• Polymer(Korea)
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• v.36 no.1
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• pp.98-103
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• 2012

Poly(2,6-dimethyl-1,4-phenylene ether) (PPE) was synthesized using $Cu(NO_2)_2{\cdot}3H_2O$ or CuCl catalyst with various amounts of ligand and base in several different solvent systems. CuCl/1-methylimidazole/ammonium hydroxide was found to be an effective catalyst system which showed the highest polymer yield and molecular weight. The effects of catalyst/monomer ratio, different amine ligands, and the content of mono-functional reagent 2,4,6-trimethylphenol (TMP) additive on the polymer yield and molecular weight were investigated. Among the co-solvent systems used in this polymerization, chloroform/methanol 9/1(v/v) gave the highest polymer yield and molecular weight ($\overline{M_n}$ 55 K, $\overline{M_w}$ 92 K, PDI 1.7). The catalytic activity between CuCl and CuI was compared by oxygen-uptake experiments and the formation of sideproduct, 5,5'-tetramethyl-4,4'-diphenoquinone (DPQ), was analyzed by ultraviolet spectroscopy.

• Polymer(Korea)
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• v.36 no.1
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• pp.71-75
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• 2012

In this study, silver nanoparticles (AgNPs) have been prepared by using aqueous $AgNO_3$ solution in the poly(vinyl alcohol) (PVA) hydrogels. PVA powders were dissolved in deionized water, and then irradiated by gamma-ray with a radiation dose of 50 kGy to make hydrogels. PVA hydrogels were dipped into 0.01 and 0.05 M $AgNO_3$ solution for 1 h respectively. After that, the swollen hydrogels were irradiated by gamma-ray at various doses to form AgNPs. UV-vis analysis indicated that the concentration of Ag NPs was enhanced by increasing absorbed dose and the concentration of $AgNO_3$. FE-SEM measurements provided further evidence for the successful formation of Ag NPs in PVA hydrogels. Also, the antibacterial effect of PVA hydrogels stabilized AgNPs against Gram-negative bacteria (S.aureus and E.coli) in liquid as well as on solid growth media has been investigated. The AgNPs consolidated in PVA hydrogel networks have an excellent antibacterial effect.

• Polymer(Korea)
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• v.33 no.2
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• pp.169-174
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• 2009

Silicone hydrogels incorporated with poly(ethylene glycol)(PEG) were prepared and characterized to evaluate the effects of PEG on contact lenses. The silicone hydrogels were copolymerized with methacryloxypropyl tris(trimethylsiloxy) silane (TRIS), methyl methacrylate (MMA), N,N-dimethyl acrylamide (DMA) and PEG-containing monomers such as poly(ethylene glycol) methyl ether methacrylate (PEG- MEM). The silicone hydrogels were characterized using Fourier transform infrared spectroscopy (FT-IR), electron spectroscopy of chemical analysis (ESCA), and scanning electron microscopy (SEM). Water absorbance, water contact angle and light transmittance of the silicone hydrogels were evaluated. The experiments of protein adsorption were also carried out to evaluate the protein adsorption in tears. The peak intensity of C-O bond was increased by the incorporation of PEG-containing monomers and thus PEG incorporation into silicone hydrogels could be confirmed. Phase separation was not shown by the SEM observation of the cross-section of silicone hydrogels. Water absorbancy was increased, while water contact angle and light transmittance were decreased with increasing incorporation of the PEG-containing monomers. The absorption of proteins in tears, albumin, lysozyme and $\gamma$-globulin, on the surface of silicone hydrogels was decreased with increasing incorporation of the PEG-containing monomers.

• Polymer(Korea)
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• v.33 no.2
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• pp.104-110
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• 2009

Demineralized boneparticle (DBP) has been widely used as and a powerful promoter of new bone growth. In this study, DBP sponges were chemically crosslinked and characterized for the potential application of tissue engineered scaffolds. The DBP sponges prepared by crosslinking with EDC. 0.1, 0.2 or 0.3% pepsin was applied to DBP dissolved in 3% (v/v) acetic acid aqueous solution for 48 hrs. The prepared sponges were crosslinked by 1, 5, 10, 50 or 100 mM of EDC solution concentration and then were lyophilized. The DBP sponges were characterized by SEM, FT-IR and DSC and analyzed in terms of their porosity and water absorption ability. The cellular viability and proliferation were assayed by MTT assay. Our investigation revealed that 0.2$\sim$0.3% of pepsin and 50$\sim$100 mM of EDC produced DBP sponges with good physical characteristics. In conclusion, DBP sponge prepared under these conditions is potentially useful for the applications of tissue construction.

• Polymer(Korea)
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• v.32 no.5
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• pp.403-408
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• 2008

Keratin is the major structural fibrous protein providing outer covering such as wool, hair, and nail. Keratin is useful as natural protein. We developed the keratin loaded poly(L-lactide-co-glycolide) (PLGA) scaffolds (keratin/PLGA) for the possibility of the application of the tissue engineering using bone marrow mesenchymal (BMSCs). Keratin/PLGA (contents 0%, 10%, 20% and 50% of PLGA weight) scaffolds were prepared by solvent casting/salt leaching method. We characterized porosity, wettability, and water uptake ability, DSC of keratin/PLGA scaffold. We seeded BMSCs isolated from the femurs of rat into the inner core of the hybrid scaffold. Celluar viability were assayed by 3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyl-tetrazolium bromide (MTT) test. We confirmed that keratin/PLGA scaffold is hydrophilic by wettability, and water uptake ability measurement results. In MTT assay results, cell viability in scaffolds impregnated 10 and 20 wt% of keratin were higher than other scaffolds. In conclusion, we suggest that keratin/PLGA scaffold may be useful to tissue engineering using BMSCs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.258-264
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• 2018

In this study, the improved performance of sprayed green soil was evaluated by incorporating functional additives. The optimal mixing ratio of the thickener and super-absorbent polymer, as an additive for moisture supply to the growth of plants within the range of mixing ratios that gives sufficient strength of green soil, was 5% and 1%, respectively. Using Portland cement as a main binder, the pH of the green soil was 9.1. To solve this alkali problem, the mixing proportion was improved so that the pH of the green soil was approximately 7.2 by mixing more than 10% of the chelate resin. The soil conductivity was measured to be 280 ~ 350mS/m under all the mixing conditions. This satisfied the criterion of less than 1000mS/m on the slope surface. As a result of measuring the soil hardness of the green soil prepared under the optimal mixing conditions of functional additives, it satisfied the criteria of 18 ~ 23mm when sprayed under a 1 bar pressure. The rebound rate was less than 15% when spraying green soil on a 75 % slope, and the hardness of the sprayed green soil was more than 18 mm.