• Macromolecular Research
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• v.17 no.9
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• pp.709-713
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• 2009

The aim of this study was to develop novel intestinal specific drug delivery systems with pH sensitive swelling and drug release properties. The carboxyl group of ibuprofen was converted to a vinyl ester group by reacting ibuprofen and vinyl acetate as an acylating agent in the presence of catalyst. The glucose-6-acrylate-1, 2, 3, 4-tetraacetate (GATA) monomer was prepared under mild conditions. Cubane-1, 4-dicarboxylic acid (CDA) linked to two 2-hydroxyethyl methacrylate (HEMA) group was used as the crosslinking agent (CA). Methacrylic-type polymeric prodrugs were synthesized by the free radical copolymerization of methacrylic acid, vinyl ester derivative of ibuprofen (VIP) and GATA in the presence of cubane cross linking agent. The structure of VIP was characterized and confirmed by FTIR, $^1H$ NMR and $^{13}C$ NMR spectroscopy. The composition of the cross-linked three-dimensional polymers was determined by FTIR spectroscopy. The hydrolysis of drug polymer conjugates was carried out in cel-lophane membrane dialysis bags, and the in vitro release profiles were established separately in enzyme-free simulated gastric and intestinal fluids (SGF, pH 1 and SIF, pH 7.4). The detection of a hydrolysis solution by UV spectroscopy at selected intervals showed that the drug can be released by hydrolysis of the ester bond between the drug and polymer backbone at a low rate. Drug release studies showed that increasing the MAA content in the copolymer enhances the rate of hydrolysis in SIP. These results suggest that these polymeric prodrugs can be useful for the release of ibuprofen in controlled release systems.

• Polymer(Korea)
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• v.36 no.4
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• pp.427-433
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• 2012

A series of poly(imide-aramid-sulfone)s with alternatingly introduced imide/aramid groups were prepared by reacting divinyl sulfone (DVS) and $N^1,N^4$-bis(4-(vinylsulfonyl)phenyl)terephthalamide (2) with pyromellitic diimide. Three model compounds, N-[2-(p-aminophnenylsulfonyl)ethyl]phthalimide (3), 2,2'-(2,2'-sulfonylbis(ethane-2,1-diyl))diisoindoline-1,3-dione (4), and N,N-bis(4-(2-(1,3-dioxoisoindolin-2-yl)ethylsulfonyl)phenyl)terephthalamide (5), resembling polymers were prepared with good yields by reacting p-aminophenyl vinyl sulfone, DVS, and 2 with phthalimide. Condensation polymerization was carried out by Michael-type addition reaction of the difunctional phthalimide group with the DVS group in the presence of tetrabutylammonium hydroxide (TBAH), resulting in poly(imide-aramid-sulfone)s 6-12 with moderate molecular weights and good yields. They were highly soluble in polar solvents such as N,N-dimethylformamide, dimethylsulfoxide, N-methylpyrrolidinone and tetrahydrofuran. The ratios of DVS/2 were 1/0, 3/1, 2/1, 1/1, 1/2, 1/3, and 0/1. Molecular weight and physical properties such as solubility, viscosity, and thermal properties of the polymers were examined.

• Korean Journal of Agricultural Science
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• v.37 no.2
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• pp.209-216
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• 2010

In order to understand the effects of a single or combined treatments of 1-MCP($1{\mu}L/L$) and $CO_2$(100%) on the firmness of melting type peach fruit(cv. Chunjungdo), fruit were harvested at commercial maturity and examined physiological changes including flesh firmness during 10 days of shelf-life. Firmness loss of fruit was delayed by both single and combined treatments of 1-MCP and $CO_2$. The treatment of 1-MCP was more effective than $CO_2$ treatment but no additive effective on firmness retention was found in the combined treatment. The upsurge of ethylene evolution occurred 5 days of shelf-life in air treated control but ethylene evolution gradually increased in fruit treated by 1-MCP and 1-MCP+$CO_2$. The suppression of ethylene evolution seemed stronger in $CO_2$ treatment. The respiration of fruit significantly inhibited up to 10 days except control where climacteric increase of respiration was found at 10 days of shelf-life. A molecular shift of pectic polymers(an increase of chelator soluble pectins and decrease of water soluble pectins) was induced by both 1-MCP and $CO_2$ treatments. An increase of water soluble pectins was coincident with firmness loss. The delay of firmness loss seemed to be associated with the migration of calcium to wall matrix, especially pectins, resulting in the increase of wall bound calcium. The polygalacturonase activity was significantly reduced by 1-MCP alone 1 day after treatment and increased to similar level of activity 5 days after treatment compared to other treatment except air treated control whereas pectin methylesterase activity seemed not to be affected by both 1-MCP and $CO_2$ treatments. Thus, the molecular shift of pectic polymers appeared not to be related with pectin methylesterase. Further study is required to clarify the softening mechanism associated with molecular shift of pectic polymers and the inter- or intra-cellular movement of calcium ions induced by postharvest treatments of 1-MCP and $CO_2$.

• Restorative Dentistry and Endodontics
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• v.42 no.4
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• pp.309-315
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• 2017

Objectives: This study assessed the effect of water storage on the flexural strength (FS) of low shrinkage composites. Materials and Methods: A total of 165 bar-shaped specimens ($2{\times}2{\times}25mm$) were fabricated of 2 low shrinkage composites (Filtek P90 [3M ESPE], GC Kalore [GC International]) and a conventional methacrylate-based composite (Filtek Z250 [3M ESPE]). The specimens were subjected to 3-point bending test at 6 time intervals, namely: immediately after curing, at 24 hours, 1 week, 1 month, 6 months, and 1 year following storage in wet and dry conditions. The FS of the specimens were measured by applying compressive load at a crosshead speed of 1.0 mm/min. Data was analyzed using 3-way analysis of variance (ANOVA) and Tukey's test. Results: Three-way ANOVA revealed significant interactions between time, type of composite, and storage condition (p = 0.001). Tukey's multiple comparison test revealed significant reductions in FS of all composites after 6 months and 1 year of storage in distilled water compared to dry condition. Conclusions: Filtek P90 showed the highest and GC Kalore showed the lowest FS after 1 year storage in distilled water. The immediate high strength of Filtek Z250 significantly decreased at 1 year and its final value was lower than that of Filtek P90.

• Journal of the Korean Applied Science and Technology
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• v.32 no.2
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• pp.326-329
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• 2015

This study is to develop the double capsulation technology in order to increase the conservativeness and stability of unstable materials such as vitamins, polyphenols, natural active ingredients. And also, best way of triple matrix capsulation using natural polymers were detail described. As the first capsulation with w/o/w (water-in-oil-in-water) emulsifying system, our study group was especially made to soft and moisture cream using 5wt% of sucrose ester emulsifier as first capsulation. Nutrient agents are squalane, camellia oil. Triple matrix capsulation was formed with the best stabilized bead type capsules when it blended of chitosan, algin, sodium-potassium alginate. The bead diameter size was about 2.0~4.5mm (mean diameter: 3.2mm). Activity of lactobacillus containing cream for depending on various pH variations showed that alkalinity ($pH=10.8{\pm}0.5$) condition was higher than acidity ($pH=4.2{\pm}0.2$) and neutrality ($pH=7.1{\pm}0.3$) conditions. After a month, it also was certified to the activity of lactobacillus in incubated at $37{\pm}1^{\circ}C$ in culture medium. As application of food industry, we developed the containing lactobacillus capsule and 7 colored kinds of double and triple matrix capsulation in yogurt cream and active ingredients. As for above mentioned those results, one of tool to stabilize the living lactobacillus, doubled matrix capsulation greatly be expected to contribute to food industry. Furthermore, it can be expected to apply the drug delivery system (DDS) to active ingredients of stabilizing technologies at drug, pharmaceutical division and cosmetic industry, etc.

• Journal of Pharmaceutical Investigation
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• v.29 no.2
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• pp.127-136
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• 1999

In order to eliminate demerits of conventional dosage forms, dipotassium glycyrrhizate was formulated as a slim mucoadhesive film type dosage form. The mucoadhesive drug layer gel containing dipotassium glycyrrhizate was prepared using $Noveon^{\circledR}$ AA-1, hydroxypropylcellulose-M, ethylcellulose N 100 and citric acid, and the protective layer gel by using ethylcellulose N 100, $Eudragit^{\circledR}$ RS and castor oil. The viscosity of drug layer gel of mucoadhesive film was enhanced as the increased amount of $Noveon^{\circledR}$ AA-1 or hydroxypropyl cellulose-M. The drug content was unifonnly $1160{\pm}14.6\;{\mu}g$, and was varied within 3.5%. The optimum film dosage form showed a good fluidity and malleability of drug layer, with 179 g of thickness, pH 5.7, 411 min of in vitro adhesion time and 172 g in gravity adhesive strength. The release time of drug from the mucoadhesive film was significantly shorter but was delayed when polymers such as ethylcellulose was added. From these results, the new mucoadhesive film may be effective for the treatment of aphthous stomatitis.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.163-166
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• 2003

Laser-Induced Thermal Imaging (LITI) is a laser addressed patterning process and has unique advantages, such as high-resolution patterning with over-all position accuracy of the imaged stripes within 2.5 micrometer and scalability to large-size mother glass. This accuracy is accomplished using real-time error correction and a high -resolution stage control system that includes laser interferometers. Here the new concept of mixed hybrid system which complement the advantages of small molecular and polymeric materials for use as an OLED; our system can realize the easy processing of polymers and high luminance efficiency of recently developed small molecules. LITI process enables to pattern the stripes with excellent thickness uniformity and multi-stacking of various functional layers without using any type of fine metal shadow mask. In this study, we report a full-color hybrid OLED using the multi-layered structure of small molecular/polymeric species.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.481.2-481.2
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• 2014

Bulk hetero junction (BHJ) polymer solar cell (PSCs) is one of the most promising fields as alternative energy source. Especially, the development of new p-type conjugated polymer is one of the main issues to get core technology. In this study, we investigated the chemical doping effects of incorporating 3,6-carbazole units into conjugated polymers based on 2,7-carbazole. We assessed the structural effects of this chemical doping by measuring the photovoltaic device performance of the copolymers with and without annealing. Note that the use of nanostructures in the bulk heterojunction layer could be a major obstacle to commercialization because nano-morphologies are frequently unstable at high temperatures. Therefore, the development of thermally stable polymer:fullerene blends with optimized PCEs is an important goal in this area of research. We studied the morphologies of the copolymers incorporating 3,6-carbazole units resulting from thermal annealing to investigate the effects of the difference between the T g values of the 2,7-carbazole unit and the 3,6-carbazole unit.

• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.624-631
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• 2014

In this study, a new series of conjugated polymer 3-(5-(5,6-bis(octyloxy)-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)-10-(4-(octyloxy)phenyl)-10H-phenothiazine (P1) and 3-(5-(5,6-bis(octyloxy)-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)-10-(4-((2-ethylhexyl)oxy)phenyl)-10H-phenothiazine (P2) were synthesised and organic photovoltaics (OPVs) properties were characterized. The push-pull structure polymer consisted of phenothiazine derivative as an electron donor and benzothiadiazole derivative as an electron acceptor. The aliphatic chain substituted aromatic ring was substituted at the position of N in phenothiazine for the electron-rich and improved solubility. Excellent thermal stabilities of P1 and P2 were confirmed by measured Td values as 321.9 and $323.7^{\circ}C$, respectively and the degrees of polymerization were 4,911 (P1) and 5,294 (P2). The maximum absorption wavelength of P1 and P2 were 549 and 566 nm, respectively. The device was fabricated and the OPVs property was measured. As a result, the power efficiency of conversion for P1 and P2 were 0.96 and 0.90%, respectively.

• Journal of Adhesion and Interface
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• v.3 no.2
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• pp.9-16
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• 2002

In the synthesis of water-based polyurethane using self-emulsification process, after being neutralized, polyurethane pre-polymers containing ionic pendant groups are dispersed by simple convective mixing. Preparation of dispersion is followed by chain extension reaction, which is considered as important step for growth of the molecular weight of polyurethane. In this work, pH variations in the aqueous phase were monitored during the chain extension process in the presence of water-soluble diamines. The optimum degree of chain extension and the average particle size in the polyurethane dispersions were examined with varying ionic pendent group contents, type of chain extenders, and feed rate of chain extenders, The initial pH value in the aqueous phase linearly increased and the optimum chain extension point could be obtained from the intersection of two linear lines having different slopes, All average particle sizes before chain extension reaction were almost same, however, the final average particle size increased as feed rates of chain extenders increased, In addition, as the ionic pendant group contents increased, the particle size decreased since the hydrophilicity and hydrodynamic volume increased. As carbon numbers of the chain extenders increased, the final particle size increased significantly. From the results, it was concluded that the chain extension reaction took place among the particles not only in a particle.