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Microemulsions of Record Low Amphiphile Concentrations Are Affected by the Ambient Gravitational Field

Ishikawa, Kazuhiro; Behrens, Manja LU ; Eriksson, Stefanie LU ; Topgaard, Daniel LU ; Olsson, Ulf LU and Wennerström, Håkan LU (2016) In The Journal of Physical Chemistry Part B 120(26). p.6074-6079
Abstract

It is shown that the ternary system heavy water-heptane-hexadecyl hexaethylene oxide (C16E6) has a stable bicontinuous microemulsion phase down to an exceptionally low concentration at the balanced temperature of 26.8 °C. It is further demonstrated that the ambient gravitational field has an influence on the observed phase equilibria for typical sample sizes (∼1 cm). Direct measurements using a nuclear magnetic resonance imaging technique demonstrate that sample compositions vary with the height in the vials. It is furthermore found that some samples show four phases at equilibrium in apparent violation of Gibbs' phase rule. It is pointed out that Gibbs' phase rule strictly applies only when effects of gravity are... (More)

It is shown that the ternary system heavy water-heptane-hexadecyl hexaethylene oxide (C16E6) has a stable bicontinuous microemulsion phase down to an exceptionally low concentration at the balanced temperature of 26.8 °C. It is further demonstrated that the ambient gravitational field has an influence on the observed phase equilibria for typical sample sizes (∼1 cm). Direct measurements using a nuclear magnetic resonance imaging technique demonstrate that sample compositions vary with the height in the vials. It is furthermore found that some samples show four phases at equilibrium in apparent violation of Gibbs' phase rule. It is pointed out that Gibbs' phase rule strictly applies only when effects of gravity are negligible. A further consequence of the ambient gravitational field is that, for the system studied, the microemulsion one-phase samples are not observed, when using standard size vials, that is, sample heights on the order of a centimeter. Quantitative determinations of concentration profiles can be used to determine parameters of the free-energy density for the system.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part B
volume
120
issue
26
pages
6 pages
publisher
The American Chemical Society
external identifiers
  • Scopus:84978062287
ISSN
1520-6106
DOI
10.1021/acs.jpcb.6b02041
language
English
LU publication?
yes
id
914b2e3b-9b3c-476c-81a7-a1c65a8b9092
date added to LUP
2016-07-26 09:57:28
date last changed
2016-09-20 03:06:57
@misc{914b2e3b-9b3c-476c-81a7-a1c65a8b9092,
  abstract     = {<p>It is shown that the ternary system heavy water-heptane-hexadecyl hexaethylene oxide (C<sub>16</sub>E<sub>6</sub>) has a stable bicontinuous microemulsion phase down to an exceptionally low concentration at the balanced temperature of 26.8 °C. It is further demonstrated that the ambient gravitational field has an influence on the observed phase equilibria for typical sample sizes (∼1 cm). Direct measurements using a nuclear magnetic resonance imaging technique demonstrate that sample compositions vary with the height in the vials. It is furthermore found that some samples show four phases at equilibrium in apparent violation of Gibbs' phase rule. It is pointed out that Gibbs' phase rule strictly applies only when effects of gravity are negligible. A further consequence of the ambient gravitational field is that, for the system studied, the microemulsion one-phase samples are not observed, when using standard size vials, that is, sample heights on the order of a centimeter. Quantitative determinations of concentration profiles can be used to determine parameters of the free-energy density for the system.</p>},
  author       = {Ishikawa, Kazuhiro and Behrens, Manja and Eriksson, Stefanie and Topgaard, Daniel and Olsson, Ulf and Wennerström, Håkan},
  issn         = {1520-6106},
  language     = {eng},
  month        = {07},
  number       = {26},
  pages        = {6074--6079},
  publisher    = {ARRAY(0x9c32910)},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {Microemulsions of Record Low Amphiphile Concentrations Are Affected by the Ambient Gravitational Field},
  url          = {http://dx.doi.org/10.1021/acs.jpcb.6b02041},
  volume       = {120},
  year         = {2016},
}