Log Number: 73
Abstract Submitted to the NT-99-Logo NANOTUBE-99 Workshop:

Nanoscopic Hybrid Materials: The Synthesis, Structure and Properties of Peapods, CATs and Kin

David E. Luzzi and Brian W. Smith

University of Pennsylvania
Contact e-mail: luzzi@lrsm.upenn.edu

A new class of materials has been discovered. These materials are composed of Fullerenes encapsulated within single wall carbon nanotubes (SWNTs) of commensurate diameter. In most cases, the encapsulated Fullerene is free to move within the surrounding SWNT with no preferred locations yet identified. Thus these materials cannot be considered as single molecules; nor are they fabricated composites since they will spontaneously form. Therefore, we have labelled this unique class of structures nanoscopic hybrid materials. We have found that nanoscopic hybrid materials form with SWNTs of different diameters, with larger fullerenes encapsulated within larger SWNTs. The most abundant of these materials have a SWNT of 1.4 nm diameter. A complete structural set of hybrid materials containing hemispherically-capped cylinders of varying length and these 1.4 nm-f SWNTs have been found. The diameter of the encapsulated cylinders is that of C60, 0.7 nm. The complete structural set can be written as {[C60+10n: n>=0](0.7 nm- f)} @ {SWNT (1.4 nm-f)}. The hybrid structure with n=0 is the SWNT containing C60 molecules (now called peapods); the hybrid structure with n=1 is the SWNT containing C70 molecules, etc. At n= (actually the maximum n commensurate with the length of the surrounding SWNT), the hybrid material is a two-walled nanotube (now called a co-axial tube or CAT). In contrast to multiwall nanotubes which typically contain many layers and a large core diameter, CATs are always two-walls with an outer diameter of 1.4 nm. In this paper, we report our continued work on these fascinating materials, concentrating on synthesis and the identification of structures. The synthesis conditions which yield only peapods has been developed and will be presented. Finally, several potential near- and long-term applications of nanotubes and nanoscopic hybrid materials that have become apparent through this work will be discussed.

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