Wettability Control of Ceramic Surfaces with Hierarchical Nano/Micro-patterns

This study presents a novel approach to control surface wettability through hierarchical nano/micro-patterns on ceramic surfaces fabricated via multi-step imprinting. Inspired by the water-repellent structures of lotus leaves, we developed patterns combining 250 nm-scale lines with 50 μm-scale structures on alumina substrates. Contact angle measurements revealed distinct anisotropic behavior, with values ranging from 95° to 125° depending on the measurement direction. Experimental results showed significant deviations from both Wenzel and Cassie-Baxter theoretical models, indicating a complex mixed wetting state. Analysis of these deviations, considering the effects of alumina grain size (100 nm) and grain boundaries, provides new insights into wetting behavior on hierarchical ceramic surfaces. This work establishes design principles for durable, biomimetic ceramic materials with controlled wettability for applications requiring self-cleaning and water-repellent properties.