• Journal of the Korean Chemical Society
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• v.40 no.6
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• pp.420-426
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• 1996

The critical micelle concentration(CMC) and the counterion binding $constant(\beta)$ at the CMC of the mixtures of Sodium dodecylsulfate(SDS) with Sodium dodecylbenzenesulfonate(DBS) in aqueous solutions have been determined from the concentration dependence of electrical conductance at several temperatures from $15^{\circ}C$ to $35^{\circ}C.$ Thermodynamic parameters(${\Delta}C_p,\;{\Delta}G_m^{\circ},\;{\Delta}H_m^{\circ}$ 및 ${\Delta}S_m^{\circ}$ and ${\Delta}C_p$), associated with the micelle formation of SDS/DBS mixtures, have been estimated from the temperature dependence of CMC and $\beta$ values. The measured values of ${\Delta}G_m^{\circ}\;and\;{\Delta}C_p$ are negative but the values of ${\Delta}S_m/^{\circ}$ are positive in the whole measured temperature region. The significance of these thermodynamic parameters and their relation to the theory of the micelle formation of SDS/DBS mixtures have been also considered.

• Journal of the Korean Applied Science and Technology
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• v.8 no.2
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• pp.105-114
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• 1991

In relation to the preparation of Langmuir-Blodgett thin film, four kinds of N-alkylpyridiniurn bromide were synthesized. The values of surface tensions of these materials, measured with a Traube stalagmometer, gave the relationship between the critical micells hydrophobic radical and between CMC and temperature. Values of thermodynamic properties(${\Delta}H^0_m,\;{\Delta}S^0_m,\;{\Delta}G^0_m,$) for the formatoin of micelle were also obtained. Experiments gave the following results; at the temperature range between 40 and 60$^{\circ}C, CMC of Hexadecyl-, Octadecyl-, Eicosyl-, and Docosyl-Pyridinium Bromide were $7.64{\times}10^{-4}{\sim}9.13{\times}10^{-4},\;3.85{\times}10^{-4}{\sim}4.60{\times}10^{-4},\;2.00{\times}10^{-4}{\sim}2.39{\times}10^{-4},\;and\;1.07{\times}10^{-4}{\sim}1.28{\times}10^{-4}$ mol/l, respectively. Surface tension, ${\Gamma}_{CMC}$, of those were 33.49${\sim}$36.00, 34.78${\sim}$37.61, 35.49${\sim}$37.61 and 38.76${\sim}$55.80 dyne/cm, respectively, The relationship between CMC and the mumber of carbon atoms in the hydrophobic radical, N was expressed as follows : Log(CMC)=A-BN where A and B are constants. At the temperature range between 40 and 60$^{\circ}C$, the change of Gibbs evergy (${\Delta}G_m$) for one methylene group ($-CH_2-$) were -0.65RT, respectively, The minus values of enthalpy change (${\Delta}H_m$) suggest that the formation of micelle is exothermic. Additionally, the overall increase in the entropy change (${\Delta}S_m$) with respect to the temperature increase suggests that the formation of micelle is attained by a exothermic enthalpy directed process.

• Analytical Science and Technology
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• v.11 no.3
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• pp.151-155
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• 1998

Electrochemical behaviours on 1.0 mM methylviologen ($MV^{2+}$) in 100 mM NaCl+27 mM $MgCl_2$ solution, without and with sodium dodecyl sulfate (SDS), were studied. The intersection of two lines on ${\Delta}E_p$ (the difference between the anodic, $E_{pa}$, and the cathodic, $E_{pc}$, peak potentials) of the first and second redox waves vs. -log[SDS] plot was determined as a critical micelle concentration (CMC). When $Mg^{2+}$ was added, the effective access of $MV{\cdot}^+$ to the glassy carbon electrode surface became possible and the formation of micelles was retarded.

• Journal of the Korean Applied Science and Technology
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• v.18 no.2
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• pp.118-126
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• 2001

Micelle formation and adsorption at the $Ti0_{2}$ interface of a series of polystyrene-polythylene oxide(PS-PEO) block copolymer in aqueous solution was studied using fluorescence probing and small-angle X-ray methods. Further, the stability of aqueous $Ti0_{2}$ dispersion in the presence of copolymer was investigated by microelectrophoresis, optical density and sedimentation measurements. The dissolution of pyrene as fluorescent probe in aqueous surfactant solution leads to a slow decrease of the $I_{1}/I_{3}$ ratio, as the copolymer concentration increase; $I_{1}$ and $I_{3}$ are respectively the intensities of the first and third vibrionic peaks in the pyrene fluorescence emission. The behaviour was due to the characteristics of the copolymers and/or to the copolymer association efficiency in water. Moreover, the adsorption at the plateau level increases with decreasing PEO until chain length. The zeta potential of $TiO_{2}$ particles decreases with increasing copolymer concentration and reaches a plateau value. Finally, stabilization using block copolymers was more effective with samples having higher weight fractions of PS block.

• Journal of the Korean Chemical Society
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• v.37 no.9
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• pp.781-786
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• 1993

In the presence of $Mg^{2+}$, the interaction of nonionic surfactants, $nonylphenol-(ethylene oxide)_n$[NP-nEO; n = 12, 40, 100] with iodine in aqueous solution were investigated by UV-visible spectrophotometer. CMC (critical micelle concentration) was decreased with increasing $Mg^{2+}$ concentration, and those effects depend upon EO (ethylene oxide) numbers. Above CMC, the intensity of interaction peaks by the addition of $Mg^{2+}$ increased and then decreased. The increase in the intensity of the interaction peaks were attributed to the compactness of micelle in the presence of $Mg^{2+}$. These phenomena may be explained by the fact that the linear ethylene oxide chains, to be free configuration in aqueous solution, could form a psuedo-crown ether structures capable of forming complex with $Mg^{2+}$.

• Korean Journal of Materials Research
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• v.22 no.4
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• pp.207-210
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• 2012

The preparation of $Sm_2O_3$ doped $CeO_2$ in Igepal CO-520/cyclohexane reverse micelle solutions has been studied. In the present work, we synthesized nanosized $Sm_2O_3$ doped $CeO_2$ powders by reverse micelle process using aqueous ammonia as the precipitant; hydroxide precursor was obtained from nitrate solutions dispersed in the nanosized aqueous domains of a micro emulsion consisting of cyclohexane as the oil phase, and poly (xoyethylene) nonylphenylether (Igepal CO-520) as the non-ionic surfactant. The synthesized and calcined powders were characterized by Thermogravimetry-differential thermal analysis (TGA-DTA), X-ray diffraction analysis (XRD), and Transmission electron microscopy (TEM). The crystallite size was found to increase with increase in water to surfactant (R) molar ratio. Average particle size and distribution of the synthesized $Sm_2O_3$ doped $CeO_2$ were below 10 nm and narrow, respectively. TG-DTA analysis shows that phase of $Sm_2O_3$ doped $CeO_2$ nanoparticles changed from monoclinic to tetragonal at approximately $560^{\circ}C$. The phase of the synthesized $Sm_2O_3$ doped $CeO_2$ with heating to $600^{\circ}C$ for 30 min was tetragonal $CeO_2$. This study revealed that the particle formation process in reverse micelles is based on a two step model. The rapid first step is the complete reduction of the metal to the zero valence state. The second step is growth, via reagent exchanges between micelles through the inter-micellar exchange.

• Analytical Science and Technology
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• v.8 no.2
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• pp.107-116
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• 1995

The critical micelle concentration(CMC) of CTAB was determined with changes in absorbance at 202nm band of 4-biphenyl acetate($BPA^-$). With $BPA^-$ as a probe, the effect of temperature on CMC of CTAB has been observed between $30^{\circ}C{\sim}70^{\circ}C$. In this range of temperature the values of CMC are $1.18{\times}10^{-4}{\sim}2.02{\times}10^{-4}M$. The free energy(${\Delta}G^{\circ}m$) and enthalpy(${\Delta}H^{\circ}m$)for the micellization of CTAB was negative and the entropy(${\Delta}S^{\circ}m$) was a large positive value. The micellization of CTAB is considered as a spontaneous process and to involve a phase transition. The orientational binding of 4-biphenyl acetate anion to the CTAB micelle interface has been studied with $300MHz\;H^1-NMR$ data. The change in chemical shift of proton in CTAB as well as those of the protons in $BPA^-$ have been investigated by increasing the mole fraction of the anion in the mixed solutions. The changes in chemical shift with increasing mole fraction of anion($BPA^-$) indicate the formation of mixed micelle between CTAB and $BPA^-$. The changes in chemical shifts of methylene protons in CTAB, demonstrate the penetration of $BPA^-$ into the palisade layer of the CTAB micelle.

• Korean Journal of Food Science and Technology
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• v.34 no.5
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• pp.770-774
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• 2002

Effect of surfactant micelles on lipid oxidation was determined in soybean oil-in-water (O/W) emulsions. The concentration of ferric irons to continuous phase in the O/W emulsions was measured as a function of various Brij type and concentrations. The concentration of ferric iron in the continuous phase increased with increasing surfactant micelles concentration $(0.5{\sim}2.0%)$ and storage time $(1{\sim}7\;days)$. At pH 3.0, the concentration of continuous phase iron was higher than at pH 7.0. Lipid oxidation rates, as determined by the formation of lipid hydroperoxides and headspace hexanal, in the O/W emulsions containing ferric iron decreased with increasing surfactant micelle concentration $(0.5{\sim}2.0%)$. These results indicate that surfactant micelles concentration could alter the physical location and prooxidant activity of iron in soybean O/W emulsions.

• Journal of the Korean Applied Science and Technology
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• v.15 no.3
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• pp.39-45
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• 1998

In recent years, there has been considerable interest in the development of new functional surfactant including new type of anionic surfactants. Anionic surfactants, ${\alpha}-sulfo$ fatty acids that straight long chain alkyl group having from 12 to 18 carbon atoms, were synthesized with sulfur trioxide-dioxane complex to good yield. Xylitol ${\alpha}-sulfo$ fatty acid esters were obtained by reaction that the acetification and esterification of xylitol, by addition reaction with sodium chloride and hydrolysis respectively. These compounds were a new group of destructible surfactants which readily hydrolyzed and oxidized in natural water reservoirs. Physical properties of these new compounds involved surface tension, critical micelle concentration(cmc), foaming power, emulsion power, and hydrolysis properties, were measured. The cmc values of the compounds by ring method were assumed to $7.0{\times}10^{-3}{\sim}3.0{\times}10^{-2}mol/{\ell}$ range and surface tensions at cmc were $25{\sim}31dyne/cm$ respectively.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.310-310
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• 2006

We have demonstrated the formation of highly nanoporous films composed of two different BCMs through layer-by-layer (LbL) assembly on substrates. The films thus prepared showed tunable optical properties, with strong antireflective properties with light transmission above 99%. Considering the wide application areas of both LbL multilayers and block copolymer thin films, the approaches introduced in present study are likely to open up new possibilities for devices with multifunctional properties.