Nanotextured super-hydrophobic transparent poly(methyl methacrylate) surfaces usinghigh-density plasma processing

Abstract

We present an environmentally friendly, rapid, no-rinse and mass-production amenableplasma process for the fabrication of super-hydrophobic (SH) poly(methyl methacrylate)(PMMA) surfaces using only a one load/unload step in a low-pressure, high-density plasmareactor. First, oxygen plasma is applied to nanotexture the PMMA surface via etchingprocesses leading to high aspect ratio (HAR) topography, with dual-roughnesscharacteristics for short process durations, as evidenced by AFM analysis. The duration ofthe process may range from 1 min to several min depending on the roughness amplitude andon the degree of transparency desired. The significance of the ion-bombardment is revealedand discussed. After this first step, the gas chemistry is changed to a fluorocarbon onewhich leads to a few nanometres-thick Teflon-like film deposition, thus altering the PMMAsurface chemistry within a few seconds. Following this process, a very large area(depending on the reactor scale) of the PMMA may become SH in less than 1.5 min(total process duration) with a transparency as desired (from fully transparent tomilky and antireflective). The contact angles (CA) measured are approximately152° with 5° hysteresis. For short process durations, the dual-roughness character of PMMA surfacesfavours the SH formation, despite the low roughness factor. Furthermore, the dry andlow-temperature character of the process ensures the intactness of PMMA’s shape and bulkmechanical properties.