Transparent conductive thin films based on polyaniline nanofibers

Conducting polyaniline (PANI) nanofibers doped with sulphuric acid were synthesized by a sonochemical method and dispersed in methyl isobutyl ketone (MIBK) with ultrasonicating. The dispersion was mixed with poly(methyl methacrylate) (PMMA) solution in MIBK and cast to fabricate transparent conductive films with evaporation of the solvent. With only a mixing procedure and without any dispersant added, the PANI nanofibers were well dispersed in the matrix polymer as indicated by scanning electron microscopy (SEM) examination. The conductive composite films showed a percolation threshold at ca. 2.2 wt% owing to the relatively larger one-dimensional aspect ratios of the nanofibers. With loadings of PANI nanofibers in the range of 5-20 wt%, composite coatings in thickness of 1 μm with conductivities of 10^-4 to 10^-2 S/cm and transmittances higher than 40% in the visible spectrum can be achieved. The composite coatings showed good stability in air and solvents like water and isopropanol. Combined with their relatively easy preparing procedures, the PANI nanofibers based transparent conductive films can be great promise in practical applications.