James P. Donley,
Bae-Yeun Ha, and
Rebecca M. Nyquist.
Polyelectrolytes are polymers with ionizable groups that can dissociate in solution,
leaving ions of one sign bound to the chain and counterions in solution. They are
of direct practical significance mainly because they are soluble in water, in
contrast to most neutral hydrocarbon polymers, which are only soluble in organic
solvents. As a result, synthetic polyelectrolytes are used in environmentally
benign polymer processing, as rheology modifiers in food, and in a host of other
applications. In addition, many biopolymers, such as DNA, RNA, and some proteins,
are polyelectrolytes. Our main interest lies in two interrelated areas.
- The structure of flexible polyelectrolyte chains in solution.
Chain structure is key to understanding the behavior of polymer solutions;
indeed, the field of polymer physical chemistry is largely based on the study
of chain structure and its consequences for static and dynamic properties.
In contrast to previous work, we have focused on the structure of a chain
in the presence of many other chains. Our results are in excellent
agreement with molecular dynamics simulations by M. Stevens and K. Kremer
[J. Chem. Phys. 103, 1669 (1995)], with no adjustable parameters.
- The nature of the interactions between polyelectrolyte chains.
Motivated by Brownian dynamics simulations by N. Grønbech-Jensen, R. J. Mashl,
R. F. Bruinsma and W. M. Gelbart [Phys. Rev. Lett. 78, 2477 (1997)], we have
studied attractions between like-charged rods, and have shown that the
attractions originate from charge fluctuations due to counterions near the rods.
We are now studying counterion condensation at nonzero concentration for rigid,
finite-length chains; previous treatments assume infinitely dilute, infinitely
long chains.
Related Publications:
Comments or suggestions? Email Rebecca Nyquist.
Last modified January 22, 1998.