Publications by authors named "Masahiko Ishitobi"

A phase diagram of a water-polyglyceryl didodecanoate ((C11)2Gn) system was constructed as a function of polyglycerol chain length (n) at 25 degrees C. The average number of dodecanoic acid residues attached to polyglycerol is in the range of 1.6-2.

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The phase behavior and structure of sucrose ester/water/oil systems in the presence of long-chain cosurfactant (monolaurin) and small amounts of ionic surfactants was investigated by phase study and small angle X-ray scattering. In a water/sucrose ester/monolaurin/decane system at 27 degrees C, instead of a three-phase microemulsion, lamellar liquid crystals are formed in the dilute region. Unlike other systems in the presence of alcohol as cosurfactant, the HLB composition does not change with dilution, since monolaurin adsorbs almost completely in the interface.

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The effects of the number of fatty acid residues (n) in decaglycerol fatty acid esters, i.e., decaglycerol laurates (abbreviated to (C11)nG10), on the phase behaviors of three laurate esters, (C11)1.

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A study of the phase and rheological behavior of sucrose hexadecanoate (C16SE)/cosurfactant/water systems in the presence of solubilized oil, using complementary techniques such as dynamic light scattering and small angle X-ray scattering, is presented. Viscoelastic wormlike micellar solutions are found when a nonionic lipophilic cosurfactant is added to C16SE aqueous systems. Contrary to previous reports, the effect of oil solubilization on these wormlike micelles is not unique and depends on several factors.

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The effect of adding tri(oxyethylene) dodecyl ether (C12EO3) on the phase and rheological behavior of sucrose hexadecanoate and CTAB aqueous solutions in the presence of added salt (NaBr) was investigated. Viscoelastic solutions are formed in CTAB and C16SE systems upon addition of lipophilic nonionic surfactant C12EO3. The zero-shear viscosity shows a maximum at a certain mixing fraction of C12EO3, except in the case of the aqueous CTAB/C12EO3 system in the absence of salt.

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We have studied the effect of adding sucrose distearate (2C(18)SE) on the solubilization capacity of microemulsions formed in the water/C(12)EO(6)/n-decane system. Upon addition of 2C(18)SE to the binary water/C(12)EO(6) system, a lamellar liquid crystal region developed. This suggests that the rigidity of the surfactant layer is strengthened.

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