으며, Ni catalyst가 얇아질수록 수직형상을 갖는 결과가 나타났다. 또한 ammonia gas의 pre-treatment여부에 따라 CNT의 수직 형상이 좌우되는 결과를 확인하였다. 향후 성장된 MWNT의 최적 조건을 도출하여 디스플레이 소자인 FED(Field Emission Display)분야 등에 응용 가능할 것으로 전망된다.

• Carbon letters
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• v.11 no.2
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• pp.102-106
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• 2010

In this work, the effect of aminized multi-walled carbon nanotubes (NH-MWNTs) on the mechanical interfacial properties of epoxy nanocomposites was investigated by means of fracture toughness, critical stress intensity factor ($K_{IC}$), and impact strength testing, and their morphology was examined by scanning electron microscope (SEM). It was found that the incorporation of amine groups onto MWNTs was confirmed by the FT-IR and Raman spectra. The mechanical interfacial properties of the epoxy nanocomposites were remarkably improved with increasing the NH-MWNT content. It was probably attributed to the strong physical interaction between amine groups of NH-MWNTs and epoxide groups of epoxy resins. The SEM micrographs showed that NH-MWNTs were uniformly embed and bonded with epoxy resins, resulted in the prevention of the deformation and crack propagation in the NH-MWNTs/epoxy nanocomposites.

• Macromolecular Research
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• v.14 no.5
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• pp.545-551
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• 2006

Aqueous dispersions of pristine and functionalized (COOH- and $NH_2$-) multi-walled, carbon nanotubes (MWNTs) were prepared by using three types of surf act ants: sodium dodecyl sulfate (SDS, anionic), PEO-PPO-PEO (Pluronic P84, non-ionic), and poly(styrene/$\alpha-methyl$ styrene/acrylic acid) random terpolymer, i.e., alkali-soluble resin (ASR). The aggregate size, $\zeta-potential$, and storage stability of the MWNT aqueous dispersions were investigated by using dynamic light scattering and the turbidity method at room temperature. The exfoliation of the MWNT aggregates was determined by a UV-visible spectrophotometer and the morphology of the surfactant-coated MWNTs was observed by transmission electron microscopy (TEM). In all cases, ASR showed better dispersion stability with the smallest aggregate size, compared with the other surfactants, because of its unique molecular structure, i.e., randomly incorporated carboxylic acid groups and planar phenyl groups that can be irreversibly and effectively adsorbed on the MWNT surface. A predominantly-exfoliated morphology of MWNTs was observed in the presence of ASR from the strong intensity of the UV-vis spectrum at 263 nm.