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Depletion Interactions in Model Microemulsions

Zackrisson Oskolkova, Malin LU ; Andersson, Robert and Bergenholtz, Johan (2004) In Langmuir 20(8). p.3080-3089
Abstract
The effects of temperature changes and polymer addition on the behavior of droplet microemulsions of

nonionic surfactant, water, and decane are reported and analyzed within polymer depletion theory. Dilution

viscometry and dynamic light scattering were used to confirm that these microemulsions behave essentially

as hard-sphere dispersions, providing us with an ideal reference system. Addition of poly(ethylene glycol)

(PEG) lowers the emulsification failure boundary, where excess oil is expelled, which can be qualitatively

understood by an analysis of the available volume for the polymer. Sufficient addition of PEG causes a

fluid-fluid phase separation in qualitative accord with... (More)
The effects of temperature changes and polymer addition on the behavior of droplet microemulsions of

nonionic surfactant, water, and decane are reported and analyzed within polymer depletion theory. Dilution

viscometry and dynamic light scattering were used to confirm that these microemulsions behave essentially

as hard-sphere dispersions, providing us with an ideal reference system. Addition of poly(ethylene glycol)

(PEG) lowers the emulsification failure boundary, where excess oil is expelled, which can be qualitatively

understood by an analysis of the available volume for the polymer. Sufficient addition of PEG causes a

fluid-fluid phase separation in qualitative accord with experiments on mixtures of rigid colloidal hard

spheres and nonadsorbing polymer. Addition of PEG or raising the temperature causes the collective

diffusion coefficient DC to decrease. From theory, the initial linear slope of DC versus droplet concentration

can be used to discriminate between attractions and repulsions. The measured DC data for the droplets

in the presence of PEG are modeled using the Asakura-Oosawa theory of depletion. Fitting the theory

to the measured DC data permits for extracting the only unknown parameter, the polymer radius of

gyration. Quantitative agreement is found with literature data, demonstrating that polymer depletion

occurs in the system and that the Asakura-Oosawatheory provides a faithful description of the phenomenon. (Less)
Please use this url to cite or link to this publication:
author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
depletion interactions, microemulsions, hard sphere interactions, collective diffusion
in
Langmuir
volume
20
issue
8
pages
3080 - 3089
publisher
The American Chemical Society
external identifiers
  • scopus:2342432787
ISSN
0743-7463
DOI
10.1021/la036132y
language
English
LU publication?
no
id
21065006-d95d-4d10-aa8a-18716136ac7c (old id 3363698)
date added to LUP
2013-01-23 13:04:51
date last changed
2017-09-03 03:45:35
@article{21065006-d95d-4d10-aa8a-18716136ac7c,
  abstract     = {The effects of temperature changes and polymer addition on the behavior of droplet microemulsions of<br/><br>
nonionic surfactant, water, and decane are reported and analyzed within polymer depletion theory. Dilution<br/><br>
viscometry and dynamic light scattering were used to confirm that these microemulsions behave essentially<br/><br>
as hard-sphere dispersions, providing us with an ideal reference system. Addition of poly(ethylene glycol)<br/><br>
(PEG) lowers the emulsification failure boundary, where excess oil is expelled, which can be qualitatively<br/><br>
understood by an analysis of the available volume for the polymer. Sufficient addition of PEG causes a<br/><br>
fluid-fluid phase separation in qualitative accord with experiments on mixtures of rigid colloidal hard<br/><br>
spheres and nonadsorbing polymer. Addition of PEG or raising the temperature causes the collective<br/><br>
diffusion coefficient DC to decrease. From theory, the initial linear slope of DC versus droplet concentration<br/><br>
can be used to discriminate between attractions and repulsions. The measured DC data for the droplets<br/><br>
in the presence of PEG are modeled using the Asakura-Oosawa theory of depletion. Fitting the theory<br/><br>
to the measured DC data permits for extracting the only unknown parameter, the polymer radius of<br/><br>
gyration. Quantitative agreement is found with literature data, demonstrating that polymer depletion<br/><br>
occurs in the system and that the Asakura-Oosawatheory provides a faithful description of the phenomenon.},
  author       = {Zackrisson Oskolkova, Malin and Andersson, Robert and Bergenholtz, Johan},
  issn         = {0743-7463},
  keyword      = {depletion interactions,microemulsions,hard sphere interactions,collective diffusion},
  language     = {eng},
  number       = {8},
  pages        = {3080--3089},
  publisher    = {The American Chemical Society},
  series       = {Langmuir},
  title        = {Depletion Interactions in Model Microemulsions},
  url          = {http://dx.doi.org/10.1021/la036132y},
  volume       = {20},
  year         = {2004},
}