Dynamic motion of air bubble on micro-structured surfaces by novel dynamic wettability evaluation method under liquid media

Generally, the wettability of liquids to substrates has been determined by static and dynamic contact angles under an atmospheric conditions. Based on these relationships, it is presumed to move air bubbles on substrates under water media. However, these dynamic behaviors in the liquid media cannot be perfectly predicted from the dynamic contact angle under atmospheric conditions and the static contact angle under liquid media. In this study, the dynamic contact angle of bubbles under liquid media was directly measured by a novel experimental method "underliquid tilting method," and these dynamic wetting behaviors in liquids were evaluated. As result, it was revealed that air bubbles under water media were dynamic moving on the hydrophilic surfaces and adhering at the transition state between Cassie-Baxter and Wenzel states. Dynamic wetting behaviors in liquids may serve as a foothold for the development of biomimetic materials.