Electrodeposition of polyaniline–carbon nanotubes composite films and investigation on their role in corrosion protection of austenitic stainless steel by SNIFTIR analysis

Composite films of polyaniline (PANI) and carbon nanotubes (CNTs) were prepared by electrochemical co-deposition from solutions of the corresponding monomer containing two different kinds of CNTs. The first type was commercial (diameter = 110–170 nm, length = 5–9 μm) and the second one was home-made (diameter = 30 nm, length = 5–20 μm). The electrochemical behaviour of PANI–CNTs composite films was investigated with Cyclic Voltammetry and the surface morphology was analysed by Scanning Electron Microscopy (SEM). Subtractively Normalised Interfacial FT-IR procedure was used to investigate the presence of corrosion products when the films were deposited on stainless steel substrates and exposed to acid environment. The spectral investigations were utilised to understand the role of composite films in the corrosion protection and to discriminate the best performance CNTs.