Microwave-assisted Cutting and Opening of Multi-walled Carbon Nanotubes Arrays with Permanganate Potassium in Acidic Medium

Abstract

A fast, facile and mild approach was developed to cut the conventional long and Array multiwalled carbon nanotubes (A-MWCNTs). We used microwave-assisted heating together 40mL mixer potassium permanganate and sulfuric acid (1/3mol) to cut A-MWCNTs. Each of the different experiment was performed at the temperature of 90oC and under different reaction times (5, 10, 20, 30, and 40 min). To harness the extent of cutting, shortened MWCNTs (S-MWCNTs) were fully characterized by UV–visible and Raman spectroscopies as well as scanning electron microscopies (SEM), transmission electron microscopies(TEM) and optical microscopy(OM). The results show that with this mild treatment, the long tubes of A-MWCNTs (>80 µm) were efficiently and significantly shortened to below about 1 µm after 40 min the treatment. In the same time, the S-MWCNTs formed stable dispersion state in water without the help of surfactants that provided possibility for further functionalizations and applications. For the first 10 min, crystallinity increased then decreased until 20 min, and after that improved slightly. This method can be considered as an efficient route for the cutting of MWCNTs due to its fast and controllable procedure.