Torsional 'Superplasticity' of Graphyne Nanotubes

TL;DR

This study demonstrates that graphyne nanotubes exhibit exceptional torsional flexibility and superplasticity, surpassing carbon nanotubes, due to bond reconstruction processes during twisting, as shown by reactive molecular dynamics simulations.

Contribution

First detailed investigation of torsional behavior of graphyne nanotubes revealing their superplasticity and underlying reconstruction mechanisms.

Findings

GNTs are more flexible than CNTs.

GNTs exhibit superplasticity with fracture angles up to 35 times higher.

Reconstruction of triple bonds explains superplastic behavior.

Abstract

Graphyne is a planar two-dimensional carbon allotrope formed by atoms in sp, sp2, and sp3 hybridized states. Topologically graphyne nanotubes (GNTs) can be considered as cylindrically rolled up graphyne sheets, similarly as carbon nanotubes (CNTs) can be considered rolled up graphene sheets. Due to the presence of single, double, and triple bonds, GNTs exhibit porous sidewalls that can be exploited in many diverse applications. In this work, we investigated the mechanical behavior of GNTs under torsional strains through reactive molecular dynamics simulations. Our results show that GNTs are more flexible than CNTs and exhibit 'superplasticity', with fracture angles that are up to 35 times higher than the ones reported to CNTs. This GNT 'superplastic' behavior can be explained in terms of irreversible reconstruction processes (mainly associated with the triple bonds) that occur during torsional strains.