Development of anti-corrosion coating based on phosphorylated ethyl cellulose microcapsules

This study reports for the first time the preparation of almond oil-based microcapsules using phosphorylated ethyl cellulose as shell material. Microcapsules of ethyl cellulose (EC) and phosphorylated ethyl cellulose (P-EC) containing almond oil as anti-corrosion inhibitor, for end use in self-healing coatings, were prepared by a solvent evaporation method. The results showed that phosphorus content in the modified ethyl cellulose was 6.26 wt.%, the specific surface area reached a high value of 21.4 m2 g−1 and a char residue of 18 wt.% at 400 °C after thermal degradation. Both prepared EC and P-EC based microcapsules were spherical shape-like. The scanning electron microscope (SEM) images showed that the freeze-drying influences the microcapsules surface morphology. The mean diameter of EC and P-EC microcapsules was about 140 μm and 150 μm, respectively. Anti-corrosion properties of prepared epoxy-based coatings loaded with microcapsules on the mild steel substrate were evaluated for 28 days using a simple salt spray test. The sample containing P-EC microcapsules showed the best anticorrosion resistance. The functionalization of the ethyl cellulose microcapsules shell with phosphonate groups can improve further the anti-corrosion resistance, the flame-retardant ability and the metal chelating properties of the final coatings.