• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1573-1574
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• 2009

Fullerene/polystyrene nanoparticles having the average size of 300 nm ~ 1 ${\mu}m$ were prepared by emulsion polymerization in aqueous medium. Poly(vinyl pyrrolidone) and potassium persulfate were used as a dispersant and an initiator, respectively. The contents of fullerene in the nanoparticle were controlled to be from 10 to 57 wt% by varying the feed ratio, which was confirmed by IR-spectroscopy, thermogravimetric analyses, and elemental analyses. Dynamic light scattering experiments revealed the particles have a broad size distribution. Further characterizations of the nanoparticles were performed by using SEM and TEM observation. The high content of fullerene in the particles will find applications in photovoltaic and organic semiconducting area.

• Journal of the Korean Applied Science and Technology
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• v.27 no.3
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• pp.240-248
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• 2010

The blending effects of surfactants on the polystyrene emulsion polymerization were studied. The blending of Triton X-100 and SDS affects to the interfacial properties of the styrene monomer and water phases, and finally, the properties of the polystyrene latex particles. As the blending ratio of SDS/Triton X-100 increases, the interfacial tension and CMC of the blended surfactants were decreased and results in a reducing the size of the latex particles. It was found that the interfacial tension was reduced when the surfactant were blended. By increasing the SDS content, the interfacial tension was reduced, and, at a certain condition, the interfacial tension was reached to an extremely low value to form micro-emulsion and the nano-sized latex particles (80~110 nm).

• Journal of Ceramic Processing Research
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• v.13 no.spc1
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• pp.145-148
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• 2012

Spherical silica aerogel powders were fabricated via an emulsion polymerization method from a water glass. A water-in-oil emulsion, in which droplets of a silicic acid solution are emulsified with span 80 (surfactant) in n-hexane, was produced by a high power homogenizer. After gelation, the surface of the spherical silica hydrogels was modified using a TMCS (trimethylchlorosilane)/n-hexane solution followed by solvent exchange from water to n-hexane. Hydrophobic silica wet gel droplets were dried at 80 ℃ under ambient pressure. A perfect spherical silica aerogel powder between1 to 12 ㎛ in diameter was obtained and its size can be controlled by mixing speed. The tapping density, pore volume, and BET surface area of the silica aerogel powder were approximately 0.08 g·cm-3, 3.5 ㎤·g-1 and 742 ㎡·g-1, respectively.

• Journal of the Korean Applied Science and Technology
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• v.22 no.2
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• pp.96-105
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• 2005

Core-shell polymers of methyl methacrylate-styrene system were prepared by sequential emulsion polymerization in the presence of sodium dodecyl benzene sulfonate(SDBS) as an emulsifier using ammonium persulfate(APS) in an initiator and the characteristics of these core-shell polymers were evaluated. Core-shell composite latex has the both properties of core and shell components in a particle, whereas polymer blends or copolymers show a combined physical properties of two homopolymers. This unique behavior of core-shell composite latex can be used in various industrial fields. However, in preparation of core-shell composite latex, several unexpected matters are observed, for examples, particle coagulation, low degree of polymerization, and formation of new particles during shell polymerization. To solve this matters, we study the effects of surfactant concentrations, initiator concentrations, and reaction temperature on the core-shell structure of PMMA-PSt and PSt-PMMA. Particle size and particles distribution were measured by using particle size analyzer, and the morphology of the core-shell composite latex was observed by using transmission electron microscope. Glass temperature was also measured by using differential scanning calorimeter. To identify the core-shell structure, pH of the composite latex solutions was measured.

• Polymer(Korea)
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• v.34 no.1
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• pp.38-44
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• 2010

Core-shell particles of inorganic/organic pair were synthesized from $CaCO_3$ absorbed sodium dodecyl benzene sulfonate(SDBS) surfactant. Shell components were synthesized by sequential emulsion polymerization. Various monomers were used as shell components such as methyl methacrylate(MMA), ethyl acrylate(EA), butyl acrylate(BA), and styrene(St). Ammonium persulfate(APS) was used as an initiator and 2-ethylhexyl acylate(2-EHA) was used as a functional monomer, In the $CaCO_3$/organic core-shell particle polymerization, $CaCO_3$ absorbed surfactant SDBS of 0.5 wt% was prepared first and then core $CaCO_3$ was encapsulated by emulsion polymerization. 0.1 wt% of APS was added sequentially to minimize the formation of new monomer particle during shell polymerization. The structure of inorganic/organic core-shell particles were characterized by measuring the decomposition degree of $CaCO_3$ using HCl solution, thermogravimetric analyzer, scanning electron microscope, and transmission electron microscope.

• 한국유가공학회:학술대회논문집
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• 2004.11a
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• pp.17-29
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• 2004

Nanofood can be simply defined as natural polymer particles containing functional food materials in nanoscale that are synthesized by polymerization or emulisification process. They have very uniform diameters in the range of 1 to 100 nm and extensive surface areas due to the small particle size in spite of their non-porosity. Although the technique to produce nanofood has not Bong developing history, many works have been achieved in various fields. Nanofood has a lot of special advantages, such as functionality, diversity, applicability, etc. In case of the domestic food industries, however, the accumulation of related technique is insufficient against developed countries except used food materials. Also, it is difficult to acquire technical know-how from the developed countries that possess those technologies. We have been studied on preparing functional nanofood and developing new production processes since 1999. Last 5 years we have laid the foundation on the preparation of nanofood and now are focusing on developing new processes of nanofood and expending the field of its applications.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.05
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• pp.7-14
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• 1993

Nowadays, microspheres are expected to be applied to biomedical areas and many studies are being performed. For biomedical applications, many kinds of microspheres were synthesized by emulsion polymerization, emulsifier-free emu]sion polymerization, and emulsifier-free emulsion polymerization with ionic surface-active comonomers. Further synthesis techniques about microencapsulation and magnetic microspheres are introduced. Among the practical applications of microspheres, some interesting subjects are introduced. These include solid-phase immunoassays, labeling and identification of lymphocyte populations, extracorporeal and hemoperfusion systems, drug delivery systems, and immunomagnetic cell separation. In addition, basic theories, problems and research trends are also introduced.

• Elastomers and Composites
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• v.28 no.4
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• pp.267-273
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• 1993

A number of hydrophilic acrylic comonomers were incorporated into styrene-butadiene soap-free emulsion polymerization. It was found that reaction rate decreased according to : AN>AA>MMA>EA>IA>AAM>MA>HEMA. It was also observed that reaction rate increased with decreasing H-bonding factor contribution to the solubility parameter of the hydrophilic comonoer. The SBR latexes were very monodisperse with the particle size distribution of $1.03{\times}1.12$. Since growth rate is proportional to polymerization time, the difference in conversion rates between various comonomers was resulted from the particle number density of SBR latexes for the various hydrophilic comonomers. It was also found that the colloidal stability of the latexes was excellent because no external emulsifier was incorporated.

• Clean Technology
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• v.11 no.1
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• pp.41-50
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• 2005

In this study, semibatch emulsion copolymerization of n-BA as adhesive component and MMA as coagulant component were carried out for the stable acrylic polymer latex in aqueous phase for polymer cement using LE-type nonionic surfactant as environmental friendly surfactant. The stable polymer emulsion was obtained with the increases of chain length(n) of this surfactant. The effect on the amount of LE-50 as nonionic surfactant were showed that the concentration of polymer latex were increased by increasing the amount of LE-50, whereas the average particle size were decreased by increasing the amount. The addition of functional monomer in initial reactor charge showed a significant effect on the final polymer concentration and the latex particle size. The single polymerization of each n-BA or MMA showed a very low concentration of polymer latex and very big particle size due to coagulation. In the polymerization composed of mixed monomer with MMA and n-BA, the larger the ratio of MMA to n-BA in the copolymers, the greater the amount of coagulum produced. It was found that a stable copolymers were obtained in the range of 15-35 % of n-BA. Moreover, incorporation of some functional monomers in addition to of main monomers became more stable polymer latex. Through DSC and IR analysis, the final polymer latex was composed by MMA/n-BA/AA/AM with a single Tg depending on the reaction conditions. As a result, the conditions of this acrylic polymerization could also be effectively controlled to get the desired final products.

• Polymer(Korea)
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• v.28 no.2
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• pp.135-142
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• 2004

Poly(vinyl acetate) (PVAc) prepared by emulsion polymerization has broad applications for additives such as paint binder, adhesive for wood and paper due to its low glass transition temperature which help to plasticize substrate resins. Since emulsion polymerization has a disadvantage that surfactant and ionic initiator degrade properties of the product polymer, poly(vinyl acetate-co-butyl acrylate) (VVc-BA) was synthesized using potassium persulfate as catalyst and poly(vinyl alcohol) (PVA) as protective colloid to prevent the degradation. The copolymer latex product was internally plasticized and has enhanced colloid stability, adhesion, tensile strength and elongation. During VAc-BA emulsion polymerization, no coagulation and complete conversion occur with the reactant mixture of 0.7wt% potassium persulfate, 15wt% poly(vinyl alcohol) (PVA-217), and the balanced monomer that the weight ratio of vinyl acetate to butyl acrylate is 19. As the concentrations of PVA increase, the copolymerization becomes faster and polymer particles are more stable, resulting in enhanced mechanical stability of the VAc-BA copolymer. However, the size of the polymer particles decreases with increasing PVA contents. Properties of the VAc-BA copolymer, such as minimum film formation temperature, glass transition temperature, surface morphology, molecular weight and molecular weight distribution, tensile strength and elongation, were characterized using differential scanning calorimeter, transmission electron microscope and other instruments.