NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Carbon Nanotubes in Water: MD Simulations of Internal and External Flow, Self OrganizationWe have developed computational tools, based on particle codes, for molecular dynamics (MD) simulation of carbon nanotubes (CNT) in aqueous environments. The interaction of CNTs with water is envisioned as a prototype for the design of engineering nano-devices, such as artificial sterocillia and molecular biosensors. Large scale simulations involving thousands of water molecules are possible due to our efficient parallel MD code that takes long range electrostatic interactions into account. Since CNTs can be considered as rolled up sheets of graphite, we expect the CNT-water interaction to be similar to the interaction of graphite with water. However, there are fundamental differences between considering graphite and CNTs, since the curvature of CNTs affects their chemical activity and also since capillary effects play an important role for both dynamic and static behaviour of materials inside CNTs. In recent studies Gordillo and Marti described the hydrogen bond structure as well as time dependent properties of water confined in CNTs. We are presenting results from the development of force fields describing the interaction of CNTs and water based on ab-initio quantum mechanical calculations. Furthermore, our results include both water flows external to CNTs and the behaviour of water nanodroplets inside heated CNTs. In the first case (external flows) the hydrophobic behaviour of CNTs is quantified and we analyze structural properties of water in the vicinity of CNTs with diagnostics such as hydrogen bond distribution, water dipole orientation and radial distribution functions. The presence of water leads to attractive forces between CNTs as a result of their hydrophobicity. Through extensive simulations we quantify these attractive forces in terms of the number and separation of the CNT. Results of our simulations involving arrays of CNTs indicate that these exhibit a hydrophobic behaviour that leads to self-organising structures capable of trapping water clusters. In the second case (internal flows) we study the behaviour of water droplets confined inside CNTs. Constant temperature simulations allow us to capture structural properties such as the contact angles and density profiles of the equilibrated drops. By heating and subsequently cooling of the CNT, we are able to measure the evaporation and the condensation rate of the entrapped water.
Document ID
20020004363
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Jaffe, Richard L.
(NASA Ames Research Center Moffett Field, CA United States)
Halicioglu, Timur
(Eloret Corp. Sunnyvale, CA United States)
Werder, Thomas
(Eidgenoessische Technische Hochschule Zurich, Switzerland)
Walther, Jens
(Eidgenoessische Technische Hochschule Zurich, Switzerland)
Koumoutsakos, Petros
(Eidgenoessische Technische Hochschule Zurich, Switzerland)
Arnold, James
Date Acquired
August 20, 2013
Publication Date
January 1, 2001
Subject Category
Solid-State Physics
Meeting Information
Meeting: 9th Conference on Molecular Nanotechnology
Location: Santa Clara, CA
Country: United States
Start Date: November 9, 2001
End Date: November 11, 2001
Funding Number(s)
PROJECT: RTOP 519-40-12
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Available Downloads

There are no available downloads for this record.
No Preview Available