Adsorption of star-branched polyelectrolytes on charged colloids

COLL 374

Arben Jusufi, ajusufi@princeton.edu1, Martin Konieczny2, and Christos N Likos2. (1) Department of Chemical Engineering, Princeton University, Engineering Quad, Princeton, NJ 08544, (2) Institute for Theoretical Physics II, University of Dusseldorf, Universitaetsstr. 1, Duesseldorf, 40225, Germany
Star-branched polyelectrolytes are systems of linear polyelectrolytes (PE) attached on a common, microscopic core. Upon solution in polar solvent, the PE chains dissociate counterions into the solution leaving behind strongly stretched chains with a total charge Qs.

We performed Molecular Dynamics simulations of a polyelectrolyte star in the presence of an oppositely

charged colloid (valency Qc) with explicit counterions.

Due to electrostatic attraction the star-colloid forms

a complex with various morphological states. This is similar to a recent study of PE stars on oppositely charged planar surfaces where well-characterized conformations occur, depending on the star-surface coupling [Konieczny, M.; Likos, C.N. Soft Matter 2007, 3, 1130]. Beside the functionality and the relative charge fraction Qs/Qc,

the size fraction of the PE star (radius ca. 6-8nm) with respect to the colloid (radius 3-15nm) is a further control parameter for the complex formation. The morphologies range from full adsorption of the star to partial adsorbed states

with a fraction of chains pointing away from the complex.

The observed states are different from those encountered for linear PE chains due to the topological constraints arising from the star-branched architecture.

 

Polymer-Nanoparticle Systems: Theory, Simulation, Experiments
9:00 AM-12:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Rm. 227, Oral

Division of Colloid & Surface Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008