Advanced

Phase behavior of the lecithin/water/isooctane and lecithin/water/decane systems

Angelico, R; Ceglie, A; Colafemmina, G; Delfine, F; Olsson, Ulf LU and Palazzo, G (2004) In Langmuir 20(3). p.619-631
Abstract
The isothermal pseudo-ternary-phase diagram was determined at 25 degreesC for systems composed of lecithin, water, and, as oil, either isooctane or decane. This was accomplished by a combination of polarizing microscopy, small-angle X-ray scattering, and NMR techniques. The lecithin-rich region of the phase diagram is dominated by a lamellar liquid-crystalline phase (L-alpha). For lecithin contents less than 60% and low hydration (mole ratio water/lecithin = W-0 < 5.5), the system forms a viscous gel of branched cylindrical reverse micelles. With increase in the water content, the system phase separates into two phases, which is either gel in equilibrium with essentially pure isooctane (for lecithin < 25%) or a gel in equilibrium... (More)
The isothermal pseudo-ternary-phase diagram was determined at 25 degreesC for systems composed of lecithin, water, and, as oil, either isooctane or decane. This was accomplished by a combination of polarizing microscopy, small-angle X-ray scattering, and NMR techniques. The lecithin-rich region of the phase diagram is dominated by a lamellar liquid-crystalline phase (L-alpha). For lecithin contents less than 60% and low hydration (mole ratio water/lecithin = W-0 < 5.5), the system forms a viscous gel of branched cylindrical reverse micelles. With increase in the water content, the system phase separates into two phases, which is either gel in equilibrium with essentially pure isooctane (for lecithin < 25%) or a gel in equilibrium with L-alpha, (for lecithin > 25%). These two-phase regions are very thin with respect to water dilution. For 8 < W-0 < 54 very stable water-in-oil emulsions form. It is only after ripening for more than I year that the large region occupied by the emulsion reveals a complex pattern of stable phases. Moving along water dilution lines, one finds (i) the coexistence of gel, isooctane and L-alpha,(ii) equilibrium between reverse micelles and spherulites, and, finally, (iii) disconnected reverse micelles that fail to solubilize water for W-0 > 54. This results in a Winsor II phase equilibrium at low lecithin content, while for lecithin > 20% the neat water is in equilibrium with a reverse hexagonal phase and an isotropic liquid-crystalline phase. The use of the decane as oil does not change the main features of the phase behavior. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Langmuir
volume
20
issue
3
pages
619 - 631
publisher
The American Chemical Society
external identifiers
  • wos:000188660600016
  • pmid:15773084
  • scopus:1342284985
ISSN
0743-7463
DOI
10.1021/la035603d
language
English
LU publication?
yes
id
e872a90c-6918-4352-99e6-13e0f7955ce8 (old id 153885)
date added to LUP
2007-07-10 16:23:00
date last changed
2017-10-08 03:39:19
@article{e872a90c-6918-4352-99e6-13e0f7955ce8,
  abstract     = {The isothermal pseudo-ternary-phase diagram was determined at 25 degreesC for systems composed of lecithin, water, and, as oil, either isooctane or decane. This was accomplished by a combination of polarizing microscopy, small-angle X-ray scattering, and NMR techniques. The lecithin-rich region of the phase diagram is dominated by a lamellar liquid-crystalline phase (L-alpha). For lecithin contents less than 60% and low hydration (mole ratio water/lecithin = W-0 &lt; 5.5), the system forms a viscous gel of branched cylindrical reverse micelles. With increase in the water content, the system phase separates into two phases, which is either gel in equilibrium with essentially pure isooctane (for lecithin &lt; 25%) or a gel in equilibrium with L-alpha, (for lecithin &gt; 25%). These two-phase regions are very thin with respect to water dilution. For 8 &lt; W-0 &lt; 54 very stable water-in-oil emulsions form. It is only after ripening for more than I year that the large region occupied by the emulsion reveals a complex pattern of stable phases. Moving along water dilution lines, one finds (i) the coexistence of gel, isooctane and L-alpha,(ii) equilibrium between reverse micelles and spherulites, and, finally, (iii) disconnected reverse micelles that fail to solubilize water for W-0 &gt; 54. This results in a Winsor II phase equilibrium at low lecithin content, while for lecithin &gt; 20% the neat water is in equilibrium with a reverse hexagonal phase and an isotropic liquid-crystalline phase. The use of the decane as oil does not change the main features of the phase behavior.},
  author       = {Angelico, R and Ceglie, A and Colafemmina, G and Delfine, F and Olsson, Ulf and Palazzo, G},
  issn         = {0743-7463},
  language     = {eng},
  number       = {3},
  pages        = {619--631},
  publisher    = {The American Chemical Society},
  series       = {Langmuir},
  title        = {Phase behavior of the lecithin/water/isooctane and lecithin/water/decane systems},
  url          = {http://dx.doi.org/10.1021/la035603d},
  volume       = {20},
  year         = {2004},
}