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The Influence of Polyelectrolytes on the Stability of Colloids

Sjöström, Lena LU (1998)
Abstract (Swedish)
Popular Abstract in Swedish

Den här avhandlingen handlar om interaktion mellan två ytor (t.ex. fibrer, lerpartiklar eller proteiner) i en vattenlösning med motjoner, salt och/eller polyelektrolyter. Polyelektrolyter är laddade polymerer. Avhandlingen är fokuserad på elektrostatisk växelverkan och interaktionerna har undersöks med hjälp av Monte Carlo-simuleringar. De kvalitativa resultaten har ofta jämförts med ytkraftsmätningar med god överensstömmelse.
Abstract
The interaction between two colloids with grafted polyelectrolytes in aqueous solution is studied within the primitive model by Monte Carlo simulations. For neutral colloids with grafted polyelectrolytes and in absence of salt the interaction is strongly repulsive in absence of salt. The interaction depends on the extension of the polyelectrolytes from the surfaces and the interaction is derived and the interaction can be estimated for different chain length.



The interaction between two charged colloids depends on the amount of surface charge neutralized by polyelectrolytes. The interaction has a minimum when the surface charge is perfectly neutralized by polyelectrolytes. When the energy term dominates in a double layer... (More)
The interaction between two colloids with grafted polyelectrolytes in aqueous solution is studied within the primitive model by Monte Carlo simulations. For neutral colloids with grafted polyelectrolytes and in absence of salt the interaction is strongly repulsive in absence of salt. The interaction depends on the extension of the polyelectrolytes from the surfaces and the interaction is derived and the interaction can be estimated for different chain length.



The interaction between two charged colloids depends on the amount of surface charge neutralized by polyelectrolytes. The interaction has a minimum when the surface charge is perfectly neutralized by polyelectrolytes. When the energy term dominates in a double layer almost all ions are found in the vicinity of the charged surfaces forming alternating layers of counterions and coions. Coions have the same charge as the surface and counterions the opposite charge. The energy term becomes dominant at high surface charge density, low dielectric constant, low temperature or by reducing the entropy by a increasing the counterions valency. Another way to reduce the importance of the entropy is replace the counterions by polyelectrolytes. In the latter case the effect increases with the chain length.



If the polyelectrolytes are only grafted to one of two equally but oppositely charged surfaces a more long-range attraction occurs than if both surfaces are neutralized by either ions or polymers. The origin of this extra atrraction is the small ions, which are spread over the whole volume and causes a charge imbalance of the system. The MC results are shown to be in qualitatively agreement with results from surface force measurements. (Less)
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author
opponent
  • Stuart, Martien Cohen, Prof. Dept of Physical & Colloid Chemistry, Wageningen University, The Netherlands
organization
publishing date
type
Thesis
publication status
published
subject
keywords
electrostatic interaction, charge reversal, colloid, asymmetric systems, electric double layer, polyelectrolyte, Monte Carlo, Physical chemistry, Fysikalisk kemi
pages
136 pages
publisher
Biophysical Chemistry (LTH), Lund University
defense location
Room D, Chemical Center, Lund
defense date
1998-03-20 10:15
external identifiers
  • Other:ISRN: LUTKDH/TKFK--98/1005--SE
language
English
LU publication?
yes
id
ae3f8bf6-d3d1-4f30-8f5f-2156d52e71a7 (old id 38449)
date added to LUP
2007-10-14 17:40:07
date last changed
2016-09-19 08:45:10
@misc{ae3f8bf6-d3d1-4f30-8f5f-2156d52e71a7,
  abstract     = {The interaction between two colloids with grafted polyelectrolytes in aqueous solution is studied within the primitive model by Monte Carlo simulations. For neutral colloids with grafted polyelectrolytes and in absence of salt the interaction is strongly repulsive in absence of salt. The interaction depends on the extension of the polyelectrolytes from the surfaces and the interaction is derived and the interaction can be estimated for different chain length.<br/><br>
<br/><br>
The interaction between two charged colloids depends on the amount of surface charge neutralized by polyelectrolytes. The interaction has a minimum when the surface charge is perfectly neutralized by polyelectrolytes. When the energy term dominates in a double layer almost all ions are found in the vicinity of the charged surfaces forming alternating layers of counterions and coions. Coions have the same charge as the surface and counterions the opposite charge. The energy term becomes dominant at high surface charge density, low dielectric constant, low temperature or by reducing the entropy by a increasing the counterions valency. Another way to reduce the importance of the entropy is replace the counterions by polyelectrolytes. In the latter case the effect increases with the chain length.<br/><br>
<br/><br>
If the polyelectrolytes are only grafted to one of two equally but oppositely charged surfaces a more long-range attraction occurs than if both surfaces are neutralized by either ions or polymers. The origin of this extra atrraction is the small ions, which are spread over the whole volume and causes a charge imbalance of the system. The MC results are shown to be in qualitatively agreement with results from surface force measurements.},
  author       = {Sjöström, Lena},
  keyword      = {electrostatic interaction,charge reversal,colloid,asymmetric systems,electric double layer,polyelectrolyte,Monte Carlo,Physical chemistry,Fysikalisk kemi},
  language     = {eng},
  pages        = {136},
  publisher    = {ARRAY(0xaa6c730)},
  title        = {The Influence of Polyelectrolytes on the Stability of Colloids},
  year         = {1998},
}