Tunable Poly(dimethylsiloxane) Topography in O₂ or Ar Plasmas for Controlling Surface Wetting Properties and Their Ageing

Abstract

A plasma-based methodology to fabricate ultraviolet (UV) curable poly(dimethylsiloxane) (PDMS) surfaces with controlled nano-texturing and wettability is described. The surface topography of photo-sensitive PDMS is modified in oxygen and argon plasmas. Plasma treatment of photo-crosslinked PDMS produces spontaneously-formed wavy structures with high nano-scale amplitude and with periodicity of a few 100's nm. With increasing plasma treatment duration, roughness increased while periodicity decreased, resulting in surfaces of enhanced surface area exploited for the enhancement and control of surface hydrophilicity and hydrophobicity. The mechanisms responsible for the plasma-induced PDMS surface nanotexturing are discussed. The beneficial effect of this nanotopography on retarding ageing of PDMS hydrophilicity is demonstrated. Possible applications in sensors and bio-microsystems are outlined.