POLYELECTROLYTES IN MIXED SALTS - SCATCHARD PLOTS OBTAINED BY MEANS OF POISSON-BOLTZMANN CALCULATIONS

The problem of the interaction between dilute polyelectrolytes and divalent counterions in the presence of a supporting uni-univalent salt is approached by means of Poisson-Boltzmann calculations. A very general definition of "bound" and "free" concentrations is given under limiting conditions, but it is shown that it can be retained also at finite polymer concentrations. With such definitions Scatchard plots can be obtained. Values of the Scatchard constant K-2(0) are given as a function of the reduced charge density, of the radius of the polymer and of the concentration of the supporting monovalent salt.