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 (TiO₂) nanoparticles. The CAP & TiO₂ 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-TiO₂@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 × 10⁷ Ω.cm² (pristine PDMS coatings) to 2.52 × 10¹⁰ Ω.cm² (7 wt% CAP-TiO₂@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.