Self-Healing Ability of Epoxy Vitrimer Nanocomposites Containing Bio-Based Curing Agents and Carbon Nanotubes for Corrosion Protection

Epoxy is extensively used for anti-corrosion coatings on metallic materials. Conventional epoxy coatings have a permanent crosslink network that is unable to repair itself when cracks and damages occur on the coating layer. This study aims to develop self-healing epoxy vitrimer/carbon nanotube (CNTs) nanocomposite for coating. Two bio-based curing agents viz., cashew nut shell liquid (CNSL) and citric acid (CA) were employed to create covalent adaptable networks. The 0–0.5 wt% CNTs were also incorporated into epoxy/CNSL/CA matrix (V-CNT0-0.5). Based on the results of our study, thermomechanical properties of V-CNT nanocomposites increased with increasing CNTs content. The bond exchange reaction of esterification was thermally activated by near infrared (NIR) light. The V-CNT0.5 showed the highest self-healing efficiency in Shore D hardness of 97.34%. The corrosion resistance of coated steel with V-CNT0 and V-CNT0.5 were observed after immersing the samples in 3.5 wt% NaCl for 7 days. The corrosion rate of coated steel with V-CNT0.5 decreased from 9.53 × 102 MPY to 3.12 × 10–5 MPY whereas an increase in protection efficiency of 99.99% was observed. By taking advantages of the superior self-healing and anti-corrosion properties, V-CNT0.5 could prove to be a desirable organic anti-corrosion coating material.