Electrochemical\nRedox Switchable Dispersion of Single-Walled\nCarbon Nanotubes in Water

Abstract

We\npresent a new, efficient approach to achieve superior dispersibility\nof single-walled carbon nanotubes (SWNTs) in water by integrating reversible\nhost–guest interaction and π–π stacking.\nIn this approach, β-cyclodextrin (β-CD) was first modified\nwith a pyrene group to be adsorbed onto the wall of pristine SWNTs\nvia π–π stacking, followed by further functionalization\nwith ferrocene (Fc)-terminated water-soluble poly­(ethylene glycol)\n(PEG) through supramolecular host–guest interaction between\nβ-CD and Fc. Upon alternate electrochemical oxidative/reductive\nstimuli, the reversible host–guest pair enabled the PEG-Fc@Py-CD@SWNTs\nto exhibit switchable conversion between dispersion and aggregation\nstates. Electric field controllable PEG-Fc@Py-CD@SWNTs with good reversibility\nand intact nanotube structure may find potential applications in selective\nscreening of SWNTs, biosensors, and targeted drug delivery.