• Polymer(Korea)
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• v.24 no.3
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• pp.306-313
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• 2000

Polycaprolactone (PCL) macromer containing terminal methacrylate group was synthesized by ring-opening polymerization. The number average molecular weight of PCL macromer was 11600 g/mole and polydispersity index was 1.09. The synthesized PCL macromer was copolymerized with styrene by stable free radical polymerization using 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), benzoyl peroxide, and well-defined poly(styrene-g-caprolactone)s were synthesized. The synthesized copolymers was characterized by $^1$H-NMR and gel permeation chromatography equipped with multiangle laser light scattering detector. Thermal properties of graft copolymers were investigated by DSC.

• Membrane Journal
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• v.27 no.5
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• pp.399-405
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• 2017

The zeta potential, called an electrokinetic potential, refers to the potential difference caused by electrodynamic phenomenon, which is a value obtained by quantifying the surface charge property. The zeta potential has been actively studied for membrane fouling, confirmation of modification and substituent confirmation through surface charge analysis. The methods of measurement for zeta potential were developed on the basis of electrophoresis, electrosmosis and streaming potential. Among them, it was known that the streaming potential method was suitable for the flat sheet membrane. So, in this study, aminated poly(styrene-ethylene-butylene-styrene) membranes were prepared by introducing ammonium groups and the streaming potentials of the prepared membranes were measured by using an electrokinetic potential analyzer (SurPASS) and the results were analyzed.

• Membrane Journal
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• v.29 no.5
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• pp.252-262
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• 2019

A sulfonated star branched poly(styrene-b-butadiene-b-styrene) triblock copolymer (SSBS) was synthesized with varying degrees of sulfonation. The effective sulfonation on the butadiene block was confirmed by FT-IR spectroscopy. Ion exchange capacity by titration was used to determine the degree of sulfonation. The synthesized polymer observed enhanced water uptake and proton conductivity. At room temperature, the SSBS with 25 mol% degree of sulfonation showed an outstanding proton conductivity of 0.114 S/cm, similar to that of commercial membrane, Nafion. The effect of temperature at constant relative humidity on conductivity resulted to a remarkable increase in proton conductivity. Methanol permeability studies showed a value lower than Nafion for all the sulfonated membranes. Structural nature observed using AFM showed that the membranes observed microphase separated nanostructures and the connectivity of the interionic channels.

• Polymer(Korea)
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• v.28 no.2
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• pp.162-169
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• 2004

Poly[styrene-b-(ethylene-1-butene)-b-styrene] triblock copolymer (SEBS) was functionalized with 0 to 3.0 phr maleic anhydride and the amount of dicumyl peroxide used as an initiator was varied from 0 to 0.3phr. The gel content of the modified SEBS was determined by xylene extraction and poly(oxymethylene) was blended with the modified SEBS. The impact, tensile, flexural strength and morphologies of the blends were investigated. The Izod impact strength of poly(oxymethylene) was improved through its blending with modified SEBS. However, the Izod impact strength of poly(oxymethylene)/modified SEBS blend decreased above 5% modified SEBS content. Regarding the effect of dicumyl peroxide content on the Izod impact strength, the blend had a maximum Izod impact strength when poly(oxymethylene) was blended with modified SEBS prepared with 0.1 phr dicumyl peroxide. It was also confirmed by SEM micrographs that the average particle size of modified SEBS in poly(oxymethylene)/modified SEBS blends was smaller than that of SEBS in poly(oxymethylene)/SEBS blends.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.291-292
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• 2003

Amphiphilic block copolymer는 self-assembly특성을 가지고 있기 때문에 선택된 용매 속에서 nanoscale-domain 즉 micelle을 형성할 수 있다. 이러한 특성은 기타 불용성 물질을 가용화하고 colloidal particle을 안정화시키거나 micro-emulsion을 형성할 수 있어 pharmaceutics, drug delivery system등 영역, 그리고 emulsion stabilizer, thickener, dispersion agent등으로 사용될 수 있다. (중략)

• Macromolecular Research
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• v.17 no.10
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• pp.729-733
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• 2009

Solution casting films of sulfonated poly[styrene-b-(ethylene-r-butylene)-b-styrene] copolymer (sSEBS)-based composite membranes that contained different amounts of organic, nanorod-shaped polyrotaxane were annealed at various temperatures for 1 h. The films' properties were characterized with respect to their use as polymer electrolyte membranes in direct methanol fuel cells (DMFCs). Different aspect ratios of polyrotaxane were prepared using the inclusion-complex reaction between $\alpha$-cyclodextrin and poly(ethylene glycol). The presence of the organic polyrotaxane inside the membrane changed the morphology during the membrane preparation and reduced the transport of methanol. The conductivity and methanol permeability of the composite membranes decreased with increasing polyrotaxane content, while the annealing temperature increased. All of the sSEBS-based, polyrotaxane composite membranes annealed at $140^{\circ}C$ showed a higher selectivity parameter, suggesting their potential usage for DMFCs.

• Macromolecular Research
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• v.11 no.6
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• pp.418-424
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• 2003

Exfoliated poly(methyl methacrylate-co-styrene) [P(MMA-co-ST)]/silicate nanocomposites were synthesized through a multistep emulsion polymerization. The methyl methacrylate monomers were polymerized first and then the styrene monomers were polymerized. The nanocomposites had core-shell structures consisting of PMMA (core) and PS (shell); these structures were confirmed by $^1$H NMR spectroscopy and TEM, respectively. P(MMA-co-ST) copolymers showed two molecular weight profiles and two glass transition temperatures (T$_{g}$) in GPC and DMA measurements. At 30 $^{\circ}C$, the nanocomposites exhibited 83 and 91 % increases in their storage moduli relative to the neat copolymer because the silicate layers were dispersed uniformly in the polymer matrix.x.

• Polymer(Korea)
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• v.35 no.5
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• pp.438-443
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• 2011

In order to enhance water permeability through the improvement of fouling phenomena and wettability of hydrophobic porous membranes, various adsorption materials, i.e., poly(vinyl amine), poly (styrene sulfonic acid), poly(vinyl sulfonic acid), and poly(acrylamide-co-acrylic acid) were adsorbed onto the surface of polyethylene (PE) porous membrane. The concentration of adsorption solutions, adsorption time, the sort of salts and their ionic strength were varied, and the pure water permeability of their resulting adsorbed membranes was measured. In general, water permeability increased with an initial increase in the concentration of adsorption solution, adsorption time, and ionic strength and then decreased with a further increase. The pure water permeability of 375 $L/m^2h$(LMH), 35% enhancement, was obtained at a condition of poly(vinyl sulfonic acid) 1000 ppm, $Mg(NO_3)_2$ ionic strength(IS) 0.1, and adsorption time 150 sec, while the 50% (411 LMH) and 35% (374 LMH) enhancements were obtained at conditions of poly(styrene sulfonic acid) 1000 ppm, adsorption time 60 sec, and NaCl IS 0.1 and 0.2, respectively.

• Polymer(Korea)
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• v.34 no.6
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• pp.491-494
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• 2010

Colored, electrophoretic polymer nanoparticles of poly (styrene-co-divinylbenzene-co-vinyl acetate)[poly(St-co-DVB-co-VAc)] were prepared by emulsifier-free emulsion co-polymerization and reactive dyeing. The emulsifier-free emulsion polymerization of styrene, divinyl benzene and vinyl acetate was carried out at $70^{\circ}C$ for 20 hrs to obtain monodisperse polymer nanoparticles of poly(St-co-DVB-co-VAc) with an average diameter of 180~200 nm. These nanoparticles were transformed into poly(styrene-co-divinylbenzene-co-vinyl alcohol) [poly(St-co-DVB-co-VA)] nanoparticles through the saponification reaction. The poly(St-co-DVB-co-VA) nanoparticles were treated with reactive dyes to obtain the colored, monodisperse electrophoretic nanoparticles, and their morphology and surface charge were characterized by scanning electron microscopy, differential scanning calorimetry, UV/Vis absorbance and zeta-potentiometry.

• Korean Chemical Engineering Research
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• v.49 no.3
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• pp.352-356
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• 2011

In this paper, we prepared new type of hydrophilic block copolymers that exhibit the long-ranged lateral ordering in thin film. It was previously demonstrated that poly(ethyleneoxide-b-styrene) and poly(ethyleneoxide-b-metharylate-b-styrene) block copolymer thin films have a high degree of lateral ordering after solvent annealing process. In these cases, the relative humidity plays an important role in long-ranged lateral ordering. However, the origin of the humidity effect on the orders of these hydrophilic block copolymers is not fully understood. To investigate the effect of the humidity further, we prepared other hydrophilic poly(N,N-dimethylacrylamide-b-styrene)(PDMA-b-PS) block copolymers via RAFT polymerization. As with PEO-containing block copolymers, PDMA-b-PS block copolymers exhibit the long-ranged lateral ordering after solvent annealing process.