The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform

Masami Ogita - One of the best experts on this subject based on the ideXlab platform.

  • Critical Micelle Concentration cmc measurements using u shaped fiber optic probes
    Sensors and Actuators B-chemical, 2003
    Co-Authors: C.d. Singh, Y. Shibata, Masami Ogita
    Abstract:

    In this paper a simple U-shape optical fiber probe, for determination of Critical Micelle Concentration (CMC), using evanescent adsorption effect has been described. Fabrication and characterization of the U-shape fiber optic probe has been discussed. The U-shaped is used to increase the evanescent field and hence it interaction with the sample solutions consisting mainly of sodium dodecylbenzenesulfonate. The effect of light launching condition and bending radius of the probe on the Critical Micelle Concentration is studied. It has been shown that, for a given value of the sample solution, decrease the bending radius of the U-shape increases the sensitivity of the sensor and improve the finding of Critical Micelle Concentration point.

  • A simple U-shaped fiber optic probes for measurement of Critical Micelle Concentration (CMC) in surfactant solutions
    IECON'03. 29th Annual Conference of the IEEE Industrial Electronics Society (IEEE Cat. No.03CH37468), 2003
    Co-Authors: Masami Ogita, C.d. Singh, Y. Shibata, Takeshi Fujinami
    Abstract:

    In this paper a simple U-shape optical fiber probe, for Critical Micelle Concentration measurement, using evanescent adsorption effect has been described. Fabrication and characterization of the U-shape fiber optic probe has been discussed. The U-shaped is used to increase the evanescent field and hence it interaction with the sample solutions consisting mainly of sodium dodecylbenzenesulfonate. The effect of light launching condition and bending radius of the probe on the Critical Micelle Concentration is studied. It has been shown that, for a given value of the sample solution, decrease the bending radius of the U-shape increases the sensitivity of the sensor and improve the condition for finding of Critical Micelle Concentration point.

  • the detection of Critical Micelle Concentration based on the adsorption effect using optical fibers
    Japanese Journal of Applied Physics, 1998
    Co-Authors: Masami Ogita, Kenji Yoshimura, Mary Anne Mehta, Takeshi Fujinami
    Abstract:

    The structure of a surfactant molecule consists of two groups, a hydrophilic and a hydrophobic group. The possibility of detection of the Critical Micelle Concentration (CMC) was examined using optical fibers, plastic cladding silica fiber (PCS) and plastic optical fiber (POF), with hydrophilic and hydrophobic core properties, respectively. The cladding was removed at the sensing region and the core was exposed to the sample solution. The output from both the PCS and POF increased drastically at the CMC of 3×10-3 mol/l. This was due to the rapid increase in the reflectance at the interface between the core and the sample solution as the surfactant molecules in the saturated solution began to adsorb onto the sensing region of the core surface.

Alexander V Neimark - One of the best experts on this subject based on the ideXlab platform.

  • calculations of Critical Micelle Concentration by dissipative particle dynamics simulations the role of chain rigidity
    Journal of Physical Chemistry B, 2013
    Co-Authors: Aleksey Vishnyakov, Alexander V Neimark
    Abstract:

    Micelle formation in surfactant solutions is a self-assembly process governed by complex interplay of solvent-mediated interactions between hydrophilic and hydrophobic groups, which are commonly called heads and tails. However, the head–tail repulsion is not the only factor affecting the Micelle formation. For the first time, we present a systematic study of the effect of chain rigidity on Critical Micelle Concentration and Micelle size, which is performed with the dissipative particle dynamics simulation method. Rigidity of the coarse-grained surfactant molecule was controlled by the harmonic bonds set between the second-neighbor beads. Compared to flexible molecules with the nearest-neighbor bonds being the only type of bonded interactions, rigid molecules exhibited a lower Critical Micelle Concentration and formed larger and better-defined Micelles. By varying the strength of head–tail repulsion and the chain rigidity, we constructed two-dimensional diagrams presenting how the Critical Micelle concentr...

  • prediction of the Critical Micelle Concentration of nonionic surfactants by dissipative particle dynamics simulations
    Journal of Physical Chemistry Letters, 2013
    Co-Authors: Aleksey Vishnyakov, Alexander V Neimark
    Abstract:

    Micellization of surfactant solutions is a ubiquitous phenomenon in natural systems and technological processes, and its theoretical description represents one of the cornerstone problems in the physical chemistry of colloidal systems. However, successful attempts of quantitative modeling confirmed by experimental data remains limited. We show, for the first time, that the dissipative particle dynamics with rigorously defined soft repulsion interaction and rigidity parameters is capable of predicting micellar self-assembly of nonionic surfactants. This is achieved due to a novel approach suggested for defining the interaction parameters by fitting to the infinite dilution activity coefficients of binary solutions formed by reference compounds that represent coarse-grained fragments of surfactant molecules. Using this new parametrization scheme, we obtained quantitative agreement with the experimental Critical Micelle Concentration and aggregation number for several typical surfactants of different chemica...

Aleksey Vishnyakov - One of the best experts on this subject based on the ideXlab platform.

  • calculations of Critical Micelle Concentration by dissipative particle dynamics simulations the role of chain rigidity
    Journal of Physical Chemistry B, 2013
    Co-Authors: Aleksey Vishnyakov, Alexander V Neimark
    Abstract:

    Micelle formation in surfactant solutions is a self-assembly process governed by complex interplay of solvent-mediated interactions between hydrophilic and hydrophobic groups, which are commonly called heads and tails. However, the head–tail repulsion is not the only factor affecting the Micelle formation. For the first time, we present a systematic study of the effect of chain rigidity on Critical Micelle Concentration and Micelle size, which is performed with the dissipative particle dynamics simulation method. Rigidity of the coarse-grained surfactant molecule was controlled by the harmonic bonds set between the second-neighbor beads. Compared to flexible molecules with the nearest-neighbor bonds being the only type of bonded interactions, rigid molecules exhibited a lower Critical Micelle Concentration and formed larger and better-defined Micelles. By varying the strength of head–tail repulsion and the chain rigidity, we constructed two-dimensional diagrams presenting how the Critical Micelle concentr...

  • prediction of the Critical Micelle Concentration of nonionic surfactants by dissipative particle dynamics simulations
    Journal of Physical Chemistry Letters, 2013
    Co-Authors: Aleksey Vishnyakov, Alexander V Neimark
    Abstract:

    Micellization of surfactant solutions is a ubiquitous phenomenon in natural systems and technological processes, and its theoretical description represents one of the cornerstone problems in the physical chemistry of colloidal systems. However, successful attempts of quantitative modeling confirmed by experimental data remains limited. We show, for the first time, that the dissipative particle dynamics with rigorously defined soft repulsion interaction and rigidity parameters is capable of predicting micellar self-assembly of nonionic surfactants. This is achieved due to a novel approach suggested for defining the interaction parameters by fitting to the infinite dilution activity coefficients of binary solutions formed by reference compounds that represent coarse-grained fragments of surfactant molecules. Using this new parametrization scheme, we obtained quantitative agreement with the experimental Critical Micelle Concentration and aggregation number for several typical surfactants of different chemica...

C.d. Singh - One of the best experts on this subject based on the ideXlab platform.

  • Critical Micelle Concentration cmc measurements using u shaped fiber optic probes
    Sensors and Actuators B-chemical, 2003
    Co-Authors: C.d. Singh, Y. Shibata, Masami Ogita
    Abstract:

    In this paper a simple U-shape optical fiber probe, for determination of Critical Micelle Concentration (CMC), using evanescent adsorption effect has been described. Fabrication and characterization of the U-shape fiber optic probe has been discussed. The U-shaped is used to increase the evanescent field and hence it interaction with the sample solutions consisting mainly of sodium dodecylbenzenesulfonate. The effect of light launching condition and bending radius of the probe on the Critical Micelle Concentration is studied. It has been shown that, for a given value of the sample solution, decrease the bending radius of the U-shape increases the sensitivity of the sensor and improve the finding of Critical Micelle Concentration point.

  • A simple U-shaped fiber optic probes for measurement of Critical Micelle Concentration (CMC) in surfactant solutions
    IECON'03. 29th Annual Conference of the IEEE Industrial Electronics Society (IEEE Cat. No.03CH37468), 2003
    Co-Authors: Masami Ogita, C.d. Singh, Y. Shibata, Takeshi Fujinami
    Abstract:

    In this paper a simple U-shape optical fiber probe, for Critical Micelle Concentration measurement, using evanescent adsorption effect has been described. Fabrication and characterization of the U-shape fiber optic probe has been discussed. The U-shaped is used to increase the evanescent field and hence it interaction with the sample solutions consisting mainly of sodium dodecylbenzenesulfonate. The effect of light launching condition and bending radius of the probe on the Critical Micelle Concentration is studied. It has been shown that, for a given value of the sample solution, decrease the bending radius of the U-shape increases the sensitivity of the sensor and improve the condition for finding of Critical Micelle Concentration point.

A. G. Nekrasov - One of the best experts on this subject based on the ideXlab platform.

  • one more extreme near the Critical Micelle Concentration optical activity
    Langmuir, 2010
    Co-Authors: A I Rusanov, A. G. Nekrasov
    Abstract:

    It is reported the discovery of optical activity of micellar solutions of sodium dodecyl sulfate, cetyltrimethylammonium bromide, and poly(oxyethilene)(4)dodecyl ether as typical representatives of anionic, cationic, and nonionic surfactants. The surfactants exhibit dextrorotation. Since the optical activity of the ionic surfactants appears only above the Krafft point, it should be ascribed to micellar aggregates. Optical rotation as a function of the surfactant Concentration displays a pronounced maximum near the Critical Micelle Concentration (the subsequent decrease of optical activity corresponds to formation of spherical Micelles that cannot possess optical activity by symmetry). For sodium dodecyl sulfate, the maximum correlates well with extremes of other properties of surfactant solutions (foaminess, foam stability, Gibbs’ and transversal elasticity of thin foam films), which was described earlier. Naturally, films and foams of sodium dodecyl sulfate solutions also demonstrate optical activity.

  • Extremes of some foam properties and elasticity of thin foam films near the Critical Micelle Concentration.
    Langmuir, 2004
    Co-Authors: Anatoly I. Rusanov, V. V. Krotov, A. G. Nekrasov
    Abstract:

    : The elasticity of open and closed thin foam films is analyzed. The elasticity modulus of a closed film is shown to be additive with respect to contributions from Gibbs elasticity and disjoining pressure. A detailed expression for the film elasticity modulus explains the pronounced maxima of foaminess and foam stability near the Critical Micelle Concentration observed earlier in many experiments. A theory of transversal elasticity of thin foam films is formulated under conditions excluding the action of Gibbs elasticity. Near the Critical Micelle Concentration, the theory predicts maxima of the transversal elasticity modulus and of the films thickness as functions of Concentration at a given disjoining pressure. The prediction has been verified experimentally by measuring the film thickness in equilibrium foam as a function of height.