Sensitivity of single-wall carbon nanotubes to chemical processing: an electron microscopy investigation

Single wall carbon nanotube (SWNT) materials subjected to Various chemical treatments including regular, published, acidic purification treatments, were investigated by high resolution transmission electron microscopy and X-ray diffraction. Results show that acid purification cannot avoid SWNT structure alteration. The liquid, acidic medium provokes the gathering of pre-existing fullerenes into crystallised fullerite. A slight temperature increase has a dramatic effect on SWNT degradation which can result in complete amorphisation. Immersion of some of the SWNT materials in dimethylformamide (DMF) was also found to be harmful to the SWNT structure. Several observations suggest that as-prepared (not treated) SWNTs contain structural defects along the tube walls which act as preferred sites for the acid (or DMF) attack, inducing side wall openings. (C) 2001 Elsevier Science Ltd. All rights reserved.