• Journal of Pharmaceutical Investigation
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• v.29 no.4
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• pp.279-285
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• 1999

Retinoids in anti-wrinkle cosmetics are widely used for the treatment of the photoaging skin these days, but very unstable in the presence of water. Multilamellar liquid crystal vesicles consisted of $poly(oxyethylene)_{15}oleyl$ ether $(POE_{15}OE)$ or $poly(oxyethylene)_{15}stearyl$ ether $(POE_{15}SE)$, cetostearyl alcohol (CSA) and cholesterol or oils were prepared to increase the stability of retinyl acetate or retinyl palmitate. $POE_{15}SE-CSA-Water$ systems were more unstable than $POE_{15}SE-CSA-Water$ systems due to the bended structure of oleyl groups. For the modification of vesicles, cholesterol was added. The enthalpy values were decreased reaching to zero and the water permeability of systems was decreased, but the stabilizaton of retinyl acetate was not greatly improved. The stability of retinyl acetate may depend on its location in the structure. Various oils were added for further stabilization and isopropyl myristate was most effective. In practice, retinyl palmitate showed better stability in the same vesicle than retinyl acetate, and the improved vesicles could be used for the anti-wrinkle cosmetics

• Proceedings of the Korean Fiber Society Conference
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• 1995.10a
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• pp.99-100
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• 1995

• Journal of the Korean Graphic Arts Communication Society
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• v.11 no.1
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• pp.71-84
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• 1993

Practically to put use high-photosensitive polymer, poly(vinyl cinnamoyl acetate), we investigated and confirmed UCHIDA`s synthesis, according to control solvent, which is the esterification of poly (vinyl alcohol) with monochloroacetic acid and can be freely conrolled the successive cinnamoyl acetoxyl esterfication of PVCiA, and intruducing photosensitizers,studied the photosensitivity of PVCiA.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.103-111
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• 2018

Transesterification of BHET (Bis (2-Hydroxyethyl) Terephthalate), monomer of PET (Poly Ethylene Terephthalate) to BHBT (Bis (4-Hydroxybutyl Terephthate), monomer of PBT (Poly Butylene Terephthalate), using 1,4-BD (1,4-butanediol) were investigated. Zinc acetate was used as a catalyst for the reaction. Amounts of BHET, EG, and THF (Tetrahydrofuran) in a batch reactor were measured for determining the reaction kinetics. Mathematical models of the batch reactor for the transesterification reaction were developed and used to characterize the reaction kinetics and the composition distribution of the reaction products. Model predictions for the transesterification were in good agreement with experimental results.

• Polymer(Korea)
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• v.29 no.3
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• pp.304-307
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• 2005

The acid-catalyzed hydrolysis reaction of poly(vinyl acetate) (PVAc) in water/acetic acid solution at $35^{circ}C$ was studied at two different solvent compositions. The mole fractions of vinyl acetate (Vac) and vinyl alcohol (VA) during the course of the reaction were determined by NMR, and the equilibrium constant $K_{eq}$ of the reaction was determined using the molar ratio of VAc to VA at the chemical equilibrium. $K_{eq}$ was 0.75 (${\pm}0.01$) when the VAc mole faction at the equilibrium was 0.78 (${\pm}0.01$) and it was 0.69 (${\pm}0.01$) when the VAc mole fraction was 0.57 (${\pm}$0.02). The reaction was found to be a pseudo 1-st order reaction with the rate coefficient at $3.4{\times}10^{-6}/sec$.

• Polymer(Korea)
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• v.24 no.5
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• pp.610-620
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• 2000

Vinyl acetate (VAc) was polymerized at 30, 40, and 5$0^{\circ}C$ using 2,2'-azobis (2,4-dimethylvaleronitrile) (ADMVN) and tertiary butyl alcohol (TBA) as the initiator and the solvent, respectively. High molecular weight (HMW) atactic poly(vinyl alcohol) (PVA) was prepared by saponifying the poly(vinyl acetate) (PVAc) synthesized. The effect of polymerization conditions were investigated in terms of conversion, degree of branching for acetyl group of PVAc, and molecular weight of both PVAc and PVA. The polymerization rate of VAc in TBA was proportional to the 0.49th power of ADMVN concentration in good accordance with the theoretical value of 0.5. HMW-PVA with high yield could be obtained successfully, probably due to lower polymerization temperature and decreased chain transfer reaction rate which was achieved by adopting ADMVN and TBA. PYAc having average degree of polymerization (P$_{n}$) of 10000~13000 was obtained at the conversion of 35~70%. Saponification of so prepared PVAc yielded PVA having P$_{n}$ of 2400~6100. The syndiotactic diad content increased with decreasing polymerization temperature and increasing VAc concentration due to a steric hindrance effect of TBA during polymerization.

• Proceedings of the Korean Fiber Society Conference
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• 1994.10a
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• pp.50-50
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• 1994

• Proceedings of the Korean Fiber Society Conference
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• 1995.10a
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• pp.120-121
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• 1995

• Journal of the Microelectronics and Packaging Society
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• v.12 no.4 s.37
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• pp.359-363
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• 2005

The organic insulation devices with MIM (metal-insulator-metal) structures as PVP gate insulation films were prepared for the application of organic thin film transistors (OTFT). The co-polymer organic insulation films were synthesized by using PVP(poly-4-vinylphenol) as solute and PGMEA (propylene glycol monomethyl ether acetate) as solvent. The cross-linked PVP insulation films were also prepared by addition of poly (melamine-co-formaldehyde) as thermal hardener. The leakage current of the cross-linked PVP films was found to be about 300 pA with low current noise. and showed better property in electrical properties as compared with the co-polymer PVP insulation films. In addition, cross-linked PVP insulation films showed better surface morphology (roughness), showing about 0.11${\~}$0.18 nF in capacitance for all PVP film samples.

• Textile Coloration and Finishing
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• v.21 no.4
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• pp.33-38
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• 2009

Poly(vinyl acetate) films containing benzophenone were photocrosslinked by continuous UV irradiation.UV irradiation of PVAc film containing 5% benzophenone induced bulk crosslinking of the polymer indicated by 84.1% of gel fraction after ethyl acetate extraction. The crosslinking was attributed to the recombination of tertiary polymer radicals generated upon UV irradiation, which was enhanced by the hydrogen abstraction of benzophenone. Also the UV irradiation resulted in scission of ester linkage and photooxidation of PVAc surface, which was verified by ATR and zeta potential analysis, implying that the PVAc surface became more polar and hydrophilic. The zeta potential proportionally increased from +4.5mV to -26.8 mV with increasing UV irradiation. Also the surface energy of the PVAc film increased with higher UV irradiation upto 56.5 $mJ/m^2$ by the enhanced Lewis acid/base component with larger contribution of Lewis acid parameter. Accordingly the crosslinked PVAc showed higher thermal stability with increasing UV energy.