Publications


Title : 2D-Ising-like critical behavior in mixtures of water and 3-methylpyridine including antagonistic salt or ionic surfactant

Language: English
Type: Article
Authors: Koichiro Sadakane, Natsuki Iguchi, Michihiro Nagao, Hitoshi Endo, Yuri B. Melnichenko and Hideki Seto
Journal: Soft Matter
Volume: 7
Number: 4
Month: 2
Year: 2011
Actual year: 2010
Pages: 1334-1340
doi:   10.1039/C0SM00598C
Abstract: The effect of an antagonistic salt on the phase behavior and nanoscale structure of a mixture of D2O and 3-methylpyridine was investigated by visual inspection and small-angle neutron scattering (SANS). The addition of the antagonistic salt, namely sodium tetraphenylborate (NaBPh4), induces the shrinking of the two-phase region in contrast to the case in which a normal (hydrophilic) salt is added. Below the phase separation point, the SANS profiles cannot be described by the Ornstein–Zernike function owing to the existence of a long-range periodic structure. With increasing salt concentration, the critical exponents change from the values of 3D-Ising and approach those of 2D-Ising. These results suggest that the concentration fluctuation of the mixture of solvents is limited to a quasi two-dimensional space by the periodic structure induced by the adding the salt. The same behaviors were also observed in mixtures composed of water, 3-methylpyridine, and ionic surfactant.

"2D-Ising-like critical behavior in mixtures of water and 3-methylpyridine including antagonistic salt or ionic surfactant"

Koichiro Sadakane, Natsuki Iguchi, Michihiro Nagao, Hitoshi Endo, Yuri B. Melnichenko and Hideki Seto, Soft Matter, 7, 1334-1340 (2011)