Structural tailoring of sharkskin-mimetic patterned reverse osmosis membranes for optimizing biofouling resistance

Controlling biofouling is critical for membrane materials exposed to aquatic environments. Specifically, the sharkskin-mimetic, so-called Sharklet, surface pattern has proven effective for suppressing biofilm formation on desalination membranes. In this study, a series of Sharklet patterns with different unit and pattern spacings were designed on reverse osmosis (RO) membrane surfaces to identify the effect of the Sharklet pattern dimension on membrane biofouling. A high fidelity of Sharklet-patterned RO membranes with different spacing dimensions were successfully fabricated by micromolding combined with layered interfacial polymerization. The biofouling behavior of the fabricated Sharklet-patterned RO membranes was systematically characterized under both static and dynamic conditions. Importantly, dynamic biofouling results showed that the anti-biofouling effect of the Sharklet pattern was optimized when the unit and pattern spacings were both 2 μm. Computational fluid dynamics simulation elucidated the surface flow characteristics of the Sharklet patterns depending on the spacing dimensions. The maximized anti-biofouling performance of the Sharklet pattern with 2 μm spacings was hypothesized to be determined by the balance between the intrinsic biofouling propensity (under static conditions) and surface flow characteristics such as vortex and primary/secondary flows (under dynamic conditions).