Directional wetting on chemically stripe-patterned surfaces : Static droplet shapes and dynamic motion on gradients

The directional wetting characteristics of droplets on chemically defined stripe-patterned anisotropic substrates are briefly reviewed. The static droplet shape as well as the observed contact angles exhibit unique scaling behavior as a function of the macroscopic wettability, as arising from patterns consisting of alternating hy-drophilic and hydrophobic stripes. In addition, the motion of liquid from surface regions with low macroscopic wettability towards more wetting areas is described. Linear patterns are presented, which induce liquid movement along the chemically defined stripes giving rise to a macroscopic gradient in surface energy. Finally, we show that lattice Boltzmann modeling enables semrquantitatively accurate simulation of the experimental observations.