Electrical Properties of Soluble Carbon Nanotube/Polymer Composite Films

A series of multiwalled carbon nanotube (MWNT) esters with various alkyl chains of n -butyl, n -hexyl, n -octyl, n -dodecyl, and n -hexadecyl has been synthesized via a concise method, and their solubilities in chloroform were determined by UV−vis absorption spectroscopy. The MWNT ester/polysulfone (PSF) composite films were made by drop casting, and their morphologies was checked by scanning electron microscopic method. The surface and volume conductivities of these films were measured. It was found that while longer alkyl chains can result in better properties such as better solubility in chloroform, better dispersibility in polymer matrix, and better electrical conductivity performance, the n -octyl modified MWNT ester always plays the inflection role, exhibiting the percolative character. While the surface electrical conductivity of the composite films is ohmic, the electrical conductivity along the thickness direction is nonohmic, which may provide the possibility to realize the unique electrical properties of carbon nanotubes on a macroscopic scale.