Colloidal Preparation of Polyaniline-Poly(vinyl alcohol) - SiO2 Nanocomposite and Study of its Anti-corrosive Properties

Polyaniline (PANI) is one of the most interesting conducting polymers due to its low cost and easy availability of raw materials، easy synthesis، good environmental stability and controllable electrical conductivity and redox properties. In recent years it has been shown that electrically conducting polymers such as polyaniline in integrated coating applications are able to protect steel from corrosion due to formation of passive oxide layer on the metal surface. In this report، a nanocomposite of polyaniline–nanoSiO2 (PSC) has been prepared by using poly (vinyl alcohol) (PVA) as surfactant and ammonium persulfate as an oxidant in the aqueous media. The prepared materials were characterized and compared by Fourier transformation infrared (FTIR) spectroscopy، transmission electron microscopy (TEM) and X-ray diffraction (XRD). In this method different concentrations (1، 3 and 5wt%) of emulsion nanocomposite were each mixed with polyvinyl acetate (PVAc) binder. SEM image showed good distribution of nanocomposite in the polyvinyl acetate matrix. The anti-corrosive properties of this blend on carbon steel in 3. 5% NaCl and HCl (1M) were evaluated by Tafel slope analysis. The corrosion inhibition performance study was carried out at room temperature in aqueous solution of 1. 0 M HCl and 3. 5 % NaCl by using Tafel method. Experiments were carried out in a conventional three electrode cell assembly using Autolab Potentiostat/Galvanostat. The results showed that addition of nanocomposite to PVAc decreased the corrosion rate and corrosion current density. According to the results، the blend of 3 wt% of this nanocomposite with polyvinyl acetate has the best corrosion protection for steel St37 in both media.