A COMPARATIVE-STUDY OF THE ELECTROCHEMICAL PROPERTIES OF DIP-COATED, SPUN, AND LANGMUIR-BLODGETT-FILMS OF POLYANILINE

The electrochemistry of polyaniline (PANi), which has been chemically synthesized and processed in a variety of ways into thin films, has been studied, and a comparison to those properties observed in thin electrochemically grown PANi films made. In this work, PANi via solution processing has been formed into thin films using dip coating, spin coating, and the Langmuir-Blodgett (LB) technique on indium tin oxide electrodes to facilitate both cyclic voltammetry and spectroelectrochemical analysis. We find that the LB technique yields films which display the most defined voltammetric properties, although in all cases electroactivity is observed. Effects due to the residual solvent contained in the films are seen. This has enabled us to comment on the role played by the solvent molecules within the PANi matrix. Further, in the case of LP-PANi, the ultrathin films, ca. 60 angstrom thick, as well as exhibiting excellent electrochemistry are found to be deposited in the fully oxidized, pernigraniline form of PANi, as confirmed by rest potential measurements, UV/visible and Fourier-transform infrared spectroscopy. From our results it is quite feasible to suggest that large scale electrochromic displays could be fabricated using PANi as the active material.