Chain structure in semidilute polyelectrolyte solutions
Abstract
Theoretical understanding of polyelectrolyte solutions has proved difficult because of the peculiar nature of the Coulomb interaction, which is long-ranged and can be either attractive or repulsive. This leads to a subtle interplay between electrostatic energy, entropy of mixing, and chain configurational entropy. We have formulated a momentum-space version of Debye-Hückel theory for ionic particles of arbitrary structure at nonzero concentration. By including fluctuations in the local densities of each ionic species to one-loop order, we recover Debye screening with a wavevector-dependent screening length that depends on the structure factors of the particles. The resulting analytical expression for the electrostatic energy allows variational calculation of the electrostatic persistence length of polyelectrolyte chains, with or without added salt. Results for salt-free dilute and semidilute polyelectrolyte solutions are in reasonable agreement with numerical simulations. Our approach can easily be generalized to include counterion condensation.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 1996
- Bibcode:
- 1996APS..MAR.O2813L