• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2379-2383
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• 2018

We report a facile one-pot aqueous-phase synthesis of PdAu bimetallic nanoparticles with different Pd/Au ratio. The synthesis was conducted by co-reduction of Pd and Au precursor using ascorbic acid as a reducing agent and in the presence of polyallylamine hydrochloride (PAH). By high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectrometry (EDS) analyses, we found that the synthesized nanoparticles had an onion-like core/shell/shell/shell structure with Au-rich core, Pd-rich shell, Au-rich shell, and Pd shell, respectively. We also investigated the catalytic performance of the synthesized PdAu nanoparticles toward hydrogen peroxide generation reaction.

• Elastomers and Composites
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• v.57 no.2
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• pp.55-61
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• 2022

In this work, we report a highly deformable covalent adaptable-liquid crystal elastomer (CA-LCE) comprising dynamic thiourea bonds that enable macromolecular network rearrangement at elevated temperatures. The exchange of chain network is verified through stress-relaxation analyses and follows Arrhenius-type behavior. The unique capability of rearranging the chain network in the CA-LCE provides useful properties, such as welding, melt reprocessing, and shape reprogramming, that cannot be achieved by the conventional LCE comprising permanent crosslinks. Reversible actuation is further demonstrated by reprogramming the polydomain CA-LCE into a monodomain via mechanical stretching at elevated temperatures.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1603-1607
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• 2012

The effects of plating process on the surface coverage of the accelerator were investigated in terms of Cu superfilling for device metallization. When a substrate having 500 nm-wide trench patterns on it was immersed in an electrolyte containing poly (ethylene glycol) (PEG)-chloride ion ($Cl^-$)-bis(3-sulfopropyl) disulfide (SPS) additives without applying deposition potential for such a time of about 100s, voids were generated inside of the electrodeposit. In time-evolved electrochemical analyses, it was observed that the process (immersion without applying potential) in the electrolyte led to the build-up of high initial coverage of SPS-Cl on the surface, resulting in the fast saturation of the coverage. Repeated experiments suggested that the fast saturation of SPS-Cl failed in superfilling while a gradual increase in the SPS-Cl coverage through competition with initially adsorbed PEG-Cl enabled it. Consequently, superfilling was achievable only in the case of applying the plating potential as soon as the substrate is dipped in an electrolyte to prevent rapid accumulation of SPS-Cl on the surface.

• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2280-2282
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• 2009

Amorphous zinc phosphate nanospheres were prepared via a sonochemical route. Zinc phosphate nanospheres were uniform in shape with an average diameter of 210 nm. The average diameter of nanospheres could be controlled by changing the pH of a precursor solution. This sonochemical method is simple, facile, economical, and environmentally benign. Non-crystalline characteristics of as-prepared zinc phosphate nanospheres were confirmed by X-ray diffraction, transmission electron microscopy, and FT-IR spectroscopy analyses. We believe this technique will be readily adopted in realizing other forms of zinc phosphate nanostructures.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.2113-2116
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• 2011

• Journal of the Korean Chemical Society
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• v.15 no.6
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• pp.359-366
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• 1971

The extended Huckel calculations on five organic accelerators of vulcanization have been carried out. Various MO quantities e.g., electron populations and AO coefficients, are used to explain accelerator reactivity of the compounds. Results of these analyses lead us to support free radical mechanism of acceleration in vulcanization.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2002.07a
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• pp.73-78
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• 2002

Microfluidic lab-on-a-chip (LOC) systems have enabled a new generation ofassay technologies in chemical and biomedical sciences. Caliper's microfluidic LOC systems contain a network of microscopic channels through which fluids and chemical are moved in order to perform experiments. The main advantages of these continuous-flow devices are integration and automation of multiple steps in complex analytical procedures to improve the reproducibility of the results, and eliminated the manual labor, time and pipetting errors involved in analyses. The present talk is devoted to give a brief introduction of microfluidic basics and to present in applying continuous-flow microchips to drug screening with model enzyme assays.

• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2429-2432
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• 2009

• Journal of the Korean Chemical Society
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• v.55 no.6
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• pp.974-977
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• 2011

Ethyl 1-aminotetrazole-5-carboxylate (1) has been utilized to construct a variety of novel tetrazolo [1,5-b]-1,2,5-oxadiazepine derivatives which repesent a relatively little explored group with interesting antibacterial activities. The synthesized compounds were elucidated using IR, $^1H$ NMR and mass spectroscopic methods, besides elemental analyses.

• Bulletin of the Korean Chemical Society
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• v.7 no.2
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• pp.145-147
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• 1986

Dichlororhodium(Ⅲ) complexes of a flexible quadridentate ligand, N,N'-dimethylethylenediamine-N,N'-diacetic acid (dmedda), have been prepared. Both cis-${\alpha}$ and cis-${\beta}$ isomers have been yielded in the $K[Rh(dmedda)Cl_2]$ complexes, which were characterized with elemental analyses, electronic absorption and proton nuclear magnetic resonance spectroscopic data.