Fabrication and flow simulation of superhydrophobic polydimethylsiloxane surfaces with macro/micro/nano trimodal structures

Biofouling is detrimental to both medical and marine engineering fields. Antifouling strategies can be engineered in material functions or using flow manipulation to prevent foulant attachment. However, the synergy of combining these two approaches has rarely been explored. Herein, we introduce a superhydrophobic polydimethylsiloxane (PDMS) surface with macro/micro/nano multi-tier structures that combines flow and material manipulation for antifouling applications. The PDMS is molded to feature millimeter-scale sharklet riblets, which modulate the bulk flow, followed by laser ablation to create micro-nano structures that confer superhydrophobicity. Lastly, the surface is functionalized with nanoscale polymer brushes using a facile vapor deposition technique to produce a slippery liquid-like surface for drag reduction. Scanning electron microscopy reveals a micro-nanoscale coral-like topology, resulting in a contact angle of 165° and a sliding angle of 2°. Finite element simulation of the superhydrophobic tri-tier PDMS under flow reveals an increase in shear stress and vorticity compared to surfaces without the millimeter-scale riblets. The effects of the sharklet riblet geometry and surface roughness will be investigated to obtain the optimized design.