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Microscopy, SAXD, and NMR studies of phase behavior of the monoolein-diolein-water system

Borné, Johanna LU ; Nylander, Tommy LU and Khan, Ali LU (2000) In Langmuir 16(26). p.10044-10054
Abstract
The phase behavior of the ternary monoolein (MO)-diolein (DO)-water ((H2O)-H-2) system is presented. The experimental phase behavior and microstructure are studied by a combination of polarizing microscopy, small-angle X-ray diffraction, and NMR methods. Monoolein forms extensive reversed bicontinuous cubic liquid crystalline phases (C) that are in equilibrium with a lamellar liquid crystalline phase (L-alpha) on the water-poor side and with excess water on the other side. The presence of small amounts of DO in the MO-water system is sufficient to destabilize the C and L-alpha liquid crystalline phases. Formation of a reversed hexagonal (HII) phase from the cubic phase occurs at a lower transition temperature than that reported for the... (More)
The phase behavior of the ternary monoolein (MO)-diolein (DO)-water ((H2O)-H-2) system is presented. The experimental phase behavior and microstructure are studied by a combination of polarizing microscopy, small-angle X-ray diffraction, and NMR methods. Monoolein forms extensive reversed bicontinuous cubic liquid crystalline phases (C) that are in equilibrium with a lamellar liquid crystalline phase (L-alpha) on the water-poor side and with excess water on the other side. The presence of small amounts of DO in the MO-water system is sufficient to destabilize the C and L-alpha liquid crystalline phases. Formation of a reversed hexagonal (HII) phase from the cubic phase occurs at a lower transition temperature than that reported for the MO-water system. Within the cubic region, the diamond cubic phase, CD, is less stable than the gyroid type, C-G. The solubility of DO increases within this phase when the MO content increases, and the phase reaches its maximum stability at 4 wt % DO. The large HII-phase formed in the ternary system is in equilibrium with water, and it solubilizes about 30 wt % DO within its stability range. A stable dispersion is formed at even higher DO concentrations. An ideal swelling of the HII-phase with increasing polar volume fraction is observed, whereas the length of the hydrocarbon chains along the hexagonal faces is constant. We measure a slight change of the average area per molecule in the H-II-phase with DO concentration. The formation and stability of the liquid crystalline phases can be qualitatively understood from the self-aggregation model, using the geometrical packing parameter of the lipids. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Langmuir
volume
16
issue
26
pages
10044 - 10054
publisher
The American Chemical Society
external identifiers
  • wos:000166161700016
  • scopus:0034514818
ISSN
0743-7463
DOI
10.1021/la000619e
language
English
LU publication?
yes
id
7c2e1306-8911-457f-a46d-8d36bcfcd42d (old id 7508751)
date added to LUP
2015-07-01 08:23:42
date last changed
2017-08-27 04:25:14
@article{7c2e1306-8911-457f-a46d-8d36bcfcd42d,
  abstract     = {The phase behavior of the ternary monoolein (MO)-diolein (DO)-water ((H2O)-H-2) system is presented. The experimental phase behavior and microstructure are studied by a combination of polarizing microscopy, small-angle X-ray diffraction, and NMR methods. Monoolein forms extensive reversed bicontinuous cubic liquid crystalline phases (C) that are in equilibrium with a lamellar liquid crystalline phase (L-alpha) on the water-poor side and with excess water on the other side. The presence of small amounts of DO in the MO-water system is sufficient to destabilize the C and L-alpha liquid crystalline phases. Formation of a reversed hexagonal (HII) phase from the cubic phase occurs at a lower transition temperature than that reported for the MO-water system. Within the cubic region, the diamond cubic phase, CD, is less stable than the gyroid type, C-G. The solubility of DO increases within this phase when the MO content increases, and the phase reaches its maximum stability at 4 wt % DO. The large HII-phase formed in the ternary system is in equilibrium with water, and it solubilizes about 30 wt % DO within its stability range. A stable dispersion is formed at even higher DO concentrations. An ideal swelling of the HII-phase with increasing polar volume fraction is observed, whereas the length of the hydrocarbon chains along the hexagonal faces is constant. We measure a slight change of the average area per molecule in the H-II-phase with DO concentration. The formation and stability of the liquid crystalline phases can be qualitatively understood from the self-aggregation model, using the geometrical packing parameter of the lipids.},
  author       = {Borné, Johanna and Nylander, Tommy and Khan, Ali},
  issn         = {0743-7463},
  language     = {eng},
  number       = {26},
  pages        = {10044--10054},
  publisher    = {The American Chemical Society},
  series       = {Langmuir},
  title        = {Microscopy, SAXD, and NMR studies of phase behavior of the monoolein-diolein-water system},
  url          = {http://dx.doi.org/10.1021/la000619e},
  volume       = {16},
  year         = {2000},
}