Carbon nanotubes (CNTs) exhibit unique and remarkably diverse electronic, optical and mechanical properties, implying potential applications ranging from ultrastrong composite materials to organic solar cells, organic light emitting diodes (O-LEDs), thin-film transistors, biomolecular sensors, nano-electro-mechanical devices (NEMS) and nanofluidic systems. This diversity in properties is at the same time a major challenge in the study and applications of CNTs, as synthesis methods produce a mixture of structures, and their virtual insolubility has long hindered their processing and purification. However, important breakthroughs have been made in our lab in the processing (by solubilization using natural bile salt surfactants), spectroscopic characterization
(thanks to the high resolution achieved on the individualized, surfactant coated CNTs), and purification of CNTs (by density gradient ultracentrifugation [DGU] of the solubilized tubes). E.g., we recently demonstrated that empty (intact, end-capped) and water-filled (opened) CNTs coexist in aqueous solution, that these can be separated by DGU, and that the former posses far more ideal, unperturbed properties than the commonly used (unwittingly) water-filled tubes. All this opens a wide range of high-impact research opportunities. The empty (and full-length) CNTs allow for an enhanced further sorting according to diameter, electronic type (metallic and semiconducting), chirality, and even handedness, through density gradient ultracentrifugation. Further
development of these separation/preparation methods will be combined with advanced optical spectroscopic techniques, for which our lab is particularly well equipped, to study the enhanced properties of these newly isolated intact CNTs, and their composites with organic functional molecules and polymers.