Development and testing of bio-based amphiphilic-designed polymer coatings as a safer approach to marine biofouling

Marine biofouling is a major environmental and economic challenge for shipping and marine infrastructure, driving the need for effective and sustainable antifouling strategies. In this study, bio-based amphiphilic-designed polymer coatings were synthesized from renewable platform chemicals via an energy-efficient free-radical polymerization approach, thereby avoiding hazardous solvents. The coatings were designed by tuning the hydrophilic-hydrophobic balance to modulate antifouling performance, with crosslinking introduced in selected formulations to improve coating integrity and durability. Polymer synthesis proceeded with high yields (65-83%) and almost successful monomer incorporation, resulting in coatings with suitable chemical properties, controlled surface wettability (>90°), and no detectable acute toxicity against Artemia sp. The environmental sustainability of the synthetic approach was evaluated using green chemistry metrics, including solvent recovery sensitivity scenarios. At the same time, a preliminary user-perception survey was conducted to assess the practical relevance and societal demand for safer antifouling solutions. Laboratory assays revealed strong inhibition of diatom adhesion in predominantly hydrophobic formulations (>90% inhibition), whereas amphiphilic-designed systems exhibited variable, formulation-dependent performance. Static field exposure on PVC panels showed that the tested amphiphilic formulations did not prevent fouling accumulation under prolonged natural immersion, as both microfouling and macrofouling communities developed similarly to those on untreated panels. Microbial community analyses further indicated that bacterial assemblages were more responsive to coating chemistry than fungal communities during early colonization. These results demonstrate the importance of combining renewable feedstocks, green synthesis and multilevel assessment to identify promising bio-based antifouling coatings and guide their future optimization for suitable applications.