UNIGE document Scientific Article
previous document  unige:13124  next document
add to browser collection
Title

Charging and aggregation of positively charged latex particles in the presence of anionic polyelectrolytes

Authors
Gillies, Graeme
Lin, Wei
Published in Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical. 2007, vol. 111, no. 29, p. 8626-33
Abstract Charging behavior and colloidal stability of amidine latex particles are studied in the presence of poly(sodium styrene sulfonate) (PSS) and KCl. Detailed measurements of electrophoretic mobility, adsorbed layer thickness, and aggregation (or coagulation) rate constant on varying the polymer dose, molecular mass of the polymer, and ionic strength are reported. Polyelectrolyte adsorption leads to the characteristic charge reversal (or overcharging) of the colloidal particles at the isoelectric point (IEP). In accordance with classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, uncharged particles tend to aggregate because of van der Waals attraction, whereas charged particles are stabilized by electrical double layer repulsion. Attractive patch-charge interactions originating from the laterally inhomogeneous structure of the adsorbed polymer substantially decrease the suspension stability or even accelerate the aggregation rate beyond diffusion control. These electrostatic non-DLVO forces become progressively important with increasing molecular mass of the polymer and the ionic strength of the solution. At higher polymer dose of typically 10 times the IEP, one observes the formation of a saturated layer of the adsorbed polymer with a thickness of several nanometers. Its thickness increases with increasing molecular mass, whereby the layer becomes increasingly porous. This layer does not seem to be involved in the suspension stabilization, since at such high polymer doses the double layer repulsion has attained sufficient strength to stabilize the suspension.
Stable URL https://archive-ouverte.unige.ch/unige:13124
Full text
Article (Published version) (254 Kb) - document accessible for UNIGE members only Limited access to UNIGE
Identifiers
PMID: 17465535
Structures

175 hits

1 download

Update

Deposited on : 2011-01-06

Export document
Format :
Citation style :