The surfaces of underwater ship hulls and aquaculture equipment, such as fish cages, are highly susceptible to damage from fouling organisms. Although traditional marine antifouling coatings exhibit effective antifouling properties, the leaching of antifouling agents into the marine environment can lead to pollution and ecological disruption. In this study, we prepared castor oil polyurethane (CO-PU) by reacting castor oil with isocyanate. We then incorporated self-synthesized acrylamide-based quaternary ammonium salts (QASs), specifically dime...