A novel two-component self-healing coating comprising vinyl ester resin-filled microcapsules with prolonged anticorrosion performance

Abstract

This study aimed to prolong the healing effects regarding anticorrosion performance by developing a self-healing epoxy-based coating comprising vinyl ester resin and benzoyl peroxide-filled microcapsules. For this purpose, dual-layer gelatin-gum Arabic/urea-formaldehyde (Gel-GA/PUF)-based microcapsules containing either benzoyl peroxide (BPO) or vinyl ester resin (VER) were prepared separately in a two steps synthesis approach using complex coacervation and in situ polymerization techniques, respectively. Scanning electron microscopy (SEM) and optical microscopy (OM) were used to evaluate the shape and morphology of the microcapsules. Fourier transform infrared (FTIR) spectroscopy confirmed the successful formation of a two-layered shell structure, Thermogravimetric analysis (TGA) also revealed acceptable thermal stability of prepared microcapsules. Thereafter, epoxy-based coatings containing 0, 2.5, 5, 10, 20 wt % of a combination of two types of microcapsules were prepared and inscribed using a scalp blade. The standard salt spray test and electrochemical impedance spectroscopy (EIS) were utilized to study the healing properties of microcapsules within the epoxy-based coating. The scratch healing performance of the coating samples was evaluated using OM images. The salt spray test and EIS results confirmed a long-lasting healing effect of the microcapsules embedded coating samples. The sample containing 20 wt% microcapsules showed no signs of corrosion after 50 days of exposure in a standard salt spray test chamber.