Why do Collapsed Carbon Nanotubes Twist?

TL;DR

This study investigates the spontaneous twisting of collapsed carbon nanotubes, revealing that charge imbalance-induced compressive strain causes the twisting, based on in-situ microscopy and diffraction analysis.

Contribution

It provides the first detailed experimental and theoretical analysis linking charge imbalance to twisting in collapsed nanotubes.

Findings

Collapsed nanotubes spontaneously twist along their axis.

Charge imbalance induces compressive strain leading to twisting.

Experimental and theoretical methods confirm the twisting mechanism.

Abstract

We study the collapsing and subsequent spontaneous twisting of a carbon nanotube by in-situ transmission electron microscopy. A custom-sized nanotube is first created in the microscope by selectively extracting shells from a parent multi-wall tube. The few-wall, large-diameter daughter nanotube is driven to collapse via mechanical stimulation, after which the ribbon-like collapsed tube spontaneously twists along its long axis. In-situ diffraction experiments fully characterize the uncollapsed and collapsed tubes. From the experimental observations and associated theoretical analysis, the origin of the twisting is determined to be compressive strain due to charge imbalance.