Eur. Phys. J. E (2006) 20: 335-346
https://doi.org/10.1140/epje/i2006-10025-1

Regular Article

Undulated cylinders of charged diblock copolymers

¹ Department of Physics and Astronomy, University of Pennsylvania, 19104, Philadelphia, PA, USA
² Department of Physics and Astronomy, University of California, 90095, Los Angeles, CA, USA

^* e-mail: grason@physics.ucla.edu
^** e-mail: santancd@physics.upenn.edu

Received: 8 May 2006
Accepted: 12 July 2006
Published online: 27 July 2006

Abstract

We study the cylinder to sphere morphological transition of diblock copolymers in aqueous solution with a hydrophobic block and a charged block. We find a metastable undulated cylinder configuration for a range of charge and salt concentrations which, nevertheless, occurs above the threshold where spheres are thermodynamically favorable. By modeling the shape of the cylinder ends, we find that the free-energy barrier for the transition from cylinders to spheres is quite large and that this barrier falls significantly in the limit of high polymer charge and low solution salinity. This suggests that observed undulated cylinder phases are kinetically trapped structures.