• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.533-542
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• 1995

The present study investigated the effectiveness of pretreatment on dentin bonding. The adhesive resin was 5% 4-methacryloyloxyethyl trimellitate anhydride (4-META) in methyl methacrylate (MMA) combined with poly-MMA powder. Polymerization of this resin was initiated by tri-n-butyl borage (TBB). Ground bovine dentin samples were etched with either an aqueous solution of 10% citric (10-0 solution) (Group I) or aqueous solution of 10% citric acid and 3% ferric chloride(10-3 solution) (Group ll ). After etching, the primer (an aqueous solution of 35% hydroxyethyl methacrylate (HEM- A) and 5% glutaraldehyde was applied on the differently etched surfaces (Group III , Group IV). The 10-0 treatment showed the lowest tensile bond strength, followed by the 10-3 treatment, primer application after the 10-0 treatment and primer application after the 10-3 treatment. The relationship among the surface morphology after pretreatment, fractured surface morphology and tensile bond strength was examined. It revealed that the surface morphology change by different pretreatment influenced the bond strength and the resulting fractured surface morphology. The correlation of tensile bond strength with the fracture morphology was explained.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.343-343
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• 2006

Surface-initiated atom transfer radical polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) was carried out to produce high-density poly(MPC) brush on silicon wafer. Frictional properties of poly(MPC) was investigated by by sliding a glass ball (${\phi}\;10\;nm$) on the substrates over a distance of 20 mm at a sliding velocity of 90 mm/min under loading of 0.49 N at 298 K. Higher friction coefficients were observed in dry N2 atmosphere and in toluene condition, whereas the friction coefficients decreased to 0.02 in humid air and in water. It is supposed that water-swollen poly(MPC) brush works as a lubricant to moderate the interaction between brush and probe.

• Macromolecular Research
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• v.15 no.3
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• pp.205-210
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• 2007

Collagen is the major structural protein of connective tissues. It can be used as a prosthetic biomaterial applicable to artificial skin, tendon, ligaments, and collagen implants. The objective of this study is to investigate the possibility of realizing wound dressing medical products by the synthesis of composite materials with collagen and a biodegradable polymer, PLLA, via a surface modification process. Type I collagen was obtained from pig skin by a separation process. The structural characteristics of the extracted collagen were confirmed by SDS-polyacrylamide (PAcr) gel electrophoresis (PAGE) and FTIR. Also, PLLA-g-PAcr was synthesized by the radical polymerization of acrylamide initiated by AIBN in the presence of PLLA. The surface of PLLA was modified by the presence of the acrylamide residues. The structural characteristics of the copolymer were analyzed by FTIR, $^1H-NMR$ and contact angle measurements. The water uptake and WVTR of the collagen/PLLA-g-PAcr composite tended to increase with increasing collagen concentration and with decreasing EDC concentration.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.221-221
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• 2013

Striving to replace the well known silicon nanocrystals embedded in oxides with solution-processable charge-trapping materials has been debated because of large scale and cost effective demands. Herein, a silicon quantum dot-polystyrene nanocomposite (SiQD-PS NC) was synthesized by postfunctionalization of hydrogen-terminated silicon quantum dots (H-SiQDs) with styrene using a thermally induced surface-initiated polymerization approach. The NC contains two miscible components: PS and SiQD@PS, which respectively are polystyrene and polystyrene chains-capped SiQDs. Spin-coated films of the nanocomposite on various substrate were thermally annealed at different temperatures and subsequently used to construct metal-insulator-semiconductor (MIS) devices and thin film field effect transistors (TFTs) having a structure p-$S^{++}$/$SiO_2$/NC/pentacene/Au source-drain. C-V curves obtained from the MIS devices exhibit a well-defined counterclockwise hysteresis with negative fat band shifts, which was stable over a wide range of curing temperature ($50{\sim}250^{\circ}C$. The positive charge trapping capability of the NC originates from the spherical potential well structure of the SiQD@PS component while the strong chemical bonding between SiQDs and polystyrene chains accounts for the thermal stability of the charge trapping property. The transfer curve of the transistor was controllably shifted to the negative direction by chaining applied gate voltage. Thereby, this newly synthesized and solution processable SiQD-PS nanocomposite is applicable as charge trapping materials for TFT based memory devices.