ELECTROCHEMICAL COPOLYMERIZATION OF PYRROLE AND ANILINE

This study covers the synthesis of homopolymers, copolymers and compos ites of aniline and pyrrole in nitrogen atmosphere using various solve nt and supporting electrolytes. With the objective of examining the st ructure of the samples and analysing their properties, FT-IR spectra w ere taken, thermogravimetric analysis (TGA) was done and scanning elec tron microscopy (SEM) was used for microstructural analysis. The condu ctivity of each sample was determined through the four-probe method. M agnetic susceptibility measurements on the Gouy scale indicated that t he polymers were diamagnetic. Hence, the synthesized polymers were fou nd to contain no unpaired electrons. Homopolymerization and copolymeri zation reactions were carried out in an acetonitrile medium, using LiC lO4, as supporting electrolyte, in a perchloric acid medium and in a s ulfuric acid medium separately, in order to analyse the effects of sol vent and supporting electrolytes. As a result, the change of medium wa s observed to have a significant effect on the structure and propertie s of the resulting homopolymers. Similarly, in bilayer synthesis, chan ging the order of coating was observed to affect the structure and pro perties of samples, either partially or fully, based on the synthesis medium. For instance, coating polyaniline (PAn) over polypyrrole (PPy) in an acetonitrile + LiClO4 medium or a water + H2SO4 medium yielded composite samples, while coating PPy over PAn in the same media yielde d copolymer samples. The resulting samples however, turned out to be c omposites regardless of the order of coating, when the same synthesis was repeated in a HClO4 medium. (C) 1998 Elsevier Science S.A. All rig hts reserved.