Single-walled carbon nanotube–polymer composites: electrical, optical and structural investigation

We present a study on the interaction between single-walled carbon nanotubes (SWNTs) and the soluble polymer poly(3-octylthiophene) (P3OT). Composites of SWNTs embedded in the polymer matrix were fabricated by drop casting of the nanotube/P3OT mixture dissolved in chloroform and have been studied using absorption spectroscopy, electrical characterization methods and high-resolution electron microscopy. The electrical conductivity was measured as a function of the SWNTs content in the solution. As the nanotube concentration increases from 0 to 20 wt.%, the conductivity of the resulting films increases by five orders of magnitude. The enhancement in conductivity can be explained by means of simple percolation path theory, resulting in an estimated percolation threshold of 11 wt.%.