Molecular Friction-Induced Electroosmotic Phenomena in Thin Neutral Nanotubes

ABSTRACT: We reveal by classical molecular dynamics simulations electroosmotic flows in thin neutral carbon (CNT) and boron nitride (BNT) nanotubes filled with ionic solutions of hydrated monovalent atomic ions. We observe that in (12,12) BNTs filled with single ions in an electric field, the net water velocity increases in the order of Na+ < K+ < Cl−, showing that different ions have different power to drag water in thin nanotubes. However, the effect gradually disappears in wider nanotubes. In (12,12) BNTs containing neutral ionic solutions in electric fields, we observe net water velocities going in the direction of Na+ for (Na+, Cl−) and in the direction of Cl − for (K+, Cl−). We hypothesize that the electroosmotic flows are caused by different strengths of friction between ions with different hydration shells and the nanotube walls. SECTION: Liquids; Chemical and Dynamical Processes in Solution In recent years, molecular transport was intensively studied insilicon,1 polycarbonate,2 PMMA,3 bio-organic and bioinor-ganic nanopores,4,5 carbon (CNT)6−14 and boron nitride (BNT) nanotubes,15 porous graphene16,17 and nanotubes,18 and other synthetic nanopores. The molecular transport i