Formation of superhydrophobic poly(dimethysiloxane) by ultrafast laser-induced surface modification.

The formation of hemispherical nanostructures and microscaled papilla by ultrafast laser irradiation was found to be a potential method to generate superhydrophbic surface of synthetic polymers. Irradiation of femtosecond laser creates roughened poly(dimethylsiloxane) (PDMS) surface in nano- and microscales, of which topography fairly well imitate a Lotus leaf in nature. The modified surface showed superhydrophobicity with a contact angle higher than 170 degrees as well as sliding angle less than 3 degrees. We further demonstrated that negative replica of the processed PDMS surface exhibit large contact angle hysteresis with a sliding angle of 90 degrees while the positive replica maintains superhydrophobicity.