Microencapsulation of the triazole derivative for self-healing anticorrosion coatings

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 mu m and shell thickness is 1.9-18.0 mu m 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.