(468j) Reversible Ion-Binding and Adaptive Structure for Polyelectrolytes in Solution and Coacervate

Ion-binding equilibrium in polyelectrolyte solution is affected by the long-ranged electrostatic correlation which, by modulating charge density, affects the conformational properties of polyelectrolytes. We investigate this coupling by combining our model for ion-binding equilibrium with the variational theory for polyelectrolyte conformations developed by Wang et al. For solutions of single type of polyions, the effects of ion-binding on the expansion and collapse of polyelectrolyte are explored. The results suggest that the behavior of adaptive chains are consistent with semiflexible rods for even modestly long chains. The non-adaptive, coil-like chains tend to overestimate electrostatic correlations, particularly in the dilute regime. Generalizing the model to solutions of multiple polyions, we explore the effects of adaptive structures and ion-binding, and identify a strong-binding regime where coacervation is dominated by the degree of ion-binding.