• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.757-767
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• 1996

Poly(alkyl acrylate-g-caprolactone) graft copolymers were prepared, and they were applied as compatibilizing agents for polycarbonate (PC) / poly(acrylonitrile-butadiene-styrene) (ABS) blends. The incompatible poly(alkyl acrylate) segment was incorporated into the graft copolymer in order to localize the copolymer at the PC/ABS interface. The blend containing 1 phr of the copolymer showed remarkable improvement in impact strength as well as in elongation at break. Impact improvement was more pronounced with a thinner test specimens of 1/8 inch thickness. Morphological study showed that the presence of the graft copolymer led to a smoother PC/ABS interface due to the interfacial enrichment of the graft copolymer.

• Proceedings of the KAIS Fall Conference
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• 2010.05a
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• pp.363-365
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• 2010

고분자 발광다이오드(polymer light emitting diode, PLED)는 초박막화, 초경량화가 가능하며 간단한 용액공정 으로 향후 휨성(flexible) 디스플레이로의 응용이 가능할 것으로 기대되고 있다. 본 연구에서는 녹색 고분자 유기 발광다이오드를 제작하고, 효율을 향상 시키고자 이중 발광층을 두어 전기 광학적 특성을 평가하였다. ITO/Glass기판 위에 정공주입층으로 PEDOT:PSS [poly(3,4-ethylenedio xythiophene):poly(styrene sulfolnate)]를 발광물질로는 형광 발광물질인 PVK(poly-vinylcarbazole)와 인광 발광 물질인 Ir(ppy)$_3$[tris(2-phenylpyridine) iridium(III)]를 각각 host와 dopant로 사용하였다. 정공 차단층 및 전자 수송층 두 개의 역할로 사용 가능한 TPBI(1,3,5-tris(2-N-phenylbenzimidazolyl) benzene)를 진공 열증착법으로 막을 형성하였다. 전자주입층으로 LiF(lithium flouride)와 음극으로 Al(aluminum)을 증착하여 최종적으로 ITO/PEDOT:PSS/PVK:Ir(ppy)$_3$/TPBI/LiF/Al 구조를 갖는 녹색 형광:인광 혼합 유기 발광 다이오드를 제작하였다.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2005.09a
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• pp.142-146
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• 2005

패턴화된 ITO (indium tin oxide)/Glass 기판 위에 정공수송층인 PEDOT:PSS [poly(3,4-othylenedioxythiophene):poly(styrene sulfolnate)]와 발광층인 MEH-PPV [poly(2-methoxy-5-(2-ethyhexoxy)-1,4phenylenvinylene)]를 사용하여 ITO/PEDOT:PSS/MEH-PPV/AI 구조를 갖는 고분자 유기 발광다이오드 (polymer light emitting diode: PLED)를 제작하였다. PLED 제작시 MEH-PPV 의 농도를 ($0.1\;wt\%\;{\~}\;0.9\;wt\%$) 변수로 하여 박막의 표면 거칠기와 박막 층의 마찰재수(friction coefficient) 측정을 통하여 농도에 따른 특성 변화를 조사하였다. MEH-PP 의 농도를 $0.1\;wt\%$ 에서 $0.9\;wt\%$ 로 증가함에 따라 발광 층의 RMS (root mean square)같은 1.72 nm 에서 1.00 nm 로 감소하여 거칠기가 개선되는 경향을 보여 주었다. 그러나 박막간의 마찰계수는 0.048 에서 0.035 로 감소하여 박막간의 접합상태가 나빠지는 현상을 나타내었다. 소자의 전기, 광학적 특성의 경우 MEH-PPV 농도가 $0.5\;{\~}\;0.9\;wt\%$ 범위에서 약 0.35 mA (at 9V)의 전류밀도를 나타내었으며, 최대 휘도는 $0.5\;wt\%$ 농도에서 $409\;cd/m^2$의 값을 나타내었다.

• Applied Chemistry for Engineering
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• v.21 no.5
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• pp.514-521
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• 2010

A new one-shot process was employed to fabricate proton exchange membranes (PEMs) over conventional solvent-casting process. Here, PEMs containing nano-dispersed silica nanoparticles were fabricated using one-shot process similar to the bulk-molding compounds (BMC). Different components such as reactive dispersant, urethane acrylate nonionmer (UAN), styrene, styrene sulfuric acid and silica nano particles were dissolved in a single solvent dimethyl sulfoxide (DMSO) followed by copolymerization within a mold in the presence of radical initiator. We have successfully studied the water-swelling and proton conductivity of obtained nanocomposite membranes which are strongly depended on the surface property of dispersed silica nano particles. In case of dispersion of hydrophilic silica nanoparticles, the nanocomposite membranes exhibited an increase in water-swelling and a decrease in methanol permeability with almost unchanged proton conductivity compared to neat polymeric membrane. The reverse observations were achieved for hydrophobic silica nanoparticles. Hence, hydrophilic and hydrophobic silica nanoparticles were effectively dispersed in hydrophilic and hydrophobic medium respectively. Hydrophobic silica nanoparticles dispersed in hydrophobic domains of PEMs largely suppressed swelling of hydrophilic domains by absorbing water without interrupting proton conduction occurred in hydrophilic membrane. Consequently, proton conductivity and water-swelling could be freely controlled by simply dispersing silica nanopartilces within the membrane.

• Polymer(Korea)
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• v.39 no.3
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• pp.468-474
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• 2015

Electrically conductive polymer nanocomposites were prepared by the inclusion of graphene-based nanofillers. Graphene oxide (GO) and reduced graphene oxide wrapped by poly(styrene sulfonate) (PSS-RGO) were used as nanofillers to make good dispersion with the aqueous dispersion of polystyrene (PS) particles. GO sheets were synthesized by the modified Hummers' method from graphite, and PSS-RGO sheets were prepared by the reduction of GO-dispersed PSS solution with hydrazine monohydrate. Morphology and properties of PS/GO and PS/PSS-RGO nanocomposites via latex technology were investigated. Both nanofillers showed well dispersed morphology in PS matrix. Rheological and electrical percolation thresholds were 0.28 and 0.51 wt% for GO, and 0.50 and 1.01 wt% for PSS-RGO respectively. It is speculated that PS/GO nanocomposites showed better conductivity than PS/PSS-RGO counterparts due to the partial recovery of GO by thermal reduction during molding.

• Resources Recycling
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• v.28 no.6
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• pp.64-72
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• 2019

Fly ash has different chemical composition depending on the type and quality of flaming coal. Fly ash is classified according to carbon content and particle size. Waste glass powder is manufactured by crushing glass. Exterior Insulation Finish System (EIFS) is generally applied by using poly-styrene foam which is economical and has excellent thermal insulation performance. However, poly-styrene foam has excellent insulation performance, but it is vulnerable to fire, which is becoming a serious problem. In this study, using a fly ash and waste glass powder to produce a finishing mortar at high temperatures. Also, High temperature strength and flame retardant properties were tested according to the cover thickness. From the test result, finishing mortar prepared using fly ash and waste glass powder is due to the improved heat resistance by alkali-activated bonding. However, since the strength decreases at high temperatures, it is necessary to select an appropriate mixing proportion.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.743-747
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• 1999

The component polymer was modified to enable the formation of intermolecular hydrogen bonding in the immiscibile polystyrene(PS)/polymethacrylate(PMA) blends. The mole percentages of hydroxystyrene of the poly(styrene-co-4-hydroxystyrene) copolymer(modified polystyrene, MPS) were controlled to 7%, 10% and 18%, respectively. MPS was used with PMA to study the variation of the miscibility in blends. PMA which had such different length of side chain as methyl, butyl, hexyl and ethylhexyl, respectively, was selected to study the effect of side chain length on the formation of intermolecular hydrogen bonding. As the hydroxyl content of MPS increased, the formation of intermolecular hydrogen bonding increased. The length of side chain of PMA had enormous effect on the miscibility of blend as confirmed from the result of cloud point measurement. As the length of side chain increased, the formation and the strength of intermolecular hydrogen bonding decreased severely due to the steric effect and the increased chain mobility.

• KSBB Journal
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• v.6 no.3
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• pp.241-247
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• 1991

The Poly (4-vinyipyridine-co-styrene) membrane containing Pyridine as fixed carrier was synthesized and characterized. And the active transport mechanism of Cl- and $CCl_3COO^-$ with changing concentration of $H^+$ and $OH^-$ was investigated. $CCl_3COO^-$ was transported not only by a symport mechanism with $H^+$ transfer but also by an antiport mechanism with $OH^-$transfer, while $Cl^-$ was transported only by a symport mechanism with $H^+$ transfer. Observing the initial flux of anions, salt formation constant between ions and membrane (K), and diffusion coefficient in membrane (D) were calculated as follows: for $Cl^-, \;K=4.60{\times}10^2\;mol^{-1}{\cdot}\textrm{cm}^3, \;D=1.57{\times}10^{-3}{\textrm{cm}^2/h$ and for $CCl_3COO^-, \;K=1.l0{\times}10^4\;mol^{-1}{\cdot}\textrm{cm}^3, \;D=1.14{\times}10^{-4}{\textrm{cm}^2}/h$.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.843-848
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• 1996

Porous resin beads of Poly(styrene-co-divinylbenzene) have been prepared by suspension polymerization. The bead could be made porous in the region above 30wt% of the crosslinking agent(divinylbenzene ) and the porogenic agent(toluene), respectively. The specific surface area of porous beads increased with increasing the concentrations of divinylbenzene and toluene. The specific surface area of the porous resin bead decreased, when sulfonated with concentrated sulfuric acid. The catalytic activity of sulfonated resin catalyses increased with increasing the degree of crosslinking in the liquid-phase reesterification of ethyl acetate with 1-propanol. The adsorbed quantity of sodium dodecylbenzene sulfonate in an aqueous solution also increased with increasing surface area of porous resins.

• Applied Chemistry for Engineering
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• v.27 no.1
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• pp.45-49
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• 2016

In the presence of poly(4-styrene sulfonate) (PSS) and excess amount of graphene oxide (GO), we conducted in-situ polymerization of 3,4-ethylenedioxythiophene (EDOT) without an oxidant. XPS and IR spectroscopies of the product (GO-P) showed that PEDOT/PSS was successfully synthesized by oxidative polymerization of EDOT and hybridized with GO. GO-P displayed a stable aqueous suspension, however, the high content (42%) of GO in GO-P diminished electrical conductivity down to $15S{\cdot}m^{-1}$. Annealing of GO-P films at $200^{\circ}C$ for 8 hr induced partial reduction of GO and finally enhanced electrical conductivity up to $212S{\cdot}m^{-1}$.