Is Young's Modulus a Critical Coating Property Determining Fouling‐Release Performance of Marine Coatings?

Marine organisms colonize all water‐contacting surfaces. The accumulation of these organisms, known as biofouling, on ship hulls can increase fuel consumption by up to 45%, causing higher emissions. Remedy is offered by nonbiocidal fouling‐release (FR) coatings, which weaken the adhesion between organisms and surfaces, enabling removal by hydrodynamic forces or gravity. This study investigates the FR performance of biocide‐free polyurethane, polyurea, and silicone‐based systems in relation to their Young's modulus. The rationale is to better understand the influence of Young's modulus across different polymer classes. Within these classes, Young's modulus varies in a narrow range (0.2–2.2 MPa) to study its effect on FR behavior. In polyurethane and polyurea systems, modulus adjustments are made by altering resin‐to‐hardener ratios, affecting crosslink density. Coatings underwent static immersion in the North Sea, and FR performance is monitored monthly. After 15 weeks, samples are cleaned with a high‐pressure water jet. Compared to a hard reference system, all soft coatings exhibit FR performance identical to Intersleek 1100 SR after full immersion period and cleaning, highlighting the importance of mechanical softness for effective fouling release.