Polyaniline/montmorillonite nanocomposites for corrosion protection of steel

Polyaniline/montmorillonite (PANI/MMT) nanocomposites were synthesized by in situ chemical oxidative polymerization for corrosion protection of steel. The polymer clay nanocomposites were prepared by varying the MMT content (1, 3, 5 and 7 wt% based on monomer content). The results showed that the maximum monomer conversion was 75.8% at MMT content of 1 wt%. PANI/MMT nanocomposites was characterized by Fourier-transform infrared spectroscopy (FT-IR). The results showed functional groups of hydroxyl (-OH), cyanide (-CN) and amide (RCONHR) which attributed to PANI and MMT characteristic. PANI intercalated between the layers of MMT was confirmed by X-ray diffractometer. The montmorillonite layer and the agglomerated spheres of polyaniline dispersed in the nanocomposites morphology were observed by scanning electron microscope (SEM). The thermal stability of PANI/MMT nanocomposites, examined by thermogravimetric analysis (TGA), was enhanced by an increasing in MMT content. From corrosion study in 1.0 M sulfuric acid solution, steel coated with PANI/MMT nanocomposites film showed better corrosion resistant than steel coated with PANI film. The increased in the amount of MMT in nanocomposites and film thickness could improve anticorrosive properties due to an increasing in tortuosity of diffusion pathway of corrosion agents. The steel coated with 50 µm thickness of PANI/MMT (5 wt%) showed the best corrosion resistance comparing to the other coated steel.