Facile synthesis of 4,4′-diaminodiphenysulfone cured oleo-epoxy/PPy-PSCeO2 blend nanocomposites for anticorrosive application by in-situ and solvent-less approach

Abstract

Epoxidized vegetable oil binary nanocomposite coatings are essential in various applications like space industry, rockets, satellites, automobile industry, paint industry, ceramic coatings, stealth fighter jets, solar energy harvesting etc. From the research perspective oleo-based coatings are promising materials due to biodegradable, environmentally friendly, and non-toxic nature with no release of volatile organic content into the atmosphere. Herein, we present the synthesis of promising organic-inorganic ceria doped polypyrrole modified hybrid epoxy nanocomposite coatings through in-situ and solventless approach which exhibited higher performance in acidic and saline environments (0.5 M H2SO4,0.5 M NaCl) over a long immersion period than pristine unloaded epoxy coatings. Further, the protective effect of hybrid nanoparticles i.e. PPy-PSCeO2 using DDS as a suitable hardener within the epoxy matrix was investigated. The trans-hydroxylation followed by SN2 nucleophilic substitution lead to the formation of extensive and highly dense network cross-linked 3D network with PPy-PSCeO2 hybrid nanofiller uniformly-dispersed within the matrix. The incorporation of PPy-PSCeO2 has a major contribution in the mechanistic formation of passive protective layer consisting of iron-cerium complex which thereby exhibits mechanical interlocking and barrier formation on the CS surface. Potentiodynamic polarisation, Electrochemical impedance spectroscopy and salt spray tests were carried out on coated and uncoated specimens with coated samples exhibiting enhanced mechanical properties, hydrophobic and strong acid-resistant behaviour, higher thermal stability (safely used up to 200 °C), negligible water absorption, strong adhesion and hence improvement in protection behaviour.