Microencapsulation of the triazole derivative for self-healing anticorrosion coatings

Abstract

Polyurethane microcapsules containing the triazole derivative and the oleate derivative as core materials were successfully prepared via interfacial polymerization in an oil-in-water emulsion of the diol-diisocyanate prepolymer and 1,4-butanediol as a chain extender under agitation or ultrasound sonication. The diameters of the resultant capsules which possess the triazole derivative core agent are 25–276 μm and shell thickness is 1.9–18.0 μm at controlled agitation rates (1000–6000 rpm). Typical core content of the microcapsule and yield of the capsule polymerization were 45–67% and 38–75%, respectively, with varied reaction conditions. The ratio of shell wall thickness to the capsule diameter was relatively constant, with an average value of 0.07. A steel substrate was coated with the synthesized PU capsules for use in self-healing anticorrosion protection. The results as determined by salt spray tests indicated noteworthy rust retardancy in self-repairing corrosion protection systems, slightly depending on kinds of corrosion inhibitors.