Silica gel fabrication of [60]fullerene aggregates and carbon nanotubes utilizing the amphiphilic nature of poly(N-vinylpyrrolidone) as a 'glue'

Sol-gel polycondensation of tetraethoxysilane in the presence of [60]fullerene/poly(N-vinylpyrrolidone) (PVP) composite or single-walled carbon nanotubes (SWNTs)/PVP composite yielded novel silica nanoparticles or silica nanorods, respectively. TEM and SEM observations and IR, UV-VIS and XPS spectroscopic analyses consistently revealed that these novel silica-based superstructures are composed of templates ([60]fullerene or SWNTs), PVP and a thin silica layer. From the silica nanoparticles it was possible to prepare the hollow silica particles by pyrolysis. In the silica nanorods, it was possible to remove PVP and then SWNTs at 500 and 1000°C, respectively, by stepwise pyrolysis. TEM and SEM images of the silica nanrods obtained after removal of PVP showed a hollow structure with SWNTs sticking out of the inner tube, like the lead of an 'automatic pencil'.