• The Korean Journal of Pesticide Science
• /
• v.14 no.3
• /
• pp.199-208
• /
• 2010

Phenylformamidine derivatives are well known as insecticides for their specific activity against the insects. It has now been established that they show insecticidal activity as agonists on the octopamine receptor. In order to get a highly active compound we have intensively exploited fluorine substituted-aromatic formamidines possessing N-dialkylaminosulfeny group. Up to now, there are several candidates we found: N-(dialkylamino)sulfenyl-N-methyl-N'-(4-fluoro-2-methylphenyl)formamidines. The miticidal activity of Compound 29 show five-fold higher than Amitraz.

• Journal of Korean Ophthalmic Optics Society
• /
• v.19 no.1
• /
• pp.69-77
• /
• 2014

Purpose: The functional ophthalmic lenses containing fluorine-substituted aniline group (2,4-difluoroaniline, 2,6-difluoroaniline, 3,4-difluoroaniline) were manufactured and the physical and optical characteristics of copolymerized ophthalmic lens were investigated. Methods: HEMA (2-hydroxyethylmethacrylate), NVP (N-vinyl pyrrolidone), MA (methacrylic acid), the cross-linker EGDMA (ethylene glycol dimethacrylate) and the initiator AIBN (azobisisobutyronitrile) were used as a basic combination and fluorine-substituted aniline group (2,4-difluoroaniline, 2,6-difluoroaniline, 3,4-difluoroaniline) were used as additives for preparing the hydrogel soft contact lenses. The hydrogel ophthalmic lens was manufactured by cast mould method and the ophthalmic lenses were stored in a 0.9% NaCl normal saline for 24 hrs. Results: The optical transmittance of the sample with addition 2,4-difluoroaniline showed that the UV-B(9.8~51.4%), UV-A(58.8~79.2%) and visible transmittance(87.0~90.4%). In the case of 2,6-difluoroaniline were measured the UV-B(80.2~83.2%), UV-A(85.8~86.4%), and visible transmittance(90.8~91.4%). Also, the optical transmittance of ophthalmic lens containing 3,4-difluoroaniline were measured the UV-B transmittance of 3.8~30.4%, UV-A transmittance of 47.8%~74.4% and the visible transmittance of 86.2~91.0% respectively. Conclusions: Based on the results of this study, 2,4-difluoroaniline and 3,4-difluoroaniline can be used effectively as additive for UV-blocking ophthalmic contact lenses.

• Journal of the Korean Chemical Society
• /
• v.55 no.3
• /
• pp.405-411
• /
• 2011

The ab initio calculations for fluoromethyl fluoroperoxides have been carried out using MP2/6-311G(d,p) and B3LYP/6-311++G(d,p) method. The structural optimizations were performed for several isomers and conformers of methyl fluoroperoxide, $CH_3OOF$ and the vibrational frequencies were calculated. The most stable conformer of $CH_3OOF$ is skew form and has fairly short O-O bond distance. The trans and cis conformers have 8-12 kcal/mol higher energies than skew form and the other isomers are very unstable. The structures of $CH_2FOOF$, $CHF_2OOF$ and $CF_3OOF$ are also optimized and vibrational frequencies were calculated. These molecules also have skew forms as the lowest energy conformers. The O-O bond distances are longer and C-O bond distances are shorter than $CH_3OOF$, but the structural parameters are almost independent of the number of fluorine atoms in methyl group.

• Journal of Sensor Science and Technology
• /
• v.13 no.4
• /
• pp.287-291
• /
• 2004

A capacitive type humidity sensor has been fabricated using a polyimide film without hydrophobic elements and its characteristics has been evaluated for hermeticity measurement of micro packages. For a highly sensitive humidity sensor, a polyimide film without hydrophobic elements has been synthesized and used instead of using a commercial one in which 7 group elements such as fluorine or chlorine are included. Sensitivity, stability and hysteresis has been performed to characterize the fabricated sensors. The sensitivity defined as normalized percent capacitance change was 0.3751%RH and hysteresis was 0.77% in the range of 10%RH to 90%RH. Maximum deviation from the average capacitance measured for 120 minutes at 50%RH was 0.25%. The proposed humidity sensor can be used for hermeticity measurement of micro packages.

• Carbon letters
• /
• v.4 no.2
• /
• pp.69-73
• /
• 2003

In this work, the effect of a direct oxyfluorination on surface and mechanical interfacial properties of PAN-based carbon fibers is investigated. The changes of surface functional groups and chemical composition of the oxyfluorinated carbon fibers are determined by FT-IR and XPS measurements, respectively. ILSS of the composites is also studied in terms of oxyfluorination conditions. As a result, FT-IR exhibits that the carboxyl/ester groups (C=O) at 1632 $cm^{-1} and hydroxyl group (O-H) at 3450 $cm^{-1} are observed in the oxyfluorinated carbon fibers. Especially, the oxyfluorinated carbon fibers have a higher O-H peak intensity than that of the fluorinated ones. XPS result also shows that the surface functional groups, including C-O, C=O, HO-C=O, and C-$F_x$ after oxyfluorination are formed on the carbon fiber surfaces, which are more efficient and reactive to undergo an interfacial reaction to matrix materials. Moreover, the formation of C-$F_x$ physical bonding of the carbon fibers with fluorine increases the surface polarity of the fibers, resulting in increasing ILSS of the composites. This is probably due to the improvement of interfacial adhesion between fibers and matrix resins.

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

• KEPCO Journal on Electric Power and Energy
• /
• v.7 no.1
• /
• pp.137-143
• /
• 2021

As an electrochemical water electrolysis for green hydrogen production, both polymer electrolyte membrane (PEM) and alkaline electrolyte are being developed extensively in various countries. The PEM electrolyzer with high current density (above 2 A/cm²) has the advantage of being able to design a simple structure. Also, it is known that it has high response to electrical output fluctuations. However, the cost problem of major components is the most important issue that a PEM electrolyzer must overcome. Instantly, there are platinum group metal (PGM)-based electrocatalysts, fluorine-based polyfluoro sulfuric acid (PFSA) membrane, Ti felt (porous transport layer, PTL) and so on. Another challenging issue is productivity. A securing outstanding productivity brings price benefits of the electrolytic cells. From this point of view, we conducted basic studies on manufacturing electrode and membrane electrode assembly (MEA) for PEM electrolyzer production.

• Journal of the Korean Electrochemical Society
• /
• v.3 no.4
• /
• pp.204-210
• /
• 2000

The control of dissolved aluminum concentration in the hot dip zinc galvanizing bath is greatly important in producing galvannealed steel sheets. The purpose of present study is to provide basic data for measurement of the aluminum concentration in site in hot dip zinc bath at the temperature of $460^{\circ}C\~500^{\circ}C$ using $CaF_2$ solid electrolyte sensor with three kinds of reference electrode. Good workability and stability of the sensor were confirmed with the $Bi+BiF_3$ reference electrode from the emf measurement. In order to measure the aluminum concentration in Zn-Al bath, the galvanic cell of fluorine ion was constructed with $CaF_2$ solid electrolyte as follows; $$(-)W|Zn-Al,\;AlF_3|CaF_2|Bi,BiF_3|W(+)$$. The emf measurement was made at the temperature of $460\pm10^{\circ}C$ in the Zn-Al bath. The following correlationship between aluminum concentration and emf was obtained by the least square regression analysis; $$E/mV=56.795log[\%Al]+1881.7\;R=0.9704$$,$$0.026wt\%{\leq}[\%Al]{\leq}0.984wt\%$$

• Korean Chemical Engineering Research
• /
• v.46 no.1
• /
• pp.118-123
• /
• 2008

In the present study, the effect of oxyfluorination treatment on multi-walled nanotubes (MWNTs) supports was investigated by analyzing surface functional groups. The surface characteristics were determined by Fourier transformed-infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). After the deposition of platinum nanoparticles on the above treated carbon supports, a crystalline size and a loading level had been investigated. Electrochemical properties of the treated MWNTs-supported Pt (Pt/MWNTs) catalysts were analyzed by current-voltage curve measurements. From the results of surface analysis, an oxygen and fluorine-containing functional group had been introduced to the surface of carbon supports. The oxygen and fluorine contents were the highest value at the treatment of 100 temperature. The Pt/100-MWNTs showed the smallest particle crystalline size of 3.5 nm and the highest loading level of 9.4% at the treatment of 100 temperature. However, the sample treated at the higher temperature showed the larger crystalline size and the lower loading level. This indicated that the crystalline size and the loading level could be controlled by changing the temperature of oxyfluorination treatment. Accordingly, an electrochemical activity was enhanced by increasing the temperature of treatment upto 100, and then decreased in the case of 200 and 300. The highest specific current density of 120 mA/mg had been obtained in the case of Pt/100-MWNTs.

• Environmental Engineering Research
• /
• v.23 no.1
• /
• pp.36-45
• /
• 2018

The phosphogypsum (PG) is a byproduct of the phosphate fertilizers manufacture. The world production estimated to 200 million tons per year induces environmental threats and storage problems, which requires strict policies to limit pollution and encourage its valorization. This paper presents a purification process of the crude PG including treatment with a diluted sulfuric acid, floatation, filtration and washing. The purified PG is used to produce plaster. The process optimization was conducted using a full factorial design. The significant factors considered in the experimental study are temperature ($X_1$), volume of sulfuric acid solution ($X_2$) and PG quantity ($X_3$). The main effects and interaction effects of these factors on the responses of the % $P_2O_5$, % F, Total Organic Carbon (TOC) ($mg{\cdot}kg^{-1}$) and pH were analyzed. The optimum conditions for $X_1$, $X_2$ and $X_3$ were found to be $60^{\circ}C$, 3 L and 1 kg, respectively and the optimized pH values was found to be 6.2. Under these conditions, 60% of $P_2O_5$, 95% of Fluorine and 98% of TOC were removed from PG. The predicted values were found approximately the same as the experimental ones. The plaster produced with purified PG was found to have similar properties to that produced from natural gypsum.