Highly carbonized polyaniline micro- and nanotubes

We have obtained unique highly carbonized polyaniline micro- and nanotubes as a new, thermally stable nanomaterial for nanosensors and nanodevices with a wide range of possible applications, comparable to carbon nanotubes. Polyaniline nanostructures are easy to prepare and handle in wet conditions, including controlled growth. Temperature-induced transformations of polyaniline micro- and nanotubes into highly carbonized analogues have been observed at and above 800 degrees C, while the temperature was elevated slowly from 20 degrees C up to 1100 degrees C. Carbonized products have the same morphology (micro- and nanotubes), but a lower spin density than the starting material (e.g. 10(14) g(-1) for the sample heated at and above 800 degrees C, and 10(19) g(-1) before heating). Simultaneously, the electrical conductivity changes from 7.4 x 10(-5) S/cm for the starting material to 4.8 x 10(-9) S/cm, 1.3 x 10(-11) S/cm and finally 2.4 X 10(-6) S/cm for samples obtained at room temperature, 250 degrees C, 500 degrees C and 800 degrees C, respectively. Chemical transformations and unique molecular structures formed are discussed. Applications in nanotechnology, including sensors and electronic nanodevices, are expected in the light of experiments already performed. (c) 2006 Elsevier Ltd. All rights reserved.