화학공학소재연구정보센터
Langmuir, Vol.25, No.20, 12293-12298, 2009
Drop Impact upon Micro- and Nanostructured Superhydrophobic Surfaces
We experimentally investigate drop impact dynamics onto different superhydrophobic surfaces, consisting of regular polymeric micropatterns and rough carbon nanofibers, with similar static contact angles. The main control parameters are the Weber number We and the roughness of the surface. At small We, i.e., small impact velocity, the impact evolutions are similar for both types of substrates, exhibiting Fakir state, complete bouncing, partial rebouncing, trapping of an air bubble, jetting, and sticky vibrating water balls. At large We, splashing impacts emerge forming several satellite droplets, which arc more pronounced for the multiscale rough carbon nanofiber jungles. The results imply that the multiscale surface roughness at nanoscale plays a minor role in the impact events for small We less than or similar to 120 but ail important one for large We greater than or similar to 120. Finally, we find the effect of ambient air pressure to be negligible in the explored parameter regime We less than or similar to 150.