2D-Ising critical behavior in mixtures of water and 3-methylpyridine

Journal Article · Sat Jan 01 04:00:00 EST 2011 · Soft Matter

DOI:https://doi.org/10.1039/c0sm00598c· OSTI ID:1004963

Sadakane, Koichiro ^[1]; Iguchi, Kazuya ^[1]; Nagao, Michihiro ^[1]; Seto, Hideki ^[1]

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1. ORNL

The effect of an antagonistic salt on the phase behavior and nanoscale structure of a mixture of D{sub 2}O and 3-methylpyridine was investigated by visual inspection and small-angle neutron scattering (SANS). The addition of the antagonistic salt, namely sodium tetraphenylborate (NaBPh{sub 4}), 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.

• Research Organization: Oak Ridge National Laboratory (ORNL); High Flux Isotope Reactor
• Sponsoring Organization: ORNL LDRD Director's R&D; SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1004963
• Journal Information: Soft Matter, Journal Name: Soft Matter Journal Issue: 4 Vol. 7; ISSN 1744-683X
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
FLUCTUATIONS
MIXTURES
NEUTRONS
SCATTERING
SODIUM
SOLVENTS
WATER