Sea Slug Inspired Smart Marine Antifouling Coating with Reversible Chemical Bonds: Controllable UV-responsive Coumarin Releasing and Efficient UV-healing Properties

Poly(dimethylsiloxane) (PDMS) has been received widespread attention as marine antifouling coatings, while its controllable release performance of antifoulants and mechanical behavior are relatively insufficient. In this study, inspired by sea slug's defensive behavior against predators by ingesting toxins from prey and then releasing these toxins, a PDMS-based smart marine antifouling polyurethane (PU) coating was prepared, which had UV-responsive controllable coumarin-releasing and UV-healing properties. The UV-responsive coumarinreleasing mechanism was based on the dimerization and de-dimerization of reversible chemical bond between two coumarin groups. As a sort of eco-friendly antifoulant, modified coumarin and eugenol were fixed in PU chain by polycondensation. Then additional free coumarin was "locked" with the fixed coumarin under 365 nm UV and released stably in response to 254 nm UV. The coating could also efficiently self-heal under 365 nm UV through dimerization between fixed coumarin groups in polymer chains. Moreover, it had satisfactory mechanical behavior, transparency, antibacterial property, anti-algae property and nine-month marine field antifouling performance, which demonstrated the promising application in marine and other antifouling fields.