Unexpectedly strong hydrophilic character of free-standing thin films from carbon nanotubes

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.