Solubilization of micellar cubic phases and their structural relationshipsin anionic-cationic surfactant-dodecane-water systems

Authors
Citation
Xf. Li et H. Kunieda, Solubilization of micellar cubic phases and their structural relationshipsin anionic-cationic surfactant-dodecane-water systems, LANGMUIR, 16(26), 2000, pp. 10092-10100
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
LANGMUIR
ISSN journal
0743-7463 → ACNP
Volume
16
Issue
26
Year of publication
2000
Pages
10092 - 10100
Database
ISI
SICI code
0743-7463(200012)16:26<10092:SOMCPA>2.0.ZU;2-K
Abstract
The morphology and solubilization of micellar cubic phases are investigated as a function of the cationic weight fraction in the mixture of two surfac tants, the surfactant-to-water ratio, and the oil weight fraction in the wa ter-dodecane-sodium dodecyl sulfate (SDS)-dodecyltrimethylammonium bromide (DTAB) or didodecyl-dimethylammonium bromide (DDAB) systems at 25 degreesC. One phase transition H-1 --> I-1 appears at low cationic weight fraction, Y, and the other L alpha --> I-1 takes place at high Y upon addition of oil . Solubilization for dodecane of the micellar solution and of the micellar cubic phase increases with an increase in the cationic surfactant weight fr action Y from 0 to 0.30. SAXS measurements index the structure of the cubic phase as the discontinuous Pm3n cubic phase for single surfactant systems and mixed surfactant systems at different levels of oil. The cross-sectiona l area of the hydrophilic head of the surfactant keeps constant with increa se in the oil weight fraction at a fixed cationic surfactant weight fractio n as the interlayer spacing of the Pm3n cubic phase greatly increases. Howe ver, it decreases with an increase in the cationic surfactant weight fracti on at fixed oil weight fraction as the interlayer spacing of the Pm3n cubic phase slowly increases. So the solubilization for oil can be increased by adjusting the mean curvature of the surfactant interface layer with the add ition of mixed surfactants and long-chain oil.