8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P2.58Tue 611:23-14:00Collective behavior of single-file water chains innanopore membranesGeorg Menzl, 1 Jürgen Köfinger, 2 and Christoph Dellago 11 University of Vienna, Boltzmanng. 5, 1090, Vienna, Austria2 National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda,Ud States of AmWhen a membrane of narrow carbon nanotubes is immersed in water, its pores are filled and thespatial confinement within the tubes leads to the formation of single-file water chains. Thesehydrogen bonded chains show ordering at room temperature such that the average dipole momentof the water molecules in the pores points along the tube axis. This order causes unique propertiesin comparison to bulk water, such as a large dielectric susceptibility and rapid proton transportalong the water wires [1]. We study membranes of parallel water wires by use of a dipolelattice model which allows the investigation of large systems and provides a physically transparentpicture of the system. Our simulations show an order-disorder transition on square membranes andthe critical temperatures for various pore lengths and pore spacings are obtained. The influenceof defects within the chains on system behavior is evaluated and we conclude that the chains, onaverage, are virtually defect-free for most lattices studied. We derive an analytic expression forcorresponding states of a lattice of ordered chains which makes our simulation results applicableto a wide range of parameters. Analysis of the susceptibilities of square and triangular latticesshows the strong influence of inter-chain coupling on the dielectric response of the system thusproviding a means of experimental verification via dielectric spectroscopy.[1] J. Köfinger, G. Hummer, C. Dellago, Proceedings of the National Academy of Sciences105, 13218 (2008)58