Nanoconfined water: Molecular dynamic simulations of cavities, model ice-pores, and modified carbon nanotube pores with applications related to ratchets and ion pumps.

摘要

This thesis is written from a physical and theoretical chemistry perspective. The intent of this report is to simulate, analyze, and characterize water in confined nanometer scale architectures. I seek to understand the cross over between bulk solutions and nanometer confined solutions from a molecular dynamics perspective. The nature of water and solutions in confined environments (on the scale of nanometers), unlike bulk water found in lakes, rivers, the ocean, or a pot of coffee, behaves differently. This is in part due to the rearrangement of the hydrogen bond network around spatial constraints. Other aspects of water's unique characteristics at these scales are due to hydrophobic or hydrophilic surface interactions.;Molecular dynamic simulations in this work are used to examine a classical mechanical treatment of this behavior. I first examine how water in confined ice-like nanometer spaces is influenced by the boundary This work shows hydrogen bond lifetimes lengthen when water is confined by hydrophilic boundaries. Model ice nanopores are used to study water flux and the importance of electrostatic effects therein. Both of these results are used as a gauge to determine the approximate length and charge necessary to modify the dynamics of water. Further work attempts to take advantage of these properties in order to address rectification of both water and salt solutions in various sized pores. I show salt exclusion for nanopore diameter on the order of 1 nm. Conclusions about the ion rectification properties of the pores studied are discussed.