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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal DOI :
The Polymer Society of Korea
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Volume & Issues
Volume 35, Issue 6 - Nov 2011
Volume 35, Issue 5 - Sep 2011
Volume 35, Issue 4 - Jul 2011
Volume 35, Issue 3 - May 2011
Volume 35, Issue 2 - Mar 2011
Volume 35, Issue 1 - Jan 2011
Selecting the target year
pH Solubility Properties and Improved Dissolution of Pranlukast as an Poorly Water-soluble Model Drug Prepared by Spray-drying with Plasdone S-630
Cho, Won-Hyung ; Lee, Young-Hyun ; Song, Byung-Joo ; Yoo, Seok-Cheol ; Lim, Dong-Kyun ; Khang, Gil-Son ;
Polymer Korea, volume 35, issue 4, 2011, Pages 277~283
Solid dispersion is mainly used for improved dissolution of poorly water-soluble drugs. Solid dispersion of pranlukast was prepared by spray-drying with plasdone S-630. When pH of water was high, pranlukast was highly soluble in the solubility experiment of solid dispersions with varying pH. The particle size of pranlukast particles in solid dispersions was measured to be in nanometers scale based on particle size analysis. Zeta-potential analysis confirmed the negative charge of solid dispersion. SEM was used to observe the surface of solid dispersion, which confirmed spherical morphology, DSC and XRD confirmed the amorphous nature of solid dispersions. The in vitro test was carried out to find improved dissolution rate of pranlukast solid dispersion in simulated juice gastric and a controlled experiment was carried out to compare pranlukast solid dispersions with a conventional drug (Onon
), These results showed the dissolution properties of pranlukast solid dispersions prepared by spray drying proper for the oral pharmaceutical formulation.
Scale-up Polymerization of L -Lactide in Supercritical Fluid
Prabowo, Benedictus ; Kim, Se-Yoon ; Choi, Dong-Hoon ; Kim, Sao-Hyun ;
Polymer Korea, volume 35, issue 4, 2011, Pages 284~288
For the purpose of the pre-industry production of poly(L-lactide) (PLLA) and full understanding of the supercritical polymerization system, large scale polymerization of L-iactide initiated by 1-dodecano/stannous 2-ethyl-hexanoate (DoOH/Sn(Oct)
) was carried out in supercritical chlorodifluoromethane under various reaction conditions (time, temperature and pressure)and reactants (monomer and supercritical solvent) concentrations. A 3 L sized-reactor system was used throughout this study. The monomer conversion increased to 72% on increasing reaction time to 5 h. The molecular weight of PLLA product also increased to 68000 g/moi over the same period. An increase in monomer concentration resulted in a higher molecular weight, up to 144000 g/mol and 97% of monomer conversion. Raising the reaction pressure from 130 to 240 bar also resulted in an increased monomer conversion and molecular weight. To increase heat resistivity of PLLA, methanol treatment and heat-vacuum methods were evaluated. Both of them successfully improved the heat resistivity property of PLLA.
Effects of Attachment and Proliferation of Retinal Pigment Epithelial Cells on Silk/PLGA Film
Jo, Eun-Hye ; Kim, Soo-Jin ; Cho, Su-Jin ; Lee, Ga-Young ; Kim, On-You ; Lee, Eun-Yong ; Cho, Won-Hyung ; Lee, Dong-Won ; Khang, Gil-Son ;
Polymer Korea, volume 35, issue 4, 2011, Pages 289~295
Biomaterials for retinal tissue engineering must demonstrate several critical features for potential utility, including mechanical integrity, biocompatibility, and slow biodegradation. Silk film biomaterials were designed and characterized to meet these functional requirements. We prepared natural/synthetic hybrid silk/PLGA films using 0, 10, 20, 40, and 80 wt% of silk by a solvent evaporation method. MIT assay was used to confirm the number of cells attached on film at 1, 2, and 3 days, respectively. The morphology of cellular adhesion on films was also confirmed by scanning electron microscope (SEM). RT-PCR was conducted to confrrm mRNA expression of retinal pigment epithelitun (RPE) using RPE65 as a RPEs marker and the expression of cytokeratin were determined by immunofluorescence staining. We confirmed that the silk/PLGA film of 20~40 wt% silk was superior for the adhesion and proliferation of RPEs.
Preparation and Characterization of the Impregnation to Porous Membranes with PVA/PSSA-MA for Fuel Cell Applications
Lee, Bo-Sung ; Jung, Sun-Kyoung ; Rhim, Ji-Won ;
Polymer Korea, volume 35, issue 4, 2011, Pages 296~301
This study focuses on the investigation of the impregnation of poly (vinyl alcohol) (PVA) crosslinked with poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA) to porous polyethylene membrane for the fuel cell application. The membranes were characterized by the measurements of the water content, contact angle, FTIR spectra, thermal gravimetric analysis, ion exchange capacity, proton conductivity, methanol permeability and elastic modulus. The existence of hydrophilic moieties in the impregnated membranes was confirmed by contact angle and FTIR measurements. The impregnated PVA/PSSAMA(90:10) membrane exhibited a higher ion exchange capacity (1.2 meq./g dry membrane) than Nafion membrane (0.91 meq./g dry membrane). Through the elastic modulus measurement, the dimensional stability of the resulting membranes was expected to increase higher than the polyethylene membranes. The methanol crossover and water content decreased even if the PSSA-MA content increased due to the reduction of the free volume.
Effect of Functionalized Binary Silane Coupling Agents by Hydrolysis Reaction Rate on the Adhesion Properties of 2-Layer Flexible Copper Clad Laminate
Park, U-Joo ; Park, Jin-Young ; Kim, Jin-Young ; Kim, Yong-Seok ; Ryu, Jong-Ho ; Won, Jong-Chan ;
Polymer Korea, volume 35, issue 4, 2011, Pages 302~307
The parameters of silanol formation reaction of organosilane including solvent type, solution concentration, pH and hydrolysis time influence the adhesion property of 2 layer flexible copper clad laminate (FCCL). Especially, the hydrolysis reaction time of silane coupling agent affects the formation of the silanol groups and their self-condensation to generate oilgomeric structure to enhance the surface treatment as an adhesive promoter. In our study, we prepared the binary silane coupling agents to control hydrolysis reaction rate and surface energy after treatment of silane coupling agents for increasing the adhesive property between a copper layer and a polyimide layer. The surface morphology of rolled copper foil, as a function of the contents of the coated binary silane coupling agent, was fully characterized. As fabricated 2-layer FCCL, we observed that adhesive properties were changed by hydrolysis rate and surface energy.
Characteristics of Ring-Opening Isomerization Polymerization of [4.3.0] Cyclic Pseudoureas
Lee, Chan-Woo ; Chung, Jin-Do ;
Polymer Korea, volume 35, issue 4, 2011, Pages 308~313
The ring-opening isomerization polymerization behavior of 2,5,6,7-tetrahydro-3H-imidazo[2,1-b] [1,3] oxazine(TII) has been studied under various conditions. The present study aimed at improving the low polymerizability of the above monomer (six-membered ring) up to a level comparable to that of 2,5,6-tetrahydroimidazo[2,1-b] [l,3] oxazole(TIO) (five-membered ring). The optimum result could be observed when methyl trifluoromethanesulfonate(MeOTf) and nitrobenzene were used as an initiator and a solvent in the polymerization at
for 24 h. Polymers were confirmed by
NMR, and m measurements. The molecular weight obtained by gel permeation chromatography (GPC) corresponded to the molecular weight theoretically calculated from the feed ratio. The melting temperature (
) of TII was conspicuously different from that of TIO, because of the difference in the alkyl group.
Intra-/lntermolecular Excimer Emission of Syndiotactic Polystyrene Having Carbazole Substituents
Jeong, Seon-Ju ; Jung, In-Tae ; Yoon, Keun-Byoung ;
Polymer Korea, volume 35, issue 4, 2011, Pages 314~319
The syndiotactic and atactic poly (2-N-carbazoylrnethyl) styrenes were obtained by a half-titanocene catalyst and a radical initiator for the investigation of photophysical properties, especially excimer formation. The atactic polymer exhibited only monomer emission, but the syndiotactic polymer showed both excimer emission and monomer emission resulting from the partial overlapping arrangement of carbazole pendants, The emission band of syndiotactic polymer was considerably dependent on solution concentration and temperature, however atactic polymer was independent because the excimer formation of syndiotactic helical conformation was more favorable than that of the random coil conformation of atactic polymer.
Study on the Improvement of Film Shrinkage in UV-curing Process
Kwon, Youn-Joong ; Cho, Ur-Ryong ;
Polymer Korea, volume 35, issue 4, 2011, Pages 320~324
Two functional urethane acrylates were synthesized by using polycarprolactonediol (PCLD) and diisocyanate. The synthesized fuctional urethane acrylate was mixed with butyl acrylate(BA) or adhesion promoters, and their properties were investigated. To synthesize an excellent transparent urethane acrylate, isophorone diisocyanate(IPDI) was used. In addition, the effect of adding butyl acrylate for the improvement of shrinkage of urethane acrylate was studied. The results showed that the addition of butyl acrylate improved the shrinkage, and the optimum butyl acrylate content was 15 wt%. Both 2-ethyl hexyl acrylate (2-EHA) and ethyl acrylate(EA) were polymerized at
for 4 hrs to use as adhesion promoters, and the polymerized adhesion promoters were mixed to the UV-curing resin. The results showed that the adhesion properties increased with the increase of adhesion promoters content up to 15 wt%.
Molecular Simulation Studies for Penetrable-Sphere Model : I. Equation of State
Kim, Chun-Ho ; Suh, Soong-Hyuck ;
Polymer Korea, volume 35, issue 4, 2011, Pages 325~331
Molecular simulations via the molecular dynamics method have been carried out to an equation of state of penetrable-sphere model fluids over a wide range of packing fraction
and finite repulsive energy
. The resulting simulation data are compared to theoretical predictions from the two limiting cases of high- and low-penetrability approximations available in the literature. A good agreement between theoretical and simulation results is observed ill the case of
<3.0. However, for the highly repulsive energy systems of
, where the potential energy barrier is more than two times higher than the particle kinetic energy, a poor agreement is found due to the clustering formation and the non-continuum size effects in the dense systems of
Clay/Acrylamide Hydrogels Having Fucoidan
Hwang, Sun-Ae ; Lee, Jong-Hwi ;
Polymer Korea, volume 35, issue 4, 2011, Pages 332~336
Hydrogels have been investigated due to their potential in a myriad of applications. The introduction of functional moiety such as sulfide has expanded their applicability. In this study, an investigation was carried out on the introduction of fucoidan into the hydrogels of clay/acrylamide. In the resulting semi-IPN nanocomposite hydrogels, the linear polysaccharide, fucoidan, has strong ionic interactions with clay. It was also confirmed from simple mixing tests that fucoidan can physically crosslink with clay without chemical crosslinks. In the semi-IPN hydrogels, equilibrium swelling ratio increased with the content of fucoidan. Elastic modulus increased with an initial increase in the content of fucoidan, and decreased with a further increase. The work of fracture results of these hydrogels showed their tough properties. These hydrogels could provide functional properties such as mucoadhesiveness with tunable hydrogel characteristics.
Development of Wide-Band Compensation Film to Improve Viewing Angle of Vertical Alignment Liquid Crystal Display
Choi, Yu-Jin ; Lim, Young-Jin ; Jeong, Kwang-Un ; Lee, Seung-Hee ;
Polymer Korea, volume 35, issue 4, 2011, Pages 337~341
To expand the viewing angle of vertical alignment liquid crystal display (VA-LCD), a wide-band compensation film has been newly developed. VA-LCD needs a retardation film with improved oblique viewing property. The retardation film for VA-LCD has been fabricated by solvent casting and subsequent drawing triacetylcellulose (TAC) containing optical additives. Here, optical birefringence and wavelength dispersion of the retardation film strongly depend on the chemical structures of optical additives. Utilizing quantum mechanical computation, the polarizing anisotropy of retardation film was calculated with respect to additives. It is also realized that the wavelength dispersion of polarizing anisotropy depends on the type and location of substituent to the selected main isomer. When two propionates are substituted to the meta position of the selected main isomer, the wavelength dispersion of polarizing anisotropy shows the most gentle slop, which is well matched with the experimental results. The most gentle slop of wavelength dispersion means that the viewing angle characteristics of LCD are less influenced according to the wavelength of light source of LCD, and it's possible to make better image quality than the present level.
Effect of Vinyltriethoxysilane Content on Mechanical and Physical Properties of Precipitated Silica Reinforced Silicone Rubber
Jin, Sung-Hoon ; Hong, Jin-Ho ; Kim, Il ; Yun, Ju-Ho ; Shim, Sang-Eun ;
Polymer Korea, volume 35, issue 4, 2011, Pages 342~349
The effect of the amount of vinyltriethoxysilane (VTEOS) in precipitated silica filled silicone rubbers was extensively investigated in terms of the change of mechanical properties, heat resistance, oil resistance, compression set, resilience, and curing characteristics. As the content of VTEOS increased from 0 to 2.0 phr, the hardness of the silicone rubber increased, however, tensile strength, elongation at break, and tear strength decreased. From heat resistance test, the change of mechanical properties was pronounced for silicone rubber treated with more VTOES. The best heat resistance was achieved at 2.0 phr VTOES. In addition, oil resistance was proportionally improved with VTEOS content. From oil resistance test. it was found that the decrease in hardness and maximum elongation was reduced for VTEOS-added systems. Finally, resilience, compression set, degree of cure and crosslink density were significantly enhanced with the amount of VTEOS.
Synthesis and Characterization of Polyamide Having Photoreactive Group in the Backbone and its Liquid Crystal Aligning Property
Jung, Eun-Young ; Lee, Tae-Jin ; Lee, Seung-Woo ;
Polymer Korea, volume 35, issue 4, 2011, Pages 350~355
A soluble polyamide containing photosensitive l,4-phenylenediacrylic acid (PDA) in main chain with biphenyl moiety was synthesized. The chemical structure of synthesized polyamide was investigated by means of
NMR spectroscopy. The polymer was stable up to
and soluble in organic solvents, giving a good quality of thin films. The photoreaction of unpolarized LTV irradiated films was investigated by means of UV-vis absorption spectroscopy and FTlR spectroscopy, and liquid crystals (LCs) alignment property was examined by exposing to linearly polarized UV light (LPUVL) of 260~380 nm. The polyamide in film has excellent photoreactivity to unpolarized UV light. Direction selective photoreaction of PDA moiety in Lhe film was found to further induce nematic liquid -crystals to align along a perpendicular direction with respect to the electric vector of LPUVL, regardless of exposure energy of LPUVL. In addition, pretilt angle was measured by means of crystal rotation method. LPUVL-exposed polymer film induced the alignment of liquid-crystals (LC) with a pretilt angle of 0.2~
A Study on the Rheological Properties of Branched Polycarbonates by Melt Polymerization
Choi, Su-Jung ; Yoon, Kyung-Hwa ; Kim, Hee-Seung ; Yoo, Seung-Yoon ; Kim, Youn-Cheol ;
Polymer Korea, volume 35, issue 4, 2011, Pages 356~362
The branched polycarbonates (B-PCs) with two different branching agents were synthesized from melt polymerization. The contents of branching agent were in the range of 0.001~0.005 mol%. The chemical structure of the synthesized PC was determined by FTIR,
NMR, spectroscopy. The molecular weight, glass transition and degradation temperatures were determined by GPC, DSC, and TGA. The molecular weight of the phloro type B-PC had a lower value than the other one, and the glass transition temperature increased with molecular weight. Compared with linear PC, the rheological properties of the B-PC indicated an increase of complex viscosity in the low frequency region and shear thinning tendency. Power law index(n) representing shear thinning was calculated by linear regression and the values were in the range of 0.483~0.996. The rheological properties of the B-PCs were measured by a dynamic rheometer.
Synthesis of Surface Crosslinked Poly(sodium acrylate) for Delayed Absorption in Cement Solution
Hwang, Ki-Seob ; Jang, Seok-Soo ; Jung, Yong-Wook ; Lee, Seung-Han ; Ha, Ki-Ryong ;
Polymer Korea, volume 35, issue 4, 2011, Pages 363~369
To study the effect of incorporation of a surface crosslinking layer on a crosslinked poly (sodium acrylate) (cPSA) absorbent with ethylene glycol dimethacrylate CEGDMA), we synthesized several surface crosslinked cPSAs with EGDMA by an inverse emulsion polymerization method to delay the absorption of excess water in concrete, Liquid paraffin was used as a continuous phase. cPSA was synthesized with acrylic acid (AA) neutralized with aqueous 8 M sodium hydroxide solution as a monomer, N,N-methylene bisacrylamide (MBA) as crosslinking agent and ammonium persulfate (APS) and sodium metabisulfite (SMBS) as a redox initiator system by inverse emulsion polymerization. FTIR spectroscopy was used to characterize
ion interaction with cPSA and cPSA-EGDMAs. The swelling ratios of synthesized absorbents were evaluated from the absorption in deionized water, cement saturated aqueous solution and aqueous solution of calcium hydroxide (pH 12). Equilibrium swelling times for cPSA and surface crosslinked cPSA with EGDMA were 2 and 3 hrs, respectively. We also observed an increase in setting time of the cement and an increase in the compressive strength of mortar by addition of the synthesized cPSA-EGDMA.
Fabrication and Characterization of Organic Thin-Film Transistors by Using Polymer Gate Electrode
Jang, Hyun-Seok ; Song, Ki-Gook ; Kim, Sung-Hyun ;
Polymer Korea, volume 35, issue 4, 2011, Pages 370~374
A conductive PANI solution was successfully fabricated by doping with camphorsulfonic acid and the polymerization of aniline and the confirmation of doping were characterized by FTIR spectroscopy. In organic thin film transistors, PANI gate electrodes were spin-coated on a PES substrate and their conductivity variations were monitored by a 4-probe method with different annealing temperatures. The surface properties of PANI thin films were investigated by an AFM and an optical microscope, OTFTs with PANI gate electrode had characteristics of carrier mobility as large as 0.15
/Vs and on/off ratio of
, Au gate OTFTs with the same configuration were fabricated to investigate the effect of polymer gate electrode for the comparison of device performances. We could obtain the comparable performances of PANI devices to those of Au gate devices, resulting in an excellent alternative as an electrode in flexible OTFTs instead of an expensive Au electrode.