Characterisation of single-walled carbon nanotube bundle dissociation in amide solvents

The implementation of single-walled carbon nanotubes (SWNTs) into a wide array of applications is hindered by the formation of bundles. Many methods have been suggested to de-bundle the SWNTs, including both covalent and non-covalent funtionalisation with surfactants, polymers and macromolecules. These methods have their advantages but the ideal situation must be to dissolve and de-bundle the SWNTs in an appropiate solvent at concentrations that are useful for their implementation in applications. In this work we have concentrated on the amide solvent N-methyl-2-pyrrolidone (NMP). This solvent has been shown to be a good dispersant of SWNTs and we have analytically characterised the dispersing and de-bundling process. Optical absorbance based studies allowed the determination of the concentration at which these dispersions deviate from the Lambert Beer law. This concentration is thought to correspond to that where individual SWNTs are held in solution. Atomic force microscopy was carried out on all solutions confirming excellent dispersion and significant debundling even at high SWNT concentration.