• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.105-110
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• 2012

A europium (III)-sensitized, spectrofluorimetric (FL) method is presented for the determination of sparfloxacin (SPAR) using an anionic surfactant, sodium dodecyl benzene sulphonate (SDBS). The method is based on the strong fluorescence (FL) enhancement of SPAR after the addition of $Eu^{3+}$ ions as fluorescence probes. The experimental results indicated that the FL intensity of the SPAR-$Eu^{3+}$ system was enhanced markedly by SDBS. The maximum FL emission signal was obtained at about 615 nm when excited at 372 nm. The experimental conditions that affected the FL intensity of the SPAR-$Eu^{3+}$-SDBS system were optimized systematically. The enhanced FL intensity of the system exhibited a good linear relationship with the SPAR concentration over the range of $1.5{\times}10^{-9}-1.2{\times}10^{-7}mol\;L^{-1}$ with a correlation coefficient (r) of 0.9987. The limit of detection ($3{\delta}$) was $4.15{\times}10^{-10}mol\;L^{-1}$ with a relative standard deviation (RSD) of 1.65%. This method was successfully applied for the determination of SPAR in pharmaceuticals, and human serum and urine samples with higher sensitivity, wide dynamic range and better stability. The possible interaction mechanism of the system is also discussed in detail by ultraviolet absorption spectra and FL spectra.

• Bulletin of the Korean Chemical Society
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• v.25 no.3
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• pp.382-388
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• 2004

The sizes and structures of micelles formed in aqueous solutions of cationic octadecyl trimethyl ammonium chloride (OTAC) and anionic ammonium dodecyl sulfate (ADS) surfactants were investigated using smallangle neutron scattering (SANS), self-diffusion coefficients by pulsed-gradient spin-echo (PGSE) NMR, and dynamic light scattering (DLS) methods. SANS and DLS data indicate that their structures are spherical at concentrations as high as 300 mM. As the total surfactant concentration increases, the peaks of SANS spectra shift to higher scattering vector and become sharper, indicating that the intermicellar distance decreases and its distribution becomes narrower. This is due to more compact packing of surfactant molecules at high concentrations. The intermicellar distance of around 100 ${\AA}$ above 200 mM corresponds approximately to the diameter of one micelle. The sizes of spherical micelles are 61 ${\AA}$ and 41 ${\AA}$ for 9 mM OTAC and 10 mM ADS, respectively. Also the self-diffusion coefficients by PGSE-NMR yield the apparent sizes 96 ${\AA}$ and 31 ${\AA}$ for micelles of 1 mM OTAC and 10 mM ADS, respectively. For ADS solutions of high concentrations (100-300 mM), DLS data show that the micelle size remains constant at $25{\pm}2{\AA}$. This indicates that the transition in micellar shape does not take place up to 300 mM, which is consistent with the SANS results.

• Macromolecular Research
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• v.12 no.5
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• pp.528-533
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• 2004

We have prepared amide dendrons having alkyl peripheral units and various focal moieties through a convergent synthetic approach. The amphiphilic properties, due to hydrophilic amide branches and the hydrophobic peripheral units, provide an opportunity for the amide dendrons to self-organize in water. The dendritic architecture itself is also one of the critical factors in the self-organization of the amide dendrons in water. In particular, function-alization was performed at the focal point to elucidate the relationship between the focal functionality and the self-organized structures of the dendritic building blocks in the aqueous phase. The dendron having a short poly(ethylene glycol) monomethyl ether (MeO-PEG) unit (M$\_$n/ =750) as the focal moiety formed a vesicular organization in water. As the size of the hydrophilic focal MeO-PEG increased to M$\_$n/ =2,000 and 5,000, the self-organized structures became rod-type and spherical micelles, respectively. Our observation of multiple morphologies for amide dendrons is in good agreement with previous reports that indicated that the micellar structures changed from vesicles to rod-types and then to spheres upon increasing the size of the hydrophilic moiety of the amphiphiles.

• Journal of the Korean Applied Science and Technology
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• v.12 no.1
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• pp.101-107
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• 1995

As the surfactants that were used in micellar reaction, emulsion polymerization and phase-transfer reaction etc. have the problems, the cleavable surfactant was converted to inactive compound after such as the reaction in the condition. Because 1, 3-dioxolane ring by ketal or acetal reactioc is lack of stability in acid condition, it is easily made to acid-hydrolysis. And cmc value of the surfactant is assumed $1.0{\times}10^{-5}mol/L$ and surface tension in cmc is 31 dyne/cm. Compared with other surfactant, this surfactant foam property is not better. But emulsion property was relatively good. According as acid-hydrolysis property was observed the interface tension change between aqueous solution and benzene by the variation of pH and time, this surfactant was made to hydrolysis within about 300minutes in pH 1${\sims}$4. Therefore this surfactant is expected to be a good emulsifier that has the bad foam property and the acid-hydrolysis property in acid condition.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.824-832
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• 2008

micellar solution which is comprised of surfactant monomers, monodisperse micelles, and solvent(water) is studied from a statistical-mechanical point of view. The model examined in this article is for the ideal mixture of monomers, micelles, and solvent with the dielectric constant identical to that of solvent, which is an assumption common to continuum models. The model also reflects interactions between monomer and solvent molecule, and also between micelle and solvent molecule. The statistical-mechanical model under consideration yields ln $X_{CMC}=A+BT+C/T+D{\ln}T$ with $X_{CMC}$ being critical mcielle concentration (in mole fraction), being temperature, and A, B, C, D being constants which depend on the properties of the surfactant molecules. The statistical-mechanical model discussed in this article provides a theoretical basis on the thermal dependence of critical micelle concentration

• Journal of the Korean Chemical Society
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• v.55 no.2
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• pp.163-168
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• 2011

The variations of molar conductivity of various surfactants such as sodium caprylate, sodium laurate, sodium palmitate, sodium stearate, sodium oleate, sodium dodecyl sulphate, and lithium dodecyl sulphate with concentrations of the surfactants for each of the solutions consisting of mixtures of varying concentrations of N-methyl acetamide in water at constant temperature of $30{\pm}0.2^{\circ}C$ were studied. The critical micelle concentration (CMC) for each surfactant is measured. It is found that the CMC values in mixtures of N-methyl acetamide and water solutions of various surfactants are lower than the CMC values in water, and the driving force for micelle formation correlates with solvophobicity. The surfactant-solvent interactions that drive amphiphilic self-organization in N-methyl acetamide in water are discussed. Thermodynamic parameters were evaluated for micellar system to explain the results.

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.330-342
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• 2003

The formation of emulsions and micelles in water/ceramide PC104/CholE $O_{20}$/C$_{16}$E $O_{20}$ and water/ceramide PC104/CholE $O_{20}$ mixtures was investigated through the phase behavior studies. The phase diagrams showed the existence of micelle and emulsion regions in both systems. The mixed surfactant system (CholE $O_{20}$/C$_{16}$E $O_{20}$) showed the wider micellar and emulsion regions than the single surfactant system (CholE $O_{20}$). From FT-IR measurements, it was found that the polyoxyethylene (POE) groups of surfactants formed the hydrogen bonds with amido carbonyl group in ceramide PC104. This result indicated that the hydrophilic part (EO) of surfactants could stabilize the lamellar structure and emulsion of ceramide PC104. The mixed surfactant system (CholE $O_{20}$/C$_{16}$E $O_{20}$) resulted in the smaller emulsion droplet size due to the effect of curvature at the interface, thus further increasing emulsion stability. With the penetration of $C_{16}$E $O_{20}$into the interfacial layer of surfactants in emulsion, the curvature of the interface might be altered for the formation of smaller emulsion droplets. The mixed surfactant system could incorporate up to 4 wt. % of ceramide PC104 into emulsion more than single surfactant system.ystem.m.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.4145-4149
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• 2012

A novel and simple method of luminescence enhancement effect for the determination of trace amounts of bile acid was proposed. The procedure was based on the luminescence intensity of the balofloxacin-europium(III) complex that could be strongly enhanced by bile acid in the presence of sodium dodecyl benzene sulfonate (SDBS). Under the optimum conditions, the enhanced luminescence intensity of the system exhibited a good linear relationship with the bile acid concentration in the range $5.0{\times}10^{-9}-7.0{\times}10^{-7}\;mol\;L^{-1}$ with a detection limit of $1.3{\times}10^{-9}\;mol\;L^{-1}$ ($3{\sigma}$). The relative standard deviation (RSD) was 1.7% (n = 11) for $5.0{\times}10^{-8}\;mol\;L^{-1}$ bile acid. The applicability of the method to the determination of bile acid was demonstrated by investigating the effect of potential interferences and by analyzing human serum and urine samples. The possible enhancement mechanism of luminescence intensity in balofloxacin-europium(III)-bile acid-SDBS system was also discussed briefly.

• Journal of the Korean Chemical Society
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• v.57 no.6
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• pp.665-671
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• 2013

The solubilization of p-bromophenol by the micellar system of TTAB(tetradecyltrimethylammonium bromide) and the micellization of TTAB were studied by the UV-vis spectrophotometric method simultaneously. And the effects of temperature on these properties have been measured for the thermodynamic study. The results show that the ${\Delta}G_s{^o}$ and ${\Delta}H_s{^o}$ values are negative and the ${\Delta}S_s{^o}$ values are positive for the solubilization of p-bromophenol within the measured range. On the other hand, the ${\Delta}G_m{^o}$ values are negative and the ${\Delta}H_m{^o}$ and ${\Delta}S_m{^o}$ values are positive for the micellization of TTAB. The effects of additives such as n-butanol and NaCl have been studied also for both properties and the relationship between these two properties has been also studied. From the results, we can postulate the solubilization site of p-bromophenol in the micelle.

• Korean Journal of Food Science and Technology
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• v.24 no.2
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• pp.111-116
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• 1992

Production of cocoa butter equivalent fat (CBE) from palm oil and stearic acid by reverse micelle lipase reaction system was studied. Qualitative and quantitative analyses of triglycerides were performed by HPLC. The reaction conditions for maximum conversion from triolein and stearic acid to 1-stearoyl-2,3-dioleoyl glycerol(SOO) and 1,3-distearoyl-2-oleoyl glycerol(SOS) were as follows: a molar ratio of water/Aerosol OT, 10; triolein, 30 mM; stearic acid, 90 mM; pH, 7.5; and temperature, $50^{\circ}C$. By lipase in reverse micellar system containing palm oil and stearic acid, 1,3-dipalmitoyl-2-oleoyl glycerol(POP), 1-palmitoyl-2,3-dioleoyl glycerol(POO) and SOO decreased, but large amounts of 1-palmitoyl-2-oleoyl-3-stearoyl glycerol(POS) and SOS was formed.