Surface state of carbon nanotubes and Hansen solubility parameters

Carbon nanotubes (CNTs) are often described as insoluble or poorly soluble in organic solvents. In a recent study, we have reported that nonfunctionalized CNTs can be solubilized in suitably chosen organic solvents. Furthermore, their solubility could be understood in terms of the Hansen Solubility Parameters (HSPs). The present work addresses further the question of the CNTs solubility by considering a larger range of solvents. A second part is devoted to the application of the HSPs to two types of functionalized CNTs: oxidized and silanized. These results stress the critical role played by the surface state of the CNTs, on the one hand, and the interest in using the HSPs to guide solubility investigations, on the other hand.