A method of functionalization of multi-walled carbon nanotube (MWNT) at room temperature using dry ozone gas is
described. The resulting MWNT were characterized by Fourier transform infrared, x-ray photoelectron spectroscopy, and
scanning electron microscopy. Combined to these analyses and solubility in liquids, it could be concluded that the dry ozone
gas exposure introduces polar functional groups such as carboxylic groups to MWNT similar to acidic modification of
MWNT. Particularly, the stable dispersion of MWNT in water after ozone treatment above a critical level could be obtained,
implying potential bio-application. The hydrophilic functional groups on the MWNT introduced by ozone oxidation were
helpful in improving the interaction with functional groups in PA6 such as −NH2 and −CONH- resulting in improved
mechanical properties.