Electropolymerization of carboxylic acid functionalized pyrrole into hybrid zirconium-silicon oxopolymer sol-gel coatings

We describe the preparation of new hybrid materials using a novel method previously reported by us. These materials are constituted of an organic part and an inorganic network of silicon and zirconium oxopolymers. The organic polymer is obtained by electropolymerization of an N-functionalized pyrrole entrapped in the xerogel. The latter was obtained from a sol prepared by hydrolysis condensation of a mixture of alkoxysilanes, zirconium alkoxydes and the organic monomer. The chemical and electrochemical conditions to prepare these hybrid materials were investigated by varying the zirconium content, the presence and the nature of doping species in the xerogel, the nature of the electrolytic salt and the hydrolysis catalyst. From the results of cyclic voltammetry, optical microscopy, scanning electron microscopy and X-ray fluorescence, we show that the formation of a conducting polymer with good properties in the xerogel depends on the zirconium content and on both the nature and the presence of doping species in the xerogel, whereas the influence of the electrolytic salt is very limited.