(55b) Electroneutrality Breakdown in Nanoconfined Domains

The conduction of ions through nanopores plays a central role in membrane-based separation technologies, biological processes, and nanofluidic devices. When ionic solutions are confined within pores with charged walls, counterions localize within the pore to neutralize the pore’s surface charge. The structuring of the screening ionic charges within the nanopore determines its charge storage and ionic transport characteristics. In this work, we show that the extent and dimensionality of confinement significantly affects the thermodynamics of ions confined within nanopores. Many models of nanofluidic transport make the standard assumption of electroneutrality, that the surface charges on the pore walls are neutralized by an equal but opposite charge of screening counterions in any given cross section of the pore. However, we find that for one-dimensional confinement, the electroneutrality assumption breaks down. In electroneutrality breakdown, the electric field escapes through the pore walls, and the screening charge is spread over membrane interfaces, changing the transport properties of the pore. Further, we show that the nanoscale physics governing the electrostatics of confined solutions leads to strong collective effects between channels due to nanopore-nanopore interactions.