New types of functionalised, water-soluble carbon fibres from carbon nanotubes
Information on how nanoparticles of catalysts are involved in the initial stage of nanotube growth, functionalisation, doping and composite formation has been obtained and used to understand the method of functionalising carbon nanotubes.
Major achievements and highlights
The effect of annealing at 1400°C in argon on the bond structure of a graphite ball milled for 100 h at 400 rpm in polar (water) and in non-polar (n-dodecane) liquids has been investigated to understand functionalisation.
Mechanisms of functionalisation during milling have been investigated. It is shown that the loss of sp3carbons on annealing proceeds via a different mechanism than that by which they are formed by milling.
Organometallic compounds such as iron phthalocyanine are useful precursors for preparing carbon nanotubes and functionalised carbon nanotubes and the action mechanism is now understood.
The effect of the milling on the iron phthalocyanine sublimation and subsequently on carbon nanotube synthesis has been elucidated. Prior milling of iron-phthalocyanine has been shown to affect the sublimation temperature of the precursor and the nanotube diameter. Without prior milling, a sublimation temperature of 600 – 650°C is necessary to produce sufficient amounts of vapour prior to pyrolysis. At that temperature there is also some decomposition. Transmission electron microscopy (TEM) shows the average diameter of the MWCNTs produced from the non-milled and milled FePc precursor is about 40 – 100 nm and 15 – 50 nm, respectively. It is suggested that the decrease in nanotube diameter caused by the milling of the precursor is due to presence of higher concentrations of un-decomposed FePc molecules with a fixed C/Fe atomic ratio in the gas phase prior to pyrolysis. These results show the importance of the crystalline structure of precursor materials for CNT synthesis since small changes in the structure of precursors affect nanotube structure and formation kinetics.
Relatively simple approaches for functionalisation and dispersion of carbon nanotubes in the water solutions of the pH sensitive polymers including poly(acrylic acid) have been developed.
Synchrotron soft X-rays (energy lower than 3000 eV) have been utilised for characterisation of the carbon nanotube interfacial interactions during functionalisation, composite and hybrid formation.
Future plans and directions
Formation and testing of composites with functionalised nanotubes. Formation of nano-hybrids using semiconductor nano-particles and functionalised nanotubes and testing of their optical-electrical properties.
In depth synchrotron radiation characterisation of carbon nanotube surface and interface.
Collaborations
Collaborator |
Organisation |
Prof John Bartlett |
University of Western Sydney |
Prof Robert Lamb |
University of Melbourne and Australian Synchrotron |
Dr Herbert Volk |
CSIRO Petroleum |
Dr Yaw-Wen Yang |
National Synchrotron Radiation Research Centre, Taiwan |
