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

We show that the efficiency of incorporating C60 in single-wall carbon nanotubes (SWCNTs) and that of the incorporated C60’s release from the SWCNTs depend on the SWCNT diameter. Through transmission electron microscopy, we found that the C60 incorporation efficiency reached its maximum at diameters of 1–2 nm, while the efficiency of C60 release from SWCNTs in toluene was maximized at 3–5 nm. The difficulty of C60 release from SWCNTs with diameters of 5–6 nm might reflect either the effective packing of C60 inside SWCNTs or a flattened SWCNT structure. We occasionally observed C60 molecules arranged in a line along the sidewall inside SWCNTs with large diameters/width (>7 nm), indicating that large diameter SWCNTs were sometimes flattened.