Electrochemistry of polyaniline Langmuir-Blodgett films

Langmuir-Blodgett (LB) manipulation of polyaniline has been variously emplo yed to obtain organized assemblies for use in molecule-based electronic dev ices. However, the electrochemical characteristics of polyaniline LB films which have a direct implication on the proposed device applications have no t been given much attention. We report here, electrochemical characterizati on of multilayer LB films of polyaniline prepared by employing N-methylpyrr olidone as the processing solvent. The films have been transferred onto a v ariety of substrates such as quartz, platinum, platinum sputtered on quartz , and conducting tin oxide on glass. The electrochemistry of polyaniline LB films has been studied using cyclic voltammetry coupled with a quartz crys tal microbalance (QCM). Cyclic voltammograms were obtained for films transf erred at different surface pressures, for films containing different number of layers. The electrochemical characteristics of LB multilayers were comp ared with those of electrochemically deposited films and were used to infer the packing behaviour of polymer chains in the LB film structure. It was f ound that multilayer LB films are electroactive but the kinetics of counter ion transport in these films is slower than that observed in electrochemic ally deposited films. The multilayer LB films also show poor electrochromic switching behaviour. (C) 1998 Elsevier Science S.A. All rights reserved.