Chemistry of Carbon Nanomaterials
W.E. Billups, F. Liang, J. Chattopadhyay, A.K. Sadana, S. Chakraborty, A. Mukherjee
Rice University, US
Keywords: single-walled carbon nanotubes
Abstract:Reductive alkylation of single-walled carbon nanotubes (SWNTs) using lithium and alkyl halides in liquid ammonia yields sidewall functionalized nanotubes that are soluble in common organic solvents [1,2]. Atomic force microscopy (AFM) and high-resolution tunneling electron microscopy (TEM) of dodecylated SWNTs prepared from raw HiPco nanotubes and n-dodecyl iodide show that extensive debundling has occurred. Analysis of the by-product hydrocarbons by mass spectrometry indicates that alkyl radicals are intermediates in the alkylation step. The debundling can be explained in term of extensive intercalation of lithium into the bundled SWNTs. Electron transfer from lithium to the SWNTs was investigated by in-situ monitoring of the Raman spectrum as lithium was added incrementally to a dispersion of the SWNTs in liquid ammonia . The electron/lithium uptake saturation level was determined to be ~C2/Li. This is higher than previous SWNT doping results and similar to C2F, which is the limit found previously for direct fluorination of SWNTs.