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 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.
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.
| Original language | English |
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| Qualification | Doctor |
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| Award date | 1998 Mar 20 |
| Publisher | |
| Publication status | Published - 1998 |
Bibliographical note
Defence detailsDate: 1998-03-20
Time: 10:15
Place: Room D, Chemical Center, Lund
External reviewer(s)
Name: Stuart, Martien Cohen
Title: [unknown]
Affiliation: Prof. Dept of Physical & Colloid Chemistry, Wageningen University, The Netherlands
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Article: Charge Reversal in Electric Double Layer - a Balancebetween Entropy and EnergyLena Sjöström, Torbjörn Åkesson and Bo JönssonBer. Bunsenges. Phys. Chem. 1996, 100 p 889.
Article: Salt Effects on the Interaction between AdsorbedCationic Polyelectrolyte Layers - Theory and ExperminentMats A. G. Dahlgren, Åsa Waltermo, Eva Blomberg, Per M. Claesson,Lena Sjöström, Torbjörn Åkesson and Bo JönssonJ. Phys. Chem. 1993, 97, p 11769.
Article: Interaction and Confromation of Polyelectrolyte ChainsAdsorbed on Neutral SurfacesLena Sjötröm, Torbjörn Åkesson and Bo JönssonJ. Chem. Phys. 1993, 99, p 4739.
Article: The Stability of charged Colloids - AttractiveDouble Layer Forces due to Assymmetric Charge DistributionLena Sjöström and Torbjörn ÅkessonJ. Colloid Interface Sci. 1996, 181, p 645.
Article: Attractive Osmotic Pressure in an Electric DoubleLayer with Grafted PolyelectrolytesJonathan Ennis, Lena Sjöström, Torbjörn Åkesson and Bo Jönssonaccepted for publication in J. Phys. Chem.
Subject classification (UKÄ)
- Physical Chemistry
Free keywords
- electrostatic interaction
- charge reversal
- colloid
- asymmetric systems
- electric double layer
- polyelectrolyte
- Monte Carlo
- Physical chemistry
- Fysikalisk kemi