Estimation of dispersion stability of UV/ozone treated multi-walled carbon nanotubes and their electrical properties

Chemical functionalization of multi-walled carbon nanotubes (MWCNTs) was carried out by UV/ozone treatment. MWCNTs were characterized by elemental analysis, transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR) before and after treatment. The dispersion stability was investigated using UV–vis spectroscopy and a dispersion stability analyzer. Results confirmed the presence of oxygen-containing groups on the MWCNT surfaces by UV/ozone treatment resulting in dispersion stability better than for pristine MWCNTs in polar solvents. A simple method described to investigate the solubility behavior of MWCNTs functionalized with UV/ozone treatment in various organic solvents. To illustrate this concept, CNT dispersions were prepared using UV/ozone treatment with controlled times, and their solubility behavior was represented on three-dimensional graphs using Hansen solubility parameters. Based on these solubility data, a MWCNT/PMMA composite was prepared using an appropriate solvent and the sheet resistance was measured using a four-point probe method. As a result, composites made with MWCNTs having undergone UV/ozone treatment showed lower sheet resistance than CNT composites made from pristine or acid-treated MWCNTs.