We investigate the influence of counter-ion valency on the flexibility of highly charged flexible polymer chains by molecular dynamics simulations that include both salt and an explicit solvent. As observed experimentally, we find that divalent counter-ions greatly reduce the chain persistence length, lp, in comparison to monovalent counter-ions, an effect correlated with the tendency of the polyelectrolyte chain to become distorted by divalent counter-ions in their close proximity. This coiling effect is further enhanced with trivalent counter-ions, making the polymer adopt a relatively compact state.
Journal of Chemical Physics
polyelectrolytes, polymer solutions, polymer stiffeness, counter-ions, counter-ion valence