• 한국응용과학기술학회지
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• 제27권1호
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• pp.93-97
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• 2010

Silicone dioxide absorbed polyoxyethylene alkylether sulfate (EU-S75D) surfactant was prepared. The core-shell composite of inorganic/organic were polymerized by using styrene(St) as a shell monomer and potassium persulfate(KPS) as an initiator. We studied the effect of surfactants on the core-shell structure of silicone dioxide/styrene in the presence of an anionic surfactant lauryl sulfate(SLS). The structure of core-shell polymer were investigated by measuring to the thermal decomposition of polymer composite using thermogravimetric analyzer(TGA) and morphology of latex by scanning electron microscope(SEM).

• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1485-1488
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• 2009

A facile, seed-mediated preparation method of trimetallic Au@Pb@Pt core-shell nanoparticles is developed. Au nanoparticles are the template seeds onto which sequentially reduced Pb and Pt are deposited. The trimetallic core-shell structure is confirmed by UV-Vis spectroscopy, TEM and EDS analysis, and cyclic voltammetry. The trimetallic Au@Pb@Pt core-shell nanoparticles show high electrocatalytic activity for formic acid and methanol electrooxidation.

• 폴리머
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• 제36권2호
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• pp.216-222
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• 2012

콘크리트 제조 시 잉여수의 지연 흡수를 위하여 가교된 crosslinked poly(styrene-$alt$-maleic anhydride)(PSMA)가 core이고, PSMA가 shell인 마이크로캡슐 흡수제를 침전중합법으로 제조하였다. Shell의 두께를 조절하기 위하여 (core 단량체의 질량)/(shell 단량체의 질량) 비가 1/1, 1/2 및 1/3이 되도록 하여 cPSMA-PSMA를 중합하였다. FTIR spectrometer를 사용하여 시멘트 포화 수용액 내에서 PSMA가 가수 분해 반응이 일어남을 확인하였다. TEM 분석으로 core/shell 단량체 비가 1/2(cPSMA #3)일 때 마이크로캡슐 구조를 잘 형성하는 것을 관찰하였고, 1/1(cPSMA #2)과 1/3(cPSMA #4)은 불완전한 마이크로캡슐 구조임을 관찰하였다. 시멘트 포화 수용액에서 cPSMA #3의 팽윤비는 초기 20분까지 증가한 후 2시간까지는 감소하였으며, 그 후 24시간까지는 다시 증가하였다. 제조된 cPSMA #3을 시멘트 페이스트에 첨가한 후 시간에 따른 점도 측정 결과 1시간까지는 거의 변화가 없었지만, 그 후 급격한 점도 증가가 일어났다. Core로만 구성된 cPSMA #1을 0.5 wt% 첨가한 시멘트 모르타르의 압축강도는 무첨가 시멘트 모르타르에 비해 약 5% 높게 나타났으며, cPSMA #3을 첨가한 모르타르는 약 7% 증가로 가장 높게 나타났다.

• 폴리머
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• 제32권3호
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• pp.276-283
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• 2008

단량체의 종류(MMA, EA, BA, St), 단량체의 중량비($80/20{\sim}20/80$) 등을 변화시켜 core shell 바인더를 제조하구 여기에 플라즈마 처리하여 물성을 향상시켰다. 각 소재별로 플라즈마 처리시간($1{\sim}10\;s$)을 변화시켜 인장강도, 접촉각 및 접착박리강도를 측정하여 최적의 core shell 바인더의 표면처리 조건을 산출하였다. 중합에서는 바인더의 종류와 조성에 관계없이 개시제는 APS, 반응온도 $85^{\circ}C$에서 0.3 wt%의 유화제를 사용했을 때 가장 높은 전환율을 나타내었고, 중합체의 유리전이온도는 공중합체의 단일 전이 곡선에 비하여 core shell 바인더는 2개 이상의 전이 곡선을 얻었다. Core shell 바인더에 플라즈마 처리 전 후의 접촉각 변화는 PEA/PSt의 경우 5초 이내에 38%의 완만한 감소를 나타내었고, 처리하지 않은 경우는 감소율이 급격히 $0^{\circ}$에 도달하였다. 인장강도는 가장 높은 값을 가지는 PSt/PMMA의 경우 $46.71{\sim}46.27\;kg_f$/2.5 cm로 처리전 후 모두 근사한 값을 나타내었다. 접착박리강도는 PEA/PMMA의 경우 처리 전 $7.89\;kg_f$/2.5 cm에서 처리 후 $14.44\;kg_f$/2.5 cm로 약 2배 이상 증가하였다. 전체적으로 접착박리강도의 크기는 shell 단량체가 MMA인 core 단량체에 대하여 PEA>PBA>PSt의 순으로 되었다.

• 한국안전학회지
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• 제18권4호
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• pp.78-84
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• 2003

Core-shell composite particles of organic/organic were polymerized by using monomers such as methyl methacrylate(MMA) and styrene(St) in the presence of sodium dodecyl benzene sulfonate (SDBS) below critical micelle concentration(CMC) changing concentration, kind of initiators, emulsifiers, addition method of monomers and speed of agitation. In the PMMA/PSt and PSt/PMMA core-shell polymerization, to suppress the generation of new particles and to minimize the coagulation during the shell polymerization, the optimum conditions were $1.45{\times}10^{-5}mol/L$ and $2.91{\times}10^{-5}mol/L$ at concentration of SDBS respectively. The optimum concentration of the other initiator was $1.58{\times}10^{-3}mol/L$ of ammonium persulfate(APS) for core polymerization and $4.0{\times}10^{-4}mol/L$ of APS for shell polymerization.

• 한국안전학회지
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• 제19권1호
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• pp.81-87
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• 2004

Composite particles using inorganic and organic chemicals were synthesized and the results of those reaction were compared to variation of temperature and agitation speed in presence of $CaCO_3$ which was adsorbed SDBS. Also the synthesises were optimized according to conversion rate of composite particles. In inorganic/organic core-shell composite particle polymerization, $CaCO_3$ adsorbed by 0.5wt% surfactant SDBS was prepared initially and then core $CaCO_3$ was encapsulated by sequential emulsion polymerization using MMA at the addition of APS 3.16${\times}$$10^{-3}$mol/L to minimize the coagulated PMMA particle itself during MMA shell polymerization. Encapsulated PMMA on $CaCO_3$ as inorganic/organic core-shell particles was verified by FT-IR and DSC analysis. It was found that the $CaCO_3$ was very well encapsulated by PMMA as shell. The surfaces were distinctly found as spindle shape and broad particle distribution after capsulation.

• 한국응용과학기술학회지
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• 제27권2호
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• pp.183-187
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• 2010

Core-Shell polymers of silicone dioxide-styrene system were prepared by sequential emulsion polymerization. In inorganic/organic Core-Shell composite particle polymerization, silicone dioxide adsorbed by surfactant sodium dioctyl sulfosuccinate (EU-DO133L) was prepared initially and then core silicone dioxide was encapsulated emulsion by sequential emulsion polymerization using styrene at the addition of potassium persulfate (KPS) as an initiator. We found that $SiO_2$ core shell of $SiO_2$/styrene structure was formed when polymerization of styrene was conducted on the surface of $SiO_2$ particles, and the concentration sodium dioctyl sulfosuccinate (EU-DO133L) was 0.5~2.0g. The structure of core-shell polymer were investigated by measuring to the thermal decomposition of polymer composite using thermogravimetric analyzer and morphology of latex by scanning electron microscope(SEM).

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.183.1-183.1
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• 2016

Due to the latest research trend toward wearable energy devices, transparent and stretchable supercapacitors which can sustain their performance even under physical deformation have steadily attracted huge attention. Despite the Ag NW is the most promising candidate for fabrication of transparent and stretchable electronics, the electrochemical instability interrupts its application to development of the energy device. Here, we introduce a transparent and highly stretchable supercapacitor made by Au-Ag core shell NW network percolation electrode. The Au-Ag core shell NW synthesized by a simple solution process not only shows excellent electrical conductivity but also greatly enhanced chemical and electrochemical stability compare to pristine Ag NW. These outstanding properties of the Au-Ag core shell NW are attributed both to the core Ag NW and the Au protecting sheath layer. The proposed Au-Ag core shell NW based supercapacitor exhibits optical transmittance with outstanding mechanical stability withstanding 60% strain without any decrease of the performance. The supercapacitors connected in series are charged and discharged stable in 30% strain turning on a red LED. These notable results demonstrate the potential of the Au-Ag core shell NW as a strong candidate for development of wearable energy devices.

• Corrosion Science and Technology
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• 제21권5호
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• pp.412-417
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• 2022

Proton exchange membrane fuel cells (PEMFCs) provide zero emission power sources for electric vehicles and portable electronic devices. Although significant progresses for the widespread application of electrochemical energy technology have been achieved, some drawbacks such as catalytic activity, durability, and high cost of catalysts still remain. Pt-based catalysts are regarded as the most efficient catalysts for sluggish kinetics of oxygen reduction reaction (ORR). However, their prohibitive cost limits the commercialization of PEMFCs. Therefore, we proposed a NiCo@Au core shell structure as Pt-free ORR electrocatalyst in PEMFCs. NiCo alloy was synthesized as core to introduce ionization tendency and autoxidation reaction. Au as a shell was synthesized to prevent oxidation of core NiCo and increase catalytic activity for ORR. Herein, we report the synthesis, characterization, electrochemical properties, and PEMFCs performance of the novel NiCo@Au core-shell as a catalyst for ORR in PEMFCs application. Based on results of this study, possible mechanism for catalytic of autoxidation core@anti-oxidation shell in PEMFCs is suggested.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.37-40
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• 2003

Amorphous $Al_2O_3$ nanotubes have been fabricated by utilizing the ZnO nanowires as template with wet etching method. ZnO nanowires synthesized by thermal evaporation are conformally coated with $Al_2O_3$ by atomic-layer deposition(ALD) method. The $Al_2O_3$-coated ZnO nanowires are of core-shell structure; ZnO core nanowires and $Al_2O_3$ shells. When the $ZnO/Al_2O_3$ core-shell structure is dipped in $H_3PO_4$ solution at $25^{\circ}C$ for a 6 min, the core ZnO materials are completely etched, and only $Al_2O_3$ nanotubes are remained. This nanotube fabrication is technically easier than others, and simply approachable. Transmission electron microscopy shows that the $Al_2O_3$ nanotubes have various thicknesses that can be controlled.