Patching and Tearing Single-Wall Carbon-Nanotube Ropes into Multiwall Carbon Nanotubes

Bundles of single-wall carbon nanotubes (SWCNTs) coalesce forming multiwall carbon nanotubes (MWCNTs), containing from two to six nested tubes, under thermal treatment at high temperatures [$(2200–2400)°\mathrm{C}$]. This structural transformation is confirmed by extensive molecular dynamics (MD) simulations. The simulations suggest a “patching-and-tearing” mechanism for the single-wall–to–multiwall transformation underlying the “concerted” coalescence of the tubes that begins with their polymerization. Tubes of different sizes and chiralities are considered.

Figure 1

HRTEM image of the sample of SWCNTs after heat treatment at (a) $1600°\mathrm{C}$, (b) $2000°\mathrm{C}$, (c) $2400°\mathrm{C}$, and (d) $2800°\mathrm{C}$ (see text for description).

Figure 2

Snapshots (top view) taken from the simulations showing the sequence of the SW-to-MW transformation of a bundle consisting of seven (10,10) SWCNTs (see text for details).

Figure 3

Snapshots (side and top views) taken from the simulations showing the sequence of the coalescence of two (10,10) SWCNTs. Top views of some portions of the tube length (embraced by brackets) are also shown next to the corresponding brackets (see text for details).