IN-SITU SCANNING PROBE MICROSCOPY FOR THE MEASUREMENT OF THICKNESS CHANGES IN AN ELECTROACTIVE POLYMER

Using Scanning Probes Methods (SPM), it is possible to monitor dimensional changes of polyaniline (PANI) films in the nm-range. Swelling and shrinking of the polymer during oxidation and reduction could be detected in-situ by this SPM-based technique. For a PANI film with a charge capacity of 8.47 mC/cm(2) a thickness change of 26.9 +/- 4.3 nm during oxidation was measured by Atomic Force Microsopy (AFM). This result is in qualitative agreement with recent in-situ Spectroscopic Ellipsometry investigations of PANI in our laboratory. The thickness changes determined with Scanning Tunneling Microscopy (STM) are significantly larger than those measured by AFM. Beside first results, intrinsic limits of this methods and the quantitative differences between STM and AFM measurements are discussed.