Characterization of core-shell microstructure and self-healing performance of electrospun fiber coatings

Electrospun fibers are a promising method for encapsulation of reactive agents in self-healing coatings. Healing is initiated by mechanical damage to the coating causing the fibers to rupture and release their core materials into the damage region. Prior work has demonstrated autonomous healing in coatings containing electrospun fibers, but full characterization of the electrospun fiber microstructure and healing performance of the coating is lacking. In this study, we utilize electrospun fibers containing liquid healing agents to achieve a crosslinking reaction of poly(dimethylsiloxane) (PDMS) to a crosslinking agent poly(diethoxysiloxane) (PDES), initiated by the catalyst dibutyltindilaurate (DBTL), to fill a damaged region and reseal the metal substrate. Fiber morphology is characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and confocal fluorescence microscopy (CFM). Successful delivery of healing agents to the damage region and subsequent crosslinking reaction is observed using SEM and chemically using infrared spectroscopy. The performance of the healed coating is evaluated electrochemically using linear polarization, where the coatings were subjected to a corrosive environment. The self-healing electrospun coating exhibits lower corrosion current than in control cases, resulting in an 88% corrosion inhibition efficiency.