Hydrophobic recovery of femtosecond laser processed silicone rubber insulator surfaces

Abstract This article demonstrates the loss and recovery in hydrophobicity of silicone rubber insulator surface processed by a femtosecond laser. The two stages of the wettability conversion were investigated. First, a rough micro/nano structure was formed on the original hydrophobic sample surface processed by the femtosecond laser, and the water contact angle on the surface was reduced from ~ 110° to a minimum of ~ 35°. This hydrophilicity loss was due to the increase in the hydrophilic OH groups and the reduction of the hydrophobic CH 3 groups on the surfaces. Second, the roughened samples were stored in a natural ambient environment. Over a certain storage time, the surface hydrophobicity recovered gradually and evolved into a superhydrophobic state. It was found that the migration of low molecular weight cycle and/or linear siloxane oligomers resulted in the recovery of the hydrophobicity property. Coupled with the increase of surface roughness caused by laser irradiation, the further evolution of the hydrophobicity was promoted. Moreover, the higher temperature accelerates the recovery of the surface hydrophobicity. The research on the conversion mechanism of the wettability on the silicone rubber insulator surface processed by femtosecond laser is of great significance for improving its reliability in practical applications.