Highly stable hydrophilic surfaces of PDMS thin layer obtained by UV radiation and oxygen plasma treatments

Surface modification of polydimethylsiloxane (PDMS, Sylgard 184) was carried out by O2 plasma and UV in broadband mode/O2 plasma treatments with different exposure times, and studied in terms of hydrophilic stability. Water contact angle measurements, Fourier Transform Infrared Spectroscopy (FTIR) and Atomic Force Microscopy (AFM) were used for the analysis of the modified surface and hydrophilic stability of the PDMS films. The results show reasonably good hydrophilic stability in the range of a week with a contact angle of around 70° for O2 plasma treated samples, whereas a more high hydrophilic stability, with a low contact angle of 65° up to 15 days, was observed for UV/O2 plasma treated PDMS. FTIR analysis of the samples reveals significant oxidation noted by large presence of Si-O-Si, and Si-OH bonds on the PDMS surface, which improves the affinity with water molecules and increases the hydrophilicy. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)