Regulation of Marine Antifouling Performance of Amphiphilic Copolymer Coatings by Steric Hindrance of Hydrophobic Units

Marine biofouling poses a major economic challenge for the maritime industry by increasing frictional drag and fuel consumption. Although nontoxic amphiphilic copolymers have emerged as promising alternatives to purely hydrophobic or hydrophilic antifouling coatings, to date, the specific role of the steric bulk (hindrance) of hydrophobic moieties in antifouling performance has not been systematically examined. In this study, we investigate the impacts of the steric bulk of hydrophobic comonomers on marine antifouling efficacy. Amphiphilic random copolymers were synthesized via reversible addition–fragmentation chain transfer polymerization using hydrophilic zwitterionic sulfobetaine methacrylate and hydrophobic butyl methacrylate (BMA) isomers ( n -, iso -, and tert -BMA) with varying steric bulk. The resulting polymers were coated onto solid substrates and evaluated through dynamic marine diatom adhesion tests in the presence of silt. Overall, this study highlights that introducing sterically bulky hydrophobic moieties is key to mitigating both silt adsorption and marine biofouling.