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

Abstract

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)

Wettability characteristics of poly(ethylene terephthalate) films treated by atmospheric pressure plasma and ultraviolet excimer light

“…32 Surprisingly, the receding contact angles remained almost a constant value (B201), independent of the rinse and storage. It was shown in the previous paper 26 that such contact angle hysteresis behavior on the PET surface after treatment by the APP is consistent with the theoretical calculation of the advancing and receding contact angles on the model heterogeneous surfaces with low-and high-energy regions.…”

Oxygen and nitrogen plasma hydrophilization and hydrophobic recovery of polymers

“…3,19,27,28,30,[33][34][35] A near universal finding is that the oxygen plasma treatment initially brings the contact angle to very hydrophilic values, after which a rapid and nearly complete hydrophobic recovery takes place for dry stored samples. The time scale for the recovery varies greatly between studies, from hours 35 to days 19,27 and weeks.…”

“…The time scale for the recovery varies greatly between studies, from hours 35 to days 19,27 and weeks. 30,34 Storing the PDMS surfaces permanently under water 19 or solvent extraction of non cross linked low molecular weight species prior to plasma treatment 13 can help to preserve the hydrophilicity for longer times. Hydrophilization of PDMS by nitrogen plasma is less studied.…”

Use of statistical design of experiments in the optimization of Ar–O2 low-pressure plasma treatment conditions of polydimethylsiloxane (PDMS) for increasing polarity and adhesion, and inhibiting hydrophobic recovery

“…Figure 9a shows the ATR-IR spectra of the untreated and LPP treated PDMS surfaces in which the main absorption bands due to PDMS can be observed. The bands at 1082 and 1016 cm -1 correspond to simmetric and asimmetric stretching of siloxane (Si-O) respectively, the band at 1260 cm -1 corresponds to bending of Si-CH 3 and the band at 795 cm -1 corresponds to stretching of Si-(CH 3 ) 2 [30]. According to Figure 9a, the treatment with oxygen or argon plasmas increases slightly the intensity of the siloxane absorption bands with regard to these of the untreated PDMS indicating that if some chemical modifications are produced by treatment with plasma they must be located on the outermost surface; however, the treatment with 93vol% oxygen + 7vol% argon plasma produces an increase of the intensity of the siloxane band likely due to the creation of thicker silica-like layer due to deeper PDMS surface modification.…”