• Macromolecular Research
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• v.17 no.9
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• pp.697-702
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• 2009

Mesoporous ethanesilica thin film was prepared using PEO-PLGA-PEO triblock copolymers as structure-directing agents and (1,2-bis(triethoxysilyl) ethane BTESE; bridged organosilicates) as inorganic precursors via one-step sol-gel condensation of ethanesilica precursors. The mesostructure of ethanesilica films is critically dependent on the processing experimental parameters after the hydrolyzed silica sol mixture was spin-cast. This study examined the effects of the block copolymer template/organosilica precursor ratio in the casting solution and aging period before calcination of the mesostructure. It was further demonstrated that mesoscopic ordering of organosilicate thin films is induced by the rearrangement of block copolymer template/organosilica hybrid during thermal decomposition of the PEO-PLGA-PEO triblock copolymer. The mesoporous structure and morphology were characterized by SAXS, TEM and solid-state NMR measurement.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.568-570
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• 2009

Octadecyltrichlorosilane (OTS) self-assembled monolayer was selectively patterned by deep ultraviolet exposure, resulting in differential surface state, hydrophilic area with OTS hydrophobic surroundings. High-resolution (<10 ${\mu}m$) nanoparticulate Ag electrodes and organic semiconductors were patterned from simple dip-casting and ink-jetting on the pre-patterned hydrophilic surface, forming all solution-processed organic thin film transistors. The devices typically have shown a mobility of 0.065 $cm^2/V{\cdot}s$ and on-off current ratio of $8{\times}10^5$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.426-427
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• 2007

Here we describe the formation of a self-assembled film of thin multiwalled carbon Nanotubes(t-MWNT) modified with hydroxy groups through hydrogen peroxide treatment. Morphologies of t-MWNT films could be controlled by the various coating method, such as filtering, drop casting, spraying method, etc. The results show that on densification of the CNT suspension during drying, multiple hydroxy group-modified MWNTs can be self-assembled through strong surface hydrogen bond interaction while MWNTs usually exist an entangled state in the film. The interaction between t-MWNT was illustrated from Raman spectrum of spray coated films.

• Polymer(Korea)
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• v.32 no.5
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• pp.478-482
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• 2008

The effect of 1,3-dioxolane on the structural development in the optical polycarbonate film was studied. The 1,3-dioxolane was used as an environmental friendly solvent for manufacturing solution-cast polycarbonate film instead of methylene chloride. The evaporation rate in film drying process decreased due to the high boiling temperature of 1,3-dioxolane. This caused the crystallization in the polycarbonate film. As a result, The increase of crystallinity and roughness led to the decrease of light transmissivity. It was also found that the lowering of mechanical properties in polycarbonate film was attributed to the morphological change due to the solvent evaporation rate in film drying process.

• Polymer(Korea)
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• v.39 no.1
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• pp.40-45
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• 2015

Simple poor-cosolvent casting was used to surface treat biodegradable elastic poly(L-lactide-co-${\varepsilon}$-caprolactone) (PLCL; 50:50) copolymer films that presented lotus-leaf-like structures. We evaluated whether the lotus-leaflike-structured PLCL (L-PLCL) films could be used as a biomaterial for artificial vascular grafts. The surface morphology, hydrophobicity, and antithrombotic efficiency of the films were examined while immersed in platelet-rich plasma (PRP) using scanning electron microscopy (SEM) and a contact angle meter. The recovery and crystallinity of the films were measured using a tensile-strength testing machine and an X-ray diffractometer, respectively. The solvent containing acetic acid, as a poor co-solvent, and methylene chloride mixed in a 1:2 ratio produced an optimal PLCL film with a water contact angle of approximately $124^{\circ}$. Furthermore, the surface of the L-PLCL films immersed in PRP showed a lower rate of platelet adhesion (<10%) than that of the surface of an untreated PLCL film immersed in PRP.

• Journal of Korea Foundry Society
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• v.30 no.6
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• pp.231-234
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• 2010

The effect of $C_2Cl_6$ for preventing to the surface oxidation and ignition of molten Mg alloy was studied with metallographic analysis, X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The alloy used for this study was AM100A Mg casting alloy with high strength. In order to investigate the surface protective characteristic of this molten alloy by $C_2Cl_6$ addition, we added them into molten AM100A alloy at $700^{\circ}C$ and then the melts were slowly cooled under a protective atmosphere of air containing Ar gas and $C_2Cl_6$ flux addition. The result found that the surface oxidation and ignition reaction of molten AM100A Mg alloy by adding $C_2Cl_6$ flux was more slowly occurred than that of the only a protective atmosphere of containing Ar gas with increasing time. This result was due to a dense protective film formed containing $MgCl_2$ on surface of molten Mg alloy during casting and solidification. The $MgCl_2$ was formed by a reaction of $C_2Cl_6$ with molten Mg.

• Elastomers and Composites
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• v.43 no.2
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• pp.82-87
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• 2008

In this study, nine kinds of polyimides were synthesized from 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA), 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA), m-pheny lenediamine (m-PDA) and 4,4'-oxydianiline (ODA) by controlling molar ratio of monomers. Synthesized polyimides were used as insulator films for 2-layer Flexible Copper Clad Laminate(FCCL) which were manufactured by the casting method. Glass transition temperature and thermal degradation temperature for 5% weight loss of the polyimide film were improved by increasing contents of m-PDA and PMDA, respectively. Water absorption of polyimide film was reduced by increasing contents of ODA and BPADA which have relatively long structure, respectively. Peel strength of 2-layer FCCL was improved by increasing contents of ODA and BPADA.

• Analytical Science and Technology
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• v.19 no.5
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• pp.389-393
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• 2006

The detector consisted of ZnS(Ag) scintillator and photomultiplier tube (PMT) is widely used as contamination monitor in the nuclear facilities. Such detectors are mainly manufactured by adhering the ZnS(Ag) powder onto the transparent plastic. In this study the preparation condition for ZnS(Ag) scintillator sheet using a simple method was established. The scintillator sheet was composed with a support polymer sheet and ZnS(Ag) scintillator layer. The base sheet was prepared by casting the polymer solution after solving the polymer with solvent and the scintillator layer was manufactured by printing the mixture solution with ZnS(Ag) and paste. It was found that the polysulfone(PSf) as a polymer for the base sheet and a cyano resin as a paste for adhering the ZnS(Ag) scintillator was suitable. Also, the prepared thin scintillator sheet had a sufficient mechanical strength, a optical transparency and an alpha-ray detection performance.

• International Journal of Industrial Entomology and Biomaterials
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• v.31 no.1
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• pp.1-6
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• 2015

Recently, sericin has attracted increasing attention in biomedical and cosmetic research because of its useful properties including acceleration of wound healing, improvement of cell attachment, and inhibition of ultraviolet-B induced apoptosis. However, sericin films have poor mechanical properties, which restricts the application to those fields. In this study, cellulose nanofibril (CNF)/sericin composite films were fabricated by solvent casting, and the effects of ultrasonication time and CNF content on the solution turbidity, molecular conformation, and film mechanical properties of sericin film were examined. As the ultrasonication time increased, the turbidity of the CNF/sericin suspension decreased. Conversely, as the CNF content increased, the turbidity increased. However, ${\beta}$-sheet crystallization and mechanical properties remained almost unchanged by varying the ultrasonication time and CNF content, indicating that CNF is not effective to improve the mechanical properties of sericin films.

• Korean Journal of Materials Research
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• v.28 no.10
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• pp.544-550
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• 2018

The passivation of AZ91D Mg alloys by plasma anodization requires deliberate choice of process parameters due to the presence of large amounts of structural defects. We study the dependence of pore formation, surface roughness and corrosion resistance on voltage by comparing the direct current (DC) mode and the pulse wave (pulse) mode in which anodization is performed. In the DC plasma anodization mode, the thickness of the electrolytic oxide film of the AZ91D alloy is uneven. In the pulse mode, the thickness is relatively uniform and the formed thin film has a three-layer structure. The pulse mode creates less roughness, uniform thickness and improved corrosion resistance. Thus, the change of power mode from DC to pulse at 150 V decreases the surface roughness (Ra) from $0.9{\mu}m$ to $0.1{\mu}m$ and increases the corrosion resistance in rating number (RN) from 5 to 9.5. Our study shows that an optimal oxide film can be obtained with a pulse voltage of 150 V, which produces an excellent coating on the AZ91D casting alloy.