title: Phase transfer catalysts drive diverse organic solvent solubility of single-walled carbon nanotubes helically wrapped by ionic, semiconducting polymers.
abstract: Use of phase transfer catalysts such as 18-crown-6 enables ionic, linear conjugated poly[2,6-{1,5-bis(3-propoxysulfonicacidsodiumsalt)}naphthylene]ethynylene (PNES) to efficiently disperse single-walled carbon nanotubes (SWNTs) in multiple organic solvents under standard ultrasonication methods. Steady-state electronic absorption spectroscopy, atomic force microscopy (AFM), and transmission electron microscopy (TEM) reveal that these SWNT suspensions are composed almost exclusively of individualized tubes. High-resolution TEM and AFM data show that the interaction of PNES with SWNTs in both protic and aprotic organic solvents provides a self-assembled superstructure in which a PNES monolayer helically wraps the nanotube surface with periodic and constant morphology (observed helical pitch length = 10 ± 2 nm); time-dependent examination of these suspensions indicates that these structures persist in solution over periods that span at least several months. Pump-probe transient absorption spectroscopy reveals that the excited state lifetimes and exciton binding energies of these well-defined nanotube-semiconducting polymer hybrid structures remain unchanged relative to analogous benchmark data acquired previously for standard sodium dodecylsulfate (SDS)-SWNT suspensions, regardless of solvent. These results demonstrate that the use of phase transfer catalysts with ionic semiconducting polymers that helically wrap SWNTs provide well-defined structures that solubulize SWNTs in a wide range of organic solvents while preserving critical nanotube semiconducting and conducting properties.
authors.affiliation: Department of Chemistry, French Family Science Center, 124 Science Drive, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Pravas
authors.initials: P
authors.lastname: Deria
authors.forename: Louise E
authors.initials: LE
authors.lastname: Sinks
authors.forename: Tae-Hong
authors.initials: TH
authors.lastname: Park
authors.forename: Diana M
authors.initials: DM
authors.lastname: Tomezsko
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Brukman
authors.forename: Dawn A
authors.initials: DA
authors.lastname: Bonnell
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Therien