• Journal of Technologic Dentistry
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• v.29 no.1
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• pp.121-131
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• 2007

A preparation process's conditions of aqueous sol which contains anatase-type nano titania particles with photocatalyic properties was established by using Yoldas process, so called, DCS(Destabilization of Colloidal Solution) process in this study. And crystal size change and phase transformation of titania particles in aqueous titania sol depending on reaction conditions was investigated by a light scattering method and XRD analysis of frozen dried powders, respectively. This sol with photo catalytic nano titania particles was used to the following hydrophilic hybrid coating film's fabrication and its properties was evaluated. Subsequently, for coating film using the above mentioned aqueous titania sol, non-aqueous titania sol was prepared without any chemical additives and its time stability according to aging time was investigate. By using the above mentioned aqueous titania sol and non-aqueous sol, a complex oxide coating sol for metal and ceramic substrate and a organic-inorganic hybrid coating sol for polymer substrate was prepared and it's hydrophilicity depending on UV irradiation conditions was evaluated. As a conclusions, the following results were obtained. (1)Aqueous titania sol The average particle size of titania in formed aqueous titania sol was distributed between 20$\sim$90nm range depending on reaction conditions. And the crystal phase of titania powders obtained by frozen drying method was changed from amorphous state to anatase and subsequently transformed to rutile crystal phase and it is attributed to concentration gradient in aqueous sol. (2)Non-aqueous titania sol Non-aqueous titania sol was prepared using methanol as a solvent and a little distilled water for hydrolysis and nitric acid as a catalyst were used. The obtained non-aqueous titania sol was stable at room temperature for 20 days. Additionally, non-aqueous titania sol with addition of chealating reagent such as acethylaceton and ethylene glycol prolonged the stability of sol by six months. (3)Complex sol and hybrid sol with super hydrophilicity The above mentioned aqueous titania sol as a main photocataylic component and non-aqueous titania sol as a binder for coating process was used to prepare a complex sol used for metal, ceramic and wood material substrate and also to prepare the organic-inorganic hybrid sol for polymer substrate such as polycarbonate and polyethylene, in which process APMS(3-Aminopropyltrimethoxysilane), GPTS(3-Glycidoxypropyl-trimethoxysilane) as a hydrophilic silane compound and HEMA(2-Hydroxyethyl methacrylate) as a forming network in hybrid coating film were used. The hybrid coating film such as prepared through this process showed a superhydrophilicity below 1$10^{\circ}$ depending on processing conditions and a pencil's hardness over 6 H.

• Journal of the Korean Ceramic Society
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• v.32 no.3
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• pp.281-288
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• 1995

to prepare the TiO2 thin films, acetyl-acetone(2.4-pentanedione)(1 : 1 molar ratio) was dissolved in the propanol solution of titanium(IV)isopropoxide(Ti[OCH(CH3)2]4). Al, Cr and Sb in the form of soluble salt and niobium ethoxide were added s dopants, respectively. Thin films were coated by the dip-coating method and characteristics were investigated by XRD, SEM and conductance meter. As a result, viscosity of sol was maintained below 4 centi Poise more than 20 days, and crystal growth and diminution of resistivity occurred as the heat treatment temperature increased. The grains grew over 1${\mu}{\textrm}{m}$ and the lowest resistivity was obtained when Nb was added at 130$0^{\circ}C$.

• Korean Journal of Materials Research
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• v.27 no.11
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• pp.577-582
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• 2017

Self-cleaning and photocatalytic $TiO_2$ thin films were prepared by a facile sol-gel method followed by spin coating using peroxo titanic acid as a precursor. The as-prepared thin films were heated at low temperature($110^{\circ}C$) and high temperature ($400^{\circ}C$). Thin films were characterized by X-ray diffraction(XRD), Field-emission scanning electron microscopy(FESEM), UV-Visible spectroscopy and water contact angle measurement. XRD analysis confirms the low crystallinity of thin films prepared at low temperature, while crystalline anatase phase was found the for high temperature thin film. The photocatalytic activity of thin films was studied by the photocatalytic degradation of methylene blue dye solution. Self-cleaning and photocatalytic performance of both low and high temperature thin films were compared.

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3299-3302
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• 2014

The In2S3 thin films of tetragonal structure and In2O3 films of cubic structure were synthesized by a spin coating method from the organometallic compound precursor triethylammonium indium thioacetate ($[(Et)_3NH]^+[In(SCOCH_3)_4]^-$; TEA-InTAA). In order to determine the electron mobility of the spin-coated TEA-InTAA films, thin film transistors (TFTs) with an inverted structure using a gate dielectric of thermal oxide ($SiO_2$) was fabricated. These devices exhibited n-channel TFT characteristics with a field-effect electron mobility of $10.1cm^2V^{-1}s^{-1}$ at a curing temperature of $500^{\circ}C$, indicating that the semiconducting thin film material is applicable for use in low-cost, solution-processed printable electronics.

• The Korean Journal of Ceramics
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• v.3 no.4
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• pp.249-252
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• 1997

Highly oriented ZnO thin films were fabricated by dip-coating technique using zinc acetate 2-methoxyethanol 2-aminoethanol solution as starting materials, and effects of substrates on the film's orientation were investigated. Product films were obtained by prefiring at 300, 400, 500 and 550℃ for 10 min, followed by final heat-treatment at the same temperatures as prefiring for 1h. c-axis oriented films on glass substrates were prepared by heat treatment of prefiring films at 300-550℃, while films on alumina showed polycrystalline structure. Films with c-axis orientation exhibited lower specific resistivities than those of polycrystalline films with partial crack and pore.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.2
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• pp.21-27
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• 2014

Recently, various biochip environments have been presented. In this study, a novel transparent film with porous membrane windows, which is an essential component in a co-cultured biochip environment, is fabricated using spin-coating, 3D printing, and electrospinning processes. In detail, a transparent polystyrene film was fabricated by means of the spin-coating process followed bywindow cutting, after which apolycaprolactone-chloroform solution was deposited along the window edge to introduce an adhesion layer between the PS film and the PCL nanofibers. Nanofibers were electrospun into the window region using a direct-write electrospinning method. Consequently, it was demonstrated that the fabricated window film could be used in a co-culture biochip environment.

• Journal of the Korean Ceramic Society
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• v.31 no.5
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• pp.499-504
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• 1994

PbTiO3 thin films were prepared by sol-gel spin coating method using metal alkoxide and diethanolamine (DEA). The precipitation of the PbTiO3 sol occurred at pH 7.3 with HNO3 addition, regardless of the amount of DEA. The gelation time of the PbTiO3 sol was reduced with increasing amount of HNO3 and/or water. When the PbTiO3 films prepared by 0.2 molar coating solution were annealed at $650^{\circ}C$ for 30 min, dense and single phase perovskite films were obtained. Dielectric constant and loss tangent of the film were 239 and 0.01 at 1 kHz, respectively.

• Progress in Superconductivity
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• v.3 no.2
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• pp.188-192
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• 2002

To introduce flux pinning center in HTS-BSCCO system, nano-size MgO particles were uniformly distributed within the Bi-2223 grain by partial hydration of MgO. The existing method MgO doped Bi-2223 used nato-size MgO powders, which resulted in agglomeration during mixing or grain growth during heat-treatment due to the high surface energy of the fine particles. By hydration of the MgO surface, the agglomeration of the MgO powders was avoided and the size of remaining MgO core was controlled by changing hydration medium and time. The thin film obtained by spin coating of (Bi_$1.8/Pb_{0.4}$)$Sr_2$$_{Ca}$$2.2/Cu_3$ $O_{y}$ nitrate solution mixed with hydrated MgO showed the even distribution of nano-size MgO particles in the Bi-2212 grains.s.s.

• Applied Science and Convergence Technology
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• v.24 no.6
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• pp.219-223
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• 2015

Enhancement of the surface hydrophobicity of polydimethylsiloxane (PDMS) thin films deposited on substrates covered with titanium dioxide ($TiO_2$) nanospheres was studied. First, a low-temperature solution-phase method using polyvinylpyrrolidone (PVP) as a surface capping agent and a water/dimethylformamide (DMF) mixture as the reaction medium was used to synthesize monodisperse $TiO_2$ nanospheres. It was possible to easily control hydrolysis rate of the Ti-precursors and the size of the synthesized nanospheres by varying the amount of PVP and the volume ratio of the solvent mixture. Spray coating of the synthesized $TiO_2$ nanospheres under the PDMS film increased the water contact angle of the film surface to $150.3^{\circ}$. This simple treatment can modify the surface morphology at a nanometer scale without any long or complicated nanoprocess; hence, the surface enters the superhydrophobic Cassie-Baxter regime.

• Applied Chemistry for Engineering
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• v.4 no.2
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• pp.264-272
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• 1993

Current research aimed at investigating of heat-resistance of magnet wire to endow miniaturizing electronic equipment with a high efficiency or reliability. Thermal stability of magnet wire has a close relationship with physical properties of polymeric coating that is formed from enamel varnish. Design of heat-resistant enamel varnish and coating technology of varnish solution were briefly described. Some factors which have a thermal effect on wire were discussed through the evaluation method of the wire properties.