Fabrication of a self-healing hydrophobic ODA@(PDA@(PMO@ODA))/ epoxy resin coating and its long-term protection performance

Successfully constructed multi-level nano-spheres of ODA@PDA@PMO@ODA with 155° of WCA. • Mechanical grinding temporarily enhances hydrophobicity. • Mechanical grinding damages the long-term barrier performance of the coating. This study aims to simultaneously enhance the hydrophobicity and mechanical durability of coatings through a hierarchical structure design. Periodic mesoporous organosilica (PMO) particles were first encapsulated with octadecylamine (ODA) via a facile one-pot synthesis. Subsequently, a polydopamine (PDA) layer was deposited on the surface, followed by further grafting of ODA, yielding a hierarchical papillary microstructure superhydrophobic quaternary nanoparticles designated as ODA@PDA@PMO@ODA. Thermogravimetric analysis (TGA) indicated a PDA encapsulation rate of 15% and an ODA grafting rate of 12%. Epoxy resin coatings incorporated with these nanoparticles exhibited water-repellent properties, demonstrating a static water contact angle (WCA) greater than 100°. The effects of mechanical grinding and thermal self-healing on the protection performance of the coatings were investigated by electrochemical impedance spectroscopy (EIS). Investigation into the performance evolution during the mechanical grinding-self-healing process showed that while grinding temporarily increased surface roughness and hydrophobicity, the introduced macroscopic defects acted as channels for corrosive media penetration, significantly compromising the long-term barrier properties. However, the healing process via heating partially restored performance of the coating, yielding better protection than the unhealed ground coating. Compared with the ground coating, the non-ground intact coating surface exhibits more outstanding and long-lasting protection performance, maintaining a single capacitive arc in Nyquist plots and a high impedance modulus of 10¹⁰ Ω·cm² throughout 60 days of immersion. This exceptional long-term stability is attributed to the synergistic effect of the inherent hydrophobicity of coating and the corrosion inhibition provided by ODA. This work underscores the critical role of surface integrity in the long-term durability of coatings and provides new strategies and a theoretical basis for developing intelligent protective coatings with both high hydrophobicity and high reliability. Download: Download high-res image (156KB) Download: Download full-size image