Issue
EPL
Volume 77, Number 1, January 2007
Article Number 16001
Number of page(s) 5
Section Condensed Matter: Structural, Mechanical and Thermal Properties
DOI http://dx.doi.org/10.1209/0295-5075/77/16001
Published online 27 December 2006
EPL, 77 (2007) 16001
DOI: 10.1209/0295-5075/77/16001

Finite-size polyelectrolyte bundles at thermodynamic equilibrium

M. Sayar1, 2 and C. Holm2, 3

1  Koc University, College of Engineering - Istanbul, Turkey
2  Max-Planck-Institut für Polymerforschung - Mainz, Germany
3  Frankfurt Institute for Advanced Studies, J. W. Goethe-Universität - Frankfurt, Germany


received 3 September 2006; accepted in final form 3 November 2006; published January 2007
published online 27 December 2006

Abstract
We present the results of extensive computer simulations performed on solutions of monodisperse charged rod-like polyelectrolytes in the presence of trivalent counterions. To overcome energy barriers we used a combination of parallel tempering and hybrid Monte Carlo techniques. Our results show that for small values of the electrostatic interaction the solution mostly consists of dispersed single rods. The potential of mean force between the polyelectrolyte monomers yields an attractive interaction at short distances. For a range of larger values of the Bjerrum length, we find finite-size polyelectrolyte bundles at thermodynamic equilibrium. Further increase of the Bjerrum length eventually leads to phase separation and precipitation. We discuss the origin of the observed thermodynamic stability of the finite-size aggregates.

PACS
61.25.Hq - Macromolecular and polymer solutions; polymer melts; swelling .
36.20.Ey - Macromolecules and polymer molecules: Conformation (statistics and dynamics) .
87.15.Aa - Theory and modeling; computer simulation .

© Europhysics Letters Association 2007