• Journal of the Korean Ceramic Society
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• v.33 no.1
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• pp.110-118
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• 1996

• Journal of the Korean Ceramic Society
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• v.39 no.11
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• pp.1011-1016
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• 2002

Colloidal particles of silica (100 nm in size) were electrostatically dispersed and adsorbed on a glass substrate coated with silica sol or alumina sol. Stability of the suspensions and microstructure of the adsorbed particle layers were discussed in terms of total potential energies between the particles and the substrate. Well-dispersed suspension resulted in a layer with densely packed and regularly arranged particles, whereas less stable suspension resulted in a porous layer with loosely packed and irregularly arranged particles. Despite repulsive interactions between the particles and the substrate coated with silica sol, the observed adsorption can be attributed to chemical bonds formed at the interface between the particle and silica sol. In contrast, the adsorption of the particles on the substrate coated with alumina sol formed a layer with strongly adhered and densely packed particles, due to large attractive interactions between the particles and alumina sol.

• Textile Coloration and Finishing
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• v.25 no.3
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• pp.172-180
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• 2013

Aramid fibers are being used increasingly in a wide range of application due to low density, high specific strength, high modulus, and high thermal resistance. But owing to its special physical and chemical structures, it is sensitive to absorb the ultraviolet light which will degrade the fiber's useful mechanical properties and structure. In this paper, the sol-gel technique was used to improve the photo-stability of p-aramid fibers. $TiO_2$, modified $SiO_2$/$TiO_2$ sol were used as coating solutions. The influence of the such coatings on the photo-stability of p-aramid fiber was investigated by an accelerated photo-ageing method using xenon lamp. The photo-stability of p-aramid fiber showed obvious improvement after the modified silica binding coating. But the amorphous $TiO_2$ sol coatings showed a negative effect. After 144h light exposure, the modified silane binder-coated fibers showed less degradation in mechanical properties with the retained tensile strength greater than about 70% of the original value.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.4
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• pp.277-281
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• 2006

Spherical micro silica sol-gel immobilized enzyme beads were prepared in an emulsion system using cyclohexanone and Triton-X 114. The beads were used for the in situ immobilization of transaminase, trypsin, and lipase. Immobilization during the sol to gel phase transition was investigated to determine the effect of the emulsifying solvents, surfactants, and mixing process on the formation of spherical micro sol-gel enzyme beads and their catalytic activity. The different combinations of sol-gel precursors affected both activity and the stability of the enzymes, which suggests that each enzyme has a unique preference for the silica gel matrix dependent upon the characteristics of the precursors. The resulting enzyme-entrapped micronsized beads were characterized and utilized for several enzyme reaction cycles. These results indicated improved stability compared to the conventional crushed form silica sol-gel immobilized enzyme systems.

• 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.

• Korean Journal of Materials Research
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• v.16 no.10
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• pp.599-605
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• 2006

N-(3-triethoxysilylpropyl)-1,4-diaminoanthrquinone-2,3-dicarboximide (TESP-DADI), an organic blue pigment, has been prepared and incorporated into silica solid matrix reacting triethyl orthosilicate (TEOS) via sol-gel method. Morphology and microstructure of resulting hybrid pigment were studied employing SEM and TEM. The micrographs and particle size distributions showed that uniform pigment can be obtained employing TEOS-based sol-gel method forming silica core. Particle size distribution of dispersed pigment in water was examined using the technique of dynamic light scattering. The ensuing pigment dispersion ink was subjected to various physicochemical evaluation such as viscosity, surface tension, inkjet stability, storage stability, and color change as inkjet ink using spectrophotometric, and microscopic techniques.

• Korean Journal of Materials Research
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• v.18 no.8
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• pp.417-421
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• 2008

$Al_2O_3$ sol with long-term stability was prepared by mechanical milling. Thin films were evaluated and created for use as coating materials. The particle size of the manufactured sol was 98 nm when 2 wt% of nitric acid was added. This indicates that the viscosity of the sol is 12 cps and that it has long-term stability. The thickness of the thin films, which varied from 100 nm to 500 nm, could be managed by adjusting the draw rate and the amount of an organic additive. A thin film heated to $500^{\circ}C$ indicated a hydrophilic property against water and excellent permeability against a visible ray.

• Textile Coloration and Finishing
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• v.25 no.2
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• pp.126-133
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• 2013

Although para-aramid fibers poss higher mechanical properties, they show very low resistance to sunlight exposure. This paper studied on the effect of nano-sol coated $TiO_2$ to improve the photo-stability of p-aramid fibers. Titanium dioxides were prepared by sol-gel method from titanium iso-propoxide at different R ratio ($H_2O$/titanium iso-propoxide). All samples were characterized by XRD, TEM and UV-vis spectrometer. The mechanical properties of p-aramid fabrics by $TiO_2$ nano-sol coating before and after sunlight irradiation were measured with tensile tester. XRD pattern of titanium dioxide particles was observed by mixing phase together with rutile and anatase type. The results showed, after sunlight irradiation, the decreased mechanical properties of the fiber. Furthermore, the sunlight irradiation obviously deteriorated the surface and defected areas of the fiber severely by photo-induced chain scission and end group oxidation in air.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.234-235
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• 2007

Transparent nanosized $TiO_2$ sol has been made by sol-gel method, using Titanium(IV) isopropoxide precursor. To promote hydrolysis for titania is needed excess water, Oil bath and temperature about $80^{\circ}C$. $TiO_2$ sol is peptized ranging from pH 1 to 1.5 using hydrochloric acid for the stability of sol during a condensation reaction. The average particle size of $TiO_2$ sol was approximately 20nm. $TiO_2$-sillane sol was synthesized by surface treatment using MTMS to the $TiO_2$ sol. TEM analysis has been used to check the degree of dispersion and FT-IR analysis has been used to see if the sillane has been chemically bonded on the surface of $TiO_2$.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1453-1456
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• 2009

Transparent sol-gel hybrid dielectric material (hybrimer) coating films were fabricated by spin coating and photo or thermal curing of sol-gel derived oligosiloxane resins. Hybrimer coating films are suitable as the passivation layer of TFT in AMLCD due to low dielectric constant, small loss tangent, low leakage current density, high transmittance and thermal stability.