Dual-Functional Coatings with Self-Lubricating and Self-Healing Properties by Combining Poly(urea–formaldehyde)/SiO2 Hybrid Microcapsules Containing Linseed Oil

Poly(urea formaldehyde)/SiO2 hybrid microcapsules containing linseed oil are successfully fabricated in a SiO2 nanoparticles stabilized Pickering emulsion system by use of in situ polymerization. The mean diameter and shell thickness of resultant microcapsules are 23 +/- 8.2 mu m and about 1 mu m, respectively. The core fraction is about 80.7 wt %. The initial thermal decomposition temperature of the microcapsules is 240 degrees C. By embedding microcapsules into an epoxy matrix, dual-functional epoxy coatings with self-lubricating and self-healing properties are obtained. Friction and wear tests indicate that the friction coefficient of the coating filled with 10 wt % microcapsules decrease from 0.151 to 0.045, and the coating with 10 wt % microcapsules has a low wear weight loss after 4 h of friction. The scratched self-healing coatings show excellent healing ability and corrosion inhibition function for microcracks. Electrochemical impedance spectroscopy reveals that the impedance modulus of coating with 10 wt % microcapsules is 4 orders of magnitude higher than that of pure epoxy after 1 day of immersion in NaCl solution and is sustained at 1.5 x 10(7) Omega.cm(2) after 30 days of immersion.