Quantitative characterization of plasma treated PDMS microfluidic substrates by inverse gas chromatography

Abstract

Abstract The effect of air plasma exposure time on the surface energies and acid-base characteristics of polydimethylsiloxane (PDMS) particles was studied. Polymerized PDMS powder was radio frequency induced air plasma irradiated for 2–10 s with the power of 500 W. The efficiency of the plasma treatments was investigated by a new generation inverse gas chromatograph, a surface energy analyzer. The dispersive component of surface energy was determined by the Dorris-Gray method describing the van der Waals interactions, while the specific component of surface energy expressed the surface ability for Lewis acid-base interactions. It was demonstrated that the air plasma treatment did not affect the dispersive and acidic parts of the surface energy and the change of surface hydrophilicity was caused by the raise of the electron-donor ability of the PDMS surface, characterized by van Oss-Good-Chaudhury’s base number. The optimal plasma treatment time was found to be 5 s. Analysis of the specific surface energy and acid-base characteristics with respect to exposure time showed that partial to complete hydrophobic recovery occurred within 38 h.