Effect of Excluded Volume on Polyelectrolytes in Salt Solutions

Publisher Website
Google Scholar
Abstract
A recently developed theory of excluded volume, relating α to z ∝ M½βL−3 by means of an integral equation, is applied to polyelectrolytes. The line describing α(M½) is the same for all polymers; the dependence of α on the polyelectrolyte parameters (ionic strength and charge density) requires, however, further elaboration. Thus, the excluded volume β is summarily identified with the high-potential shell coaxially surrounding the charged filament, as treated in a polyelectrolyte theory presented some time ago. Distinction is made between two cases: (a) When the shell radius is smaller than the link length L characterizing the polymer and (b) when the converse holds—so that the length of free hinged links becomes determined by the shell radius. The predicted dependence of α on the molecular weight and on the ionic strength is found to agree satisfactorily with the extensive viscosity data reported by Takahashi and Nagasawa. Additional aspects of investigating α(z) are also discussed.