Electrophoretically deposited carbon nanotube thin films: a route to functional nanostructures and their assembled nanocomposites

The integration of single-walled carbon nanotubes (SWCNTs) in fuctional devices represent a challenge that has to be overcome in order to assess the potentiality of their unique properties [1-3]. As recently reported [4], "a two dimensional random network of SWCNTs is one simple and straight forward direction to the deposition of a nanotube network that can be obtained with a precise nanotube density". For this reason there is a growing interest in depositing SWCNT thin films to obtain multifunctional nanostructured composites and hybrid materials for applications in the area of optoelectronics where flexible, transparent and conductive coatings together with scalable and cheap fabrication methods are required [5-9]. One-step elecrophoretic depositon process of carboxylated SWCNTs suspended in acetonitrile between two electrodes under the influence of a DC electric field has enabled us to anchor them as bundle on the positive electrode, thus providing a simple methodology to obtain SWCNTs films. The use of UV-VIS and FTIR spectroscopies show that the carboxylic functionalities and the electronic properties of the SWCNTs are retained, leading to the formation of a SWCNT adsorptive nanostructure. It was also demonstrated how this process provides a simple route to obtain layered functional nanostructures using predeposited semiconducting polymers as the working electrode. According to SEM and AFM analyses we propose that SWCNT films could be a much more efficient 3-D charge collector, due to their network morphology. It was also possible to combine this technique with infiltration process for obtaining nanocomposites formation. One way to achieve this aim is the deposition of homogeneous films of carbon nanotubes and the subsequent infiltration with monomer solution, followed by in-situ polymerization. We report here an example where electrophoretically deposited SWCNTs films were infiltrated with methylmethacrylate (MMA) and the MMA was then polymerized. In conclusion we believe that the presence of this deposition process is envisaged to make it very useful for the development of novel architectures with nanotubes and polymers having outstanding properties.