Syntheses of diphenolic resin based anti-corrosion coating material and reinforce its performance through MWCNT-Ag and MWCNT-Ag/PANI nanofillers

Abstract

In the present work, a novel anti-corrosion coating material was developed using diphenolic resin and multiwalled carbon nanotube (MWCNT) based nanofillers. In this concern, phenylmethylene diphenolic resin (PMD) and its 2-(4-methylbenzyl) oxirane derivative (PMDD) were synthesized using phenol and benzaldehyde. Silver-decorated MWCNT (MWCNT-Ag) and polyaniline (PANI) synthesized on MWCNT-Ag (MWCNT-Ag/PANI) were also fabricated and employed as filler materials to enhance the anti-corrosion performance of PMDD. The resins were analyzed by LC-MS and FT-IR, and the nanofillers were characterized using XRD, SAED, EDX, TEM, and XPS techniques. The synthesized PMD and PMDD and different weight percentages of fillers blended PMDD were coated on the mild steel (MS) sample using doctor blade method. The surface morphology and roughness of the coatings were examined by SEM and AFM analyses. The anti-corrosion ability of the coated samples was assessed by electrochemical impedance spectroscopy (EIS) and salt spray testing (SST). All the results showed an excellent anti-corrosion performance of PMDD by the incorporation of 0.2 wt% of MWCNT-Ag/PANI. Withstanding the 5 wt% NaCl salt spray atmosphere for about 144 h and >460 days in 3.5 wt% NaCl solution reflects its strong barrier property and long-term durability. The cross-linking of resins, blockade of defects by nanofiller and an additional protective layer developed by conductive PANI make the coating material efficient and durable in highly corrosion environments.