Surface electrical conductivity in ultrathin single-wall carbon nanotube/polymer nanocomposite films

Ultrathin composite films of single-wall carbon nanotubes dispersed in polymer matrices of polystyrene and polyurethane elastomers with the thickness ranging from 100nmto3μm were formed by dip-coating procedure. Electrical conductivity in plane of the film was measured with application of silver electrodes deposited through shadow mask techniques at polymer-air and polymer-substrate interfaces. Peculiarities of the surface electrical conductivity in the nanocomposite films have been related to the surface free energy of the components and the strength of polymer-substrate interfacial interaction, which promotes a nonuniform distribution of the conductive filler within the film thickness (vertical phase separation).