Vesicle formation and other structures in aqueous dispersions of monoolein and sodium oleate.
The macroscopic appearance and microstructure in the dilute corner of the ternary monoolein (MO)-sodium oleate (NaO)-water (2H2O) system have been investigated by visual inspection and by using direct structural imaging with light microscopy and cryogenic transmission electron microscopy. The microstructural transformations that take place between the micellar phase (binary NaO2H2O axis) and the dispersed cubic phase (binary MO2H2O axis) upon increasing the ratio of MO to NaO are micelles, ruptured multilamellar vesicles together with flexible threads, various vesicle structures, vesicles in equilibrium with densely packed layers that either represent bilayers or domains of H(II) tubes visible from the side, and finally a pattern that may be either a cubic phase or domains of H(II) tubes visible in a cross section. Spontaneously formed uni- and multilamellar vesicles that show long-term stability are found to be the dominant structure for mixed dispersions over almost the entire concentration range. The addition of NaOH to the non-bilayer-forming system, the ternary MOOA (oleic acid)-2H2O system, leads to the formation of vesicles. Vesicles were also observed in other ternary MO-aqueous-based systems with potassium oleate, cetyltrimethylammonium bromide, sodium taurodeoxycholate, or dipalmitoylphosphatidylcholine instead of NaO.
Borné
Johanna
J
Physical Chemistry 1, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
Nylander
Tommy
T
Khan
Ali
A
D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry; D020285:Cryoelectron Microscopy; D005989:Glycerides / Q000737:chemistry*; D008081:Liposomes / Q000138:chemical synthesis* / Q000737:chemistry; D008823:Micelles; D008859:Microscopy, Polarization; D019301:Oleic Acid / Q000737:chemistry*; D044367:Phase Transition; D012972:Sodium Hydroxide / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry; D013657:Taurodeoxycholic Acid / Q000737:chemistry; D014867:Water / Q000737:chemistry
D002593:Cetrimonium Compounds; D005989:Glycerides; D008081:Liposomes; D008823:Micelles; D013501:Surface-Active Agents; D014867:Water; D019301:Oleic Acid; C013173:osteum; D013657:Taurodeoxycholic Acid; D012972:Sodium Hydroxide; C005953:monoolein; D000077286:Cetrimonium