Polyion–Counterion Interactions in Mixtures of Sodium Carboxymethylcellulose (aq) with Different Molar Masses
Year: 2026
Type: article
Abstract: This study explored polyion-counterion interactions in aqueous mixtures of a polyelectrolyte sodium carboxymethylcellulose having two different molar masses. Previous DLS studies indicated an invariance of the polyion-counterion interactions with the total concentration or with the composition in mixed sodium polystyrensulfonate solutions, while conductivity revealed a definite dependence of these interactions. The objective of this research is to shed more light on these interactions for a different system with quite low charge density. Counterion-dissociation governing the polyion-counterion interactions were quantified using conductivity as the probe to unravel the nature of these interactions. Degrees of counterion-dissociation and hence the effective charges on the carboxymethylcellulose chains were found to increase with the total polyelectrolyte concentration. This study revealed a reduction in the degree of counterion-dissociation in mixtures richer in the higher molar mass sample, which became more pronounced in dilute solutions. Roles of the effective dielectric constant, screening of chain charges, and polyion chain-coiling in governing counterion-dissociation were critically assessed. Substantial proportion of the counterions was found to move with the polyions, corroborating the inferences drawn on the basis of counterion-condensation. This study demonstrated a definite dependence of polyion-counterion interactions on both the total polyelectrolyte concentration and the composition of the mixtures.
Source: Journal of Solution Chemistry
Authors: Sudipa Santra, Bidyut Debnath, Bijan Das
Institutions: Presidency University, Basirhat College
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7214528007