The intrinsic viscosity of polyelectrolytes revisited

Abstract

Some 25 years ago, Smidsrød and Haug (Smidsrød, O. & Haug, A., Biopolymers, 10 (1971) 1213) constructed an empirical method, the ‘B-value’ method to evaluate the charge effect for flexible and semi-flexible polyelectrolytes. More recently Odijk (Odijk, T., J. Polym. Sci.: Polym. Phys. Ed., 15 (1977) 477), and Skolnick and Fixman (Skolnick, J. & Fixman, M., Macromolecules, 10 (1977) 944) constructed more theoretical models for the polyelectrolyte worm-like chain. These approaches have been tested by comparison with experimental results of synthetic polymers and biopolymers, but a re-examination of the experimental data so far reported has revealed that application of the models is rather limited. The most serious problem found in both theoretical and empirical models is the salt concentration dependence of the intrinsic viscosity, where it is assumed that [η] is proportional to -0·5 (or sometimes -1) power of ionic strength. Here we re-examine models for the intrinsic viscosity of polyelectrolytes and propose a new empirical model for the electrostatic charge effect. ©1997 SCI