Improving self-healing characteristics of polyurethane composite coatings by surface modification of polyaniline using dodecylamine

Abstract

Corrosion is one of the most critical problems affecting the structural integrity of metals. Polymeric nanocomposite coatings reinforced with anti-corrosive pigments are currently being used to mitigate corrosion. This study involves the synthesis of polyaniline (PANI) nanoparticles and their modification with dodecylamine (DOC), which functions as acorrosion inhibitor. Polyurethane coatings (PU-PANI@DOC) were developed by incorporating modified nanoparticles (PANI@DOC) into the polyurethane matrix, and blank polyurethane coatings (PU-blank) were prepared without any nanoparticles. Fourier-transform infrared spectroscopy (FTIR), Transmission electron microscopy, and Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX) analysis confirmed the successful modification of dodecylamine (DOC) with the surface of polyaniline (PANI) nanoparticles. The electrochemical impedance spectroscopy (EIS) and salt spray test (SST) revealed that the impedance values of the modified coating follow an inclined trend (1010 Ω.cm2) in comparison with PU-blank coatings (107 Ω.cm2) after the 14thday ofimmersion in 3.5 wt% NaCl. Moreover, the hydrophobic characteristics of PANI@DOC nanoparticles shift the contact angle from 60° to 90°, thus lowering the wettability nature of modified coatings. Overall, Polyurethane coatings (PU-PANI@DOC) exhibiting potential attributes such as barrier properties, hydrophobic nature, inhibition effect, and high compatibility with polyurethane matrix can be a suitable material for the development of smart self-healing coatings to protect the metals from the hostile effects of corrosion.