Epoxy resin coatings with the competitive relationship of hydrophobic and aerophilic towards anticorrosion application

Recently, hydrophobic and corrosion-resistant coatings have garnered significant attention. However, existing strategies often focus on enhancing hydrophobicity without considering that higher hydrophobicity may attract more air, increasing the exposure of the coating to oxygen molecules and thereby reducing its anti-corrosion performance. In this study, a series of coatings with varying hydrophobicity were prepared by controlling variables. A non-monotonic relationship was observed between hydrophobicity and corrosion resistance, with the coatings' performance first improving then declining. Through simulation calculations, it was found that coatings with balanced hydrophobicity and gas affinity exhibited approximately an order of magnitude improvement in corrosion resistance compared to those with the highest hydrophobicity. DFT calculations further confirm that moderate H₂O adsorption can optimize the repulsion of *O, reducing the possibility of contact between the substrate H₂O and *O, thereby enhancing the anti-corrosion performance of the coating. This reveals that the relationship between surface wettability and anti-corrosion performance is not simply linear but involves a dynamic equilibrium critical point. Further experimental characterization showed that moderate hydrophobicity enables the coating surface to not only repel moisture, reducing electrolyte penetration pathways, but also avoid excessive oxygen molecule accumulation due to extreme gas affinity. In this balanced state, microstructural defects within the coating are effectively covered, and the resistance significantly increases, resulting in superior long-term stability during simulated salt spray corrosion accelerated aging tests. By deconstructing the paradigm that correlates increased hydrophobicity with superior corrosion resistance, this study paves the way for the development of durable hydrophobic coatings with theoretically grounded and practically viable performance.