• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.906-910
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• 2012

Hollow gold-silver bimetallic nanoparticles (AuAg-HNPs) have been synthesized and their optical and structural properties were characterized. Initially Ag nanoparticles (Ag-NPs) were prepared using poly(ethylenimine) (PEI) as a reducing and a stabilizing agent simultaneously. AuAg-HNPs could then be synthesized via galvanic replacement reaction in a PEI aqueous solution by reacting sacrificial Ag template with a precursor compound of Au, i.e., $HAuCl_4$. Due to the presence of abundant amine functional groups in PEI, which could act as the dissolving ligand for AgCl, the precipitation problem of $Ag^+$ in the presence of Cl from $HAuCl_4$ salt was avoided. On this basis, the relatively high concentrations of $HAuCl_4$ and PEI-stabilized Ag nanoparticles could be used for the fabrication of AuAg-HNPs. Because of their increased surface areas and reduced densities, the AuAg-HNPs were expected and confirmed to outperform their solid counterparts in applications such as catalysis for the reduction of 4-nitrophenol in the presence of $NaBH_4$.

• Textile Coloration and Finishing
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• v.11 no.2
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• pp.27-37
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• 1999

Polypropylene(PP) films were treated with plasma glow discharge to produce peroxy radicals on the surfaces. The peroxy radicals formed on the PP film surfaces were subsequently used for the graft polymerization of acrylic acid and acrylamide in an aqueous solution by heating, respectively. Introduction of acrylic acid and acrylamide on the PP film could be confirmed by the observation of carbonyl and primary amine absorptions based on carboxylic acid and amide, respectively. And introduction of functional group could be confirmed by weight analysis and ESCA. The water contact angle(90$^{\circ}$) of PP film was constant, irrespective of elapsed time, while plasma-treated and functional monomer-grafted PP films were slowly increased with elapsed time, showing the rearrangement of surface polar groups in air condition. The water contact angle$(90^\circ)$ of PP film was decreased by the plasma treatment$(56^\circ)$ and further decreased by the grafting of acrylic acid$(34^\circ)$ and acrylamide$(37^\circ)$, indicating increased hydrophilicity of the modified surfaces. The water contact angle of plasma-treated PP film increased a little as time elapsing. The half-life periods of surface voltage on acrylic acid-(31sec) and acrylamide-grafted PP(42sec) were significantly decreased when compared to those on PP(950sec) and plasma-treated PP film(241sec). In the experiments using acid, basic and disperse dyes, absorbance and $\Delta{E}$ values of functional monomer-grafted PP films were significantly increased than that of oxygen plasma-treated one.

• Macromolecular Research
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• v.12 no.3
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• pp.303-310
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• 2004

We have prepared an aqueous dispersion of poly(aniline-dodecyl benzene sulfonic acid complex) (PANI-DC) that has an intrinsic viscosity (〔η〕) near 1.3 dL/g using aniline as a monomer, dodecyl benzene sulfonic acid(DBSA) as a dopant/emulsifier, and ammonium peroxodisulfate(APS) as an oxidant. We found that the electrical conductivity of a PANI-DC pellet was 0.7 S/cm. A waterborne-polyurethane (WBPU) dispersion, obtained from isophorone diisocyanate/polytetramethylene oxide glycol/dimethylol propionic acid/ethylene diamine/triethylene amine, was used as a matrix polymer. We prepared blend films of WBPU/PANI-DC with variable weight ratios (from 99/1 to 66/34) by solution blending/casting and investigated the effects that the PANI-DC content has on the mechanical and dynamic mechanical properties, hardness, electrical conductivity, and antistaticity of these films. The tensile strength, percentage of elongation, and hardness of WBPU/PANI-DC blend films all decreased markedly upon increasing the PANI-DC content. The antistatic half-life time ($\tau$$\sub$$\frac{1}{2}$/) of pure WBPU film was about 110 s, but we found that those of WBPU/ultrasound-treated PANI-DC blend films decreased exponentially from 1.2 s to 0.1 s to almost 0 s upon increasing the PANI-DC content from 1 wt% to 15 wt% to > 15 wt%, respectively.

• Textile Coloration and Finishing
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• v.10 no.3
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• pp.43-49
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• 1998

Polyvinyl chloride (PVC) sheets were treated with corona discharge to produce peroxy radicals on the surfaces. The peroxy radicals formed on the PVC surfaces were subsequently used as initiators for the graft polymerization of acrylic acid or acrylamide in an aqueous solution. Introduction of acrylic acid and acrylamide on the PVC sheet could be confirmed by the observation of carbonyl and primary amine absorptions based on carboxylic acid and amide, respectively. The water contact angle$(90^\circ)$ of PVC sheet was constant, irrespective of time, while corona-treated and functional monomer-grafted PVCs were slowly increased with time, showing the rearrangement of surface polar groups in air condition. The water contact angle of PVC sheet$(90^\circ)$ was decreased by corona treatment$(78^\circ)$, and further decreased by the grafting of acrylic acid$(55^\circ)$ and acrylamide$(56^\circ)$ , indicating increased hydrophilicity of the modified surfaces. The half-life periods of surface voltage on acrylic acid- (62 sec) and acrylamide-grafted PVC (147sec) were significantly decreased when compared to those on PVC (3,115 sec) and corona-treated PVC (463sec). These results mean that acrylic acid- and acrylamide-grafted PVCs could be used as the antistatic sheets.

• Journal of the Korean Applied Science and Technology
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• v.31 no.3
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• pp.375-386
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• 2014

Carbon dioxide ($CO_2$) is a green-house gas which causes the global warming problems. Anthropogenic emissionspredominantly from the combustion of coal, oil, and natural gas in electricity generations are expected to increase continuously in the future, resulting in increased $CO_2$ concentration in the atmosphere. In this study, we investigated materials properties and process systems for $CO_2$ separation with an emphasis of the post-combustion process.

• Bulletin of the Korean Chemical Society
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• v.18 no.6
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• pp.653-656
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• 1997

The new unsymmetric $N_6$ ligand 1-amino-13-(2-pyridyl)-3,6,9,12-tetraazatridecane (aptatd) containing one pyridyl group has been synthesized and characterized by EA, IR, and NMR. Its proton association constants $(log K_H^n)$ and stability constants $(log K_{ML})$ for Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ), and Zn(Ⅱ) ions were determined at 298.1 K and ionic strength 0.100 mol $dm^{-3}$ (KNO₃) in aqueous solution by potentiometry: log $K_H^1$=8.80, log $K_H^2$=8.49, log $K_H^3$=6.84, log $K_H^4$=4.17, log $K_H^5$=3.47; log $K_{ML}(Co^{2+})$=18.00, log $K_{ML}(Ni^{2+})$=21.31, log $K_{ML}(Cu^{2+})$=23.62, log $K_{ML}(Zn^{2+})$=15.60. The X-ray structure of its nickel(Ⅱ) complex [Ni(aptatd)]$(ClO_4)_2$ are reported: orthorhombic space group Pbca, a=15.715(1) Å, b=14.280(2) Å, c=19.443(2) Å, V=4363.4 (9) ų with Z=8. The geometry around nickel is a distorted octahedron with the pyridine nitrogen atom being cis to the nitrogen atom of the terminal primary amine.

• Analytical Science and Technology
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• v.11 no.4
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• pp.305-310
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• 1998

A reactive dye synthesized with an amine containing Eriochrome Black T derivative and cynauric chloride was immobilized on a cellulose membrane to construct an optical sensor for the detection of divalent transition metal ions in aqueous solution. The response of this reactive dye-based optical sensor was as sensitive as that of Eriochrome Black T in solution phase. Its typical detection limits for $Zn^{2+}$ and $Co^{2+}$ were $6.3{\times}10^{-5}mol/l$ and $2.5{\times}10^{-4}mol/l$, respectively. No loss in the sensitivity of reactive dye-based sensor was observed even the pH of flowing solutions continually varied for an extended period of time.

• Journal of Pharmaceutical Investigation
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• v.25 no.1
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• pp.9-17
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• 1995

To stabilize omeprazole(OMP), ethylenediamine(ED) complex of omeprazole(OMPED) was prepared by reaction between OMP and ED in methanol, and the complex formation was confirmed by the instrumental analysis, i.e., IR, DSC, EA, NMR, MS and XRD. The rates of decomposition of OMP and OMPED in aqueous solution and the shelf lives at standard temperature were measured by accelerated stability analysis. The results are summarized as follows; The mole ratio of OMP and ED in OMPED complex is 1:1, the energy of formation within OMPED might be combined between polar imidazole group of OMP with induced a dipole amine group in the readily polarizable ED molecule. At standard temperature the degradation rate constant of OMP in aqueous solution is $2.540{\times}10^{-2}\;hr^{-1}$ and the shelf life is 4.15 hrs, and in the case of OMPED the degradation rate constant is $7.986{\times}10^{-4}\;hr^{-1}$ and the shelf life is 131.96 hrs. So, the OMPED has about 31 times longer shelf life than OMP. The activation energy of OMP and OMPED are 5.23 and 18.55 kcal $mole^{-1}$ respectively. The stability of OMP is dependent chiefly on pH in the solutions and it decomposes readily in acidic medium by hydrogen ion catalized reaction but becomes stable beyond pH 9.0. In case of the ED-complex, OMPED is stable in neutral as well as in dilute acidic solutions even in pH 6, OMPED is very stable to light(UV), that is, the rate constant and shelf life of OMP are $k=1.0188{\times}10^{-2}\;day^{-1}$, $T_{90%}=4.5 \;days$, on the other hand, the those of OMPED are $k=7.138{\times}10^{-4}\;day^{-1}$, $T_{90%}=64.1\;days$, respectively. From the above results, it is thought that new dosage forms could be developed by using the OMPED as a potential OMP complex.

• Polymer(Korea)
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• v.36 no.2
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• pp.223-228
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• 2012

Temperature and pH sensitive graft copolymers [Pluronic-$g$-poly(NIPAAm-$co$-MMA), Polymer A] and [Pluronic-$g$-poly( NIPAAm-$co$-MAA), Polymer C] were synthesized by macro radical graft polymerization with $N$-isopropylacrylamide (NIPAAM)/$N,N$-diethylaminoethylmethacrylate (DEAEMA) and $N$-isopropylacrylamide (NIPAAm)/methacrylic acid (MAA) based on Pluronic, respectively. The chemical structure and molecular weight of the graft copolymers was characterized by $^1H$ NMR and gel permeation chromatography. The aqueous solution properties of graft copolymers were measured using a UV-visible spectrophotometer, contact angle and dynamic light scattering equipment with different temperature and pH conditions. The obtained graft copolymers showed a very sensitive phase transition in response to temperature and pH in aqueous media which suggested that the amine group of DEAEMA segment and carboxylic group of MAA had a great influence on the lower critical solution temperatures (LCST) in Polymer A and C, respectively. The graft copolymers can be utilized for drug delivery system and molecular switching applications where responses to temperature and pH changes are relevant.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.795-800
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• 2009

In this study, the $CO_2$ removal characteristics of the Vortex tube type absorbtion apparatus were investigated to enhance the compactness of $CO_2$ absorption process and to reduce the amount of absorbing solution of the $CO_2$ separation process. The Vortex tube with the diameter of 17 mm and the length of 250mm was introduced in the experimental apparatus to treat $20Nm^3/hr$ of $CO_2$ containing flue gas. The flue gases for experiments containing 11~13 vol% of $CO_2$ were supplied from the coal-firing CFBC power plant with 12 ton/hr of steam producing capacity. The mixed solutions of 20 wt% of MEA as base solution with the adding solutions like HMDA, AMP and KOH were used as absorbents. The experiments were executed under the various conditions like the absorbing solution concentrations in the range of 20 to 50 wt%, the flow rate of $CO_2$ containing flue gases in the range of 6 to $15Nm^3/hr$ and the flow rate of absorbing solution in the range of 1.0 to 3.0 l/min. As a results, the $CO_2$ removal efficiency of mixed absorbent of 20 wt% of MEA with HMDA was remarkable. From this study, we concluded that the efficient separation of $CO_2$ from flue gases using the features of the Vortex tube type absorbing unit for gas/liquid contact and the separation of gas/liquid be possible. But more works are needed to increase the $CO_2$ removal efficiency of Vortex tube process.