Anticorrosion performance of polyaniline/clay nanocomposites in epoxy coatings

Thickness-tunable triple-layer polyaniline (PANI)/clay nanocomposites were synthesized via in situ intercalative polymerization of PANI within the clay layers. The PANI/clay nanocomposites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. In this study, the thickness of the PANI/clay nanocomposites was easily controlled by adjusting the proportions of PANI and pristine clay. Based on oxygen transmission rate measurements, the oxygen barrier properties of pristine clay can be enhanced by the growth of PANI. Notably, the oxygen barrier property of epoxy loaded PANI/clay nanocomposites was linearly dependent on the PANI growth thickness. After 30 days immersion electrochemical impedance spectroscopy test under saline conditions, the resistance (R_c) of the pure epoxy coating (2.47 × 10⁶ Ω) increased to 5.76 × 10¹⁰ Ω when 1 wt.% PANI was added to the epoxy coating. However, when 1 wt.% PANI/clay was added into the epoxy coating, the R_c of the composite coating increased further to 7.66 × 10¹¹ Ω. Notably, the ratio of PANI to PANI/clay was only 36.5 wt.%, indicating synergistic anticorrosion properties can be obtained by the intercalation of PANI/clay additives. Therefore, PANI/clay nanocomposites have a high potential as anticorrosion additives for industrial epoxy resin coatings.