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Persistence length of a strongly charged rodlike polyelectrolyte in the presence of salt Gil Ariel and David Andelman*
 

Summary: Persistence length of a strongly charged rodlike polyelectrolyte in the presence of salt
Gil Ariel and David Andelman*
School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel-Aviv University, 69978 Tel-Aviv, Israel
Received 18 June 2002; published 30 January 2003
The persistence length of a single, intrinsically rigid polyelectrolyte chain, above the Manning condensation
threshold is investigated theoretically in the presence of added salt. Using a loop expansion method, the
partition function is consistently calculated, taking into account corrections to mean-field theory. Within a
mean-field approximation, the well-known results of Odijk, Skolnick, and Fixman are reproduced. Beyond
mean field, it is found that density correlations between counterions and thermal fluctuations reduce the
stiffness of the chain, indicating an effective attraction between monomers for highly charged chains and
multivalent counterions. This attraction results in a possible mechanical instability collapse , alluding to the
phenomenon of DNA condensation. In addition, we find that more counterions condense on slightly bent
conformations of the chain than predicted by the Manning model for the case of an infinite cylinder. Finally,
our results are compared with previous models and experiments.
DOI: 10.1103/PhysRevE.67.011805 PACS number s : 61.25.Hq, 36.20. r, 87.15. v
I. INTRODUCTION
The behavior of charged polymers has received consider-
able attention since the early 1970s. However, despite exten-
sive efforts, much of the phenomena observed in systems
containing polyelectrolytes PEs is still not very well under-

  

Source: Andelman, David - School of Physics and Astronomy, Tel Aviv University

 

Collections: Materials Science; Physics