Facile fabrication of self-healing silicone-based poly(urea-thiourea)/tannic acid composite for anti-biofouling

A novel silicone-based poly(urea-thiourea)/tannic acid composite (PDMS-P(Ua-TUa)-TA) with excellent mechanical, self-healing and antifouling properties is developed. The multiple dynamic hydrogen bonds formed by thiourea groups, urea groups, and tannic acid (TA) molecules ensured a tough elastomer (ultimate strength: 2.47 MPa) with high stretchability (∼1000%). TA molecules as partial hydrogen bonding cross-linking sites interacted rapidly with urea and thiourea groups before the migration of polymer chains, resulting in fast and efficient self-healing. Scratches on the film completely disappeared within 12 min, and the repair efficiency of strength was up to 98.4% within 3 h under ambient condition. Self-healing behavior was also evaluated in artificial seawater and the healing efficiency (HE) was 95.1%. Furthermore, TA uniformly dispersed in the polymer matrix provides good antibacterial and anti-diatom properties, as well as strong adhesion to the substrate (∼2.2 MPa). Laboratory bioassays against marine bacteria adhesion (∼96%, ∼95% and ∼93% reduction for P. sp., E. coli , and S. aureus , respectively) and diatom attachment (∼84% reduction) demonstrated an outstanding antifouling property of the PDMS-P(Ua-TUa)-TA. This work provides a promising pathway towards the development of high-performance silicone-based coatings for marine anti-biofouling.