Mesoscopic structure in near-critical mixtures of D₂O and 3-methylpyridine with salts

Abstract

Small‐angle neutron scattering (SANS) experiments were performed on mixtures of 3‐methylpyridine, D2O, and salts to investigate concentration fluctuations and structures in the vicinity of the critical point. The SANS profiles of ternary mixtures with large critical temperature shifts can be analyzed by the sum of the concentration fluctuation and a scattering from spherical clusters. The size of the clusters increases as the critical point is approached. These results can be interpreted in terms of a strong coupling of the critical fluctuation and the solvation effect of salt ions.

Local theory for ions in binary liquid mixtures

“…[31] for water+2,6-dimethylpyridine and Ref. [14] for heavy water+3-methylpyridine). Moreover, the measured critical point shifts exhibit a strong dependence on the size of the ions (compare Ref.…”

Solvation and Dissociation in Weakly Ionized Polyelectrolytes

“…It is worth noting that the scattering amplitude was maximum at q = 0 upon addition of NaCl, KCl, etc. in the same mixture D 2 O-3MP 35 . These salts consist of hydrophilic anions and cations with g 1 ∼ g 2 , so γ p should be much smaller leading to no mesophase formation.…”

Mesoscale phenomena in solutions of 3-methylpyridine, heavy water, and an antagonistic salt

“…In these works, a number of different effects were reported: (i) When a hydrophilic salt, such as LiCl (lithium chloride) or NaBr, was added mesoscale structures (order of 100 nm in size) were observed. These structures were interpreted as either lamellar or spherical structures, depending on the nature and concentration of the salt 23,25 . (ii) When small amounts (5 mmol/L) of an amphiphilic salt (also known as "antagonistic salt"), such as sodium tetraphenylborate (NaBPh 4 ) or tetraphenylphosphonium chloride (PPh 4 Cl), were added to 3MP-D 2 O solutions, a periodic structure was observed (with a typical periodicity of 10 nm) 24,26 .…”