• Journal of Adhesion and Interface
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• v.14 no.2
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• pp.82-87
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• 2013

Preliminary studies on the synthesis of magnetic nanoparticles including nanoporous carbon materials have been done via a direct carbonization process from resol, ferric nitrate and triblock copolymer F127. The results show that the nanoporous magnetite/carbon ($Fe_3O_4$/carbon) with a low $Fe_3O_4$ content (1 wt%) possesses an ordered 2-D hexagonal (p6mm) structure, uniform nanopores (3.6 nm), high surface areas (up to 635 $m^2/g$) and pore volumes (up to 0.48 $cm^3/g$). Magnetite nanoparticles with a small particle size (10.2 nm) were confined in the matrix of amorphous carbon frameworks with superparamagnetic property (7.7 emu/g). The nanoporous magnetite/carbon showed maximum adsorption amount (995 mg/g) of ibuprofen after 24 h at room temperature. The nanoporous magnetite/carbon was separated from solution easily by using a magnet. The nanoporous magnetite/carbon material is a good adsorbent for hydrophobic organic drug molecules, i.e. ibuprofen.

• Polymer(Korea)
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• v.30 no.6
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• pp.545-549
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• 2006

Blends of poly(acrylic acid- co-maleic acid) (PAM) with poly (vinyl alcohol) (PVA) were pre -pared in distilled water PVA/PAM/saponite (PVA/PAM/SPT) nanocomposite films were prepared with various clay contents by using the solution intercalation method. The variations of the dispersion, morphology, and thermo-mechanical properties of the nanocomposites with clay content in the range 0 to 9 wt% were examined. Up to 3 wt% clay loading, the clay particles were homogeneously dispersed in the PVA/PAM blends. However, some agglomerated structures form in the polymer matrix above a clay content of 7 wt%. The thermal stability of the hybrids was increased linearly with increasing the clay loading up to 9 wt%. The maximum strength and modulus were obtained at a clay content of 7 wt%. Thus, the addition of small amounts of clay to the PVA/PAM blends produced PVA/PAM nano-composites with improved the thermo-mechanical properties.

• Composites Research
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• v.24 no.6
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• pp.1-6
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• 2011

A new water-soluble and self-doped poly(styrenesulfonic acid-graft-aniline), PSSA-g-PANI, for dispersing carbon nanotubes (CNTs) in water was synthesized and its ability to stabilize aqueous CNT dispersions was examined. It was observed that the PANI in PSSA-g-PANI, which has benzoid and quinoid structure, was strongly adsorbed onto the nanotube surface via a strong ${\pi}-{\pi}$ interaction, and thus only gentle sonication causes exfoliation of CNT ropes to small bundles and the long-term stability of their resulting dispersions was much better than commercial surfactants. Furthermore, when thin films of PSSA-g-PANI/CNT are prepared from aqueous dispersion and their electrical conductivities are measured by the four probe technique, it is observed that their conductivities are in the range of 1.5-2.5 S/cm.

• Polymer(Korea)
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• v.33 no.1
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• pp.33-38
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• 2009

Monodisperse polystyrene and its copolymer beads containing amine function were prepared for the electroless silver plating using reduction of silver alkylcarbamate complex in organic solvent. Soap-free emulsion polymerization was adopted for the polymerization of styrene, divinylbenzene (DVB), and 2-(N,N-dimethylamino) ethyl methacrylate (DAEMA) in the presence of poly (vinyl alcohol) in a water/methanol solvent. The resulting poly (styrene/DVB/DAEMA), containing 30/0$\sim$1.5/0$\sim$3 wt% in monomer composition, were found to be a sphere-type particle with diameter of 1 ${\mu}m$. Silver Ag-coated polystyrene beads were prepared by in sito reduction of a silver 2-ethylhexylcarbamate (Ag-EHCB) complex solution with hydrazine without pretreatment of polystyrene beads. Robust Ag/polystyrene beads were analyzed by SEM, UV -visible spectrometer and XRD.

• Polymer(Korea)
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• v.34 no.4
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• pp.369-375
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• 2010

We used melt polymerization method to prepare a series of aromatic liquid crystals (LCs) based on aromatic ester and amide units with the reactive methyl-maleimide end group, and then the resulting thermally cross-linked LCs to produce LC thermoset films by means of solution casting and the followed heat treatment. The synthesized LCs and LCTs were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermomechanical analysis (TMA), X-ray diffractometry (XRD), and polarizing optical microscopy (POM) with a hot stage. All of the LCs prepared by melt polymerization method formed smectic mesophases. The thermal properties of the LC and LCT films were strongly affected by the mesogen units in the main chain structures. The thermal expansion coefficients of samples were in the range of 27.72~50.95 ppm/$^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.33 no.1
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• pp.70-81
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• 1989

Reverse phase liquid chromatographic elution behaviors of salicylic acid and its derivatives were studied with classical and modern high-performance liquid chromatography(HPLC) using Amberlite XAD-4 and XAD-7 resin packed columns. Capacity factors(k') were determined in the comparatively high concentration(from 0. 010F to 0. 150F) of ferric nitrate-50% methanol solution to elucidate the elution behaviors with classical method. On the other hand, k's were measured in the various concentrations of methanol and ferric nitrate(from $2.5{\times}10^{-4}F\;to\;1.0{\times}10^{-3}F$) solution of pH 2. 25 and 293K with HPLC to explain the elution mechanism of them, and to find their optimum separation condition. As a result, it was found that log k's of salicylic acid and its derivatives were decreased with increasing the concentration of ferric ion, and the decreasing slopes of the compounds on the increasing ferric ion concentrations were related with each stability constant of ferric salicylates. Some isomers of derivatives of salicylic acid could be separated in the optimum condition.

• Clean Technology
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• v.12 no.2
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• pp.53-61
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• 2006

A PGSS (Particles from Gas Saturated Solutions) process designed to generate nano-particles using supercritical fluids has been conducted for the fabrication of Poly(lactide-co-glycolide) (PLGA) microparticles that encapsulate a protein drug. It is demonstrated that the polymer and the dry powder of a protein can be mixed under supercritical carbon dioxide conditions and that the protein component retains its biological activity. In this experiment, the mixture of polymer which is plasticized and dry powder protein was sprayed to form solid polymer that encapsulate the protein. It is found that supercritical fluid process give fine tuning of particle size and particle size distribution by simple manipulations of the process parameters. Porous particles were formed with irregular shape. Protein encapsulated in the polymer was found to have enzymatic activity without significant loss of its initial value.

• Journal of the Korean Chemical Society
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• v.47 no.5
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• pp.479-486
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• 2003

In this study, poly(DL-lactide-co-glycolide) nanoparticles loaded with water-insoluble vitamins such as vitamin A (Retinol) and vitamin E acetate were prepared by the emulsification diffusion method. Polymer solution was prepared by the two water-miscible organic solvent, such as ethanol and acetone. Because of its biocompatible property, polyethyleneglycol-polypropyleneglycol diblock copolymer was used as surfactant and stabilizer. The influence of some preparative variables on the nanoparticle formation and on the loading efficiency of active agents, such as the type and concentration of stabilizing agent, the stirring methods, the water/oil phase ratio and the polymer concentration were investigated in order to control and optimize the process. After preparation of nanoparticles loaded with active agent, particle size and distribution were evaluated by the light scattering particle analyzer. The loading efficiency of active agents was evaluated by the UV-visible spectroscopy. As the results, particle size were 50-200 nm and dispersibility was monodisperse. The optimum loading efficiency of active agents was observed 50-60%. It was found that the appropriate of selections of binary solvent mixtures and polymeric concentrations in both organic and aqueous phases could provide good yield and favorable physical properties of PLGA nanoparticles.

• Polymer(Korea)
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• v.29 no.3
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• pp.282-287
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• 2005

A novel ice particle leaching method for fabrication of porous and biodegradable PLGA scaffold has been proposed for the application to tissue engineering. After uniform mixing of poly(L-lactide-co-glycolide) (PLGA) and bovine serum albumin-fluorescein isothiocyanate (FITC-BSA), the FITC-BSA loaded scaffold was fabricated by adding various ratio of ice particle. The release profiles of FITC-BSA were examined using pH 7.4 PBS for 28 days at $37^{circ}$. The release amount was determined by fluorescence intensity by using the fluorescence spectrophotometer and the morphological change of the scaffolds was observed by scanning electron microscope. The release initial burst of BSA containing scaffolds was lower than that of simple dipping scaffolds resulting in constant release aspect. Although the BSA concentration increased. the initial burst was not increased. As a result of this study, it can be suggested that ice particle leaching method for the tissue engineered scaffold miff be very useful and it is possible to impregnate with water soluble factors like cytokine. We suggest that ice particle leaching method may be useful to tissue engineered organ regeneration.

• Polymer(Korea)
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• v.34 no.6
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• pp.565-573
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• 2010

Copoly(2-(dimethylamino)ethyl methacrylate)(DAEMA)/butyl acrylate (BA) and copoly(methyl methacrylate)(MMA)/BA/2-(cinnamoyloxy)ethyl methacryate (CEMA), which were cross-linked with dibromoalkane and UV irradiation, respectively, were prepared for the precursors of interpenetrating polymer network (IPN) humidity-sensitive films. 3-(Triethoxysilyl)propyl cinnamate (TESPC) was used as a surface-pretreating agent for the attachment of IPN-polyelectrolyte to the electrode surface by UV irradiation. Humidity sensitive polymeric thin films with an IPN structure were prepared by crosslinking reactions of copoly(DAEMA/BA) with 1,4-dibromobutane (DBB) and copoly(MMA/BA/CEMA) by UV-irradiation. The anchoring of an IPN-polyelectrolyte into the substrate was carried out via the photochemical $[2{\pi}+2{\pi}]$ cycloaddition. The resulting humidity sensors showed a high sensitivity in the range of 20~95%RH and a small hysteresis (<1.5%RH). The response time for adsorption and desorption process at 33~94%RH was 48 and 65 s, respectively, indicating a fast response. The effects of the concentration of copolymers, molar ratio of crosslinking agents and time of the precursor solution for dip-coating on their humidity sensitive properties including water durability were investigated.