Effect of functionalization of carbon nanotubes on mechanical and electrochemical behavior of polyaniline nanocomposite coatings

• PANI nanocomposite coatings were prepared using different f-CNTs.
• IR and UV studies confirm the existence of f-CNTs in PANI matrix.
• Surface analysis indicates that the a-CNTs are entirely wrapped by PANI dense layer.
• Scratch and hardness tests reveal the enhanced mechanical behavior by PANI with a-CNT.
• PANI with a-CNT exhibits lower icorr with nobler shift in Ecorr and higher Rct.

Functionalization of carbon nanotubes (CNTs) is recognized to enhance their dispersion nature and improves the overall performance of the CNT-polymer nanocomposite. In this current study, effective attempt of constructing nanocomposite comprised of polyaniline (PANI) and functionalized CNTs has been done for the purpose of surface protection of mild steel (MS). The synthesized nanocomposites were investigated in terms of morphology, chemical structure and thermal stability with scanning electron microscope (SEM), attenuated total reflectance infrared (ATR-IR), UV–visible spectral and thermal gravimetric analysis (TGA) methods, respectively. SEM investigations evidenced the uniform fibrous morphology in PANI/CNT nanocomposites with nanometer-sized diameters. TGA curves confirmed the enhanced thermal behavior of PANI with the inclusion of functionalized CNTs. The improved corrosion performance of PANI/CNT nanocomposite in 3.5% NaCl solution was corroborated by electrochemical impedance spectroscopy, electrochemical frequency modulation and potentiodynamic measurements. The origin of such enhanced corrosion protection property is explained from the view point that the interfacial interactions between functionalized CNTs and PANI matrix, greatly improves at the polymer/filler bond stability resulting in a better corrosion performance.