Electrochemical preparation of composite coatings of 3,4- etylenodioxythiophene (EDOT) and 4-(pyrrole-1-yl) benzoic acid (PyBA) with heteropolyanions Lidia Adamczyk a, * , Krystyna Giza a , Agata Dudek b a Division of Chemistry, Department of Materials Processing, Technologyand Applied Physics, Czestochowa University of Technology, Al. Armii Krajowej 19, PL 42-200 Czestochowa, Poland b Institute of Materials Engineering, Department of Materials Processing, Technology and Applied Physics, Czestochowa University of Technology, Al. Armii Krajowej 19, PL 42-200 Czestochowa, Poland highlights graphical abstract  The composite SiMo 12 -PEDOT/PyBA coatings on carbon and steel sub- strates were investigated.  The coatings have exhibited very good adhesion to the substrate.  The coatings are capable of largely blocking the access of chlorides anions. article info Article history: Received 2 October 2012 Received in revised form 7 January 2014 Accepted 10 January 2014 Keywords: Composite materials Polymers Corrosion test Electrochemical properties abstract The possibility of incorporating 4-(pyrrole-1-yl) benzoic acid, (PyBA), and heteropolyacids (SiMo 12 ) during the electrodeposition of poly (3,4-ethylenedioxythiophene), PEDOT, is demonstrated in the paper. The formed novel composite material was applied on the electrode surface as a moderately thin (ca. 0.9e1 mm thick) PEDOT/PyBA/SiMo 12 coating. The physicochemical identity of our composite coating was established with the use of electrochemical, spectroscopic, and microscopic techniques. The fact that carboxylate-containing PyBA units link with positively charged and PEDOT structures tend to improve the overall stability and adherence of composite coatings to glassy carbon and stainless steel. The PEDOT/ PyBA composite serves as a stable host matrix for large negatively charged silicium hetero- polymolybdates inorganic species. Consequently, due to the formation of denser polymeric structures and due to the existence of electrostatic repulsion effects, the large polyanion-containing composite coatings are capable of blocking the access of smaller pitting-causing anions (chlorides) to the surface of stainless steel. Ó 2014 Elsevier B.V. All rights reserved. 1. Introduction Over the last several years, there has been growing interest in conducting polymer coatings on electrodes [1e 13] due to the prospects of their application in various microtechnological sys- tems, including charge storage devices, sensors, gas separating membranes, molecular electronics, displays and light emitting di- odes, and corrosion protection. From among the many conducting polymers, poly(3,4-ethylenedioxytiophene) or PEDOT has been recently of interest as a particularly stable, highly conductive and electroactive organic polymer [14e20]. For example, PEDOT has * Corresponding author. E-mail address: adamczyk@wip.pcz.pl (L. Adamczyk). Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys 0254-0584/$ e see front matter Ó 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.matchemphys.2014.01.012 Materials Chemistry and Physics xxx (2014) 1e7 Please cite this article in press as: L. Adamczyk, et al., Electrochemical preparation of composite coatings of 3,4-etylenodioxythiophene (EDOT) and 4-(pyrrole-1-yl) benzoic acid (PyBA) with heteropolyanions, Materials Chemistry and Physics (2014), http://dx.doi.org/10.1016/ j.matchemphys.2014.01.012