Magnesium and calcium surfactants Ternary phase diagrams of magnesium and calcium dodecylsulphate with decanol and water

Abstract

The isothermal ternary phase diagrams for the systems magnesium dodecylsulphate-decanol-water at 40 ~ and calcium dodecylsulphate-decanol-water at 50 ~ are determined by water deuteron NMR and polarizing microscopic studies. In the magnesium system, three liquid crystalline phases (lameUar and normal and reverse hexagonal) and two isotropic (normal and reverse) solution phases are characterized and their ranges of existence are obtained. The calcium system yields the same liquid crystalline phases, but only the lamellar liquid crystalline phase is investigated in detail. The important observations made are: (i) The lamellar liquid crystalline phase for the magnesium and calcium systems can incorporate, respectively, a maximum of 22.5 and 14.3 mole water per mole surfactant ion against 139 mole water for the corresponding sodium system. (ii) The reverse hexagonal liquid crystalline phase is formed for both the magnesium and calcium systems while no such liquid crystalline phase exists for the corresponding sodium system. (iii) The 2H NMR quadrupole splittings obtained in the liquid crystalline phases for C8SO4 and C12SO4 surfactant systems with different counterions (Ca 2 +, Mg 2+, Be 2 +, Na +) reveal that surfactant hydration is almost independent of alkyl chain length and counterions.

Sodium and Calcium Laurylamidomethylsulfate: Aqueous Micellar Phases, Their Properties, and a Precipitate of Vesicles

“…Here, however, extensive searches were unsuccessful. Lindman et al (24)(25)(26)(27) searched for swollen lamellar phases in the system Ca(DS) 2 (and Mg(DS) 2 ), decanol, and water, but found none. Similarly, Sein et al (28) investigated sulfonate-based surfactants with bivalent counterions and also found no swollen lamellar phases.…”

Novel Vesicles from Single-Chain Surfactants

“…Nevertheless, compensation of the charges at the interface is not sufficient for the pure system to form a L α -phase in dilute solution. It is likely that the system cannot form bilayers on its own because the steric repulsion between the bulky sulfate groups is too large and does not allow the dense packing in the dilute phase that is required for the formation of the L α -phase. , It is only when the repulsion between the headgroups is reduced by the incorporation of an alkyldimethylaminoxide when the formation becomes possible. It is suggested, therefore, that the large observed synergism between Ca(DS) 2 and C 14 DMAO has its origin in the bulkiness of the sulfate headgroups.…”

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

“…Swelling is expected not to occur due to electrostatic consideration. 1,17 The discussed additional ion-ion correlation-attraction should prevent swelling even more. It is an important observation that mixtures of SDS with CDS are able to form swelling phases in decanol and water.…”

“…18 Similar results have been found with magnesium dodecyl sulfate/decanol/water. 1 At 50 °C, lamellar phases at high CDS concentrations have been described in the system CDS/decanol/water. 1 It is well-known that sodium dodecyl sulfate (SDS) forms swollen lamellar phases in water at room temperature when pentanol and hexanol are added.…”

“…1 At 50 °C, lamellar phases at high CDS concentrations have been described in the system CDS/decanol/water. 1 It is well-known that sodium dodecyl sulfate (SDS) forms swollen lamellar phases in water at room temperature when pentanol and hexanol are added. The system with pentanol has been studied most intensively.…”