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Potential Determining Salts in Microemulsions: Interfacial Distribution and Effect on the Phase Behavior

Johans, Christoffer ; Behrens, Manja LU ; Bergquist, Karl-Erik LU ; Olsson, Ulf LU and Manzanares, Jose A. (2013) In Langmuir 29(51). p.15738-15746
Abstract
In this work we consider potential determining salts, also referred to as phase transfer agents for a future objective of electrochemistry at the oil-water interface in microemulsions. We have studied these salts, composed of a hydrophilic and a hydrophobic ion, in microemulsion stabilized by nonionic surfactants with an oligo ethylene oxide headgroup. NMR measurements show that the salts preferentially dissociate across the surfactant interface between the oil and water domains, and hence create a potential drop across the surfactant film, and back to back diffuse double layers in the oil and water phases. These observations are also supported by Poisson-Boltzmann calculations. This adsorption like event stabilizes the microemulsion.... (More)
In this work we consider potential determining salts, also referred to as phase transfer agents for a future objective of electrochemistry at the oil-water interface in microemulsions. We have studied these salts, composed of a hydrophilic and a hydrophobic ion, in microemulsion stabilized by nonionic surfactants with an oligo ethylene oxide headgroup. NMR measurements show that the salts preferentially dissociate across the surfactant interface between the oil and water domains, and hence create a potential drop across the surfactant film, and back to back diffuse double layers in the oil and water phases. These observations are also supported by Poisson-Boltzmann calculations. This adsorption like event stabilizes the microemulsion. Repulsive long-range interactions between thin lamellae of surfactant and water lamellae in oil were observed using SAXS, thus confirming the presence of electrostatic forces mediated through the oil domain. We also observed that reversing the charges on the potential determining salts had opposite effects on the phase inversion temperature. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Langmuir
volume
29
issue
51
pages
15738 - 15746
publisher
The American Chemical Society (ACS)
external identifiers
  • wos:000329137000003
  • scopus:84896536156
ISSN
0743-7463
DOI
10.1021/la404263v
language
English
LU publication?
yes
id
48b4c9c9-2a28-4059-ba60-20bbddf67f75 (old id 4255930)
date added to LUP
2016-04-01 10:46:23
date last changed
2020-03-18 01:23:47
@article{48b4c9c9-2a28-4059-ba60-20bbddf67f75,
  abstract     = {In this work we consider potential determining salts, also referred to as phase transfer agents for a future objective of electrochemistry at the oil-water interface in microemulsions. We have studied these salts, composed of a hydrophilic and a hydrophobic ion, in microemulsion stabilized by nonionic surfactants with an oligo ethylene oxide headgroup. NMR measurements show that the salts preferentially dissociate across the surfactant interface between the oil and water domains, and hence create a potential drop across the surfactant film, and back to back diffuse double layers in the oil and water phases. These observations are also supported by Poisson-Boltzmann calculations. This adsorption like event stabilizes the microemulsion. Repulsive long-range interactions between thin lamellae of surfactant and water lamellae in oil were observed using SAXS, thus confirming the presence of electrostatic forces mediated through the oil domain. We also observed that reversing the charges on the potential determining salts had opposite effects on the phase inversion temperature.},
  author       = {Johans, Christoffer and Behrens, Manja and Bergquist, Karl-Erik and Olsson, Ulf and Manzanares, Jose A.},
  issn         = {0743-7463},
  language     = {eng},
  number       = {51},
  pages        = {15738--15746},
  publisher    = {The American Chemical Society (ACS)},
  series       = {Langmuir},
  title        = {Potential Determining Salts in Microemulsions: Interfacial Distribution and Effect on the Phase Behavior},
  url          = {http://dx.doi.org/10.1021/la404263v},
  doi          = {10.1021/la404263v},
  volume       = {29},
  year         = {2013},
}