Next generation polymer composites that utilize the high electrical conductivity and tensile strength of carbon nanotubes are of interest. To effectively disperse carbon nanotubes into polymers, a more fundamental understanding of the polymer/nanotube interface is needed. This requires the development of new analytical methods and techniques for measuring the adhesion between a single molecule and the sidewalls of carbon nanotubes.
Atomic Force Microscopy is an integral tool in the characterization of materials on the nanoscale. The objectives of this research were to: 1) characterize the binding force between single molecules and the backbone of a single walled carbon nanotube (SWNT), and 2) measure and interpret the mechanical response of carbon-based nano-objects to compressive loads using an atomic force microscope.
To identify chemical moieties that bind strongly to the sidewall of the nanotubes, two experimental approaches have been explored. In the first, force volume images of SWNT paper were obtained using gold-coated AFM tips functionalized with terminally substituted alkanethiols and para-substituted arylthiols. Analysis of these images enabled quantification of the adhesive interactions between the functionalized tip and the SWNT surface. The resultant adhesive forces were shown to be dependent upon surface topography, tip shape, and the terminal group on the alkanethiol.
The mechanical response of several single- and multi-walled carbon nanotubes under compressive load was examined with an AFM. When the scanner, onto which the substrate has been mounted, was extended and retracted in a cyclic fashion, cantilever deflection, oscillation amplitude and resonant frequency were simultaneously monitored. By time-correlating cantilever resonance spectra, deflection and scanner motion, precise control over the length of nanotube in contact with the substrate, analogous to fly-fishing was achieved. This multi-parameter force spectroscopy method is applicable for testing the mechanical and interfacial properties of a wide range of nanoscale objects.
This research has led to a clearer understanding of the chemistry at the nanotube/polymer interface, as well as the mechanical response of nanoscale materials. A new force spectroscopic tool, multi-parameter force spectroscopy, should be extremely helpful in characterizing the mechanical response of a myriad of nanoscale objects and enable nanoscale devices to become a reality.
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/4948 |
| Date | 22 September 2004 |
| Creators | Poggi, Mark Andrew |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
| Format | 7780946 bytes, application/pdf |
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