One-pot efficient synthesis of amino-functionalized polyurethane capsules via photopolymerization for self-healing anticorrosion coatings

In this paper, a novel kind of amino-functionalized polyurethane capsules encapsulating self-healing agent (linseed oil) and corrosion inhibitor (benzotriazole) with an average size of 1.0 μm were prepared by "phase separation inside emulsion droplet" combined with photopolymerization. In our strategy, the formation of capsule and the modification of capsule shell by amino group were realized simultaneously in one-pot process for the first time, which was much simpler and more efficient compared with other well-developed synthetic methods. The amino-functionalized polyurethane capsules were incorporated in UV-curable resins to prepare green coatings with outstanding self-healing and anticorrosion performances. After modification by amino group, the dispersibility of PUA capsule in coatings was significantly improved and the interfacial compatibility between capsule and coating matrix was enhanced, which was beneficial to prepare coatings with excellent anticorrosion as well as self-healing performances. It has been demonstrated that the low frequency impedance of the coating based on amino-functionalized PUA capsules remained basically unchanged within 30 days and no obvious corrosion products were observed on the surface of coatings within 500 h. In the meanwhile, the scratches of coating with amino-functionalized PUA capsules were almost completely repaired, demonstrating much higher healing efficiency than the coating with unmodified capsules. With the scalable fabrication process, it can be envisioned that the one-pot efficient synthesis of amino-functioned capsules in this work has significant potentials for application in coatings, especially in self-healing and anti-corrosion coatings.