Structure Analyses of Dodecylated Single-Walled Carbon Nanotubes

• Published in: Journal of the American Chemical Society 2005-10, Vol.127 (40), p.13941-13948
• Main Authors: Liang, Feng, Alemany, Lawrence B, Beach, Jonathan M, Billups, W. Edward
• Format: Article
• Language: English
• Subjects: Alkylation; Carbon Isotopes; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Hydrocarbons, Iodinated - chemistry; Magnetic Resonance Spectroscopy; Materials science; Metals, Alkali - chemistry; Molecular Structure; Nanoscale materials and structures: fabrication and characterization; Nanotubes; Nanotubes, Carbon - chemistry; Particle Size; Physics; Spectrum Analysis, Raman; Thermogravimetry; Time Factors
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja052870s

Alkylation of nanotube salts prepared using either lithium, sodium, or potassium in liquid ammonia yields sidewall-functionalized nanotubes that are soluble in organic solvents. Atomic force microscopy and transmission electron microscopy studies of dodecylated SWNTs prepared from HiPco nanotubes and 1-iodododecane show that extensive debundling results from intercalation of the alkali metal into the SWNT ropes. TGA-FTIR analyses of samples prepared from the different metals revealed radically different thermal behavior during detachment of the dodecyl groups. The SWNTs prepared using lithium can be converted into the pristine SWNTs at 180−330 °C, whereas the dodecylated SWNTs prepared using sodium require a much higher temperature (380−530 °C) for dealkylation. SWNTs prepared using potassium behave differently, leading to detachment of the alkyl groups over the temperature range 180−500 °C. These differences can be observed by analysis of the solid-state 13C NMR spectra of the dodecylated SWNTs that have been prepared using the different alkali metals and may indicate differences in the relative amounts of 1,2- and 1,4-addition of the alkyl groups.