Modification of single-walled carbon nanotubes by hydrothermal treatment

Single-walled carbon nanotubes (SWNTs) have been conditioned in water and aqueous acidic solutions at elevated temperatures and pressures; i.e., by hydrothermal treatments (HT). Transmission electron and scanning force microscopies revealed that disentanglement of SWNT bundles, structural changes of amorphous carbon, and complete destruction of the SWNTs with the simultaneous formation of new carbon nanoclusters can be achieved by HT. The introduction of specific surface groups onto SWNTs is investigated by Raman, X-ray, and ultraviolet photoemission spectroscopies. Depending on the type of acid used, chlorine, bromine, or sulfonate could be selectively attached in various densities. With the proper choice of temperature and solvent/agent, HT provides ways to efficiently purify and modify SWNTs in a manageable process.