Enhanced marine antifouling hydrogel coatings achieved through simultaneous enhancement of contact-killing, low surface energy and fluorescence properties

Hydrogel is recognized as highly promising antifouling coatings. The introduction of other antifouling strategies has emerged as an essential research direction for enhancing hydrogel antifouling applications. However, simultaneous integration of multiple antifouling strategies within the same hydrogel remains challenging, while attenuation of hydrogel hydration layer antifouling effect during functionalization is still problematic. Herein, a multifunctional coating combines the hydrogel hydration layer surface with multiple antifouling mechanisms including low surface energy characteristics, cationic contact-killing structure, and fluorescence performance was developed. Through elevation of 2-(dimethylamino)ethyl methacrylate (DM) content, the hydration layer characteristics, low surface energy characteristics, cationic contact-killing effect, and fluorescence performance were simultaneously enhanced. This approach effectively overcomes antagonistic interactions between co-existing multiple antifouling mechanisms. Crucially, the fluorescence functionality was engineered in this coating without employing exogenous fluorophores through precisely designed intermolecular aggregation. Meanwhile, an enhanced dual-stage defense was imparted to the coatings through synergistic mechanism integration. First stage of antifouling defense: hydration layer, low surface energy, and fluorescence performance collectively impart enhanced fouling-resistance adhesion capability into coating. Second stage of antifouling defense: surface-adhered organisms are killed via contact-killing. Consequently, the hydrogel demonstrates excellent anti-protein adsorption performance (minimum normalized value <1 %), algal adhesion and growth inhibition performance, inhibition of bacterial growth (up to 98.27 %) and adhesion performance (up to 96.36 %). It employs absolutely no metallic antifouling agents and fluorescent agents, thereby providing important insights for eco-friendly marine antifouling coatings.