A novel PDMS-based coating incorporated with capsaicin and TiO2-modified CNTs: Performance and mechanisms of antifouling and anticorrosion in seawater

We report a novel hydroxyl-terminated polydimethylsiloxane (PDMS)-based antifouling coating that incorporates hydroxyl-terminated multi-walled carbon nanotubes (CNTs) modified with capsaicin (CAP) and titanium dioxide (TiO 2 ) nanoparticles. The CAP & TiO 2 cladding layer provides the CNTs with excellent dispersibility within the PDMS matrix, leveraging the abundant hydroxyl functionalities of both modifiers. The resulting composite displays a synergistic combination of mechanical, biocidal, and corrosion-resistant properties. Mechanical tests show a significant increase in stress-strain values and a more than sixfold rise in adhesion to the mild steel substrate. The seawater immersion test demonstrates that the PDMS-based coating containing 7 wt% CAP-TiO 2 @CNTs achieves an impressive reduction of over 97 % in protein adhesion (measured via FITC-BSA assay) and over 99 % in antibacterial performance (against E. coli and S. aureus ). Additionally, this coating significantly decreases microalgal colonization and macrofouling attachment compared to pristine PDMS coatings. Besides the excellent antifouling properties, the PDMS-based coatings also demonstrate reasonable anticorrosion properties with their |Z| 0.01Hz (impedance at 0.01 Hz) increasing from 3.57 × 10 7  Ω.cm 2 (pristine PDMS coatings) to 2.52 × 10 10  Ω.cm 2 (7 wt% CAP-TiO 2 @CNTs modified PDMS coatings). These findings may highlight the potential application of PDMS-based coating in the antifouling field of ship hulls and coastal wind power piles.