Single‐walled carbon nanotubes modified by PFO: An optical absorption and Raman spectroscopic investigation

Abstract

In this contribution, we present preliminary results from an optical absorption and resonance Raman spectroscopic investigation on single-walled carbon nanotubes (SWCNT) functionalized by poly(9,9-dioctylfluorenyl-2,7-diyl)-cobithiophene (PFO-BTP). A route for a stable suspension of SWCNT in a solution of fluorine-base copolymer is shown. Additionally, the detailed analysis of the supernatant and sediment after centrifugation of the functionalized sample is given. The resonance Raman and optical absorption spectroscopic data suggest that selective wrapping of the carbon nanotubes by PFO occurs. Additionally, one can see that the abundance of SWCNT in the supernatant in a bulk sample increased by a factor of 2.

Effect of side-chain halogenation on the interactions of conjugated polymers with SWNTs

“…20,21 In recent years, several methods for nanotube purification and enrichment of specific semiconducting chiralities have been demonstrated, including density gradient ultracentrifugation (DGU), 19,20 gel filtration, 20,22 dielectrophoresis, 23 aqueous two-phase extraction, 24,25 and selective extraction using conjugated polymers. 26,27 Although each technique has its own unique advantages and provides comparatively reliable routes to enrichment of semiconducting SWNTs (sc-SWNTs), the relative simplicity of the π-conjugated polymer extraction process makes it a cost-effective and scaleable method for sc-SWNT isolation. 27,28 Research in this area began with reports of noncovalent functionalization of SWNTs using π-conjugated polyfluorenes, such as poly(9,9′-dioctylfluorene) (PFO) 29,30 and poly (9,9′-didodecylfluorene) (PDDF), 31,32 as well as fluorene containing copolymers, 33,34 which demonstrated excellent dispersions and highly enriched samples of sc-SWNTs in aqueous and organic media.…”

“…Subsequent progress extended the scope of conjugated polymers to polythiophenes, 35 poly( p-phenylene ethynylenes), 36 polycarbazoles, 37,38 and a number of derivative structures. 26,39 Furthermore, several reports have described the effect of conjugated polymer structure, 40,41 molecular weight 42,43 solvent effects, 44 sonication conditions, 44,45 and side-chain structure (including alkyl group architecture and length) 46,47 on the selectivity toward dispersion of specific SWNT chiralities. These studies have shown that small changes in polymer structure can result in dramatic changes in the nanotube chiralities that are selectively dispersed in solvents.…”