Carbon nanotube plasma functionalization: The role of carbon nanotube/maleic anhydride solid premix

Carbon nanotubes (CNT) were functionalized by radio-frequency plasma using maleic anhydride (MA) as a source of functional groups. The MA insertion was performed in the solid form through a mixture with CNT conducted under two different methods: in a planetary mill; and manually, using mortar and pestle assistance. The premix influence on CNT functionalization and the functionalization itself were evaluated using Fourier Transform Infrared (FTIR), Raman Spectroscopy, Transmission Electronic Microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results indicate CNT plasma functionalization by the carboxyl groups provided by the opened MA ring. Neither the mixture methods nor the plasma process affected the integrity of the CNT, maintaining their initial morphology. Structural analyses indicate increased presence of O-C=O groups attached to the CNT's surface after functionalization operation and subsequent moisture removal from the nanoparticles. Such effect was more pronounced for samples with a higher amount of O-C=O groups (>3 at.%) premixed in the mortar, suggesting a potential use of the functionalized CNT as an agent for wastewater cleaning.