Controlling the shape, orientation, and linkage of carbon nanotube features with nano affinity templates

doi:10.1073/pnas.0511022103

Controlling the shape, orientation, and linkage of carbon nanotube features with nano affinity templates

*Department of Chemistry and Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113; and
^‡Center for Nanoscale Science and Technology, Carbon Nanotechnology Laboratory, and Departments of Chemistry and Physics, Rice University, MS-100, P.O. Box 1892, Houston, TX 77251-1892

Contributed by George C. Schatz, December 21, 2005

Abstract

Directed assembly of nanoscale building blocks such as single-walled carbon nanotubes (SWNTs) into desired architectures is a major hurdle for a broad range of basic research and technological applications (e.g., electronic devices and sensors). Here we demonstrate a parallel assembly process that allows one to simultaneously position, shape, and link SWNTs with sub-100-nm resolution. Our method is based on the observation that SWNTs are strongly attracted to COOH-terminated self-assembled monolayers (COOH-SAMs) and that SWNTs with lengths greater than the dimensions of a COOH-SAM feature will align along the boundary between the COOH-SAM feature and a passivating CH₃-terminated SAM. By using nanopatterned affinity templates of 16-mercaptohexadecanonic acid, passivated with 1-octadecanethiol, we have formed SWNT dot, ring, arc, letter, and even more sophisticated structured thin films and continuous ropes. Experiment and theory (Monte Carlo simulations) suggest that the COOH-SAMs localize the solvent carrying the nanotubes on the SAM features, and that van der Waals interactions between the tubes and the COOH-rich feature drive the assembly process. A mathematical relationship describing the geometrically weighted interactions between SWNTs and the two different SAMs required to overcome solvent–SWNT interactions and effect assembly is provided.

Footnotes

^†To whom correspondence may be addressed. E-mail: schatz{at}chem.northwestern.edu or chadnano{at}northwestern.edu
Author contributions: Y.W., D.M., and S.Z. performed research; and Y.W., D.M., S.Z., G.C.S., R.E.S., and C.A.M. wrote the paper.
Conflict of interest statement: No conflicts declared.
Abbreviations:

Abbreviations:

SWNT,

single-walled carbon nanotube;

AFM,

atomic force microscopy;

DPN,

dip-pen nanolithography;

SAM,

self-assembled monolayer;

MHA,

16-mercaptohexadecanoic acid;

ODT,

1-octadecanethiol;

AUT,

11-amino-1-undecanethiol;

μCP,

microcontact printing;

MUO,

1-mercaptoundecanol;

PEG-SH,

11-mercaptoundecyl-penta-ethyleneglycol.