Amphiphilic Non‐Isocyanate Polyurethane Coatings With Tunable Antifouling and Fouling‐Release Performance: A Log‐Ratio Assessment Framework

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This study investigates amphiphilic non‐isocyanate polyurethane (NIPU) coatings containing reactive hydrophobic poly(dimethylsiloxane) (PDMS) and hydrophilic methoxy poly(ethylene glycol) (MPEG) prepolymers for marine antifouling (AF) and fouling‐release (FR) applications. The amphiphilic coating composition was systematically tuned by varying the molecular weights of the hydrophilic and hydrophobic segments, amphiphilic prepolymer concentration, and coating cross‐link density to establish structure–property relationships governing AF/FR performance. The coatings were evaluated against representative marine foulants, including Navicula incerta , Cellulophaga lytica , Ulva linza , and Chlorella vulgaris . Coatings with lower cross‐link density and higher molecular weight MPEG exhibited the best overall AF/FR performance across multiple species, outperforming silicone elastomer and polyurethane standard coatings. We attributed enhanced performance to improved mobility of amphiphilic segments and increased interfacial hydration associated with the hydrophilic MPEG component, as reflected in lower water contact angles and increased water absorption. We introduced a log‐ratio framework to compare AF/FR performance across different organisms and experimental conditions using a unified dimensionless metric. Overall, this work demonstrates the potential of amphiphilic NIPU coatings as tunable, non‐fluorinated materials for marine antifouling applications.