NON-CONVENTIONAL SYNTHESIS OF CARBON NANO-RIBBONS BY THE LOW- TEMPERATURE UNFOLDING OF MWCNTS.

摘要

In the present work, we have studied the treatment of multi-wall carbon nanotubes (MWCNTs) with the water-soluble cobalt octacarboxyphthalocyanine derivative theraphthal (TP, a cancer therapy drug) under ultrasonic conditions in the presence of ascorbic acid (AA) leading to the dispersion and unfolding of MWCNTs and production of ribbon-like nanostructures (NRs) at low temperatures. The synthesis was carried out using different amounts of slightly magnetic MWCNTs, AA and TP, which were ultrasonicated in 30 mL flasks with DI water for 1 -6 h in ultrasonic cleaner at 42-45°C. In these conditions, even at low intensity ultrasound in cleaners (20-40 kHz), partial destruction of TP slowly takes place and it is known to be accompanied by formation of Reactive Oxygen Species (ROS). TP can be first coordinated to CNT surface via π-π-stacking through aromatic supramolecular ring or covalently through COO- group(s) of the TP molecule. Unfolding of MWCNTs in the conditions of TP/AA addition can be explained by the in situ formation of ROS in TP solutions under ultrasonic treatment and their further attack on MWCNTs surface, destroying and unfolding them forming graphene sheets and ribbons. The obtained results differ from the conventional concepts of classic π-π-stacking interactions and/or σ-bonding between macrocycles and carbon nanotubes. Characterization of samples was made by Raman spectroscopy. Transmission Electron Microscopy (TF.M) and IR-spectroscopy.