Effect of Inorganic Salts on the Phase Behavior of an Aqueous Mixture of Heptaethylene Glycol Dodecyl Ether

Abstract

The effect of LiCl, NaCl, and CsCl on the phase behavior of an aqueous mixture of heptaethylene glycol dodecyl ether (C12E7) was investigated by means of differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), and Fourier transform infrared (FT-IR) spectroscopy. Phase diagrams for the mixtures containing the inorganic salts with a concentration of 1.0 M were constructed on the basis of the DSC experiments. The addition of the salts induced an expansion of the lamellar (Lα) phase region toward higher temperatures and a shrinkage of the normal hexagonal (H1) and the bicontinuous cubic (V1) phase regions toward lower temperatures. The effectiveness of the salt species followed the sequence of CsCl < NaCl < LiCl for the expansion of the Lα phase region and of LiCl < CsCl ≤ NaCl for the shrinkage of the H1 and V1 phase regions. The influence of different salts on the phase behavior of the mixture is qualitatively interpreted in terms of the hydration of ions. The SAXS and FT-IR results revealed the salt effect on the molecular assemblies in the Lα phase and H1 phase and on the conformational changes of the surfactant molecules in the two mesophases, respectively.

A New, Highly Conductive, Lithium Salt/Nonionic Surfactant, Lyotropic Liquid‐Crystalline Mesophase and Its Application

“…The mesophase is a collaborative assembly of a hydrated salt species in the liquid phase and surfactant molecules. Earlier studies on salt–water–surfactant mesophases focus on the effect of salts on the phase behavior of surfactants in dilute aqueous solutions (18–∞, water/salt mole ratio) 21–26. Here, we demonstrate that as little as two water molecules per molecule of lithium salt is sufficient to form a LLC mesophase.…”

Hofmeister anion effect on aqueous phase behavior of heptaethylene glycol dodecyl ether

“…In a previous work [12], we investigated the influence of a series of alkali chlorides on the phase behavior of an aqueous mixture of heptaethylene glycol dodecyl ether (C 12 E 7 ), where it was found that the area of mesophase regions varies depending on the cation species, and this salt dependence is correlated to the viscosity B-coefficient of the cation species, which is a measure of the water-structuremaking potency of the ions. In the present study, we focused our attention on the effect of anion species, in particular chaotropic anions, on the mesophase regions formed in an aqueous C 12 E 7 mixture.…”

Lyotropic Behavior of a Mono-tailed Glycolipid Assembly during Solidification and Melting of Electrolyte/Ice Eutectic Systems

“…14) Moreover, Zheng et al have reported that heptaethylene glycol ether liquid crystalline systems readily solidify in the presence of eutectic composition. 18) Therefore, the cooperative changes in the aggregation state upon solidification and melting of eutectic demonstrate the attractive freeze tolerance of glycolipids with a sugar ring as their hydrophilic component.…”

“…Owing to the attractive hydration property of the sugar moiety, the β-OGlu assembly exhibits lyotropic behavior from micelle solution, depending on its concentration, which was regulated by the temperature, even under competition with the solidification of eutectic, which often induce the significant dehydration of lipids. 14,18) Such attractive freeze tolerance properties that persist a lyotropic behavior without precipitating a crystalline are expected to contribute as the stabilizing containers to the preservation of water-insoluble drugs and membrane proteins under arid conditions.…”