Efficiency of C60 incorporation in and release from single-wall carbon nanotubes depending on their diameters

We show that the efficiency of incorporating C-60 in single-wall carbon nanotubes (SWCNTs) and that of the incorporated C-60's release from the SWCNTs depend on the SWCNT diameter. Through transmission electron microscopy, we found that the C-60 incorporation efficiency reached its maximum at diameters of 1-2 nm, while the efficiency of C-60 release from SWCNTs in toluene was maximized at 3-5 nm. The difficulty of C-60 release from SWCNTs with diameters of 5-6 nm might reflect either the effective packing of C-60 inside SWCNTs or a flattened SWCNT structure. We occasionally observed C6o molecules arranged in a line along the sidewall inside SWCNTs with large diameters/width (> 7 nm), indicating that large diameter SWCNTs were sometimes flattened. (c) 2007 Elsevier Ltd. All rights reserved.