Long-Term Immersion Study for Durability of Interconnected Micropatterned Surfaces with Sustained Water Repellency

The sustained water repellency of interconnected micropatterned surfaces is explored over an extended duration, with a focus on their resilience during a 90-day water-immersion test. Initially, the microstructure surfaces exhibit high water repellency, a characteristic of the Cassie-Baxter state. However, subsequent detailed temporal analyses reveal varying responses depending on the structural topology. The interconnected micropatterned surfaces exhibit remarkable long-term resistance to water; this is attributed to the formation of large and stable air pockets enabled by their unique microcavity structures. In comparison, hierarchical microcavity surfaces with micropillars exhibit a notable decrease in water repellency, as evidenced by reduced contact angles, suggesting a transition to a wetting state owing to the emergence of surface hydrophilicity during long-term water exposure. This study demonstrates the importance of stable air-pocket effects, particularly in applications where the long-term stability of liquid repellency is critical, and suggests the role of interconnected structures in maintaining water repellency over time. Exploring sustained water repellency in micropatterned surfaces during a 90-day immersion test, this study highlights varying responses based on structure. Interconnected surfaces maintain long-term resistance with stable air pockets, while hierarchical surfaces show decreased repellency, transitioning to a wetting state. This underscores the importance of stable air-pocket effects in maintaining water repellency over time. image