QUANTITATIVE DESCRIPTION OF THE INTRINSIC-VISCOSITY OF BRANCHED POLYELECTROLYTES

A set of critically cross-linked polystyrenesulfonates with fractal ge ometry having molecular weights in the range 4.96 x 10(5) < M-w < 3.07 x 10(6) was prepared and characterized by viscometry in salt free aqu eous solutions. Also these structures show the polyelectrolyte effect, which is a strong increase in reduced viscosity with decreasing conce ntration. Contrary to that in linear chains, the viscosity below the o verlap concentration turned out to be molecular weight independent, wh ich interestingly bridges the behavior between spheres and linear chai ns. A quantitative evaluation of the data on the basis of a recently d ecribed model of polyelectrolyte viscosity considering single particle and cooperative multiparticle effects of the charges on viscosity rev eals that the complete dependence on polymer concentration is describe d by assuming only the effective charge number per polymer molecule, Z (eff). It is not necessary to assume any concentration-dependent confo rmational changes.