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Driving forces of phase transitions in surfactant and lipid systems

Kocherbitov, Vitaly LU (2005) In The Journal of Physical Chemistry Part B 109(13). p.6430-6435
Abstract
In aqueous surfactant and lipid systems, different liquid crystalline phases are formed at different temperatures and water contents. The "natural" phase sequence implies that phases with higher curvature are formed at higher water contents. On the other hand, there are exceptions to this rule, such as the monoolein/water system. In this system an anomalous transition from lamellar to reverse cubic phase upon addition of water is observed. The calorimetric data presented here show that the hydration-induced transitions to phases with higher curvature are driven by enthalpy, while the transitions to phases with lower curvature are driven by entropy. It is shown that the driving forces of phase transitions can be determined from the... (More)
In aqueous surfactant and lipid systems, different liquid crystalline phases are formed at different temperatures and water contents. The "natural" phase sequence implies that phases with higher curvature are formed at higher water contents. On the other hand, there are exceptions to this rule, such as the monoolein/water system. In this system an anomalous transition from lamellar to reverse cubic phase upon addition of water is observed. The calorimetric data presented here show that the hydration-induced transitions to phases with higher curvature are driven by enthalpy, while the transitions to phases with lower curvature are driven by entropy. It is shown that the driving forces of phase transitions can be determined from the appearance of the phase diagram using the approach based on van der Waals differential equation. From this approach it follows that the slope of the phase boundary should be positive with respect to water content if the phase diagram obeys the "natural" phase sequence. The increase of entropy, which drives the anomalous phase transitions, arises from the increase of disorder of the hydrocarbon chains. (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
The Journal of Physical Chemistry Part B
volume
109
issue
13
pages
6430 - 6435
publisher
The American Chemical Society
external identifiers
  • wos:000228111200056
  • scopus:17044368359
ISSN
1520-5207
DOI
10.1021/jp045555l
language
English
LU publication?
yes
id
21b79279-5a47-4a25-b028-614836e419f9 (old id 157425)
date added to LUP
2007-07-11 14:39:45
date last changed
2017-05-14 04:14:51
@article{21b79279-5a47-4a25-b028-614836e419f9,
  abstract     = {In aqueous surfactant and lipid systems, different liquid crystalline phases are formed at different temperatures and water contents. The "natural" phase sequence implies that phases with higher curvature are formed at higher water contents. On the other hand, there are exceptions to this rule, such as the monoolein/water system. In this system an anomalous transition from lamellar to reverse cubic phase upon addition of water is observed. The calorimetric data presented here show that the hydration-induced transitions to phases with higher curvature are driven by enthalpy, while the transitions to phases with lower curvature are driven by entropy. It is shown that the driving forces of phase transitions can be determined from the appearance of the phase diagram using the approach based on van der Waals differential equation. From this approach it follows that the slope of the phase boundary should be positive with respect to water content if the phase diagram obeys the "natural" phase sequence. The increase of entropy, which drives the anomalous phase transitions, arises from the increase of disorder of the hydrocarbon chains.},
  author       = {Kocherbitov, Vitaly},
  issn         = {1520-5207},
  language     = {eng},
  number       = {13},
  pages        = {6430--6435},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {Driving forces of phase transitions in surfactant and lipid systems},
  url          = {http://dx.doi.org/10.1021/jp045555l},
  volume       = {109},
  year         = {2005},
}