Experimental Measurement of the Binding Configuration and Coverage of Chirality-Sorting Polyfluorenes on Carbon Nanotubes

TitleExperimental Measurement of the Binding Configuration and Coverage of Chirality-Sorting Polyfluorenes on Carbon Nanotubes
Publication TypeJournal Article
Year of Publication2014
AuthorsShea MJ, Mehlenbacher RD, Zanni M T., Arnold MS
Volume5
Issue21
Pagination3742–3749
Date Published10/2014
PublisherPhysical Processes in Nanomaterials and Nanostructures
Keywordscarbon nanotube; semiconductor; Langmuir adsorption; anisotropy; photoluminescence
Abstract

Poly(9,9-dioctylfluorene-2,7-diyl) (PFO) exhibits exceptional (n,m) chirality and electronic-type selectivity for near-armchair semiconducting carbon nanotubes. To better understand and control the factors governing this behavior, we experimentally determine the surface coverage and binding configuration of PFO on nanotubes in solution using photoluminescence energy transfer and anisotropy measurements. The coverage increases with PFO concentration in solution, following Langmuir-isotherm adsorption behavior with cooperativity. The equilibrium binding constant (PFO concentration in solution at half coverage), KA, depends on (n,m) and is 1.16 ± 0.30, 0.93 ± 0.12, and 1.13 ± 0.26 mg mL–1 for the highly selected (7,5), (8,6), and (8,7) species, respectively, and the corresponding PFO wrapping angle at low coverage is 12, 17, and 14 ± 2°, respectively. In contrast, the inferred KA for metallic nanotubes is nearly an order of magnitude greater, indicating that the semiconducting selectivity increases with decreasing PFO concentration. This understanding will quantitatively guide future experimental and computational efforts on electronic type-sorting carbon nanotubes.

URLhttp://pubs.acs.org/doi/abs/10.1021/jz5017813
DOI10.1021/jz5017813