• Polymer(Korea)
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• v.26 no.4
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• pp.462-467
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• 2002

Blends of polymethylmethacrylate (PMMA) with polyvinylidenefluoride (PVDF) were prepared by melt mixing and investigated for optical waveguide devices by using hot embossing process. The glass transition temperatures ($T_g$) of the blends were decreased with increasing PVDF contents. However, the crystalline of PMMA/PVDF blends was not appeared by DSC and XRD due to miscibility between PMMA and PVDF. Shear viscosities and refractive indices of the blends were decreased with increasing PVDF contents. Optical transmittances and absorption losses of the blends were improved with increasing PVDF contents. This is due to a decreasing of polarizability of molecules by fluorine molecule in the PVDF.

• Journal of the Korean Chemical Society
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• v.22 no.4
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• pp.221-228
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• 1978

Rates of reactions of 2,4-dinitrofluorobenzene and 2,4-dinitrobromobenzene with para substituted anilines in acetonitrile-methanol binary mixtures have been measured. It has been shown that methanol acts as nucleophilic catalyst upon reaction of 2,4-dinitrobromobenzene with anilines and as bifunctional catalyst upon reaction of 2,4-dinitrofluorobenzene with anilines. The electrophilic catalysis by methanol probably consists of formation of hydrogen bond in the transition state between alcoholic hydrogen and leaving group, fluorine. Nucleophilic catalysis by methanol may be ascribed to formation of hydrogen bond between alcoholic oxygen and amine hydrogen in the transition state.

• Journal of the Korean Applied Science and Technology
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• v.28 no.2
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• pp.232-239
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• 2011

Fabric fibrous filter has been used in various industrial applications owing to the low cost and wide generality. However, the basic properties of fabric materials often limit the practical utilization including hot gas cleaning. This study attempts to find new coatings of porous fibrous filter media in order to overcome its insufficient thermal resistance and durability. Teflon was one of the plausible chemicals to supplement the vulnerability against frequent external thermal impacts. A foaming agent composed of Teflon and some organic additives was tentatively coated on the glass fiber mat. The present test Teflon foam coated filter was fount to be useful for hot gas cleaning, up to $250^{\circ}C$-$300^{\circ}C$. Close examination using XPS(X-ray Photoelectron Spectroscopy) and Contact angle proved the binding interactions between carbon and fluorine, which implies coating stability. The PTFE/Glass foam coated filter consisted of more than 95% (C-F)n bond, and showed super-hydrophobic with good-oleophobic characteristics. The contact angle of liquid droplets on the filter surface enabled to find the filter wet-ability against liquid water or oil.

• Journal of the Microelectronics and Packaging Society
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• v.8 no.3
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• pp.63-67
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• 2001

Up to now, most studies about Pt-etching have been focused on physical sputtering mechanism with Cl-based plasma, while only a limited results are available for etching characteristics with fluorine-based plasma. In this study, etch characteristics of Pt thin film with $Cl_2$/Ar and $SF_{6}$/Ar Ar gas chemistries have been studied with ECR plasma etching system. It is confirmed that $SF_{6}$/Ar Ar plasma chemistry could make volatile etch-products through the reaction with Pt thin film. Also the improvement in etch rate, etch profile and surface roughness is obtained due to the formation of volatile platinum fluoride compounds.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1061-1066
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• 2009

Two fluoro-substituted 2-pyrazoline derivatives, 1-phenyl-3-(4-methoxyphenyl)-5-(4-fluorophenyl)-2-pyrazoline (1) and 1-phenyl-3-(4-methoxyphenyl)-5-(2-fluoro-phenyl)-2-pyrazoline (2) have been synthesized and characterized by elemental analysis, IR, UV-Vis and fluorescence spectra. The crystal structure of 1 has been determined by X-ray single crystal diffraction. For the two compounds, density functional theory (DFT) calculations of the structures and natural population atomic charge analysis (NPA) have been performed at B3LYP/6-311G** level of theory. By using TD-DFT method, electron spectra of 1 and 2 have been predicted, which are very approximate with the experimental ones. Comparative studies on 1 and 2 indicate that the location change of fluorine atom in 5-position phenyl ring of 2-pyrazoline does not make significant change of geometries and electronic transition bands, but it leads to evident change of atomic charge distributions and peak intensities of UV and fluorescence spectra.

• Journal of the Korean Ceramic Society
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• v.23 no.4
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• pp.1-10
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• 1986

The crystallization behaviour and the machinability of mica glass-ceramics with the content of F1 were studied. The material was made from the $K_2O-MgO-Al_2O_3-B_2O_3-SiO_2-F$ glasses by the heattreatment at 80$0^{\circ}C$-110$0^{\circ}C$ where the content of F-1 was changed in the range from 1, 3wt% to 6.1wt%. X-ray diffraction phase analysis and optical observation were adopted to study the crystallization behaviour. The machinability was measured by a manual sawing test and MOR. The crystal phases of these glass-ceramics identified by XRD were chondrodite fluoborite and norbergite at low temperature but fluorophlogopite at high temperature. The crystallization of glasses containing 1.3wt% -2.5wt% F-1 were predominately controlled by surface crystallization while the crystallization of glasses containing 3.8 wt% -6.1wt% F-1 were controlled by volume crystallization. Among the test the best machinability and strength value were obtained from those specimens contained fluoride 4.2wt% -4.4wt% and when the heattreatment was performed at 95$0^{\circ}C$-110$0^{\circ}C$ for 2 hours.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.12
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• pp.814-818
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• 2016

DSSCs (dye-sensitized solar cells) based on $TiO_2/SiO_2$ multi layer AR (anti-reflection) coating on the outer glass FTO (fluorine-doped tin oxide) substrate are investigated. We have coated an AR layer on the surface of a DSSCs device by using an IAD (ion beam-assisted deposition) system and investigated the effects of the AR layer by measuring photovoltaic performance. Compared to the pure FTO substrate, the multi layer AR coating increased the total transmittance from 67.4 to 72.9% at 530 nm of wavelength. The main enhancement of solar conversion efficiency is attributed to the reduction of light reflection at the FTO substrate surface. This leads to the increase of Jsc and the efficiency improvement of DSSCs.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.9
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• pp.714-719
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• 2001

SrBi$_2$Ta$_2$$O_{9}$ thn films were etched in inductively coupled Cl$_2$/CF$_4$/Ar plasma. THe maximum etch rate was 1060 $\AA$/min at a Cl$_2$/(Cl$_2$+CF$_4$+Ar)=0.2. The 20% additive Cl$_2$ into CF$_4$/Ar plasma decreased carbon and fluorine radicals, but increased Cl radicals. Sr was effectively removed by reacting with Cl radical because the boiling point of SrCl$_2$(125$0^{\circ}C$) is lower than that of SrF$_2$(246$0^{\circ}C$). The chemical reactions on the etched surface were studied with x-ray photoelectron spectroscopy and secondary ion mass spectrometry. The etching profile was evaluated by using scanning electron microscopy.y.

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1989-1992
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• 2012

We present a low temperature (${\approx}70^{\circ}C$) method to prepare anatase, vertically aligned feather-like $TiO_2$ (VAFT) nanowire arrays $via$ reactive pulsed DC magnetron sputtering. The synthesis method is general, offering a promising strategy for preparing crystalline nanowire metal oxide films for applications including gas sensing, photocatalysis, and 3rd generation photovoltaics. As an example application, anatase nanowire films are grown on fluorine doped tin oxide coated glass substrates and used as the photoanode in dye sensitized solar cells (DSSCs). AM1.5G power conversion efficiencies for the solar cells made of 1 ${\mu}m$ thick VAFT have reached 0.42%, which compares favorably to solar cells made of the same thickness P25 $TiO_2$ (0.35%).

• Corrosion Science and Technology
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• v.9 no.6
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• pp.317-324
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• 2010

Marine transportation by ships is characterized by remote, large-volume and lower rates than the others carry system. Ships account for over 80% of all international trading, and marine transportation is an internationally competitive, strategic, and great national important industry. The construction of larger and faster ships has brought about many problems such as cavitations and erosion corrosion. Cavitations and erosion corrosion make damages on materials and leads to break down members due to continuous physical contacts with shock waves and fluids from the generation and extinction of air bubbles in sea water vortex. The steel used for ship constructions was spray-coated with Al wire, and additionally sealed with fluorine silicone sealing material. Results of experiment, corrosion resistance of sealed thermal spray coating was improved, however in cavitation resistance, the large effect was not appeared. Accordingly, this study applied for thermal spray coating to provide better electrochemical characteristics and corrosion resistance in marine environment.