Interactions and Transport of Charged Species in Bulk and at Interfaces
Counterion condensation and dynamics at interfacesHitoshi Washizu
Ionic interactions in solid-liquid interface plays important role since the long range Coulomb interaction is the essentially the most strong intermolecular interaction. In the biological systems, functional polymers have high charge density. In the industries, electrodes of secondary batteries and fuel cells have electric double layer in their interface. In the mechanical engineering point of view, low friction surfaces of polyelectrolyte brushes are known as a model system of synovial joints.
In this talk we report the effect of surface or linear charge densities on the interface using molecular simulations. Counterion condensation is the essential phenomena on these systems . We extended the study for the charged plane [2, 3], sphere and polymer brushes  and found not only the static structure but the dynamical behavior change of ion atmosphere.
For the system of charged pane, inverted flow in electro-osmotic pump is found when counterion condensation occurs . For the sphere system, inhomogeneous ion transfer due to ion condensation is found in the soggy sand electrolyte solution, which may be a candidate of the additives for secondary batteries. In the polyelectrolyte brushes systems, we found anomalous structural changes due to the counterion condensation .
1 H. Washizu, K. Kikuchi, J. Phys. Chem. B, 110 (6) 2855 (2006).
2 H. Yoshida, H. Mizuno, T. Kinjo, H. Washizu, J. L. Barrat, Phys. Rev. E 90 052113 (2014).
3 H. Yoshida, T. Kinjo, H. Washizu, H. Mizuno, J. L. Barrat, J. Chem. Phys. 140 214701 (2014).
4 H. Washizu, T. Kinjo, H. Yoshida, Friction, 2 (1) 73 (2014).