English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Journal Article

Overcharging: The crucial role of excluded volume

MPS-Authors
/persons/resource/persons48420

Messina,  R.
MPI for Polymer Research, Max Planck Society;

/persons/resource/persons48054

Holm,  Christian
MPI for Polymer Research, Max Planck Society;

External Resource
No external resources are shared
Fulltext (restricted access)
There are currently no full texts shared for your IP range.
Fulltext (public)
There are no public fulltexts stored in PuRe
Supplementary Material (public)
There is no public supplementary material available
Citation

Messina, R., Gonzalez-Tovar, E., Lozada-Cassou, M., & Holm, C. (2002). Overcharging: The crucial role of excluded volume. EPL, 60(3), 383-389. doi:10.1209/epl/i2002-00275-y.


Cite as: https://hdl.handle.net/11858/00-001M-0000-000F-64BE-D
Abstract
In this letter we investigate the mechanism for the overcharging of a single spherical colloid in the presence of aqueous salts within the framework of the primitive model by molecular dynamics (MD) simulations as well as integral- equation theory. We find that the occurrence and strength of overcharging strongly depends on the salt-ion size, and the available volume in the fluid. To understand the role of the excluded volume of the microions, we first consider an uncharged system. For a fixed bulk concentration we find that upon increasing the fluid particle size one strongly increases the local concentration nearby the colloidal surface and that the particles become laterally ordered. For a charged system the first surface layer is built up predominantly by strongly correlated counterions. We argue that this is a key mechanism to produce overcharging with a low electrostatic coupling, and as a more practical consequence, to account for charge inversion with monovalent aqueous salt ions.