Hysteresis and reversibility of a superhydrophobic photopatternable silicone elastomer.

We report upon the wetting property of layers of a micropatterned photodefinable silicon elastomer, PDSE, repetitively and alternatively treated with oxygen plasma and temperature cycles. At low power plasma treatments, we observed a hysteresis in terms of contact angle between phases lowering the contact angle and phases of recovery. As opposed to high power plasma for which we show that by generating fissures on the surface, the structure can be cycled between superhydrophobic and superhydrophilic states. The plasma-generated diffusion paths were characterized by electron microscopy and were found to be directly related to the recovery of the wetting properties of the plasma treated layers of PDSE. The cycling between the superhydrophobic and superhydrophilic states was dependent on the power of the applied plasma as well as the condition during the contact angle recovery amplified by a temperature-controlled baking step.