Jeong‐A Yu

National Rehabilitation Center

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

Joon‐Seop Kim

Chosun University

Daniel G. Nocera

Harvard University

Jin‐Who Hong

Chosun University

Hyunkee Hong

National Institute of Environmental Research

Yu‐Ri Park

Animal and Plant Quarantine Agency

Deok-Rae Kim

National Institute of Environmental Research

Jinkyu Hong

Yonsei University

Daewon Kim

Korea Institute of Machinery and Materials

Sung‐Hwa Oh

Korea Institute of Industrial Technology

Hanlim Lee

Pukyong National University

Cooperative Institutions

Chosun University

Korea University

Korea Institute of Science and Technology

Seoul National University

Korea Advanced Institute of Science and Technology

National Rehabilitation Center

Catholic University of Korea

National Institute of Environmental Research

Michigan State University

Sungkyunkwan University

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

Effects of Molecular Weights of Sulfonated Polystyrene Ionomers on the Formation of Stable Colloidal Particles in Tetrahydrofuran/Water (1/99) Mixture

Journal of Nanoscience and Nanotechnology (2008)

Jeong‐A Yu Kwang‐Hwan Ko Joon‐Seop Kim

The effects of the molecular weights (MWs) of sulfonated polystyrene copolymers on the colloidal particle sizes and the size distributions were investigated. It was found that the size of colloidal particle of acid copolymer of relatively low MW, being largest in comparison with higher MW sample, decreased strongly and then remained constant at ca. 11 nm upon dilution. These findings implied that at relatively high concentrations the colloids aggregated together due to the interactions between particles having relatively non-polar surface and that the colloids might contain more than one polymer chain. In the cases of copolymers of high MWs, the colloid sizes did not change much with the solution concentration, but the particle size of the higher MW copolymer was slightly larger than that of the lower MW sample. This was understood; the higher MW copolymer, the longer polymer chain, and the larger colloid. The size of the ionomeric colloids was found to increase slightly upon dilution, which was due to the repulsion of ionic groups on the surface. As expected, the size of the particles of the ionomers showed a similar trend found in the acid samples.

Polystyrene

Dilution

Tetrahydrofuran

Particle (ecology)

10.1166/jnn.2008.1113

Cite

Citations (0)

Comparison of the mechanical properties of styrene-based ionomers containing either crown ether or pentaethylene glycol with those of underneutralized ionomers

Journal of Polymer Science Part B Polymer Physics (2015)

Hye-Ryeon Park Eun‐Hee Kim Lee Bum-Kyu Jeong‐A Yu Young‐Wun Kim

Dynamic mechanical properties of styrene-based ionomers containing varying amounts of either 15-crown-5 ether (CE) or pentaethylene glycol (PG) are compared with those of ionomers of varying degree of neutralization (ND). The cluster Tg (Tg,c) and ionic modulus of the ionomers decrease with increasing amount of CE or PG or decreasing ND. Thus, we propose that the CE binds Na+ strongly to form a large-sized complex. Thus, the electrostatic interactions between charges decrease, leading to lower Tg,c. For the PG-containing ionomers, the PG acts as polar plasticizer, further lowing the Tg,c. In the case of the underneutralized ionomers, the Tg,c is reduced by the existence of both relatively weak hydrogen bonds between carboxylic acid groups and relatively strong ionic bonds between ion pairs in the multiplets. The small-angle X-ray scattering results are also supportive of the above interpretations. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1358–1367

Ionomer

Plasticizer

10.1002/polb.23772

Cite

Citations (2)

UV cured transparent films including non‐aqueous conductive microgels

Polymers for Advanced Technologies (2002)

Yang‐Bae Kim Wha‐Suk Kim Jeong‐A Yu Jin‐Who Hong

Abstract UV cured transparent films containing non‐aqueous conductive microgels coated with poly(aniline)/dodecyl benzenesulfonic acid(DBSA) were obtained. The conductive microgels were prepared by interface polymerization of aniline/DBSA in the presence of non‐aqueous polymeric microgels. The electrical conductivity and the particle size of the prepared conductive microgel were 0.5 S/cm and 58 nm, respectively. The prepared conductive microgels were easily blended with a UV curable coating formulation, and then were cured to make highly optically transparent films. For the UV cured film containing about 35 wt% of the conductive microgels, a surface resistance in the range of 10 7 to 10 8 Ω/square was obtained. In a polar cosolvent, such as NMP and m ‐cresol, the critical volume was shifted to the lower range, with a value of 10 wt%. The UV cured films containing the conductive microgels exhibited good electrical stability against the thermal aging and humidity. Copyright © 2002 John Wiley & Sons, Ltd.

Thermal Stability

10.1002/pat.220

Cite

Citations (2)

Plasticization effects on the mechanical properties and morphology of cobalt and sodium neutralized poly(ethyl acrylate-co-acrylate) ionomers

Polymer (2005)

Jungwon Kim Ju‐Myung Song Youn-Jeong Cho Joon‐Seop Kim Jeong‐A Yu

Ionomer

Plasticizer

Small-angle X-ray scattering

Ethyl acrylate

10.1016/j.polymer.2005.12.022

Cite

Citations (13)

Mechanical Properties Of P(S-co-Itana)/P(S-Co-Mana), P(S-co-Ssna)/P(S-co-Mana), And P(S-co-Itana)/P(S-co-Ssna) Ionomer Homoblends

MRS Proceedings (2003)

Sung‐Hwa Oh Joon‐Seop Kim Jeong‐A Yu Kwanwoo Shin

Ionomer

10.1557/proc-778-u3.9

Cite

Citations (0)

Monitoring photo-polymerization reaction using near-IR spectroscopic technique

Analytical Science and Technology (2002)

Soo-Chung Chung Jin‐Who Hong Jeong‐A Yu

The extent of UV-curing photo-polymerization reaction was monitored by near-IR spectroscopic method. Acrylates containing quaternary ammonium salts and Darocur 1173 were used as reactive monomer and a photo initiator, respectively. The extent of photo-polymerization reaction was obtained from the conversion ratio of acrylate double bond calculated from the intensities of measured bands at 1615 nm and at 2105 nm. Near-IR spectroscopic methods can be an useful tool for the monitoring of the progress of photo-polymerization.

Bulk polymerization

Source

Cite

Citations (0)

Thermoreversible Gelation of Syndiotactic Poly(methyl methacrylate) Based Block Copolymers in o-Xylene

ACS symposium series (1999)

Jeong‐A Yu R. Jérôme

Thermoreversible gelation has been studied in o-xylene for syndiotactic poly(methyl methacrylate) based block copolymers. The dynamic properties of solutions and gels have been analyzed and discussed on the basis of scaling assumptions. At the gel point, where the loss angle tan δc=G"/G' is independent of the probing frequency, the samples obey the typical power law G'(ω)~ G"(ω) ~ ω Δ . The scaling exponent Δ is found in the 0.65-0.75 range, independently of the experimental conditions, the copolymers composition and the nature of the midblock. Modulus-frequency master curves have been built up by using appropriate reaction time dependent renormalisation factors for the individual frequency and modulus data. The scaling of these factors with reaction time has allowed to calculate the static scaling exponents for the increase observed in both modulus and viscosity.

Exponent

Tacticity

Scaling law

10.1021/bk-1999-0726.ch019

Cite

Citations (0)

Formation of the Colloidal Particles of Sulfonated Polystyrene Ionomers Neutralized with Either Na(I) or Ba(II) in THF/Water (1/99) Mixture

Journal of Nanoscience and Nanotechnology (2008)

Kwang‐Hwan Ko Jeong‐A Yu Joon‐Seop Kim

The sizes of colloidal particles in THF/water (1/99 v/v) of the sulfonated polystyrene copolymers containing 2.1, 5.1 and 9.4 mol% of either acidic or ionic repeat units were determined using a dynamic light scattering technique. It was observed that for the acid copolymer containing 2.1 mol% of acidic units the size of the particle and size distribution decreased significantly as the solution concentration decreased from 2.0 x 10(-4) to 5.0 x 10(-6) g/mL. However, when the content of acidic units increased to 5.1 and 9.4 mol%, the size of the particles and size distribution increased slightly with decreasing solution concentrations. It was also found that the neutralization of the acid group with Na(I) induced the slow increase in the diameter of colloidal particles of the ionomers with decreasing solution concentration, and that the size of the colloids decreased with increasing ion contents. Thus, it was suggested that the former and latter findings could be understood using the polyelectrolyte effect and charge density concepts, respectively. For the ionomers neutralized with Ba(II), it was found that the size of the single colloidal particles was similar to that of the Na(I) ionomer. However, the aggregates of the colloids were not easily separated by the ultrasonication. Thus, it was speculated that the Ba(II) cations placed inside the aggregates of hydrophobic environment acted as the links between colloidal particles.

Polystyrene

Ionomer

Particle (ecology)

10.1166/jnn.2008.1132

Cite

Citations (1)

Raman Spectroscopic Investigations of the Amide-Amide and Amide-Solvent Interactions

Journal of the Korean Chemical Society (1983)

Jeong‐A Yu Young‐Sang Choi

아미드와 아미드-용매계의 C=O stretching band에 해당하는 Raman 스펙트럼으로 부터 카르보닐기와 질소에 치환된 알킬기가 수소결합에 미치는 영향을 조사하였다. Formamide 계에서는 상호작용의 세기가 아미드-아미드>아미드-물>아미드-알코올 순으로 감소했으며, acetamide와 propionamide 계에서는 아미드-물>아미드-아미드>아미드-알코올 순으로 감소하였다. 카르보닐기에 알킬기가 치환되면 카르보닐기의 proton acceptor의 세기가 증가되며, 질소에 알킬기가 치환되면 proton donorcity가 감소함을 보이는데 이는 이론적인 계산 결과와도 일치한다. 【Raman spectra for the carbonyl stretching mode of the amides, and amide-solvent systems have been recorded to investigate the effect of alkyl substitutions at the carbonyl carbon and at the nitrogen on the amide hydrogen-bonding. The data have shown that the interaction affinities are in the order of amide-amide > amide-water > amide-alcohol in formamide system, and amide-water > amide-amide > amide-alcohol in acetamide and propionamide systems. The strength of the proton acceptor of the carbonyl oxygen is increased by the presence of alkyl group to the carbonyl carbon and the proton donorcity of the amide is decreased by the alkyl substitution at the nitrogen. The above results are in good agreement with the ab initio SCF MO calculation.】

Amide

Acetamide

Source

Cite

Citations (0)

Properties of styrene ionomers containing zwitterion-type salts

Polymer Bulletin (1998)

Hee-Seok Kim Yeon-Hwa Nah Joon‐Seop Kim Jeong‐A Yu Yeonhee Lee

Ionomer

Polystyrene

Zwitterion

Plasticizer

10.1007/s002890050403

Cite

Citations (9)