Highly Swollen Lamellar Phases in the System Calcium Dodecyl Sulfate, Pentanol or Hexanol, and Water

Abstract

Calcium dodecyl sulfate (CDS) is insoluble both in water and in alcohols at room temperature. However, it can be dissolved up to high concentrations in mixtures of water and ethanol, propanol, or butanol. No liquid-crystalline phases are formed with ethanol and propanol at 25 °C but are observed with butanol at higher concentrations of CDS. With pentanol and hexanol, lamellar phases are observed, which can be swollen largely. Neutron scattering measurements of phases with a weight ratio CDS:hexanol ) 1:1 show stiff lamellae in the concentration range of 1.5-25 wt % CDS. The repeat distance grows linearly with dilution. The effective thickness for the hydrocarbon part of the lamellae decreases to some extent at high CDS concentrations.

Self-assembly of metal–ligand coordinated charged vesicles

“…Anionic surfactants with multi-valent metal counterions have high Krafft points which make them hardly dissolve in water and exhibit very simple phase behaviors in solution at room temperature. However, when they are mixed with nonionic surfactants or cosurfactants, the rich sequence of phases can be observed, forming diverse aggregates such as micelles, novel sponge phase (L 3 -phase), and the lamellar phase with high swollen capability [34][35][36][37][38]. The aggregation behaviors of Ca 2+ -surfactants with additives were reviewed by H Hoffmann et al [39 • ].…”

Novel morphologies and phase transformation of CaCO3 crystals formed in CDS and urea aqueous solution

“…Effects of concentration of urea on polymorph and morphology of CaCO 3 CDS behaves like a two-chain nonionic surfactant and can be dissolved in the mixture of water and n-pentanol, which an isotropic micellar phase is formed [18,19]. The Krafft point and the critical micellization concentration (CMC) of CDS were about 50 1C [20] and 1.0 Â 10 À 3 M [15], respectively.…”

Surfactant directed synthesis of calcium aluminum layered double hydroxides nanoplatelets

“…The process may be driven by the very low solubility constant (K sp ) of Ca(DDS) 2 (3.72 Â 10 À10 mol 3 l À3 at 25 C). 20 The water to surfactant ratio also has an influence on the rate of leaching and concomitant formation of Ca(DDS) 2 . Similar phenomena have been reported on the exfoliation of LDHs by post-synthesis methods such as ultrasonication technique.…”