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 distan ce, the squared radius of gyration, the apparent persistence length, t he charge distribution over the segments, the average distance between the charges and the center of mass, and the eccentricities of the mas s and charge distributions. Lattice polyelectrolytes are self-avoiding random walks on a (3-dimensional) cubic lattice, bearing either equid istantly fixed or mobile, discrete charges. For the electrostatic inte raction a Debye-Huckel potential is used. Differences due to charge mo bility along the chain are analyzed. It is found that most of these di fferences can be explained in terms of a more uniform average charge d istribution in the mobile case, and a charge accumulation of the mobil e 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 compar ed with the theoretical results given by Katchalsky, Odijk, Schmidt, S kolnick and Fixman, and also with (other) simulation results by Carnie , Christos, and Creamer.