Morphology and electrochemical properties of amphiphilic viologen functionalized multiwalled carbon nanotube hybrids in Langmuir-Blodgett films

Amphiphilic viologens were electrostatically adsorbed on the surface of multiwalled carbon nanotubes (MWCNT) to form viologen-MWCNT hybrids, in which the content of viologens was about 5-10% in weight. Although both viologens and MWCNT hardly dispersed in the water-insoluble organic solvents, the as-prepared viologen-MWCNT hybrids were well dispersed in them with a strong long-term stability, the features of which provided a possibility to prepare their insoluble monolayers at the air-water interface. The surface pressure-area isotherms of these hybrids revealed that they could form stable monolayers, which were transferred on the substrate surfaces by the Langmuir-Blodgett (LB) method. Morphologies of the LB films were characterized by using scanning electron microscopy and atomic force microscopy, the images of which revealed the formation of network two- or three-dimensional films of the functionalized MWCNT. Cyclic voltammograms of the LB films revealed one or two couples of one electron transfer process corresponding to the viologen-MWCNT hybrids with the cathodic and anodic potentials closely related to the alkyl chains of the viologens.