Thermostable and defect-repairable urushiol nanocomposite protective coating crosslinked by sodium tartrate-stabilized Ti3C2Tx

Thermal-assisted exploitation of heavy crude oil poses severe corrosion threats to transportation pipelines, necessitating the development of high-temperature protective coatings. Herein, sodium tartrate (ST)-stabilized two-dimensional alkalized-Ti₃C₂T_x (SMX), one of the typical transition metal carbides (MXene), was employed as a dual-functional nanofiller and crosslinker to fabricate urushiol-based composite coatings (SMX_n@U). The incorporation of 0.3 g/L ST effectively stabilized the colloidal state of Ti₃C₂T_x nanosheets, ensuring their uniform dispersion within the urushiol matrix. The alkalization process introduced abundant hydroxyl terminations on SMX surface, providing ample active sites for crosslinking with the catechol groups of urushiol. A novel crosslinking mechanism between SMX and urushiol was elucidated through binding configuration analyses and theoretical simulations. Benefiting from the high-density crosslinking and exceptional barrier property of SMX, the optimized composite coating, crosslinked with 1.5 % SMX (SMX_1.5@U), delivered outstanding protection performance. SMX_1.5@U-coated sample maintained a coating resistance of 7.42 × 10⁸ Ω·cm² after 30 days of immersion in CO₂-saturated 3.5 % NaCl solution at 140 °C, significantly outperforming its organotitanium-crosslinked counterpart. Neutral salt spray and scanning electrochemical microscopy measurements further demonstrated the defect-repairing capability of SMX_1.5@U, where the structural degradation of SMX and the release of ST molecules at scratched regions contributed to its active repairing capability. This work presents a promising solution for corrosion protection in the extraction and transport of unconventional petroleum resources.