Efficient direct water-solubilisation of single-walled carbon nanotube derivatives

Application under mild conditions of a one-pot reductive–oxidative synthetic protocol to single-walled carbon nanotubes (SWNT) affords water-soluble oxygenated products that have been characterised by mean of XPS, solution 1H-NMR, UV-VIS-NIR, vibrational FTIR and Raman, SEM–energy dispersive x-ray (EDX), XRD, and ESI-MS techniques. Different oxygenated functionalities are evicted to be covalentlybonded to carbon nanotubes frameworks, due to electrophilic insertion of O2 upon reduced carbon structures. The pH-dependent behaviour in water solution and the observed partial fragmentation of oxidised nanotubes, that can contribute in enhancing water solubility by shortening structures, are discussed. Prolonged heating of the material affords a higher graphitisation index of the functionalised carbonaceous water- soluble frameworks, and possible chemical paths for the partial recovering of pristine carbon nanostructures are reported. The achieved hydrophily due to polar oxygen moieties insertions on nanostructures provides a remarkable unprecedented water solubility for these carbon substrates without the attachment of large polar appendages.