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Ellipsometry studies of nonionic surfactant adsorption at the oil-water interface

Benjamins, Jan-Willem LU ; Thuresson, Krister LU and Nylander, Tommy LU (2005) In Langmuir 21(1). p.149-159
Abstract
In the presented study we have developed and implemented a methodology for ellipsometry measurements at liquid interfaces that makes it possible to determine the amount adsorbed without assumptions of refractive index or thickness of the adsorbed layer. It was demonstrated that this is possible by combined measurements from different aqueous phases, H2O and D2O, which were shown to have sufficiently different refractive indices. The methodology was tested by studying adsorption of two types of nonionic poly(ethylene glycol) alkyl ether surfactants, CnH2n+1(OC2H4)(m)OH or CnEm at the decane-aqueous interface, where C12E5 was adsorbed from the oil phase and C18E50 from the aqueous phase. The observed plateau values of the adsorbed amounts... (More)
In the presented study we have developed and implemented a methodology for ellipsometry measurements at liquid interfaces that makes it possible to determine the amount adsorbed without assumptions of refractive index or thickness of the adsorbed layer. It was demonstrated that this is possible by combined measurements from different aqueous phases, H2O and D2O, which were shown to have sufficiently different refractive indices. The methodology was tested by studying adsorption of two types of nonionic poly(ethylene glycol) alkyl ether surfactants, CnH2n+1(OC2H4)(m)OH or CnEm at the decane-aqueous interface, where C12E5 was adsorbed from the oil phase and C18E50 from the aqueous phase. The observed plateau values of the adsorbed amounts were 1.38 and 0.93 Mg/M-2 for C12E5 and C18E50, respectively, which is in agreement with the corresponding values of 1.49 and 1.15 Mg/M-2 obtained from applying the Gibbs equation to interfacial tension data for the same systems. We will briefly discuss the adsorption behavior in relation to the molecular structure of the surfactant and the phase behavior of the oil - surfactant- aqueous systems in relation to our experimental results. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Langmuir
volume
21
issue
1
pages
149 - 159
publisher
The American Chemical Society
external identifiers
  • wos:000226232700021
  • pmid:15620296
  • scopus:11844274629
ISSN
0743-7463
DOI
10.1021/la049848h
language
English
LU publication?
yes
id
869cdb3f-a13b-4f70-a4aa-5f9d7eb520dd (old id 157200)
date added to LUP
2007-07-10 17:12:16
date last changed
2017-08-13 03:43:21
@article{869cdb3f-a13b-4f70-a4aa-5f9d7eb520dd,
  abstract     = {In the presented study we have developed and implemented a methodology for ellipsometry measurements at liquid interfaces that makes it possible to determine the amount adsorbed without assumptions of refractive index or thickness of the adsorbed layer. It was demonstrated that this is possible by combined measurements from different aqueous phases, H2O and D2O, which were shown to have sufficiently different refractive indices. The methodology was tested by studying adsorption of two types of nonionic poly(ethylene glycol) alkyl ether surfactants, CnH2n+1(OC2H4)(m)OH or CnEm at the decane-aqueous interface, where C12E5 was adsorbed from the oil phase and C18E50 from the aqueous phase. The observed plateau values of the adsorbed amounts were 1.38 and 0.93 Mg/M-2 for C12E5 and C18E50, respectively, which is in agreement with the corresponding values of 1.49 and 1.15 Mg/M-2 obtained from applying the Gibbs equation to interfacial tension data for the same systems. We will briefly discuss the adsorption behavior in relation to the molecular structure of the surfactant and the phase behavior of the oil - surfactant- aqueous systems in relation to our experimental results.},
  author       = {Benjamins, Jan-Willem and Thuresson, Krister and Nylander, Tommy},
  issn         = {0743-7463},
  language     = {eng},
  number       = {1},
  pages        = {149--159},
  publisher    = {The American Chemical Society},
  series       = {Langmuir},
  title        = {Ellipsometry studies of nonionic surfactant adsorption at the oil-water interface},
  url          = {http://dx.doi.org/10.1021/la049848h},
  volume       = {21},
  year         = {2005},
}