• Polymer(Korea)
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• v.35 no.1
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• pp.94-98
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• 2011

Poly(2-hydroxyethyl methacrylate), PHEMA, hybrid gels containing Pluronic and acrylic acid (AAc) were prepared as new biocompatible and stimuli-responsive hydrogels by photo-polymerization technique. The prepared hybrid gel showed reversible, temperature-responsive swelling behavior due to the presence of Pluronic component, which underwent sol-gel transition at an elevated temperature to cause gel shrinkage. The hydrogel also exhibited increased swelling degrees and pH-sensitivity due to the AAc component with ionizable carboxylic acid groups. The microporous gel morphology and its changes upon stimuli was observed by scanning electron microscopy.

• Polymer(Korea)
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• v.35 no.6
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• pp.520-525
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• 2011

Superporous hydrogels (SPHs) with fast swelling and superabsorbent properties are useful materials in various biomedical fields, by improving the swelling properties of conventional hydrogels based on their unique porous structure. In this study, Eudragit polymers were used as coating materials to control the swelling properties of poly(acrylic acid-co-acrylamide) based SPHs by environmental pH. The SPHs were coated with Eudragit L100 and S100 that have different pH characteristics as enteric coating materials by a dip coating method, and their pH dependent swelling behaviors were observed in various pH environments. The swelling of SPHs was inhibited at a low pH range, but significantly enhanced above a characteristic pH of Eudragit polymers. This pH dependent swelling behavior of hydrogels could be modulated by the characteristics of the enteric coating polymers.

• Membrane Journal
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• v.6 no.4
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• pp.227-235
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• 1996

poly(acrylic acid)(PAA)-poly(vinyl alcohol)(PVA) membranes have been prepared by crosslinking reaction between the carboxylic acid groups of PAA and the hydroxylic groups of PVA. In the measurements of the swelling and preferential sorption of the membranes, sorption behaviors of the membranes in pure water, pure acetic acid and a mixture of them have been investigated, respectively. From the measurements of the preferential sorption in 90wt% acetic acid of aqueous mixture, the sorption of water component was found to be more enhanced at high PAA content in the membrane than that of acetic acid component due to the interaction of water with acetic acid. The sorption behavior and the degree of crosslinking influenced competitively the permeation behavior of permeants. Permeation behavior of perrecants through the membranes was analyzed by using permeation activation energies which had been obtained from the Arrhenius plots of fluxes.

• Elastomers and Composites
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• v.42 no.2
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• pp.102-106
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• 2007

Water swelling behaviors of SBR vulcanizates with different reinforcing systems of carbon black, silica without a coupling agent, and silica containing a coupling agent were studied. Distilled water and 3.5% NaCl solution were used as swelling media. The water swelling ratios in the distilled water were higher than those in the salt solution. The water swelling ratios of the carbon black-filled samples were lower than those of the silica-filled ones. For the silica-filled SBR vulcanizates, the specimens without the silane coupling agent had higher water swelling ratios than those containing it. Water swelling behaviors of SBR composites with different 1,2-unit contents were also compared. The water swelling ratios tended to decrease by increasing the 1,2-unit content.

• Journal of the Mineralogical Society of Korea
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• v.19 no.2 s.48
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• pp.123-128
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• 2006

Beidellite, a member of the dioctahedral smectite group, was synthesized hydrothermally from dickite. Organophilic [DEACOOH]-beidellite intercalation complex was formed by the cation exchange reaction between synthetic Na-beidellite and [DEACOOH]Br. The products dried in high vacuum were treated with various organic solvent such as methanol, ethanol, acetone, ether, acetonitrile and caprolactam in order to determine the swelling behaviour of the prepared complexes. After drying under high vacuum, basal spacing of [DEACOOH]-beidellite shows 15.1 ${\AA}$, and it changed to 19.4, 29.9, 15.9, 16.8, 14.8, 26.5 and 14.8 ${\AA}$ under distilled water, methanol, ethanol, acetone, ether, acetonitrile and caporlactam, respectively. Especially, the characteristics of the intercalation complexes and their swelling behavior of the synthetic beidellite and natural montmorillonite were compared.

• The Journal of Engineering Research
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• v.6 no.2
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• pp.119-124
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• 2004

In this research montmorillonite intercalations complexes as organophilic clay compounds which have very different properties as the starting clay mineral were synthesized by the substitution of metal ions which exist in the montmorillonite layers with the organic cations which have long alkyl chain by the cation exchange reaction. Thereafter the obtained products dried in high vacuum were treated with the various swelling liquids such as dist. water, methanol, acetone, ether and acetonitrile in order to know the swelling behaviour of the synthesized complexes. Especially for this research Korean and Turkish clays were selected to compare the intercalations complexes of both clays and their swelling behaviour.

• Polymer(Korea)
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• v.31 no.4
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• pp.349-355
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• 2007

Poly(N-isopropylacrylamide-co-acrylonitrile) [P(NIPAAm-co-AN)] copolymers with AN content of up to 10 mol% and their hydrogels were synthesized using water as a reaction medium, and the effects of AN unit incorporation on the critical gel transition temperature(CGTT) and swelling behaviors of the hydrogels were investigated. The CGTT of the copolymer hydrogel was $30{\sim}32\;^{\circ}C$, decreasing with increasing AN content. Below CGTT, swelling rate and equilibrium swelling ratio of the copolymer hydrogel decreased with increasing AN content. On the other hand, it exhibited faster deswelling and lower equilibrium deswelling ratio with increasing AN content above CGTT.

• Elastomers and Composites
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• v.29 no.3
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• pp.256-270
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• 1994

• Fashion & Textile Research Journal
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• v.8 no.1
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• pp.1-6
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• 2006

• Polymer(Korea)
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• v.24 no.2
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• pp.194-200
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• 2000

The diffusion coefficients in polyimide/N-methyl-2-pyrrolidone (NMP) systems were proposed using tile Vrentas-Duda's hole free volume theory. Several free volume parameters included in the diffusion coefficients were obtained from the fundamental physical properties of polyimide and NMP and group contribution theory, and the pre-exponential diffusion coefficient, D$_{0}$ was also determined from the dynamic swelling behavior of polyimide in NMP solution. The experimental swelling behavior of polyimide films in NMP was well described by the theoretical one using the proposed diffusion coefficient.t.