• The Journal of Korean Society for Radiation Therapy
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• v.19 no.1
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• pp.7-17
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• 2007

Purpose: As increasing complexity of modern radiotherapy technique, more developing dosimetry is required. Polymer gel dosimeters offer a wide range of potential applications with high resolution and assured quality in the thee-dimensional verification of complex dose distribution such as intensity-modulated radiotherapy (IMRT). The purpose of this study is to find the most sensitive and suitable gel as a dosimeter by varying its composition ratio and its condition such as temperature during manufacturing. Materials and Methods: Each polymer gel with various ratio of composition was irradiated with the same amount of photon beam accordingly. Various polymer gels were analyzed and compared using a dedicated software written in visual C++ which converts TE images to R2 map images. Their sensitivities to the photon beam depending on their composition ratio were investigated. Results: There is no dependence on beam energy nor dose rate, and calibration curve is linear. Conclusion: The polymer gel dosimeter developed by using anti-oxidant in this study proved to be suitable for dosimetry.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.263-263
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• 2006

Poly (ethylene glycol)(PEG) - Poly (${\varepsilon}-caprolactone(CL)$) - Poly (D,L lactide(LA) (PCLA-PEG-PCLA) was synthesized by ring-opening polymerization to form temperature sensitive hydrogel triblock copolymer. The triblock copolymer was acrylated by acryloyl chloride. ${\beta}-amino$ ester was used as a pH sensitive moiety, in this study ${\beta}$- amino ester obtained from 1,4-butandiol diacrylate, and 4, 4' trimethylene dipiperidine, it have pKb around 6.6. pH/temperature sensitive penta-block copolymer (PAE-PCL-PEG-PCL-PAE) was synthesized by addition polymerization from acrylated triblock copolymer, 1,4-butandiol diacrylate, and 4, 4' trimethylene dipiperidine. Their physicochemical properties of triblock and penta-block copolymers were characterized by $^1H-NMR$ spectroscopy and gel permeation spectroscopy. Sol-gel phase transition behavior of PAE-PCL-PEG-PCL-PAE block copolymers were investigated by remains stable method. Aqueous media of the penta-block copolymer (at 20 wt%) changed from a sol phase at pH 6.4 and $10^{\circ}C$ to a gel phase at pH 7.4 and $37^{\circ}C$. The sol-gel transition properties of these block copolymers are influenced by the hydrophobic/hydrophilic balance of the copolymers, block length, hydrophobicity, stereo-regularity of the hydrophobic of the block copolymer, and the ionization of the pH function groups in the copolymer depended on the changing of environmental pH, respectively. The degradation and the stabilization at pH 7.4 and $37^{\circ}C$, and the stabilization at pH 6.4 and $10^{\circ}C,\;5^{\circ}C,\;0^{\circ}C$, of the gel were determined. The results of toxicity experiment show that the penta block copolymer can be used for injection drug delivery system. The sol?gel transition of this block copolymer also study by in vitro test ($200{\mu}l$ aqueous solution at 20wt% polymer was injected to mouse). Insulin loading and releasing by in vitro test was investigated, the results showed that insulin can loading easily into polymer matrix and release time is around 14-16days. The PAE-PCL-PEG-PCL-PAE can be used as biomaterial for drug, protein, gene loading and delivery.

• Korean Journal of Microbiology
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• v.28 no.3
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• pp.278-282
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• 1990

Diffusion and partition of progesterone into the polyacrylamide gel was examined. Diffusion coefficient of progesterone decreased down to an asymptotic value as the concentration of the organic solvents in the diffusing medium increased. However the partition coefficient diminished steadily. Crosslinking density in the gel didn't affected the diffusion coefficient considerably but lowered the partition coefficient due to the contraction of pore volume of the gel. Progesterone showed higher diffusion coefficient as well as partition coefficient in the polyurethane than in the polyacrylamide gel, which seems to be ascribed to the difference in hydrophobicity, pore volume and pore size of the polymer matrix.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.69-69
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• 2006

• Bulletin of the Korean Chemical Society
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• v.27 no.12
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• pp.1981-1984
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• 2006

Novel amphiphilic, thermo-responsive polyaspartamides which showed both LCST (lower critical solution temperature), and sol-gel transition were prepared and characterized. The polyaspartamide derivatives were synthesized from polysuccinimide, the polycondensate of aspartic acid monomer, via successive nucleophilic ring-opening reaction by using dodecylamine and N-isopropylethylenediamine (NIPEDA). At the intermediate composition ranges, the dilute aqueous solution exhibited a thermally responsive phase separation due to the presence of LCST. The phase transition temperature was controllable by changing the content of pendent groups. In addition, a physical gelation, i.e. the sol-gel transition was observed from the concentrated solutions, which was elucidated by dynamic viscoelastic measurements. These novel injectable and thermo-responsive hydrogels have potential for various biomedical applications such as tissue engineering and current drug delivery system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.42-45
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• 2003

Inorganic polymer based hybrid membranes consisting of zirconium oxide and polydimethylsiloxane (PDMS) have been synthesized by sol-gel processes. The hybrid membranes showed thermal stability and flexibility up to $300^{\circ}C$. The membrane becomes proton conducting polymer electrolyte when added with 12-phosphotungstic acid (PWA). The conductivity of the membranes was measured in the temperature range from room temperature to $150^{\circ}C$ under saturated humidity and a maximum conductivity of $5{\times}10^{-5}\;Sm^{-1}$ was obtained at $150^{\circ}C$.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.168-172
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• 2018

This study first investigates the effect of the choice of cation on three different ionic-liquid-based gel polymer electrolytes (ILPEs) with polyimide membranes. The preparation of three ILPEs based on electrospun membranes of PI and incorporating a room-temperature ionic liquid, 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide complexed with lithium bis(trifluoromethylsulfonyl)imide, is described. ILPE-EMImTFSI has an ionic conductivity as high as $5.3{\times}10^{-3}S\;cm^{-1}$ at $30^{\circ}C$. Furthermore, it shows higher thermal stability and electrochemical oxidation stability compared to the other two ILPEs because of its stronger bonds. These results indicate that polyimide-based ILPE-EMImTFSI is a good candidate for use in high-safety rechargeable lithium metal batteries.

• Polymer Science and Technology
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• v.14 no.6
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• pp.748-754
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• 2003

• 한국전기화학회:학술대회논문집
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• 2003.10a
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• pp.20-20
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• 2003

• 한국전기화학회:학술대회논문집
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• 2003.04a
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• pp.21-21
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• 2003