• Journal of the Korean Chemical Society
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• v.34 no.2
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• pp.197-202
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• 1990

Polyethylene glycol (PEG) grafted poly γ-benzyl L-glutamate (PBLG) were prepared from esterification or substitution reaction of PBLG with PEG having hydroxyl group at one end or primary amino groups at both ends. The viscosity of these polymer solution was decreased with decrease of polymer concentration. But in more dilute solution the viscosity was increased with decrease of polymer concentration. PEG-grafted PBLG polymers showed smaller water contact angles than PBLG homopolymer, and the water contact angles of the surface of PEG-grafted PBLG polymers were largely dropped by reacting with aminoethanol, resulting in hydrogel surfaces.

• 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.

• Polymer(Korea)
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• v.25 no.1
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• pp.108-114
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• 2001

Crosslinked poly(glycerol-co-malate)s were synthesized from L-malic acid in Krebs cycle and glycerol. The synthesized polymer was identified by FT-IR spectroscopy. Swelling degrees of the copolymer hydrogels were increased with an increase in pH of the aqueous solution. Hydrolytic behaviors of the crosslinked copolymers were investigated in various pH buffer solutions at 37${\circ}C$. The Hydrolysis of the copolymers proceeded faster with increasing pH of the aqueous solution. Releasing behaviors of the model drug such as diclofenac monosodium salt were also measured in various pH aqueous solutions at 37${\circ}C$. The release concentration of diclofenac monosodium salt from the hydrogel systems was increased with increasing pH. These facts indicate that the unreacted carboxyl and hydroxyl groups in the copolymers are greatly affected by pH in the conditions.

• Polymer(Korea)
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• v.30 no.3
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• pp.259-265
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• 2006

Small intestinal submucosa (SIS) consists of some growth factors which can stimulate cell activity, and PVA has been widely utilized in the area of wound dressing as hydrogel which is easy to be removed from wounds. In this study, native SIS sheets were coated with PVA by immersing them into 2, 4, and 10 wt% of PVA solution and then lyophilized on two type of molds to endow the prepared wound dressing with easy removal property from wounds. The mechanical properties were examined through tensile test. Moreover, enzymatic degradation, water uptake, and in vitro test were carried out to characterize the prepared SIS sheets. The tensile strength of the SIS sheets coated with PVA (PVA-SIS) were decreased, whereas the elongation were increased. Degradation ratio of the PVA-SIS sheets was decreased compare to native SIS. Water uptake ability was improved at 2 and 4 wt% of PVA. The degree of fibroblast attachment was lower than the native SIS sheets. In conclusion, this study suggests that the PVA coated SIS sheets have a potential for the applications of wound dressing and biodegradable injectable materials.