# The Stability of UV-Defluorination-Driven Crosslinked Carbon Nanotubes: A Raman Study

## TL;DR

This study shows that UV-defluorination crosslinked carbon nanotubes are less thermally stable than untreated ones, making them suitable for applications requiring easy post-use removal.

## Contribution

The paper reveals the metastability of UV-defluorination-driven crosslinked CNTs under laser irradiation.

## Key findings

- UV-defluorinated CNTs decompose more readily than pristine or fluorinated CNTs under Raman laser irradiation.
- Metallic CNTs in crosslinked networks revert to their pristine state more easily than semiconducting CNTs.
- Crosslinked CNTs combust at temperatures about 100 °C lower than non-crosslinked fluorinated CNTs.

## Abstract

Carbon nanotubes (CNTs) are often regarded as semi-rigid, all-carbon polymers. However, unlike conventional polymers that can form 3D networks such as hydrogels or elastomers through crosslinking in solution, CNTs have long been considered non-crosslinkable under mild conditions. This perception changed with our recent discovery of UV-defluorination-driven direct crosslinking of CNTs in solution. In this study, we further investigate the thermal stability of UV-defluorination-driven crosslinked CNTs, revealing that they are metastable and decompose more readily than either pristine or fluorinated CNTs under Raman laser irradiation. Using Raman spectroscopy under controlled laser power, we examined both single-walled and multi-walled fluorinated CNTs. The results demonstrate that UV-defluorinated CNTs exhibit reduced thermal stability compared to their pristine or untreated fluorinated counterparts. This instability is attributed to the strain on the intertube crosslinking bonds resulting from the curved carbon lattice of the linked CNTs. The metallic CNTs in the crosslinked CNT networks decompose and revert to their pristine state more readily than the semiconducting ones. The inherent instability of crosslinked CNTs leads to combustion at temperatures approximately 100 °C lower than those required for non-crosslinked fluorinated CNTs. This property positions crosslinked CNTs as promising candidates for applications where mechanically robust, lightweight materials are needed, along with feasible post-use removal options.