Transparent marine antifouling coatings for underwater optical devices: strategies, mechanisms and future perspectives

Underwater optical devices are indispensable for marine scientific research, resource exploration, national defense, and environmental monitoring. However, marine biofouling poses a significant threat to underwater optical devices, as it reduces monitoring accuracy and impairs image clarity. Transparent marine antifouling coatings, which offer an effective means of balancing high optical transmittance with reliable protection for marine optical devices, have emerged as a focal point of research. This review summarizes recent advances in the structural design and functionalization of transparent marine antifouling coatings. First, the dynamic evolution of marine biofouling is described, and the optical failure starting point of underwater optical devices and its key influencing factors are clarified. Then, the key performance indicators of transparent antifouling coatings are systematically summarized. Meanwhile, the antifouling mechanisms are examined in depth. Subsequently, design strategies for transparent marine antifouling coatings are comprehensively discussed, including wettability regulation strategies, biocide-releasing strategies, bioinspired design, intelligent response, and composite design strategies. Finally, the key challenges faced by current transparent antifouling strategies are identified, and future research directions are proposed. This work provides a comprehensive and valuable reference for the future development and practical application of transparent marine antifouling coatings.