Preparation of double-layered nanotubes consisting of an inner carbon layer and outer silicon carbide layer by elongation of core-shell polymer particles

The feasibility of preparing double-layered nanotubes consisting of an inner carbon layer and outer silicon carbide layer was explored. Fine particles consisting of a poly (methyl methacrylate) core and polyacrylonitrile shell were coated with polycarbosilane by spray-drying. The resulting particles were buried in PVA fibers and elongated mechanically. After the removal of PVA, the particles were stabilized and finally heated at 1000°C in an inert atmosphere. Nanotubes were rarely observed. A nanotube showed a diameter of ca. 100 nm, wall thickness of 30 nm and composition (by weight) of 9.8% Si, 69.5% C and 20.7% O. The feasibility was confirmed by the composition and the structure of particles prepared by spray-drying.