title: Ribbon-to-fiber transformation in the process of spinning of carbon-nanotube dispersion.
abstract: We describe a phenomenon of ribbon-to-fiber transformation observed in the process of spinning of single wall carbon nanotubes dispersed in polymer solutions. In the process of spinning, a gel-like ribbon comprised of nanotube bundles bound by polymer is withdrawn from a solvent bath. We show that upon crossing the liquid-air interface, the ribbon may either retain its flat shape or fold into a compact hairlike fiber. The ribbon-to-fiber transformation is caused by the capillary action of the liquid meniscus embracing the ribbon. Only sufficiently stiff ribbons can withhold the capillary compression. The critical conditions of folding, as well as the number of folds in the contractive ribbon, depend on the ribbon width, its flexural rigidity, and the solvent surface tension. We show that the ribbon rigidity can be efficiently modulated by varying the solvent composition, allowing us to control the pore structure of carbon-nanotube fibers.
authors.affiliation: Center for Modeling and Characterization of Nanoporous Materials, TRI/Princeton, 601 Prospect Avenue, Princeton, New Jersey 08542-0625, USA.
authors.forename: Konstantin G
authors.initials: KG
authors.lastname: Kornev
authors.forename: Gerardo
authors.initials: G
authors.lastname: Callegari
authors.forename: John
authors.initials: J
authors.lastname: Kuppler
authors.forename: Sigrid
authors.initials: S
authors.lastname: Ruetsch
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Neimark
mesh_terms: D008855:Microscopy, Electron, Scanning; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D044367:Phase Transition; D011142:Polyvinyl Alcohol / Q000737:chemistry; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013500:Surface Tension
chemical_list: D037742:Nanotubes, Carbon; D012967:Sodium Dodecyl Sulfate; D011142:Polyvinyl Alcohol