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ABSTRACT: CdTe nanorribons were successfully synthesized from individual nanoparticle. Slow oxidation of Te(2-) in CdTe nanoparticles resulted in the assembly of ribbons consisting of several layers of individual nanocrystals. The light-controlled self-assembly of CdTe nanoparticles led to twisted ribbons with variable pitch. Transmission electron microscopy, scanning electron microscopy, and atomic force microscopy were performed to characterize the synthesized nanostructures. The suggested synthetic procedure provides a viable pathway for the fabrication of nanomaterials with helical conformations.
Journal of Nanoscience and Nanotechnology 05/2012; 12(5):4309-12. · 1.56 Impact Factor
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ABSTRACT: In this paper, we investigated the resonant frequencies of multi-walled carbon nanotube (MWCNT) resonators with short outertubes according to the classical molecular dynamics approach. The resonant frequencies of the MWCNT resonators with short outertubes were influenced in both the wall number and the length of the short outertubes. The resonance frequencies of MWCNTs with short outertubes could be modeled by Gaussian distribution functions. Both the bandwidth and the sensitivity increased with increasing the wall number of the outertubes. The maximum frequency increased with increasing the diameter and with increasing the wall number of the outertubes for MWCNTs. So the effects of increasing the wall number of the outertubes were very important factors for understanding the vibrational frequency changes of MWCNTs with short outertubes as well as the effect of increasing the lengths of the outertubes.
Journal of Nanoscience and Nanotechnology 05/2012; 12(5):4224-7. · 1.56 Impact Factor
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ABSTRACT: Poly(vinylidenefluoride)-hexafluoropropylene (PVdF(HFP))-ionic liquid gel electrolytes were prepared by using ionic liquids
based on N-(2-hydroxyethyl)-N-methyl morpholinium tetrafluoroborate and N-(2-hydroxyethyl)-N-methyl morpholinium hexafluorophosphate.
TGA and FT-IR analyses confirmed that the solvent, N,N-dimethylacetamide (DMAC), used for mixing the PVdF(HFP) polymer with
the ionic liquid, was almost totally removed during the gelling and drying processes. SEM photographs were taken of the surface
structure of the PVdF(HFP)-ionic liquid in order to evaluate the morphology of the film’s surface according to the mixing
ratio, as well as the nature of the ionic liquid. The thermal behaviors of PVdF(HFP)-ionic liquid gels were observed to be
similar to those of neat ionic liquids through a DSC analysis, and the compatibility between the polymer and the ionic liquid
was investigated by an XRD analysis. The ionic conductivities of all the gels were 10−4–10−8S·cm−1 in a temperature range of 20°C to 70°C.
Korean Journal of Chemical Engineering 04/2012; 23(6):940-947. · 0.99 Impact Factor
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ABSTRACT: We have successfully synthesized palladium (Pd) nanoparticles (NPs) protected by dialkylmorpholinium ionic liquids (ILs) via
chemical reduction. ATR-FTIR, UV, and NMR spectroscopies and transmission electron microscopy (TEM) were employed for characterization
of the Pd NPs. The ILs effectively stabilized the Pd NPs, and the particle sizes were precisely controlled by the alkyl chain
length of the cation in the ILs. The produced particles had a highly crystalline structure with a face-centered cubic (fcc)
lattice. Broadening of the (111) plane in the X-ray diffraction (XRD) patterns was observed and the particle sizes calculated
by Scherrer’s equation were in good agreement with the TEM results. Additionally, UV, IR, and NMR spectra indicated that nano-sized
particles were produced and ILs were bound to the surface of the NPs, thereby protecting the particles from aggregation.
Korean Journal of Chemical Engineering 04/2012; 26(3):760-764. · 0.99 Impact Factor
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ABSTRACT: We have successfully synthesized ionic liquid (IL)-stabilized palladium (Pd) nanoparticles (NPs) by electrochemical reduction. The particle size was controlled by adjusting the current density. Transmission electron microscopic (TEM) images showed that the average diameters of the Pd NPs were 2.4, 3.2, and 3.5 nm, depending on the synthetic conditions. Particle size increased as the current density and the length of the alkyl chain in the cation decreased. X-ray diffraction of the resulting NPs indicated that the particles had a crystalline structure. Overall, the results show that NPs can be finely tuned according to the kinds of ILs employed, as well as by electrochemical reduction.
Journal of Nanoscience and Nanotechnology 04/2012; 12(4):3641-5. · 1.56 Impact Factor
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ABSTRACT: We conceptually investigated a carbon-nanotube-based tuner operated by the telescoping nanotube motion in a multi-walled carbon-nanotube induced by electromigration of an encapsulated nanoparticle. The telescoping lengths in the proposed carbon-nanotube-based tuner could be achieved from the electromigration phenomena of the nanoparticle embedded in the carbon nanotube. So the core part is the nanoparticle shuttle and a multi-walled carbon-nanotube with ultra-low interlayer friction. The tuning of this telescoping carbon-nanotube-based tuner is achieved from the electric current flow. The properties of operation were investigated via classical molecular dynamics simulations and then the parameters of the continuum model were then calibrated to fit the results of the molecular dynamics simulations. Since the effective boundary considered as the movable clamp affected the vibration of the telescoping nanotube, the calibrated Young's modulus of this work were lower than the those of the previous works. Presented tuners are controllable in a few nanometers, and their operations are robust and reliable.
Journal of Nanoscience and Nanotechnology 07/2011; 11(7):6359-63. · 1.56 Impact Factor
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ABSTRACT: We investigate the nano mass transfer in an ultrahigh frequency carbon-nanotube-resonator encapsulating a nanocluster via classical molecular dynamics simulations. When the carbon-nanotube-resonator vibrated, the encapsulated copper nanocluster more rapidly approached the end of the cantilevered carbon-nanotube-resonator. Such phenomena were due to the migration of the encapsulated copper nanocluster due to the centrifugal force induced by the vibrating nanotube resonator. So the resonance frequency change could be time-dependently found. For the movable copper nanocluster in carbon nanotube resonator, the vibrational spectra when the copper nanocluster inside the carbon nanotube resonator rapidly settled at the capped edge were different from those obtained when the copper nanocluster continuously oscillated inside the carbon nanotube resonator. Such results showed that the frequency of the carbon-nanotube-resonator encapsulating the movable copper nanocluster could be adjusted by controlling the mean position of the oscillating copper nanocluster. The movable nanocluster inside a carbon-nanotube can be applied to a nanotube-based data storage media by sensing the position of the nanocluster.
Journal of Nanoscience and Nanotechnology 07/2011; 11(7):5856-60. · 1.56 Impact Factor
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ABSTRACT: Pyrrolidinium cation-based ionic liquids were synthesized, and their inhibition effects on methane hydrate formation were investigated. It was found that the ionic liquids shifted the hydrate equilibrium line to a lower temperature at a specific pressure, while simultaneously delaying gas hydrate formation.
Chemical Communications 06/2011; 47(22):6341-3. · 6.17 Impact Factor
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ABSTRACT: We investigated a linear nanomotor based on the telescoping carbon nanotube motion induced by electromigration of an encapsulated nanoparticle. The nanoparticle motion induced by the electric current makes the inner nanotube linearly telescope or retreat. Theoretical results using a kinetic Monte Carlo method were in good agreement with previous experiments. The telescoping speed of the linear nanomotor exponentially decreased with increasing mass of the inner nanotube.
Journal of Nanoscience and Nanotechnology 02/2011; 11(2):1573-6. · 1.56 Impact Factor
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ABSTRACT: Metal nanoparticles were successfully synthesized from the self-regulated reduction of hydroxylated ionic liquids in aqueous phase without additives. A new water-phase synthesis of gold and palladium nanoparticles using N-(2-hydroxyethyl)-N-methylmorpholinium tetrafluoroborate is described. Transmission electron microscopy was performed to characterize the metal nanoparticles. The average sizes of the gold and palladium nanoparticles were 4.3 nm and 3.2 nm, respectively. Hydroxylated ionic liquids served as both reductants and protective agents, significantly simplifying the preparation of nanoparticles. The produced particles were highly crystalline in structure with a face-centered cubic (fcc) lattice. Finally, we showed preliminary results that suggest different hydroxylated ionic liquids can also be used to prepare various metal nanoparticles.
Journal of Nanoscience and Nanotechnology 01/2011; 11(1):716-20. · 1.56 Impact Factor
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ABSTRACT: The vibrational properties of various double-walled carbon nanotube resonators were investigated via a classical molecular dynamics approach. The fundamental frequencies of double-walled carbon nanotube resonators with short outer tubes were closely related to the intertube spacing and the chirality of the outer tubes. Even though the length of the outer tube was 1 nm, the vibration of the outer tube affected that of the inner tube. For nanotubes with similar intertube spacing, both maximum frequencies were similar. For their corresponding maximum frequencies, the lengths of the outer tubes of the zigzag nanotubes were slightly less than those of the armchair ones.
Modelling and Simulation in Materials Science and Engineering 04/2010; 18(4):045011. · 2.30 Impact Factor
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ABSTRACT: We investigated the characteristics of a capacitive nano-accelerometer based on a telescoping carbon nanotube by means of classical molecular dynamics simulations. The position of the telescoping nanotube was controlled by an externally applied force, and feedback sensing was based on the capacitance change. The capacitance variations, which were almost linearly proportional to the applied acceleration, were monitored within an error tolerance.
Modelling and Simulation in Materials Science and Engineering 01/2009; 17(2):025011. · 2.30 Impact Factor
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ABSTRACT: We have successfully synthesized morpholinium ionic liquid-stabilized palladium (Pd) nanoparticles by electrochemical reduction.
For characterization of Pd nanoparticles, FT-IR, UV-visible spectroscopy, and Transmission electron microscopy (TEM) were
employed. The FT-IR spectrum of Pd nanoparticles indicated the surface binding of the IL to the nanoparticles. The UV-visible
spectrum showed that nano-sized Pd particles were produced. The particle size was controlled by the adjustment of the current
density, temperature, and electrolysis duration. The TEM images showed an average size of 2.0, 2.2, 2.4, 2.9, 3.5, 3.9, and
4.5 nm. Nearly a 0.5 nm-sized control of the nanoparticle was achieved. The particle size increased with a decrease in the
current density and an increase in temperature and electrolysis duration. The electron diffraction patterns of resulting nanoparticles
indicated that the particles had a crystalline structure.
Korean Journal of Chemical Engineering 10/2007; 24(6):1089-1094. · 0.99 Impact Factor
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ABSTRACT: Silver nanoparticles exhibiting antimicrobial properties via self-regulated reduction were successfully prepared by using
hydroxylated ionic liquids in an aqueous phase without additives. A new water-phase synthesis of silver nanoparticles using
1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([HEMIm][BF4]) and 1-(2′-hydroxyethyl)-2-methyl-3-dodecylimidazolium chloride ([C12HEMIm][Cl]) was described. 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate serves as both a reductant and a stabilizer
in this fabrication. Furthermore, we presented the antimicrobial properties of the resulting silver nanoparticles through
the minimal inhibitory concentrations (MIC) test.
Korean Journal of Chemical Engineering 08/2007; 24(5):856-859. · 0.99 Impact Factor
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ABSTRACT: A series of ionic liquids based on morpholinium cations were prepared. N-alkyl-N-methylmorpholinium bromide, N-alkyl-N-methylmorpholinium
tetrafluoroborate, N-alkyl-N-methylmorpholinium hexafluorophosphate and N-alkyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide
were synthesized, and then thermal and electrochemical properties of prepared ionic liquids were measured. These morpholinium
salts were found to be thermally stable near 673 K and electrochemically stable up to 6 V at room temperature. In conclusion,
these new series of morpholinium based ILs might be potential candidates for electrolytes in batteries and other electrolytic
devices.
Korean Journal of Chemical Engineering 08/2006; 23(5):795-799. · 0.99 Impact Factor
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ABSTRACT: The surface tension and viscosity of 1-butyl-3-methylimidazolium iodide ([bmim][I]) and 1-butyl-3-methylimidazolium tetrafluoroborate
([bmim][BF4]) were measured over a temperature range of 298. 15 to 323.15 K. It was found that both the viscosity and surface tension
decrease with increasing temperature and that the surface tension and viscosity values of [bmim][I] were higher than those
of [bmim][BF4]. Additionally, the solubility of lithium bromide (2)+1-butyl-3-methylimidazolium bromide ([bmim][Br]) (3) in water (1) was
measured at three different mass ratios (w2/w3=4 and 7, w3=0) by using a visual polythermal method. The solubility of the suggested systems was better than that of lithium bromide
in water.
Korean Journal of Chemical Engineering 12/2005; 23(1):113-116. · 0.99 Impact Factor
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ABSTRACT: Poly(vinylidenefluoride)-hexafluoropropylene (PVdF(HFP))-ionic liquid gel electrolytes were prepared using ionic liquids based on 1-(2-hydroxyethyl)-3-methyl imidazolium tetrafluoroborate and 1-(2-hydroxyethyl)-3-methyl imidazolium hexafluorophosphate. A conventional metathesis reaction was used to prepare these ionic liquids, which have high purity and exhibit a liquid state at room temperature. The prepared polymer-ionic liquid gel proved to be a free-standing and rubbery film in which the degree of transparency differed according to the ratio and type of ionic liquid used. TGA and FTIR analyses confirmed that the solvent, N,N-Dimethylacetamide (DMAC), used for mixing PVdF(HFP) polymer with ionic liquid was almost totally removed during the gelling and drying processes. SEM photographs were taken of the surface structure of the PVdF(HFP)-ionic liquid gel in order to evaluate the morphology of the film's surface according to the mixing ratio and the nature of the ionic liquid. The thermal behaviors of PVdF(HFP)-ionic liquid gels were observed to be similar to those of neat ionic liquids through DSC analysis, and the compatibility between the polymer and ionic liquid was investigated by XRD analysis. The ionic conductivities of all the gels were 10(-3)-10(-5) S cm(-1) in a temperature range of 20-70 degrees C.
The Journal of Physical Chemistry B 10/2005; 109(38):17928-35. · 3.70 Impact Factor
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ABSTRACT: Thiol-functionalized ionic liquid (TFIL: 1,3-di(2’,3’-dimercaptoacetoxypropyl) imidazolium, 3′’-mercapto1 ″-propanesulfonic
acid) as a stabilizer for preparing palladium (Pd) nanoparticles was synthesized. The suggested TFIL was designed to have
thiol groups on both cation and anion as well as on symmetrical positions in cation. Transmission electron microscopy (TEM)
shows that the average diameter of the palladium nanoparticles was 3.0 nm and that the standard deviation was 0.15 nm. The
overall results strongly suggest that this potential TFIL can act as a highly effective stabilizer for the preparation of
Pd nanoparticles
Korean Journal of Chemical Engineering 08/2005; 22(5):717-720. · 0.99 Impact Factor
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ABSTRACT: A series of a new type of ionic liquids was prepared. The synthesis and purification procedure of N-alkyl-N-methylmorpholinium
bromide, N-alkyl-N-methylmorpholinium tetrafluoroborate, N-alkyl-N-methylmorpholinium hexafluorophosphate, and N-alkyl-N-methylmorpholinium
bis(trifluoromethanesulfonyl)imide were presented. Thermal properties of morpholinium salts and ionic conductivities of lithium-doped
ionic liquids were measured in the temperature range of 303.15 to 323.15 K. In the case of the pure ionic liquids, the ionic
conductivities were 10-4 S·cm-1.
Korean Journal of Chemical Engineering 02/2005; 22(2):281-284. · 0.99 Impact Factor
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ABSTRACT: This work presents the vapor pressures of the following binary imidazolium-based ionic liquid (IL) + water solutions: 1-butyl-3-methylimidazolium bromide ([bmim][Br]) + water, 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) + water, and 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([hydemim][BF4]) + water. Vapor pressures were measured by using the boiling-point method in the temperature range of (304.8 to 475.2) K and in the concentration range of (20.0 to 80.0) mol % of ILs and were correlated with an Antoine-type equation. The resulting average absolute deviations (AAD) between the experimental and calculated values were found to be (0.419, 1.16, and 0.682) % for the [bmim][Br] + water, [bmim][BF4] + water, and [hydemim][BF4] + water solutions, respectively.
10/2004;
