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Effects of Bulk Colloidal Stability on Adsorption Layers of Poly(diallyldimethylammonium Chloride)/Sodium Dodecyl Sulfate at the Air-Water Interface Studied by Neutron Reflectometry

Campbell, Richard A.; Yanez, Marianna LU ; Angus-Smyth, Anna; Nylander, Tommy LU and Varga, Imre (2011) In The Journal of Physical Chemistry Part B 115(51). p.15202-15213
Abstract
We show for the oppositely charged system poly(diallyldimethylammonium chloride)/sodium dodecyl sulfate that the cliff edge peak in its surface tension isotherm results from the comprehensive precipitation of bulk complexes into sediment, leaving a supernatant that is virtually transparent and a depleted adsorption layer at the air/water interface. The aggregation and settling processes take about 3 days to reach completion and occur at bulk compositions around charge neutrality of the complexes which lack long-term colloidal stability. We demonstrate excellent quantitative agreement between the measured surface tension values and a peak calculated from the surface excess of surfactant in the precipitation region measured by neutron... (More)
We show for the oppositely charged system poly(diallyldimethylammonium chloride)/sodium dodecyl sulfate that the cliff edge peak in its surface tension isotherm results from the comprehensive precipitation of bulk complexes into sediment, leaving a supernatant that is virtually transparent and a depleted adsorption layer at the air/water interface. The aggregation and settling processes take about 3 days to reach completion and occur at bulk compositions around charge neutrality of the complexes which lack long-term colloidal stability. We demonstrate excellent quantitative agreement between the measured surface tension values and a peak calculated from the surface excess of surfactant in the precipitation region measured by neutron reflectometry, using the approximation that there is no polymer left in the liquid phase. The nonequilibrium nature of the system is emphasized by the production of very different interfacial properties from equivalent aged samples that are handled differently. We go on to outline our perspective on the "true equilibrium" state of this intriguing system and conclude with a comment on its practical relevance given that the interfacial properties can be so readily influenced by the handling of kinetically trapped bulk aggregates. (Less)
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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
115
issue
51
pages
15202 - 15213
publisher
The American Chemical Society
external identifiers
  • wos:000298214700008
  • scopus:84255191238
ISSN
1520-5207
DOI
10.1021/jp2088803
language
English
LU publication?
yes
id
eb50a468-d09f-49b9-8d3f-938ae91cf72c (old id 2316190)
date added to LUP
2012-02-07 08:57:41
date last changed
2017-10-01 04:23:53
@article{eb50a468-d09f-49b9-8d3f-938ae91cf72c,
  abstract     = {We show for the oppositely charged system poly(diallyldimethylammonium chloride)/sodium dodecyl sulfate that the cliff edge peak in its surface tension isotherm results from the comprehensive precipitation of bulk complexes into sediment, leaving a supernatant that is virtually transparent and a depleted adsorption layer at the air/water interface. The aggregation and settling processes take about 3 days to reach completion and occur at bulk compositions around charge neutrality of the complexes which lack long-term colloidal stability. We demonstrate excellent quantitative agreement between the measured surface tension values and a peak calculated from the surface excess of surfactant in the precipitation region measured by neutron reflectometry, using the approximation that there is no polymer left in the liquid phase. The nonequilibrium nature of the system is emphasized by the production of very different interfacial properties from equivalent aged samples that are handled differently. We go on to outline our perspective on the "true equilibrium" state of this intriguing system and conclude with a comment on its practical relevance given that the interfacial properties can be so readily influenced by the handling of kinetically trapped bulk aggregates.},
  author       = {Campbell, Richard A. and Yanez, Marianna and Angus-Smyth, Anna and Nylander, Tommy and Varga, Imre},
  issn         = {1520-5207},
  language     = {eng},
  number       = {51},
  pages        = {15202--15213},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {Effects of Bulk Colloidal Stability on Adsorption Layers of Poly(diallyldimethylammonium Chloride)/Sodium Dodecyl Sulfate at the Air-Water Interface Studied by Neutron Reflectometry},
  url          = {http://dx.doi.org/10.1021/jp2088803},
  volume       = {115},
  year         = {2011},
}