The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Naoki Yoshioka - One of the best experts on this subject based on the ideXlab platform.
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amphiphilic meso disubstituted porphyrins synthesis and the effect of the Hydrophilic Group on absorption spectra at the air water interface
Langmuir, 2005Co-Authors: Yuko Iwamura, Hidenari Inoue, Naoki YoshiokaAbstract:Five amphiphilic meso-disubstituted porphyrins bearing one polar Group were synthesized, and their monolayer films were prepared. Their limiting molecular areas obtained from π−A isotherms were 0.5−0.6 nm2, which were smaller than those of the corresponding meso-tetrasubstituted porphyrins. At the air−water interface, the disubstituted porphyrins showed a broad band in visible absorption spectra compared with the solution state, and the red shift of the Soret band exhibited a significant dependence on the kind of Hydrophilic Groups at the meso positions. Interestingly, the monolayer of the disubstituted porphyrin bearing a carboxyphenyl Group (1-CO2H) showed a blue shift of the Soret band by adding cadmium chloride to the subphase, and the spectra varied upon multilayer deposition. The observed phenomena were interpreted by using the exciton theory. The effect of Hydrophilic substituents on the absorption spectra of disubstituted porphyrin monolayers is discussed.
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Amphiphilic meso-Disubstituted Porphyrins: Synthesis and the Effect of the Hydrophilic Group on Absorption Spectra at the Air−Water Interface
Langmuir, 2005Co-Authors: Yuko Iwamura, Hidenari Inoue, Naoki YoshiokaAbstract:Five amphiphilic meso-disubstituted porphyrins bearing one polar Group were synthesized, and their monolayer films were prepared. Their limiting molecular areas obtained from π−A isotherms were 0.5−0.6 nm2, which were smaller than those of the corresponding meso-tetrasubstituted porphyrins. At the air−water interface, the disubstituted porphyrins showed a broad band in visible absorption spectra compared with the solution state, and the red shift of the Soret band exhibited a significant dependence on the kind of Hydrophilic Groups at the meso positions. Interestingly, the monolayer of the disubstituted porphyrin bearing a carboxyphenyl Group (1-CO2H) showed a blue shift of the Soret band by adding cadmium chloride to the subphase, and the spectra varied upon multilayer deposition. The observed phenomena were interpreted by using the exciton theory. The effect of Hydrophilic substituents on the absorption spectra of disubstituted porphyrin monolayers is discussed.
Yuko Iwamura - One of the best experts on this subject based on the ideXlab platform.
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amphiphilic meso disubstituted porphyrins synthesis and the effect of the Hydrophilic Group on absorption spectra at the air water interface
Langmuir, 2005Co-Authors: Yuko Iwamura, Hidenari Inoue, Naoki YoshiokaAbstract:Five amphiphilic meso-disubstituted porphyrins bearing one polar Group were synthesized, and their monolayer films were prepared. Their limiting molecular areas obtained from π−A isotherms were 0.5−0.6 nm2, which were smaller than those of the corresponding meso-tetrasubstituted porphyrins. At the air−water interface, the disubstituted porphyrins showed a broad band in visible absorption spectra compared with the solution state, and the red shift of the Soret band exhibited a significant dependence on the kind of Hydrophilic Groups at the meso positions. Interestingly, the monolayer of the disubstituted porphyrin bearing a carboxyphenyl Group (1-CO2H) showed a blue shift of the Soret band by adding cadmium chloride to the subphase, and the spectra varied upon multilayer deposition. The observed phenomena were interpreted by using the exciton theory. The effect of Hydrophilic substituents on the absorption spectra of disubstituted porphyrin monolayers is discussed.
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Amphiphilic meso-Disubstituted Porphyrins: Synthesis and the Effect of the Hydrophilic Group on Absorption Spectra at the Air−Water Interface
Langmuir, 2005Co-Authors: Yuko Iwamura, Hidenari Inoue, Naoki YoshiokaAbstract:Five amphiphilic meso-disubstituted porphyrins bearing one polar Group were synthesized, and their monolayer films were prepared. Their limiting molecular areas obtained from π−A isotherms were 0.5−0.6 nm2, which were smaller than those of the corresponding meso-tetrasubstituted porphyrins. At the air−water interface, the disubstituted porphyrins showed a broad band in visible absorption spectra compared with the solution state, and the red shift of the Soret band exhibited a significant dependence on the kind of Hydrophilic Groups at the meso positions. Interestingly, the monolayer of the disubstituted porphyrin bearing a carboxyphenyl Group (1-CO2H) showed a blue shift of the Soret band by adding cadmium chloride to the subphase, and the spectra varied upon multilayer deposition. The observed phenomena were interpreted by using the exciton theory. The effect of Hydrophilic substituents on the absorption spectra of disubstituted porphyrin monolayers is discussed.
Kenji Aramaki - One of the best experts on this subject based on the ideXlab platform.
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temperature sensitivity of wormlike micelles in poly oxyethylene surfactant solution importance of Hydrophilic Group size
Journal of Colloid and Interface Science, 2009Co-Authors: Toufiq Ahmed, Kenji AramakiAbstract:Abstract We have studied the temperature sensitivity of the rheology of the wormlike micellar solutions formed in poly(oxyethylene) cholesteryl ether (ChEOm, m = 15 and 30) upon addition of tri(ethyleneglycol) mono n-dodecyl ether (C12EO3) and monolaurin. We have found that increasing the poly(oxyethylene) chain length of ChEOm greatly reduces the temperature-sensitivity of the viscosity of the solution. In the viscous region small changes in the cosurfactant composition can subtly change the temperature sensitivity depending on the temperature range and type of cosurfactant. For, C12EO3, which is a poly(oxyethylene) surfactant, the temperature sensitivity is lower at lower temperatures and higher at higher temperatures if the cosurfactant mixing fraction is high and vice versa if the mixing fraction is low. For monolaurin, the temperature sensitivity increases with cosurfactant mixing fraction in the viscous region. In the ChEO30–monolaurin system viscous solutions are not formed at any temperature that we studied. We have discussed these results in terms of the reduction of the average curvature of micellar interface with temperature due to dehydration of the poly(oxyethylene) chain and formation of branches in long micelles. We indicate the scientific and technical significance of our findings.
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wormlike micelles in poly oxyethylene surfactant solution growth control through Hydrophilic Group size variation
Journal of Colloid and Interface Science, 2008Co-Authors: Toufiq Ahmed, Kenji AramakiAbstract:Abstract Viscoelastic micellar solutions are formed in poly(oxyethylene) cholesteryl ether (ChEOm, m = 15 , 30) aqueous solutions on addition of tri(ethyleneglycol) mono n-dodecyl ether (C12EO3). The steady-shear and dynamic rheological behavior of the systems is characteristic of wormlike micellar solution. In either system, the plateau modulus ( G 0 ) and relaxation time (τ) are found to increase with increasing cosurfactant mixing fractions. The plateau modulus of the ChEO30–C12EO3 system at the maximum viscosity region is found to be higher than that in the ChEO15–C12EO3 system at the maximum viscosity region, whereas for the relaxation time the opposite relation is found. The maximum viscosities obtained in the two systems are of the same order of magnitude. In the ChEO30–C12EO3 system, the maximum viscosity is obtained at a higher cosurfactant mixing fraction than that in the ChEO15–C12EO3 system. It is concluded that decreasing the head-Group size of the Hydrophilic surfactant favors micellar growth. Monolaurin, another hydrophobic surfactant known to induce growth in some systems, is found to cause phase separation before significant micellar growth occurs in ChEOm solutions, although the effect of head-Group size of ChEOm is found to be similar to the ChEOm–C12EO3 systems.
Hidenari Inoue - One of the best experts on this subject based on the ideXlab platform.
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amphiphilic meso disubstituted porphyrins synthesis and the effect of the Hydrophilic Group on absorption spectra at the air water interface
Langmuir, 2005Co-Authors: Yuko Iwamura, Hidenari Inoue, Naoki YoshiokaAbstract:Five amphiphilic meso-disubstituted porphyrins bearing one polar Group were synthesized, and their monolayer films were prepared. Their limiting molecular areas obtained from π−A isotherms were 0.5−0.6 nm2, which were smaller than those of the corresponding meso-tetrasubstituted porphyrins. At the air−water interface, the disubstituted porphyrins showed a broad band in visible absorption spectra compared with the solution state, and the red shift of the Soret band exhibited a significant dependence on the kind of Hydrophilic Groups at the meso positions. Interestingly, the monolayer of the disubstituted porphyrin bearing a carboxyphenyl Group (1-CO2H) showed a blue shift of the Soret band by adding cadmium chloride to the subphase, and the spectra varied upon multilayer deposition. The observed phenomena were interpreted by using the exciton theory. The effect of Hydrophilic substituents on the absorption spectra of disubstituted porphyrin monolayers is discussed.
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Amphiphilic meso-Disubstituted Porphyrins: Synthesis and the Effect of the Hydrophilic Group on Absorption Spectra at the Air−Water Interface
Langmuir, 2005Co-Authors: Yuko Iwamura, Hidenari Inoue, Naoki YoshiokaAbstract:Five amphiphilic meso-disubstituted porphyrins bearing one polar Group were synthesized, and their monolayer films were prepared. Their limiting molecular areas obtained from π−A isotherms were 0.5−0.6 nm2, which were smaller than those of the corresponding meso-tetrasubstituted porphyrins. At the air−water interface, the disubstituted porphyrins showed a broad band in visible absorption spectra compared with the solution state, and the red shift of the Soret band exhibited a significant dependence on the kind of Hydrophilic Groups at the meso positions. Interestingly, the monolayer of the disubstituted porphyrin bearing a carboxyphenyl Group (1-CO2H) showed a blue shift of the Soret band by adding cadmium chloride to the subphase, and the spectra varied upon multilayer deposition. The observed phenomena were interpreted by using the exciton theory. The effect of Hydrophilic substituents on the absorption spectra of disubstituted porphyrin monolayers is discussed.
Toufiq Ahmed - One of the best experts on this subject based on the ideXlab platform.
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temperature sensitivity of wormlike micelles in poly oxyethylene surfactant solution importance of Hydrophilic Group size
Journal of Colloid and Interface Science, 2009Co-Authors: Toufiq Ahmed, Kenji AramakiAbstract:Abstract We have studied the temperature sensitivity of the rheology of the wormlike micellar solutions formed in poly(oxyethylene) cholesteryl ether (ChEOm, m = 15 and 30) upon addition of tri(ethyleneglycol) mono n-dodecyl ether (C12EO3) and monolaurin. We have found that increasing the poly(oxyethylene) chain length of ChEOm greatly reduces the temperature-sensitivity of the viscosity of the solution. In the viscous region small changes in the cosurfactant composition can subtly change the temperature sensitivity depending on the temperature range and type of cosurfactant. For, C12EO3, which is a poly(oxyethylene) surfactant, the temperature sensitivity is lower at lower temperatures and higher at higher temperatures if the cosurfactant mixing fraction is high and vice versa if the mixing fraction is low. For monolaurin, the temperature sensitivity increases with cosurfactant mixing fraction in the viscous region. In the ChEO30–monolaurin system viscous solutions are not formed at any temperature that we studied. We have discussed these results in terms of the reduction of the average curvature of micellar interface with temperature due to dehydration of the poly(oxyethylene) chain and formation of branches in long micelles. We indicate the scientific and technical significance of our findings.
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wormlike micelles in poly oxyethylene surfactant solution growth control through Hydrophilic Group size variation
Journal of Colloid and Interface Science, 2008Co-Authors: Toufiq Ahmed, Kenji AramakiAbstract:Abstract Viscoelastic micellar solutions are formed in poly(oxyethylene) cholesteryl ether (ChEOm, m = 15 , 30) aqueous solutions on addition of tri(ethyleneglycol) mono n-dodecyl ether (C12EO3). The steady-shear and dynamic rheological behavior of the systems is characteristic of wormlike micellar solution. In either system, the plateau modulus ( G 0 ) and relaxation time (τ) are found to increase with increasing cosurfactant mixing fractions. The plateau modulus of the ChEO30–C12EO3 system at the maximum viscosity region is found to be higher than that in the ChEO15–C12EO3 system at the maximum viscosity region, whereas for the relaxation time the opposite relation is found. The maximum viscosities obtained in the two systems are of the same order of magnitude. In the ChEO30–C12EO3 system, the maximum viscosity is obtained at a higher cosurfactant mixing fraction than that in the ChEO15–C12EO3 system. It is concluded that decreasing the head-Group size of the Hydrophilic surfactant favors micellar growth. Monolaurin, another hydrophobic surfactant known to induce growth in some systems, is found to cause phase separation before significant micellar growth occurs in ChEOm solutions, although the effect of head-Group size of ChEOm is found to be similar to the ChEOm–C12EO3 systems.
