Microencapsulation of UV-Curable Self-healing Agent for Smart Anticorrosive Coating

Abstract

UV-curable polyurethane prepolymer and photoinitiator 1173 were facilely encapsulated in a poly(urea-formaldehyde) shell, which was in situ formed by the polymerization of formaldehyde and urea in an oil-in-water emulsion. The diameters of the microcapsules ranged from 118 µm to 663 µm depending on agitation speed, and were obtained via optical microscopy and scanning electron microscopy analyses. The encapsulation percent and the yield of microcapsules prepared at the agitation speed of 600 r/min can reach 97.52wt% and 65.23wt%, respectively. When the water-borne polyurethane (WPU) coating embedded with the prepared microcapsules were scratched, the healing agent could be released from ruptured microcapsules and filled the scribed region. The excellent anticorrosion properties of the WPU coating embedded with the prepared microcapsules were confirmed by the results obtained from both electrochemical impedance spectroscopy and Tafel curves.