• Carbon letters
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• v.13 no.3
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• pp.157-160
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• 2012

In this work, iron oxide ($Fe_3O_4$) nanoparticles were deposited on multi-walled carbon nanotubes (MWNTs) by a simple chemical coprecipitation method and $Fe_3O_4$-decorated MWNTs (Fe-MWNTs)/polypyrrole (PPy) nanocomposites (Fe-MWNTs/PPy) were prepared by oxidation polymerization. The effect of the PPy on the electrochemical properties of the Fe-MWNTs was investigated. The structures characteristics and surface properties of MWNTs, Fe-MWNTs, and Fe-MWNTs/PPy were characterized by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The electrochemical performances of MWNTs, Fe-MWNTs, and Fe-MWNTs/PPy were determined by cyclic voltammetry and galvanostatic charge/discharge characteristics in a 1.0 M sodium sulfite electrolyte. The results showed that the Fe-MWNTs/PPy electrode had typical pseudo-capacitive behavior and a specific capacitance significantly greater than that of the Fe-MWNT electrode, indicating an enhanced electrochemical performance of the Fe-MWNTs/PPy due to their high electrical properties.

• Korea-Australia Rheology Journal
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• v.16 no.4
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• pp.193-199
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• 2004

Poly(o-ethoxy)aniline (PEOA)/organoclay nanocomposite was prepared via a solvent intercalation using chloroform as a cosolvent with organically modified montmorillonite (OMMT) clay. The PEOA initially synthesized from a chemical oxidation polymerization in an acidic condition at pH = 1 was intercalated into interlayers of the clay with $25\;wt{\%}$ clay content. Electrical conductivity of the PEOA/OMMT nano­composite was found to be controlled via the intercalating process. The synthesized PEOA/OMMT nano­composite was characterized via an XRD and a TGA, and then adopted as an electrorheological (ER) material. The PEOA/OMMT synthesized with controllable electrical conductivity without a dedoping pro­cess was found to show typical ER characteristics possessing a yield stress from both steady state and dynamic measurements under an applied electric field.

• Bulletin of the Korean Chemical Society
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• v.23 no.8
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• pp.1144-1148
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• 2002

We prepared the polyaniline (Pani) film and powder by chemical polymerization and doping with different dopants and also investigated the capability of Li//polyaniline cells after assembling. The oxidation/reduction potentials and electrochemical reaction of Li//polyaniline cells were tested by cyclic voltammetry technique. The Li//Pani-HCl cells with 10% and 20% conductors show a little larger specific discharge capacities than that without conductor. The highest discharge capacity of almost 50 mAh/g at 100th cycle is also achieved. However, Li//Pani-LiPF6 with 20% conductor shows a remarkable performance of ~90 mAh/g at 100th cycle. This is feasible value for using as the positive electrode material of lithium ion secondary batteries. It is also proved that the powder type electrode of Pani is better to use than the film type one to improve the specific discharge capacity and its stability with cycle.

• BMB Reports
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• v.47 no.7
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• pp.376-381
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• 2014

Enzymatic oxidation of pyrogallol was efficiently transformed to an oxidative product, purpurogallin (PPG). Here, the anticoagulant activities of PPG were examined by monitoring activated partial thromboplastin time (aPTT), prothrombin time (PT), and the activities of thrombin and activated factor X (FXa). And, the effects of PPG on expression of plasminogen activator inhibitor type 1 (PAI-1) and tissue-type plasminogen activator (t-PA) were evaluated in tumor necrosis factor (TNF)-${\alpha}$ activated human umbilical vein endothelial cells (HUVECs). Treatment with PPG resulted in prolonged aPTT and PT and inhibition of the activities of thrombin and FXa, as well as inhibited production of thrombin and FXa in HUVECs. In addition, PPG inhibited thrombin-catalyzed fibrin polymerization and platelet aggregation. PPG also elicited anticoagulant effects in mice. In addition, treatment with PPG resulted in significant reduction of the PAI-1 to t-PA ratio. Collectively, PPG possesses antithrombotic activities and offers a basis for development of a novel anticoagulant.

• Journal of Environmental Health Sciences
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• v.31 no.4 s.85
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• pp.241-245
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• 2005

Laccase catalyzes the oxidation and polymerization of aromatic compounds in the presence of molecular oxygen. Studies were conducted to characterize the use of polyethylene glycol (PEG) as an additive to keep up the enzymatic stability. The enzymatic activities highly remained and bisphenol A (BPA) was rapidly converted in the presence of 5 mg/l of PEC. These effects were accomplished with PEG of molecular weight 3,350. A linear relationship was found between the quantity of BPA to be converted $(10-120\;{\mu}M)$ and the optimum dose of PEC required for greater than $95\%$ conversion. This result suggests that it is the interaction between the PEG and the reaction products. In the optimum dose of PEG, the aeration of reaction mixture neither enhanced the conversion of BPA nor retarded the inactivation of the enzyme.

• Journal of Environmental Health Sciences
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• v.33 no.1 s.94
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• pp.63-67
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• 2007

Laccase catalyzes the oxidation and polymerization of aromatic compounds in the presence of molecular oxygen. The oxidative transformation of chlorophene with laccase was conducted in a closed, temperature controlled system. The optimal pH for transformation of chlorophene was proven to be about 5-6. As the temperature rose up to $55^{\circ}C$, the transformation of chlorophene increased. The chlorophene transformation was not enhanced in the presence of soluble polymers. The toxicity of the reaction mixture was increased two times than that of initial reaction mixture after the enzymatic treatment. ABTS has enhanced chlorophene transformation at 0.1 mM and showed negative linear relationship with residual chlorophene by the reaction.

• Bulletin of the Korean Chemical Society
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• v.17 no.8
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• pp.707-712
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• 1996

Growth and changes of electronically conducting polypyrrole (PPy) in the form of thin films polymerized on metal electrodes were investigated by electrochemical and in situ three-parameter ellipsometry methods at the wavelength of 632.8 nm. Although the optical equations produced multiple sets of solution, it was possible to determine a unique set of thickness and the optical constants of a film by auxiliary measurements and/or physical reasoning. The changes in the thickness and the optical properties of the polymers during polymerization and electrochemical oxidation/reduction was successfully followed by the three-parameter ellipsometric technique. The optical properties of the polymers continuously changed as the film grew. The imaginary part of the refractive index of polypyrrole seemed to be dominantly determined by the existence of an absorption band around the visible range.

• Bulletin of the Korean Chemical Society
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• v.9 no.4
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• pp.248-251
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• 1988

Mechanism of electrochemical polymerization of pyrrole (Py) on a Pt electrode in acidic aqueous solutions was studied by means of potentiostatic measurements, cyclic voltammetry and chronopotentiometry. Pyrrole molecule appeared to be initially oxidized via two-electron transfer step to produce oxidized pyrrole ion ($Py^+$), which was coupled with a non-oxidized pyrrole to yield a dimerized species, Py-Py. The Py-Py thus formed was further oxidized again via two-electron transfer step, which was followed by coupling with non-oxidized monomer and by concomitant expulsion of a $H^+$. Then the latter chain extension process was repeated. The chain extension and polypyrrole oxidation reactions occurred competitively.

• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.86-92
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• 2005

Poly(urethaneethyl acrylate) hybrid emulsions were synthesized to improve their thermomechanical and solvent resistance properties. In the synthesis, dimethylol propionic acid was used to impart hydrophilicity to the hybrid polymers, and ethyl acrylate monomer was added to the polyurethane prepolymer after neutralization with triethylamine. After dispersion of the neutralized prepolymer, chain extension was carried out with ethylene diamine. Consequently, poly(urethaneethyl acrylate) hybrid emulsion was prepared via soap free emulsion polymerization of ethyl acrylate with reduction-oxidation initiator couple of t-butyl hydroperoxide/sodium bisulfite at $50^{\circ}C$. Tehsile strength, 100% modulus, elongation, and solvent-resistance properties of the hybrid emulsion were measured and compared with those of polyurethane homopolymer, poly(ethyl acrylate) homopolymer, and simple blended samples.

• Journal of the Korean Chemical Society
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• v.54 no.6
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• pp.711-716
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• 2010

New electroluminescent polymers with fluoro groups in vinylene units, poly(m-silylphenyl-p-phenylene-difluorovinylene) (m-SiP-PPDFV) have been synthesized by GILCH polymerization. These polymers have been used as the electroluminescent (EL) layers in single layer light-emitting diodes (LEDs) (ITO/PEDOT/polymer/Ca:Al). m-SiP-PPDFV shows PL around $\lambda_{max}$ = 452 nm and green EL around $\lambda_{max}$ = 497 nm. The current-voltage-luminance (I-V-L) characteristics of the polymers show turn-on voltages of 4.0 V approximately. Two fluoro groups were introduced on every vinylene units of m-SiP-PPV to give m-SiP-PPDFV in an attempt to increase the electron affinity of the parent polymer, and the devices show an increased color stability even with vinylene units. The color stability is attributed to the electron-withdrawing effect of the fluoro groups, which protect vinylene units from oxidation in PPV derivatives. We believe that fluoro groups can be introduced in vinylene units in order to attain excellent stability of PPV derivatives.