Partial oxidation of nanocarbon materials is one of the most straightforward methods to improve their compatibility with other materials, which widens its application potential. This work studied how the microstructure and properties of high crystallinity single-walled carbon nanotubes (SWCNTs) can be tailored by applying the modified Hummers method. The influence of temperature (0, 18, 40 °C), reaction time (0 min to 7 h), and the amount of KMnO₄ oxidant was monitored. The results showed that depending on the oxidation conditions, the electronic characteristics of the material could be adjusted. After optimizing the parameters, the SWCNTs were much more conductive (1369 ± 84 S/cm with respect to 283 ± 32 S/cm for the untreated material). At the same time, the films made from them exhibited hydrophilic character of the surface (water contact angle changed from 71° to 27°).

We report on the development of a method of formation of hydrophilic carbon nanotube (CNT) films. The technique is simple, straightforward and does not require specialized equipment or use of harsh chemical compounds. Elimination of the need for oxidizing agents has paramount implications because it preserves the inherent CNT properties. A reference study, in which the traditional method of oxidation of CNTs was used to introduce functional groups, gave smaller reduction of water contact angle and made a negative influence on the surface chemistry. From the practical point of view, this method is an important step towards implementation of CNTs in the real life by making them more compatible with interface materials. Interestingly, the method gives high level of control over the surface character of CNT films and hydrophilic character can be precisely patterned where required.

Despite the widespread use of sonication for individualization of nanomaterials, its destructive nature is rarely acknowledged. In this study, we demonstrated how exposure of the material to a hostile sound wave environment can be limited by the application of another preprocessing step. Single-walled carbon nanotubes (CNTs) were initially ground in a household coffee grinder, which enabled facile deagglomeration thereof. Such a simple approach enabled us to obtain high-quality CNT dispersion at reduced sonication time. Most importantly, electrical conductivity of free-standing films prepared from these dispersion was improved almost fourfold as compared with unground material eventually reaching 1067 ± 34 S/cm. This work presents a new approach as to how electrical properties of nanocarbon ensembles may be enhanced without the application of doping agents, the presence of which is often ephemeral.