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Functionalization of Multi-Walled Carbon Nanotubes with Poly(2-ethyl-2-oxazoline)
Tan, Soon Huat,Goak, Jeung Choon,Lee, Naesung,Kim, Jeong-Yeol,Hong, Sung Chul WILEY-VCH Verlag 2007 Macromolecular symposia Vol.249 No.1
<P>Multi-walled carbon nanotubes (MWCNTs) were successfully functionalized with water-soluble poly(2-ethyl-2-oxazoline) (PEOX) through a polymer wrapping process. Pristine MWCNTs were first treated with nitric acid (HNO<SUB>3</SUB>) at 120 °C for 24 hours. The resulting carboxylated MWCNTs were then mixed with 10 wt.% PEOX in ethanol, followed by sonication using a horn-type sonicator for 30 min and stirring at room temperature for 24 hours. Thereafter, unreacted free polymer was washed out repeatedly by centrifugation with an excess amount of ethanol. Scanning electron microscopy exhibited that the diameter of MWCNTs increased approximately by 10 nm after the functionalization of MWCNT with PEOX. Thermogravimetric analysis showed that approximately 15 wt.% polymer was incorporated in the functionalized MWCNTs. The functionalized MWCNTs gave excellent and stable dispersion in water as well as other organic solvents such as ethanol and DMF.</P>
MEHRNOUSH KHAVARIAN,SIANG-PIAO CHAI,SOON HUAT TAN,ABDUL RAHMAN MOHAMED 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2010 NANO Vol.5 No.3
Multi-walled carbon nanotubes (MWCNTs) were prepared by floating catalyst (FC) method, using methane as a carbon source and iron (III) chloride (FeCl3) as a catalyst precursor, followed by purification with air oxidation and acid treatment. The as-grown and purified MWCNTs were characterized by transmission electron microscopy, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetry analysis and Raman spectroscopy. The average inner and outer diameters of the MWCNTs were 25 and 39 nm, respectively. The purity and yield of the purified MWCNTs were more than 92% and 71% weight fraction, respectively.
MEHRNOUSH KHAVARIAN,SIANG-PIAO CHAI,SOON HUAT TAN,ABDUL RAHMAN MOHAMED 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2009 NANO Vol.4 No.6
Carbon nanotubes (CNTs) were synthesized by a low-cost floating catalyst (FC) chemical vapor deposition (CVD) method in a horizontal reactor. It was found that iron (III) chloride (FeCl3) is a high efficient FC precursor for methane CVD to grow CNTs. In this study, the effects of reaction temperature and flow ratio of methane to nitrogen (CH4:N2) on the morphology of the CNTs were investigated. The morphological analysis by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that increasing the reaction temperature and flow ratio of CH4:N2 grew CNTs of larger diameters. Energy dispersive X-ray (EDX) and thermogravimetric analysis (TGA) were employed to study the purity of the produced CNTs. As shown by the TGA, the highest yield of 74.19% was recorded for the CNTs grown at 1000°C and flow ratio CH4:N2 of 300:200.
An, Jung Sook,Nam, Byeong-Uk,Tan, Soon Huat,Hong, Sung Chul WILEY-VCH Verlag 2007 Macromolecular symposia Vol.249 No.1
<P>Through the introduction of carboxylic acid or thionyl chloride groups in multi-walled carbon nanotubes (MWNT-COOH or MWNT-COCl) and amine group in poly(ethylene oxide) (PEO-NH<SUB>2</SUB>), complexation of MWNT with PEO was successfully performed, yielding MWNT/PEO complex having approximately 40 wt.% of PEO. The MWNT/PEO complexes exhibited excellent dispersibility in solvents including water, ethanol and DMF. From SEM observation, the increases in the diameter of the nanotubes were observed. The presence of PEO on the nanotube surface was also confirmed through EDX and FT-IR. The effects of different functionality on MWNTs (&n.bond;COOH vs. &n.bond;COCl) and different molecular weight of PEOs (1000 g/mol vs. 2000 g/mol) were not so prominent.</P>
HASSAN ADELI,SHARIF HUSSEIN SHARIF ZEIN,SOON HUAT TAN,ABDUL LATIF AHMAD 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2011 NANO Vol.6 No.2
In this study the response surface methodology (RSM) coupled with the central composite design (CCD) were used to optimize the mechanical strength properties of poly(L-lactide)/multi-walled carbon nanotube (MWCNT) scaffolds. The scaffolds were prepared by the freeze-extraction method. MWCNTs were incorporated into PLLA composite as a reinforcement agent in order to improve the strength properties of the scaffolds. The effect of process parameters such as ratio of PLLA/(PLLA + MWCNT) (93–100%), solvent amount (100–200 ml), freezing time (5–7 h) and immersing time (2–4 days) were studied using the design of experiment (DOE). Based on CCD, quadratic model was obtained and developed to correlate the process parameters to the strength of the scaffolds. An analysis of variance (ANOVA) was applied to determine the significant factors affecting the experimental design response (strength) of the scaffolds. The predicted values after optimization process were in good agreement with the experimental values. The model was able to accurately predict the response of strength with less than 5% error.