Motion of liquid droplets on a superhydrophobic oleophobic surface

Developing a superhydrophobic oleophobic material is achieved by two criteria: low surface energy and properly designed surface morphology. The relationships among surface tensions, contact angles, contact angle hystereses, roll-off angles, and surface morphologies of such materials are studied. Numerical formulae related to the surface energy of liquids and solids are used to predict the wetting behavior of superhydrophobic and oleophobic materials. Using chemical and geometrical modifications, a superhydrophobic oleophobic surface was prepared. Good agreement between the predicted and measured contact angles and roll-off angles were obtained. The effect of the contact angle hysteresis on the roll-off angle is described to understand the motion of a droplet when the droplet begins to roll off.