Fabrication of a scalable slippery surface via novel sprayable breath figure technique for sustainable drag reduction and anti-biofouling in marine environments

The maritime industry has been seeking efficient solutions to combat hydrodynamic friction and biofouling, which increase operational costs and environmental issues. To address these concerns, we developed a novel sprayable breath figure (sBF) method to create a scalable and cost-effective liquid-infused surface for reducing frictional drag forces on marine vehicles. The proposed sBF method facilitated the rapid production of multilayered porous polymer films with micron-scale spherical cavities, which can be applied to large and curved surfaces, thus overcoming the limitations of traditional breath figure methods. Further surface treatment of oxygen plasma etching followed by polydimethylsiloxane (PDMS) brush grafting was employed to optimize the interfacial slip and lubricant retention of the slippery surface coating. The PDMS brush-grafted slippery surfaces demonstrated significant drag reduction under turbulent flow conditions, as confirmed by direct velocity field measurements, which revealed nonzero slip velocity unlike conventional no-slip surfaces. The same surfaces also exhibited remarkable anti-biofouling performance, severely resisting marine biofouling in real-sea field tests over 50 days. The successful application of the proposed sBF method to large and curved submerged bodies, achieving a noticeable drag reduction under high-speed turbulent flows, is a critical step toward the practical implementation of this technology in the marine industry.