Dynamics of spreading on ultra-hydrophobic surfaces

Despite the extensive variety of applications for ultra-hydrophobic surfaces in industry, technology, and biology, due to their wetting characteristics, there has not been considerable attention in the area of dynamics of wetting on ultra-hydrophobic surfaces. In this research, the experimental investigations have been done by applying forced spreading of several polyethylene-glycol/water mixtures in different weight ratios on Teflon plates and ultra-hydrophobic sprayed glass substrates. Hydrodynamics theory and molecular-kinetic theory have been applied to investigate the dynamics of wetting on these substrates. It has been found that the dynamics of receding motion of liquid contact line on ultra-hydrophobic surfaces could be described perfectly with the molecular-kinetic theory. In the case of advancing motion on an ultra-hydrophobic surface, dynamic contact angle is independent of liquid contact line velocity. The advancing and receding motions of liquid contact line on smooth Teflon plates followed molecular-kinetic theory.