• Polymer(Korea)
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• v.32 no.2
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• pp.143-149
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• 2008

We synthesized PEG-PLA (or PLGA) amphiphilic di-block copolymers, which consist of PEG as biocompatible and hydrophilic block and PLA (or PLGA) as biodegradable and hydrophobic block, by ring opening polymerization of LA in the presence of methoxy PEG as a macroinitiator. The compositions and the molecular weights of the copolymers were controlled by changing the feed ratio of LA (and GA) to PEG initiator. The di-block copolymers could self-assemble in aqueous media to form micellar structure. A hydrophobic model drug, pioglitazone, was loaded into the polymer micelle using solid dispersion and dialysis methods, and the drug-loaded micelles were characterized by AFM, DLS and HPLC measurements. The drug loading capacity and in vitro release studies were performed and evaluated under various conditions. These results indicated that the amphiphilic di-block copolymers of PEG-PLA (or PLGA) could solubilize pioglitazone by solid dispersion method and the drug release was modulated according to micellar chemical compositions.

• Microbiology and Biotechnology Letters
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• v.37 no.1
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• pp.75-79
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• 2009

In this study, we polymerized new materials for soft contact lens using HEMA (2-hydroxyethyl methacrylate) which is the based-monomer of soft contact lens, EGDMA (ethylene glycol dimethacrylate) as cross linkage agent, and the new additives of monoester or di-ester derived from itaconic acid commercially produced by the fermentation of Asp. itaconicus. New polymer materials for soft contact lens were synthesized with the mixture of HEMA and mono- or diester at different ratios and presented to a good water content and oxygen transmissibility (Dk/L) values. In case of polymerization with HEMA and mono-ester (15%), the water content and oxygen transmissibility of contact lens were found to be good values at 57.6% and 28.5 Dk respectively. The mixture of HEMA and mono-ester is more excellent than HEMA/di-ester in the water content and oxygen transmissibility. The toxicity of new contact lens materials were confirmed in the fibroblast L-929 cell line using a agar overlay test and a growth inhibition test with the extract solution of contact lens.

• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.224-230
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• 2012

In this paper, flame-resisting PMMA(polymethyl methacrylate) sheet was manufactured and its characteristics were tested. PMMA was synthesized by bulk polymerization of a monomer methyl methacrylate with addition of phosphorous flame retardant, triethyl phosphate and ethylene glycol dimethacrylate as a cross linking agent. PMMA sheet was manufactured by using the cell molding method, which does not alter or affect the existing property of PMMA. Then the characteristics of PMMA sheet were tested for the TEP content, the content and curing time of EGDMA. As TEP content increases, the length of carbonization lessens and the amount of char production increases. As a result, it strengthened the effect of flame retardants. But the hardness of the sheet decreased as TEP content increased. However, hardness increased when EGDMA was added up to 3 wt% while curing time was decreased from 3 hours to 2 hours. There was no change of hardness when more than 3 wt% of EGDMA was used.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.470-474
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• 2010

In this study, we presents a simple microfluidic approach for generating uniform Poly(ethylene glycol)(PEG) microfiber. Elongated flow pattern of monomer induced by sheath flow of immiscible oil as continuous phase is generated in Y-shape junction and in situ polymerization by UV exposure. For uniform microfiber, we investigate the optimized flow condition and draw phase diagram as function of Ca and Qd. At the region for stable elongated flow pattern, the microfiber generated in microfluidic chip is very uniform and highly reproducible. Importantly, the thickness of microfibers can be easily controlled by flow rate of continuous and disperse phase. We also demonstrate the feasibility for biological application as encapsulating FITC-BSA in PEG microfiber.

• Applied Chemistry for Engineering
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• v.7 no.1
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• pp.136-144
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• 1996

Polyacrylic super absorbent polymer(SAP) containing sorbitol was synthesized by inverse-suspension polymerization method. Sodium acrylate and acrylic acid were used as a monomer, ethylene glycol dimethacrylate(EGDMA) and glycerol polyglycidyl ether(GPGE) were used as a crosslinking agent, potassium persulfate(PPS) was used as an initiator, and cyclohexane was used as a solvent. Content of sorbitol was from 10mol% to 50mol% according to the mol ratio of acrylic acid monomer. The size distribution of the round shaped polymeric particle was $177{\sim}707{\mu}m$. Absorption amount of the polymer containing sorbitol was 785 to 1086 times of the polymer weight in distilled water, was 50 to 83 times in 0.9 % NaCl solution. Absorption and retention amount of the polymer were decreased with increasing the amount of sorbitol, but the polymer has an endothermic property which is +5 cal/g SAP.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.9
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• pp.3753-3758
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• 2015

Background: Polymeric nanoparticles are attractive materials that have been widely used in medicine for drug delivery, with therapeutic applications. In our study, polymeric nanoparticles and the anticancer drug, chrysin, were encapsulated into poly (D, L-lactic-co-glycolic acid) poly (ethylene glycol) (PLGA-PEG) nanoparticles for local treatment. Materials and Methods: PLGA: PEG triblock copolymers were synthesized by ring-opening polymerization of D, L-lactide and glycolide as an initiator. The bulk properties of these copolymers were characterized using 1H nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. In addition, the resulting particles were characterized by scanning electron microscopy. Results: The chrysin encapsulation efficiency achieved for polymeric nanoparticles was 70% control of release kinetics. The cytotoxicity of different concentration of pure chrysin and chrysin loaded in PLGA-PEG ($5-640{\mu}M$) on T47-D breast cancer cell line was analyzed by MTT-assay. Conclusions: There is potential for use of these nanoparticles for biomedical applications. Future work should include in vivo investigation of the targeting capability and effectiveness of these nanoparticles in the treatment of breast cancer.

• Journal of the Korean Chemical Society
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• v.31 no.1
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• pp.110-117
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• 1987

For the preparation of linear low density polyethylene (LLDPE), the copolymerization of ethylene and 1-butene was carried out with various catalysts of titanium alkoxidealkylaluminum compound in slurry phase. The effects of catalyst components, aging time, concentration of catalyst components, polymerization time and temperature on the catalytic activity and copolymer composition were examined. The properties of copolymer obtained were also considered with the correlation to the 1-butene contents. It has been found that the titanium tetra-n-butoxide-diethylaluminum chloride catalyst system was the most suitable for the production of LLDPE with higher catalytic activity, more 1-butene content and less soluble parts. The density, glass transition temperature, melting point and heat of fusion of copolymer were decreased with increasing 1-butene contents.

• Journal of Integrative Natural Science
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• v.6 no.1
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• pp.1-7
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• 2013

Polyurethane resin containing isocyanate is marked by excellent tensile and mechanical strengths and this test aims to gauge its applicability as a medical high polymer. Tris [2-(acryloyloxy)ethyl]isocyanurate and hexamethylenediisocyanate were added to a basic mixing ratio of HEMA (2-hydroxyethyl methacrylate), MMA (methyl methacrylate), NVP (n-vinyl-2-pyrrolidone) and crosslink agent, EGDMA (ethylene glycol dimethacrylate) with increasing proportions and copolymerized respectively. Also, the basic physical properties of the polymerized high polymers including refraction rate, tensile strength, light transmission and water content were measured to confirm that they are appropriate as hydrogelcontact lenses. After measuring the physical properties of high performance polymers produced by adding tris [2-(acryloyloxy) ethyl]isocyanurate, it was found that the average tensile strengths of sample TRIS1 to TRIS10 were between 0.285 and 0.612 kgf, while the average values of refractive index were ranged from 1.441 to 1.449 with water content from 30.00 to 37.35%.The measurement of physical properties of the copolymers generated by adding hexamethylenediisocyanate showed that the average tensile strength of sample HEXA1 to HEXA10 ranged from 0.267 to 1.742 kgf, the refractive index ranged from 1.443 to 1.475 and water contents were in the range of 21.22 to 35.58%. In all combinations the transmission rates satisfied the transmittance of general hydrogel contact lenses. From theresults, it is possible to conclude that the produced copolymers can be used as contact lens materials with excellent tensile strength.

• Macromolecular Research
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• v.15 no.5
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• pp.437-442
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• 2007

Poly(ethylene glycol) methyl ether (PEG)-poly(${\beta}$-amino ester) (PAE) block copolymers were synthesized using a Michael-type step polymerization, and the construction of pH-sensitive polymeric micelles (PM) investigated. The ${\beta}$-amino ester block of the block copolymers functioned as a pH-sensitive moiety as well as a hydrophobic block in relation to the ionization of PAE, while PEG acted as a hydrophilic block, regardless of ionization. The synthesized polymers were characterized using $^1H-NMR$, with their molecular weights measured using gel permeation chromatography. The $pK_b$ values of the pH-sensitive polymers were measured using a titration method. The pH-sensitivity and critical micelle concentration (CMC) of the block copolymers in PBS solution were estimated using fluorescence spectroscopy. The pH dependent micellization behaviors with various bisacrylate esters varied within a narrow pH range. The critical micelle concentration at pH 7.4 decreased from 0.032 to 0.004 mg/mL on increasing the number of methyl group in the bisacrylate from 4 to 10. Also, the particle size of the block copolymer micelles was determined using dynamic light scattering (DLS). The DLS results revealed the micelles had an average size below 100 nm. These pH-sensitive polymeric micelles may be good carriers for the delivery of an anticancer drug.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.139-144
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• 2022

This study reports a microfluidic approach to produce monodisperse hydrogel microparticles in a simple and highly efficient manner. Specifically, we produce double emulsion drops with a thin oil shell surrounding an aqueous prepolymer solution, which is solidified via UV-induced free radical polymerization. When they are dispersed in an aqueous solution, the oil shell is dewetted due to the absence of surfactants, resulting in production of highly uniform hydrogel microparticles (C.V.=1%). Results show that production of monodisperse hydrogel microparticles with controllable size and composition can be achieved with minimal use of oil unlike water-in-oil (w/o) single emulsion-based approach. Furthermore, in-depth study of flow patterns in microfluidic device using a phase diagram exhibits a crucial relationship among relative flow rates while providing windows of readily controllable parameters for reliable manufacturing of hydrogel microparticles.