Electrochemistry of polyaniline Langmuir±Blodgett ®lms

Langmuir±Blodgett (LB) manipulation of polyaniline has been variously employed to obtain organized assemblies for use in molecule-based electronic devices. However, the electrochemical characteristics of polyaniline LB ®lms which have a direct implication on the proposed device applications have not been given much attention. We report here, electrochemical characterization of multilayer LB ®lms of polyaniline prepared by employing N-methylpyrrolidone as the processing solvent. The ®lms have been transferred onto a variety of substrates such as quartz, platinum, platinum sputtered on quartz, and conducting tin oxide on glass. The electrochemistry of polyaniline LB ®lms has been studied using cyclic voltammetry coupled with a quartz crystal microbalance (QCM). Cyclic voltammograms were obtained for ®lms transferred at different surface pressures, for ®lms containing different number of layers. The electrochemical character-istics of LB multilayers were compared with those of electrochemically deposited ®lms and were used to infer the packing behaviour of polymer chains in the LB ®lm structure. It was found that multilayer LB ®lms are electroactive but the kinetics of counter ion transport in these ®lms is slower than that observed in electrochemically deposited ®lms. The multilayer LB ®lms also show poor electrochromic switching behaviour