Ti3C2MXene/Polyaniline/Montmorillonite Nanostructures toward Solvent-Free Powder Coatings with Enhanced Corrosion Resistance and Mechanical Properties

Abstract

Solvent-free powder coatings have become very popular in the coating industry in replacing conventional liquid coatings for the last decades. However, poor adhesion of powder coatings to the substrate and micropores inevitably created during the curing process of coatings lead to localized corrosion and reduced mechanical resistance. For this purpose, Ti3C2MXene/polyaniline (PANI)/montmorillonite (MMT) nanocomposites with superior conductivity and adhesion capabilities were incorporated into the eco-friendly powder coating. The as-synthesized nanocomposites were analyzed using various techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, field-emission scanning electron microscopy, and Raman spectroscopy. To evaluate the effectiveness of the powder coating in preventing corrosion on a mild steel substrate, two methods were employed: potentiodynamic polarization and electrochemical impedance spectroscopy. The electrochemical tests revealed that an excellent dispersion of 1.5 wt % Ti3C2MXene/PANI/MMT nanosheets in a polyester/epoxy powder coating resulted in superior anti-corrosion performance (4.8 × 106ω) after 42 days of immersion in 3.5 wt % NaCl as compared to blank samples (7.2 × 102ω). According to Tafel analysis, the corrosion potential of the optimal sample is -0.062 V, which is more positive than that of the pristine powder coating (-0.83 V). The polarization resistance (Rp) and corrosion current (icorr) of the optimal sample are determined to be 3.39 × 106ω·cm2and 7.69 × 10-9A·cm-2, respectively. Moreover, the optimal sample marginally increased the hardness (229.42 MPa) compared to the pure sample (152.68 MPa) due to the synergistic effect of Ti3C2MXene and flake-like MMT nanoparticles, which results in an improvement in the mechanical strength of powder coatings. Additionally, the presence of PANI caused further crosslinking and modulation of the electrical conductivity of the produced nanocomposites. The present study proposes a practical method to enhance the mechanical and shielding properties of solvent-free powder coatings, making them suitable for use in various real-world applications, including commercial, medical, and household sectors.