title: Dispersions of functionalized single-walled carbon nanotubes in strong acids: solubility and rheology.
abstract: The manipulation and processing of single-wall carbon nanotubes (SWNTs) is limited by their poor solubility in most common solvents. Covalent sidewall functionalization of SWNTs provides an excellent route to improve their solubility. Here we have studied the relationship between sidewall functionalization and phase behavior of solutions of functionalized SWNTs (f-SWNTs) in strong acids. We use centrifugation in conjunction with UV-Vis-nlR spectroscopy to quantify the solubility of f-SWNTs in strong acids. We image the dispersions of functionalized tubes by polarized light microscopy. We find that adding butyl groups increases marginally the solubility of SWNTs in 102% sulfuric acid in the isotropic phase; adding 9-nonadecyne groups roughly doubles the solubility of SWNTs. Viscosity measurements in dilute solutions are sensitive to de-bundling. We compare the viscosity-concentration dependence of dilute pristine and f-SWNTs to assess whether and how functionalization promotes de-bundling and stabilizes the tubes. The phase behavior and rheology of these f-SWNTs parallels with that of pristine SWNTs; 9-nonadecylated SWNTs have higher solubility and should be easier to process.
authors.affiliation: Carbon Nanotechnology Laboratory, Smalley Institute for Nanoscale Science and Technology, rice University, Houston, Texas 77005, USA.
authors.forename: Pradeep K
authors.initials: PK
authors.lastname: Rai
authors.forename: A Nicholas G
authors.initials: AN
authors.lastname: Parra-Vasquez
authors.forename: Jayanta
authors.initials: J
authors.lastname: Chattopadhyay
authors.forename: Robert A
authors.initials: RA
authors.lastname: Pinnick
authors.forename: Feng
authors.initials: F
authors.lastname: Liang
authors.forename: Anil K
authors.initials: AK
authors.lastname: Sadana
authors.forename: Robert H
authors.initials: RH
authors.lastname: Hauge
authors.forename: W Edward
authors.initials: WE
authors.lastname: Billups
authors.forename: Matteo
authors.initials: M
authors.lastname: Pasquali
mesh_terms: D000143:Acids / Q000737:chemistry*; D003102:Colloids / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D004548:Elasticity; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D012212:Rheology / Q000379:methods; D012995:Solubility; D012997:Solvents / Q000737:chemistry; D013499:Surface Properties; D014783:Viscosity
chemical_list: D000143:Acids; D003102:Colloids; D046911:Macromolecular Substances; D037742:Nanotubes, Carbon; D012997:Solvents