Flat-to-Flat Polymerization of Single-Walled Carbon Nanotubes under High Pressure Mediated by Carbon Chain Encapsulation

Abstract

In this work, we studied single-walled carbon nanotube bundles filled with linear carbon chains under high-pressure conditions. We used density functional theory (DFT) to explore new polymerized high-pressure phases of carbon nanotubes due to cross-linking between carbon chains and the internal surface of nanotubes. Carbon nanotubes are known to transform their circular cross section into elliptical and finally peanut-shaped, which characterizes the collapse of the structure. High-pressure cycles (compression–decompression) up to a maximum of 40–50 GPa reveal the production of new polymerized carbon nanotube phases characterized by sp3 bonds in flat regions of collapsed phases. Such new carbon bonds differ from those of conventional edge-to-edge polymerization obtained for highly curved regions of collapsed tubes. We also investigated the details of the geometry, electronic structure, and thermal stability of such new polymerized hybrid structures. We observed that carbon nanotube properties are deeply changed after high-pressure cycles. Furthermore, molecular dynamics calculations at higher temperatures suggest that such type of flat-to-flat polymerization of carbon nanotubes could be more stable than conventional edge-to-edge polymerization.

Density Function Theory Predicted Carbon Allotropes: Recent Developments

“…When CNTs are subjected to external physical forces or chemical modifications, their structures and properties could be considerably changed. Thus, possible formation of polymerized high‐pressure (cycles “compression‐decompression” up to 40–50 GPa) phases of SWCNTs due to cross‐linking between the internal surface of CNTs and carbon chains, yielding sp 3 bonds in the flat regions of collapsed phases, was studied using DFT [63] . After these cycles, the properties of SWNTs changed significantly.…”

“…Thus, possible formation of polymerized highpressure (cycles "compression-decompression" up to 40-50 GPa) phases of SWCNTs due to cross-linking between the internal surface of CNTs and carbon chains, yielding sp 3 bonds in the flat regions of collapsed phases, was studied using DFT. [63] After these cycles, the properties of SWNTs changed significantly. Also, DFT calculations at the HSEh1PBE/6-311G(d,p) level of theory, applied to the (5,5) SWCNTs modified with dehydrogenated hydrocarbons (C5, C6, C7, and C8), revealed [64] their geometrical distortion, leading to an opening in their diameter.…”