Self healing coatings containing dual active agent loaded urea formaldehyde (UF) microcapsules

Urea formaldehyde (UF) microcapsules loaded with linseed oil and mercaptobenzothiazole (MBT) as core materials have been synthesized by in situ emulsion polymerization. The capsules were characterized by FTIR. Surface morphology of microcapsules was analyzed using scanning electron microscope. The thermal stability of the microcapsules is in the temperature range around 600 °C as confirmed by TG analysis. The open circuit potential measurements have shown that the coatings with microcapsules maintain the potential in the noble range (≈−0.390 V vs. SCE) while the coating without microcapsules exhibit potentials in the active range. EIS studies at the artificial defect area have shown that the coating containing microcapsules is able to protect steel in neutral media since the impedance values remained at 107 Ω cm2 even after 15 days exposure where as the coatings without microcapsules have lost their protection ability. The self healing ability of the coating containing microcapsules was studied by SVET.