A Study on the Effects of Potassium Permanganate on the Functionalization of Multi-Walled Carbon Nanotubes

In this work, multi-walled carbon nanotubes (MWCNTs) are functionalized by a wet chemical oxidation method using a mixture of potassium permanganate (KMnO 4 ) and sulfuric acid (H 2 SO 4 ) at 70 °C, for 12 h. The effects of various KMnO 4 amounts on the functionalization of MWCNTs are studied and reported. The surface morphologies, structural properties, dispersion and thermal stability of the MWCNTs are characterized using a field emission scanning electron microscope (FE-SEM), Raman spectroscopy, UV-visible spectroscopy (UV–vis), thermal gravimetric analysis (TGA). The FE-SEM images display some surface roughness, cutting and open ends of functionalized MWCNTs (f-MWCNTs). The TGA curves of f-MWCNTs indicate a weight loss between 150 °C and 350 °C, which is attributed to the loss of carboxyl groups on the MWCNTs surface and the weight loss is increased when KMnO 4 mass is increased. The highest weight loss value of 22.23% is recorded for the oxidation treatment with a mixture of 5 M H 2 SO 4 and 200 mg KMnO 4 . UV–vis measurements indicate that the f-MWCNTs are highly dispersed in the aquoues solution in comparision to the pristine MWCNTs (p-MWCNTs). And f-MWCNTs with higher functionalization degree show better dispersibility. This study provides a great prospect of effective method to cut, end-open, functionalize and disperse MWCNTs.