Self-Healing Coatings Incorporating Microcapsules With Imidazole and APTES: Characterization Using Electrochemical Accelerated Technique

Abstract

The exposure of metals to corrosion results in significant economic and environmental losses. One approach to mitigate corrosion is the use of coatings, particularly organic coatings, which act as physical barriers, isolating the metal from corrosive environments. However, these coatings are prone to failure, leading to substrate exposure and subsequent corrosion. Smart self-healing coatings have emerged as a promising solution by regenerating damage and restoring the protective barrier. In this study, a smart self-healing coating was developed based on epoxy resin and microcapsules with urea-formaldehyde walls, containing different active cores (epoxy, silicon alkoxide precursor, and imidazole). The coatings, incorporating 15 wt% microcapsules, were evaluated using the Accelerated Cyclic Electrochemical Technique (ACET). A controlled scratch was introduced on the sample surfaces, followed by six ACET cycles. Electrochemical tests revealed that all coatings containing microcapsules exhibited superior anticorrosive and self-repair performance compared to the pure epoxy resin coating. The impedance modulus at 0.01 Hz increased from |Z|0.01 = 506 Ω cm2 for the epoxy coating to |Z|0.01 = 17,960 Ω cm2 for coatings containing microcapsules with an epoxy core. Nyquist plots showed larger semicircle radii, higher pore resistance, and lower capacitance with the addition of microcapsules.