Aging and self-healing properties of superhydrophobic silicone rubber

Silicone rubber is widely used for outdoor insulation because of its hydrophobicity. Meanwhile, superhydrophobic surfaces with self-cleaning property are ideal as outdoor insulating materials. An efficient technique to fabricate superhydrophobic silicone rubber with a contact angle of 151° and a sliding angle of 5° is reported. Long-term stability of polymeric superhydrophobic insulating surfaces was examined under electrical and non-electrical stresses. Results show that silicone rubber transforms from superhydrophobic to superhydrophilic after corona aging. Superhydrophobic characteristic is fully recovered through a self-healing process. After water immersion, it results in large contract angle hysteresis, although the static contact angle on the surface is large. The increase in surface free energy caused by aging for self-healing superhydrophobic material affects the stability of superhydrophobic properties. Once the hydrophobicity decreases and Wenzel contact mode is formed, the sliding angle and contact angle hysteresis are difficult to recover because of a large energy barrier between the Wenzel-Cassie transitions.