Synthesis of magnetic targeted delivery microcapsules and its anti-corrosion self-healing behavior in epoxy resin coatings

This study proposed a tung-oil based magnetic targeted delivery microcapsules (MDTMs) to enhance the efficiency of self-healing coatings (SHC). Magnetic particles were used as function particles and emulsifier in synthesis of microcapsules (MC). DSC, OM, SEM, TEM, VSM, NSS, EIS and SKP were used to characterize the compounds, structure, healing behavior and anti-corrosion performance. Results indicate that magnetically driven SHC (MD-SHC) reduces 50% migration path of the released tung oil, and increases the release rate of tung oil after the coating is mechanically damaged. SKP and EIS results suggest that the healing part has impressive anti-corrosion performance, scratches were filled with a large amount of tung oil in a short time, and the released tung oil had formed a complete oil film on scratches at 24 h with higher polarization resistance (R_p). R_p of MD-SHC (2.5 × 10⁵–3.6 × 10⁵ Ω cm²) is 2.0–2.8 times of that the SHC (1.1 × 10⁵–1.8 × 10⁵ Ω cm²). The enrichment in MD-SHC at the interface decreases bonding strength from 7 to 4.5 MPa as the mass additive of microcapsules reaches 15 wt.%. The current work proves the effectiveness of MD-SHC in improving self-healing ability.