Transforming PDMS surface to super-hydrophobic by surface arc-discharge

Super-hydrophobic surfaces have many applications e.g. ice-accumulation reduction, self-cleaning and enhancement of condensation-heat-transfer. In this paper, we transform the PDMS surface into super-hydrophobic through surface arc-discharge under controlled conditions. It has been found that the times of arc-discharge result in surfaces with different hydrophobic levels. The hydrophobic characteristics, microstructures and chemical composition of the superhydrophobic surface are characterized by water contact-angle measurement, scanning-electron microscopy (SEM) and infrared (IR), respectively. Experimental results show that the superhydrophobic surfaces have a microstructure that embedded with nanostructure (so called dual micro- and nano- scale hierarchical structure). The obtained surfaces exhibit different hydrophobicity: the water contact-angle firstly increases to a top value of ca. 152°, then decreases with more arc-discharge times. The sliding angle is resultantly decreases to a value which is lower than 4 ° followed by a growing to a value than that of the virgin PDMS surface. Our microstructure and composition analyses (SEM, IR) have shown that the super-hydrophobic surface is dominantly composing of SiO₂ particles that are grafted by organic groups. The hierarchical structure and the low-surface-energy organic groups result in the superhydrophobic surface.