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On the ripening of vesicle dispersions

Olsson, Ulf LU and Wennerström, Håkan LU (2002) In The Journal of Physical Chemistry Part B 106(20). p.5135-5138
Abstract
We analyze the ripening process where, in a dispersion of vesicles, amphiphile monomers diffuse between vesicles of different sizes, leading to a change in the size distribution. Since, typically, vesicles are not under tension, the driving force for the process comes from the curvature energy. With the conventional expansion of the curvature energy density, g,, to harmonic order we find that the free energy change on adding a monomer is independent of vesicle radius. The monomer exchange is then a purely random process. By introducing corrections to the harmonic curvature energy, either by expanding g,, to fourth order in the curvatures, or by a term logarithmic in the vesicle size, one obtains a driving force for ripening. Depending on... (More)
We analyze the ripening process where, in a dispersion of vesicles, amphiphile monomers diffuse between vesicles of different sizes, leading to a change in the size distribution. Since, typically, vesicles are not under tension, the driving force for the process comes from the curvature energy. With the conventional expansion of the curvature energy density, g,, to harmonic order we find that the free energy change on adding a monomer is independent of vesicle radius. The monomer exchange is then a purely random process. By introducing corrections to the harmonic curvature energy, either by expanding g,, to fourth order in the curvatures, or by a term logarithmic in the vesicle size, one obtains a driving force for ripening. Depending on the correction, different scenarios are predicted. The fourth-order correction and a negative logarithmic correction term result in a ripening toward unimodal vesicle distribution around the mean vesicle size of the initial distribution. For a positive logarithmic correction term, on the other hand, the ripening by itself should result in the formation of many small vesicles and a few very big ones. The rate of the monomer redistribution is primarily determined by the magnitude of the thermodynamic driving force and by the monomer solubility. For vesicles formed by single chain surfactants we estimate that the size redistribution should occur at a measurable rate, providing an opportunity to experimentally study which correction to the leading curvature energy is most significant. (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
106
issue
20
pages
5135 - 5138
publisher
The American Chemical Society
external identifiers
  • wos:000175639300001
  • scopus:0037162193
ISSN
1520-5207
DOI
10.1021/jp0257101
language
English
LU publication?
yes
id
a8a5f57f-b7df-4ff0-bb83-0a45bc90b09b (old id 337534)
date added to LUP
2007-11-08 08:35:42
date last changed
2017-08-27 05:37:48
@article{a8a5f57f-b7df-4ff0-bb83-0a45bc90b09b,
  abstract     = {We analyze the ripening process where, in a dispersion of vesicles, amphiphile monomers diffuse between vesicles of different sizes, leading to a change in the size distribution. Since, typically, vesicles are not under tension, the driving force for the process comes from the curvature energy. With the conventional expansion of the curvature energy density, g,, to harmonic order we find that the free energy change on adding a monomer is independent of vesicle radius. The monomer exchange is then a purely random process. By introducing corrections to the harmonic curvature energy, either by expanding g,, to fourth order in the curvatures, or by a term logarithmic in the vesicle size, one obtains a driving force for ripening. Depending on the correction, different scenarios are predicted. The fourth-order correction and a negative logarithmic correction term result in a ripening toward unimodal vesicle distribution around the mean vesicle size of the initial distribution. For a positive logarithmic correction term, on the other hand, the ripening by itself should result in the formation of many small vesicles and a few very big ones. The rate of the monomer redistribution is primarily determined by the magnitude of the thermodynamic driving force and by the monomer solubility. For vesicles formed by single chain surfactants we estimate that the size redistribution should occur at a measurable rate, providing an opportunity to experimentally study which correction to the leading curvature energy is most significant.},
  author       = {Olsson, Ulf and Wennerström, Håkan},
  issn         = {1520-5207},
  language     = {eng},
  number       = {20},
  pages        = {5135--5138},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {On the ripening of vesicle dispersions},
  url          = {http://dx.doi.org/10.1021/jp0257101},
  volume       = {106},
  year         = {2002},
}