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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 32, Issue 6 - Nov 2008
Volume 32, Issue 5 - Sep 2008
Volume 32, Issue 4 - Jul 2008
Volume 32, Issue 3 - May 2008
Volume 32, Issue 2 - Mar 2008
Volume 32, Issue 1 - Jan 2008
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Sibutramine Release Behavior from Microspheres Prepared by Spray-Dry Method
Park, Jung-Soo ; Oh, Jung-Soo ; Oh, Jae-Min ; Kim, Yun-Tae ; Lee, Jun-Hee ; Mo, Jong-Hyun ; Lee, Hai-Bang ; Khang, Gil-Son ;
Polymer Korea, volume 32, issue 3, 2008, Pages 193~198
Sibutramine is a highly crystalline and poorly water soluble drug as the appetite depressant for obesity treatment. In order to increase water solubility of sibutramine, microspheres including sibutramine were prepared by solid dispersion method using a spray dryer. The crystallinity and morphology of the prepared microspheres were confirmed by SEM and XRD. The morphology of micro spheres has gradually changed into spherical shape as increasing evaporation rate of solvent. According to XRD analysis, crystallinity of sibutramine in micro spheres was decreased by below 10%. Release behavior of microspheres was investiaged at pH 1.2, pH 6.8, and solubility of the sibutramine was significantly different depending on pH. The hard capsule showed fast release of sibutramine comparing with the tablet. These results demonstrated that the pharmaceutical preparation is able to control the release behaviors.
Sustained Release of Proteins Using Small Intestinal Submucosa Modified PLGA Scaffold
Ko, Youn-Kyung ; Choi, Myung-Kyu ; Kim, Soon-Hee ; Kim, Geun-Ah ; Lee, Hai-Bang ; Rhee, John-M. ; Khang, Gil-Son ;
Polymer Korea, volume 32, issue 3, 2008, Pages 199~205
In this study, we fabricated poly (lactide-co-glycolide) (PLGA) scaffold modified with small intestinal submucosa (SIS) as a drug delivery matrix of bioactive molecules. SIS derived from the submucosa layer of porcine intestine has been widely used as biomaterial because of low immune response. PLGA scaffold was prepared by the method of solvent casting/salt leaching. Novel composite scaffolds of SIS/PLGA were manufactured by simple immersion method of PLGA scaffold in SIS solution under vacuum. SEM observation shows that PLGA and SIS/PLGA scaffolds have interconnective and open pores. Especially, SIS/PLGA scaffold showed that micro-sponge of SIS with interconnected pore structures were formed in the pores of PLGA scaffold. In order to assay release profile of proteins, we manufactured FITC conjugated BSA loaded PLGA and SIS/PLGA scaffold. And the release amount was identified by fluorescence intensity using the fluorescence spectrophotometer. The initial burst of BSA containing SIS/PLGA scaffolds was lower than that of PLGA scaffolds resulting in constant release. And release of BSA in SIS/PLGA scaffold was fast and incremental because of the increased content of BSA. In conclusion, we confirmed that penetrated SIS solution prevented the initial burst of BSA and PLGA modified with SIS scaffold is useful as protein carriers with controlled release pattern.
Preparation and Characterization of Sodium Alginate/PEO and Sodium Alginate/PVA Nanofiber
Park, Ko-Eun ; Park, Su-A ; Kim, Geun-Hyung ; Kim, Wan-Doo ;
Polymer Korea, volume 32, issue 3, 2008, Pages 206~212
Alginate obtained from marine brown algae, is a copolymer with repeating units of
)-L-guluronic acid(G) and
)-D-mannuronic acid(M). It has good properties such as biocompatibility, non-toxicity. and hydrophilicity. However, alginate alone cannot be electrospun due to high viscosity and conductivity. To solve this problem. electro spinning of sodium alginate(SA) was performed by blending with poly(ethylene oxide)(PEO) and poly(vinyl alcohol)(PVA) in this study. Characteristics of SA/PEO nanofibers and SA/PVA nanofibers were estimated by SEM and XRD analyses. Optimal nanofiber webs are obtained from 2/2 wt% of SA/PEO and 2/7 wt% of SA/PVA. SA/PEO and SA/PVA nanofiber webs may have potentials for tissue engineering scaffold and wound dressing.
Conservation Study of Stones by Using Acrylic Monomer
Kang, Sang-Yong ; Suh, Man-Cheol ; Kim, Un-Young ; Kim, Hyung-Joong ;
Polymer Korea, volume 32, issue 3, 2008, Pages 213~218
About 17% of historical properties in Korea were made of stones and most of them are exposed to weathering, as such that discoloring, cracking, and shattering occur from physical, chemical, mechanical, and biological effects due to outdoor placement. Proper treatments for conservation are necessary to prevent the weathering damage and to retain the original shape of stones. MMA, an acrylic monomer having low viscosity can be impregnated deep inside stones by consecutive compression and decompression process in a pressurized vessel. After the polymerization of MMA impregnate, the space inside of the stone was filled with PMMA. It is expected that water repellent and weather resistant properties will be improved because of the improved bonding of constituent materials in stones. In this study, moisture absorption, chemical resistance, and mechanical property of two domestic granites were examined after treating them with MMA for the purpose of determining the conservation value of this method that was possibly useful to the conservation of stone cultural assets.
Synthesis and Swelling Kinetics of a Cross-Linked pH-Sensitive Ternary Copolymer Gel System
Zafar, Zafar Iqbal ; Malana, M.A. ; Pervez, H. ; Shad, M.A. ; Momma, K. ;
Polymer Korea, volume 32, issue 3, 2008, Pages 219~229
A pH sensitive ternary copolymer gel was synthesized in the presence of ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent through radical polymerization of vinyl acetate (VA), acrylic acid (AA) and methyl acrylate(MA) with a weight ratio of 1 : 1.3 : 1. A number of experiments were carried out to determine the swelling behavior of the gel under a variety of pH conditions of the swelling medium. As the pH of the swelling medium was changed from 1.0 to 8.0 at
, the gel showed a shift in the pH-dependent swelling behavior from Fickian (n=0.3447) to non-Fickian (n=0.9125). The resulting swelling parameters were analyzed using graphical and statistical methods. The results showed that the swelling of the gel was controlled by the pH of the medium, i.e.
, where n is the diffusion exponent,
is the pre-exponential factor and
(=0.1417) is pH sensitivity coefficient. The swelling behavior of the gel was also examined in aliphatic alcohols. The results showed that the rate of swelling increased with increasing number of carbon atoms in the alcoholic molecular chain.
Thermal and Optical Properties of Cellobiose Octa(cholesteryloxycarbonyl)alkanoates
Jeong, Seung-Yong ; Ma, Yung-Dae ;
Polymer Korea, volume 32, issue 3, 2008, Pages 230~238
The thermal and optical properties of cellobiose octa(cholestryloxycarbonyl)alkanoates CCCBn,
,10, the number of methylene units in the spacer) were investigated. All the samples formed monotropic cholesteric phases with left-handed helical structures. CCBn with n=2 or 10, in contrast with CCBn with
, did not display reflection colors over the full cholesteric range, suggesting that the helical twisting power of the cholesteryl group highly depends on the length of the spacer connecting the cholesteryl group to the cellobiose chain. The isotropic-cholestropic transition (
) and glass transition temperatures decreased with increasing n and showed no odd-even effect. The transition entropy at
increased with increasing n from 2 up 6, but at n=7 it drops significantly and then increased again with increasing n from 8 to 10. The sharp change at n=7 may be attributed to a difference in arrangement of the side groups. The thermal stability and degree of order in the mesophase and the temperature dependence of the optical pitch observed for CCBn were significantly different from those reported for the cellulose tri(cholesteryloxycarbonyl)alkanoates and glucose penta(cholesteryloxycarbonyl)alkanoates. The results were discussed in terms of the differences in the degree of polymerization, the number of the mesogenic units per mole-glucose unit, and the conformation of the molecules.
Synthesis, Structural Characterization and Thermal Behaviour of Block Copolymers of Aminopropyl-Terminated Polydimethylsiloxane and Polyamide Having Trichlorogermyl Pendant Group
Gill, Rohama ; Mazhar, M. ; Mahboob, Sumera ; Siddiq, Muhammad ;
Polymer Korea, volume 32, issue 3, 2008, Pages 239~245
Block copolymers of the general formula
, [n=18.00 to 1175.0] where
were prepared by a polycondensation reaction of polyamide containing a pendant trichlorogermyl group and terminal acid chloride
with aminopropyl-terminated polydimethylsiloxane
, (PDMS). These polymers were characterized by elemental analysis,
-NMR, solid state
-NMR, and molecular weight determination. The thermal stability of these copolymers was examined using thermal analysis techniques, such as TGA and DSC. Their molecular weights as determined by laser light scattering technique ranged
. These polymers display their
in the range of 337 to
with an average decomposition temperature at
Evaluation of the Stability of Biodegradable Nanoparticle with Time via Particle Size Measurement
Cho, Kuk-Young ; Yim, Jin-Heong ; Park, Jung-Ki ; Lee, Ki-Seok ;
Polymer Korea, volume 32, issue 3, 2008, Pages 246~250
Colloidal stability of the biodegradable nanoparticle was characterized by measuring the variation of particle size with time using photon correlation spectroscopy. Three kinds of polymers, namely, poly(D,L-lactide-co-glycolide)(PLGA), PLGA/poly(L-lactide) blends, and PLGA/poly(L-lactide)-g-poly(ethylene glycol) blends were used as matrix material for nanoparticle preparation. Nanoparticles were prepared with or without using poly(vinyl alcohol)(PVA) as suspension stabilizer to evaluate the condition of preparation. Nanoparticles from the blend of amphiphilic graft copolymer with short poly(ethylene glycol) chain and PLGA maintained suspension for 1 day when protein stock solution was introduced. This is somewhat improvement in colloidal stability against protein adsorption compared with that of nanoparticles without PEG moiety. Suspension stabilizer, PVA, had a significant effect on the colloidal stability against freezing and protein adsorption which led to coagulation of nanoparticles. It is important to consider effect of suspension stabilizer as well as materials used to prepare nanoparticle on the colloidal stability.
Electrical Properties of High Impact Polystyrene (HIPS)/Thermoplastic Urethane (TPU) Blend with Poly(styrene-co-maleic anhydride) as a Compatibilizer
Lee, Young-Hee ; Lee, Tae-Hee ; Kim, Won-Jung ; Kim, Tae-Young ; Yoon, Ho-Gyu ; Suh, Kwang-S. ;
Polymer Korea, volume 32, issue 3, 2008, Pages 251~255
This study suggested antistatic material which can increase anti-static properties and mechanical strength by mixing polystyrene for conveying electronic stuffs with metal salt and ester compound as a anti-static agent. We studied about mechanical, thermal and electrical characteristics by changing the contents of MAH of poly(styrene-co-maleic anhydride), compatibilizer. As the result of measuring residue space charge of the blends of HIPS(75)/TPU(25)/poly(styrene-co-maleic anhydride)(MAH weight ratio : 25, 32, 43.5 wt%), we could find small residue charge in the blend which MAH(25 wt%) was added and it showed the highest values in tensile strength. Additionally we found out the material to which compatibilizer was added kept better anti-static properties than one to which compatibilizer was not added. In the event we could confirm that the adding of PS-co-MAH enables two polymers were mixed well when HIPS/TPU was blended and anti-static agent made easier dissipative in the blend.
Colorless Copolyimide Films: Thermo-mechanical Properties, Morphology, and Optical Transparency
Jin, Hyo-Seong ; Chang, Jin-Hae ;
Polymer Korea, volume 32, issue 3, 2008, Pages 256~262
Copolyimides containing pendant trifluoromethyl (
) groups were synthesized from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and bis[4-(3-aminophenoxy)phenyl]sulfone (BAPS) with various concentrations of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane(BAPP) to poly(amic acid)(PAA), followed by thermal imidization. These copolyimides were readily soluble in N,N'-dimethylacetamide (DMAc) and could be solution-cast into a flexible and tough film. The thermomechanical properties, morphology and an optical transparency of the copolyimide films were determined using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide angle X-ray diffraction (XRD), scanning electron microscopy (SEM), universal tensile machine (UTM), and a UV-Vis spectrometer. The cast copolyimide films exhibited high optical transparency with a cut-off wavelength (
in UV-vis absorption and a low yellow index(YI) value of
. The thermo-mechanical properties of copolyimide films were enhanced linearly with increasing a BAPP content. In contrast, the optical transparency of the copolyimide films was found to get worse with increasing a BAPP content.
Preparation and Characterization of Lithocholic Acid Conjugated Chitosan Oligosaccharide Nanoparticles for Hydrophobic Anticancer Agent Carriers
Park, Jun-Kyu ; Kim, Dong-Gon ; Choi, Chang-Yong ; Jeong, Young-Il ; Kim, Myung-Yul ; Jang, Mi-Kyeong ; Nah, Jae-Woon ;
Polymer Korea, volume 32, issue 3, 2008, Pages 263~269
To develop carriers of hydrophobic anticancer agents based on chitosan, chitosan oligosaccharide lactate (COS) was chemically modified with lithocholic acid (LA) which is one of the bile acids as a hydrophobic group. The physicochemical properties of the lithocholic acid conjugated chitosan nanoparticles (COS-LA) were investigated using
-NMR spectroscopy, dynamic light scattering (DLS) and spectrofluorophotometer. COS-LA-paclitaxel (CLs-Tx) nanoparticles loading paclitaxel as an anticancer agent were prepared by a dialysis method and its loading efficiency was measured through HPLC. On the basis of DLS results, the estimated particle sizes of CLs-Tx were around 300 nm. Also, the critical micelle concentration (CMC) was proven to be dependent on the degree of substitution of lithocholic acid. It showed that the CLs-Tx has the superior potential for the application as a paclitaxel carrier.
Effects of Fillers on Fatigue Crack Growth Rate of Ethylene Propylene Diene Monomer
Hong, Chang-Kook ; Jung, Jae-Yeon ; Cho, Dong-Lyun ; Kaang, Shin-Young ;
Polymer Korea, volume 32, issue 3, 2008, Pages 270~275
Crack growth characteristics of elastomeric materials are an important factor determining the strength and durability. In this study, the fatigue crack growth characteristic of filled EPDM compounds with different reinforcing fillers, such as silica and carbon black, was investigated using a newly designed tester. Frequency and test temperature had significant effects on the fatigue crack growth. The crack growth rate decreased with increasing frequency and the rate increased with increasing temperature. A power law relationship between the tearing energy and crack growth was observed for filled EPDM compounds. The crack growth rate reduced with increasing filler contents. Silica filled EPDM showed a better fatigue resistance than carbon black filled EPDM. The crack growth rate of silica filled EPDM decreased up to 30 phr and increased again at 50 phr. The formation of microductile type pits was observed on the fatigue-failure surface of unfilled EPDM, and relatively coarse surface with randomly distributed tear lines was observed on the failure surface of silica filled EPDM.
Synthesis and Effect of Plasma Treatment of Acrylic Composite Particle Binder
Sim, Dong-Hyun ; Seul, Soo-Duk ;
Polymer Korea, volume 32, issue 3, 2008, Pages 276~283
Kind of monomer(MMA, EA, BA, St)and the monomer ratio(80/20 to 20/80) where changed in the preparation of the core shell binder, and property was improved the plasma processing. Each material changed by plasma treatment time(
) to change to measure the tensile strength, contact angle and adhesion peel strength for the core shell binder optimal conditions for handling the output of the surface treatment. The type of polymerization and composition of the binder is a regardless initiator of APS, the reaction temperature of
to 0.3 wt% of the surfactant used to indicate when the conversion rate was the highest, core shell composite particle binder got two glass temperature curves. Core shell binder after the plasma processing contact angle change is the PEA/PSt 38 percent of cases within five seconds to indicate slight decrease was a decline rapidly if not handled
to reach. Tensile strength PSt/PMMA varies
/2.5 cm and adhesion strength PEA/PMMA varies
/2.5 cm increases. Overall, adhesion strength of core shell composite particle is in the order of order PEA>PBA>PSt for shell monomer MMA.
Inhibition of Intimal Hyperplasia by Perivascular Delivery of Paclitaxel Using Poly(n-butylmethacrylate) or Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) in Balloon-Injured Rat Carotid Arteries
Kwon, Jin-Sook ; Lee, Ho-Yeon ; Heo, Shin-Haeng ; Park, Rho-Kwan ; Shim, Tae-Jin ; Kim, Yu-Kyug ; Kim, Beom-Soo ; Kim, Dong-Woon ;
Polymer Korea, volume 32, issue 3, 2008, Pages 284~289
Polymer is a critical component of local drug delivery to prevent restenosis. This study tested whether poly(n-butylmethacrylate)(PBMA) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate)(PHA) was candidates for this purpose. In vitro release of paclitaxel from PBMA and PHA loaded with 10% paclitaxel exhibited a triphasic release profile, with a fast initial and intermediate second phase followed by a slow release phase. Perivascular delivery of paclitaxel using these films inhibited neointimal hyperplasia in balloon-injured rat carotid arteries. The paclitaxel-loaded PBMA or PHA groups showed significant neointimal formation reductions versus the control groups (PBMA vs control:
, p<0.05; PHA vs control:
, p<0.05). This study suggests that PBMA and PHA could be good candidate polymers of local drug delivery to prevent restenosis. Perivascular delivery using these films represents a possible approach for prevention of restenosis. These can be candidate polymers for drug eluting stents.
Orientation of Evaporated Pentacene Molecules on Rubbed Polyvinylcinnamate Film
Park, Sun-Hee ; Song, Ki-Gook ;
Polymer Korea, volume 32, issue 3, 2008, Pages 290~294
Induction mechanism of molecular orientations for a rubbed polymer film as an alignment layer was investigated using polarized UV/Vis spectroscopic experiments for polyimide and polyvinylcinnamate whose conjugated electrons are located along main chain and side chain, respectively. By determining anisotropy formed in the rubbed film, LC director formed in the LC cell, and orientation direction of deposited pentacene molecules, it was found that LC orientation was induced mainly by molecular interactions whereas surface microgrooves formed by the rubbing process affect the orientation direction of deposited pentacene molecules.