Reversible functionalization of multi-walled carbon nanotubes with organic dyes

Multi-walled carbon nanotubes can be dispersed in water via the formation of adducts with dyes; this process may be qualitatively monitored by the visual observation of colour variations of dye solutions. Atomic force microscopy images corroborate evidence for attachment of dyes on nanotubes. Laser Raman and Fourier transform infrared spectroscopies suggest intimate electronic interactions between nanotubes and dyes. The dyes can be successfully exfoliated from the nanotubes by thin layer chromatography, showing the reversible nature of the process.