Orientational Melting in Carbon Nanotube Ropes

TL;DR

This study uses Monte Carlo simulations to explore orientational melting in carbon nanotube ropes, revealing a transition at temperatures above 160 K driven by twiston dynamics.

Contribution

It introduces a lattice gas model to describe orientational melting in nanotube ropes, linking microscopic interactions to a phase transition.

Findings

Orientational melting occurs above 160 K.

Twistons facilitate the transition.

A lattice gas model effectively captures the energetics.

Abstract

Using Monte Carlo simulations, we investigate the possibility of an orientational melting transition within a "rope" of (10,10) carbon nanotubes. When twisting nanotubes bundle up during the synthesis, orientational dislocations or twistons arise from the competition between the anisotropic inter-tube interactions, which tend to align neighboring tubes, and the torsion rigidity that tends to keep individual tubes straight. We map the energetics of a rope containing twistons onto a lattice gas model and find that the onset of a free "diffusion" of twistons, corresponding to orientational melting, occurs at T_OM > 160 K.