Synergistic Catechol Adhesion and Hydrophobic Barriers for Enhanced Corrosion Resistance of Urushiol‐Modified Epoxy Resin

ABSTRACT Metal corrosion severely reduces the service life of marine equipment. Herein, a dual‐functional urushiol modification strategy is proposed, where natural urushiol is physically incorporated into epoxy resin to simultaneously utilize its catechol adhesion groups and hydrophobic long alkyl chains for synergistic corrosion resistance enhancement. The FTIR spectra and contact angle measurements confirmed successful urushiol incorporation. Cross‐sectional analysis revealed the absence of nano‐cracks in the resin matrix, attributable to H‐bonding, π–π stacking interactions, and reduced Young's modulus. Adhesion strength testing confirmed the interfacial bonding was enhanced by the incorporation of urushiol, resulting from the catechol‐metal coordination and improved mechanical interlocking at the resin/substrate interface. EIS test demonstrated the optimized anti‐corrosion performance of UE‐10. After 50 days immersion in 3.5% NaCl solution, UE‐10 exhibited a |Z| 0.01 Hz value of 5.68 × 10 9 Ω·cm 2 , 40.59% higher than the control sample ER. This corrosion resistance enhancement is attributed to the combined effects of an interfacial hydrophobic barrier, strengthened adhesion, and eliminated nano‐cracks within the urushiol‐modified epoxy matrix. This study provides novel design strategies for developing high‐performance urushiol‐based anti‐corrosion coatings.