A facile cleaner approach towards the synthesis of silver-doped cardanol-based hydrophobic antimicrobial and anticorrosive polymeric coating material

This work reports the solvent, catalyst and cross-linker free green synthesis of silver (Ag)-doped cardanol-based multifunctional polymer nanocomposite (PNC) coatings. The interaction of Ag ions with the polymeric backbone and in-situ formation of nanoparticles (NP) was confirmed by various characterization techniques. The optimum curing temperature (120–160 °C) and Ag concentration (1%) required for the free-standing film/coating with durable mechanical and chemical resistant properties in acidic/basic/salt solutions was studied. The high gel content (degree of crosslinking, 98%) and thermal stability up to 345 °C endorse the formulation of a well-cross-linked polymeric film/coating. XRD (approx. 27 nm) indicated the formation of crystalline silver nanoparticles within the polymer matrix, whereas SEM and TEM explored the distribution (200–700 nm). EIS studies for three weeks in 3.5% NaCl solution showed the exceptional corrosion inhibition efficiency (98-91%) of the coatings on steel substrate. The stable coating resistance value (MΩ.cm⁻²) throughout the study highlights the formation of a hydrophobic barrier with good resistance against the corrosive ions. Additionally, the potent antibacterial impact against Gram-positive, and Gram-negative bacteria, and the antifungal activity of the nanocomposite were attributed to the presence of Ag in the PNC. The multifunctional properties arise from the in-situ formed nanostructure and its synergistic effect with the biopolymer matrix projects its versatile industrial application.