Synthesis of Water-Soluble PEGylated Single-Walled Carbon Nanotubes

Carbon nanotube salts prepared by treating single-wall carbon nanotubes (SWNTs) with lithium in liquid ammonia react with ω-bromocarboxylic acids to yield sidewall-derivatized SWNTs. These can be reacted with amine-terminated polyethyleneglycol (PEG) chains (e.g., H2N−mPEG−OMe, MW = 5000 Da) to yield water-soluble PEGylated SWNTs. Short nanotubes (average length ∼ 60 nm) functionalized by PEGylation of the carboxylic acid groups at the end of the nanotubes exhibit greater solubility in water than the longer (average length ∼ 300 nm) sidewall-PEGylated pristine nanotubes.