INFLUENCE OF CHARGE MOBILITY ON THE EQUILIBRIUM PROPERTIES OF POLYELECTROLYTES IN SALT-SOLUTIONS - A MONTE-CARLO STUDY

Using a Metropolis algorithm, various average properties of ''lattice polyelectrolytes'' were calculated, i.e. the squared end-to-end distance, the squared radius of gyration, the apparent persistence length, the charge distribution over the segments, the average distance between the charges and the center of mass, and the eccentricities of the mass and charge distributions. Lattice polyelectrolytes are self-avoiding random walks on a (3-dimensional) cubic lattice, bearing either equidistantly fixed or mobile, discrete charges. For the electrostatic interaction a Debye-Huckel potential is used. Differences due to charge mobility along the chain are analyzed. It is found that most of these differences can be explained in terms of a more uniform average charge distribution in the mobile case, and a charge accumulation of the mobile charges near the ends of the chain. Furthermore, the mobile charges will tend to preferentially localize themselves away from bends in the chain, thus enhancing its flexibility. Our results for the end-to-end distance and chain stiffness for increasing charge density are compared with the theoretical results given by Katchalsky, Odijk, Schmidt, Skolnick and Fixman, and also with (other) simulation results by Carnie, Christos, and Creamer.