Dynamics of Soft Wetting

The wetting on soft surfaces has garnered great interest in the past decade. The interplay between liquid surface tension forces with the elastic properties of a soft solid have been shown to be significant, resulting in a diverse set of behaviors in both technological and natural environments. This thesis focusses on the dynamics of such a partial wetted system. More specifically, the liquid surface tension deforms the solid in to a so called wetting ridge, whose presence dominates the dynamics of this system. We explore a large range of velocities of a single contact line, showing an intimate relation between the contact angle of the liquid and the shape of the wetting ridge. We observe quasi-static behavior for the low speed regime that is accurately predicted by theory, while we see a departure from the prediction at larger speeds. This departure is attributed to an unexplained change in the surface energy of the solid. For speeds larger still we observe an unsteady stick-slip-like motion and we succeed in explaining this regime by analyzing the shape of the wetting ridge as compared to the liquid contact angles. Lastly we show that the application of an electrostatic force by applying a voltage over the soft solid, known as electrowetting, changes the macroscopic wetting behavior. The macroscopic changes adhere to the prevailing electrowetting theoretical predictions, while the system retains an identical dynamical behavior.