Test of Oosawa-Manning condensation in a semiflexible polyelectrolyte across solvents of varying Bjerrum length

This is the authors' abstract. We don't add key points for this paper.

The effective charge of polyelectrolytes is a crucial parameter that determines their conformational and thermodynamic properties in solution. The Oosawa-Manning condensation model predicts that when the distance between charges becomes smaller than the Bjerrum length ( l B ), additional charges condense onto the backbone, rendering the effective charge independent of the chemical charge density. This implies that above the condensation threshold the effective charge is inversely proportional to l B . This prediction has remained largely untested due to the limited solubility of common polyelectrolytes in apolar media. Here we use a semiflexible polyelectrolyte, carboxymethyl cellulose with organic counterions, which extends its solubility across a wide range of solvents, enabling a test over a broad range of l B . The effective charge is found to be inversely proportional to l B in the low dielectric region and independent of l B when nm, in agreement with the theory.