Slip Flow of Water through Carbon Nanotubes: Pronounced Role of Many-Body Polarization Effects on the Friction Coefficient of Nanoconfined Water

Recent experimental and molecular dynamics (MD) simulation studies have demonstrated that carbon nanotubes (CNTs), which are 1D cylindrical allotropes of carbon, offer very little hydrodynamic resistance to water flow, thereby generating tremendous hope for practical applications of CNTs in membrane-based applications. Although several MD simulation studies have already been carried out to investigate the slip flow of water through CNTs, in all reported studies, the interaction of water molecules with the CNT has been modeled using a pair-wise additive Lennard-Jones potential. In this talk, we discuss our formulation of polarizable force fields which can self-consistently model the polarization of CNTs resulting from the finite electric fields exerted by water molecules under confinement. By carrying out classical MD simulations using polarizable force fields, we investigate the dependence of the friction coefficient of water on the CNT diameter and chirality. We also develop a microscopic theory to elucidate the static and dynamic origins of the water friction coefficient, and show that many-body polarization effects have a pronounced influence on the density and on the hydrogen-bond structure of the interfacial water molecules.