With the ever increasing utilisation of carbon nanostructures across many fields, researchers are continuously looking for new and more efficient methods for the reliable and controllable functionalisation of these materials, in a way that is easily scalable. This is particularly true for the one dimensional carbon nanotube (CNT). While plasma science is not a new field, its application towards the covalent attachment of chemically reactive species to the sidewalls of the initially somewhat inert CNT structure has only more recently been investigated. Furthermore, in-depth studies of the plasma functionalisation of CNTs using fluorine-rich species such as sulphur hexafluoride (SF6) are limited for a process that is capable of not only providing reactive sites for further chemical attachment but also the modification of the electronic structure of the nanotube [1, 2].

In this presentation research efforts into the fluorination of single-walled CNTs (SWCNTs) in a controlled manner using SF6 plasma will be discussed. Control over the amount of fluorine attached to the CNT surfaces is demonstrated through variation in experimental conditions such as plasma power. Furthermore, the type of fluorine bonding present on the surface (covalent or semi-ionic) is shown to be controllable through the addition of oxygen containing species into the fluorination mechanism. This can be achieved through either the doping of the plasma itself with oxygen or water vapour, or by an oxidative surface pretreatment of the CNTs through wet-chemical or plasma methods. With this level of control, greatly enhanced C-F covalency can be achieved over a pure SF6 plasma treatment alone. Results will be presented from lab-based XPS analysis of SWCNT surfaces performed at Flinders University, South Australia, as well as synchrotron-based XPS analysis performed at the Australian Synchrotron.

1. Park, K.A., Y.S. Choi, and Y.H. Lee, Atomic and electronic structures of fluorinated single-walled carbon nanotubes. Phys. Rev. B, 2003. 68: p. 045429.

2. Plank, N.O.V., et al., Electronic properties of n-type carbon nanotubes prepared by CF4 plasma fluorination and amino functionalisation. J. Phys. Chem. Lett. B, 2005. 109: p. 22096-22101.