Fabrication of tunable wetting PDMS membrane by nanostructuring and plasma treatment

In this paper, we present the tunable wetting behavior of Poly(dimethylsiloxane) (PDMS) by nanostructuring and plasma treatments, which shows stable superhydrophobicity and superhydrophilicity. The PDMS film with high-density nanoporous was prepared by replica molding of the black silicon surface fabricated by an improved deep reactive ion etching (DRIE) process. This simple nanostructuring can increase the roughness and reduce the surface energy of PDMS. The conventional equipment for micro fabrication (i.e. inductively couple plasma etcher) was used to realize plasma treatment to modify the wettability. The effects of different plasma gases on wettability are attributed to physical and chemical mechanisms, which have been investigated by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX), respectively. The optimized recipe was obtained after additional chemical analysis. Eventually, the static contact angles of this PDMS membrane remarkably achieved ~160° and ~3°, respectively. Furthermore, the recovery of wettability was reduced by nanostructuring PDMS surface.