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The surface properties of polydimethylsiloxane (PDMS) were modified by treatment with an atmospheric pressure rotating plasma jet (APPJ) and the surface modifications were studied to assess its hydrophilicity and adhesion to acrylic adhesive tape intended for medical applications. Furthermore, the extent of hydrophobic recovery under different storage conditions was studied. The surface treatment of PDMS with the APPJ under optimal conditions noticeably increased the oxygen content and most of the surface silicon species were fully oxidized. A brittle silica-like layer on the outermost surface was created showing changes in topography due to the formation of grooves and cracks. A huge improvement in T-peel and the shear adhesive strength of the APPJ-treated PDMS surface/acrylic tape joints was obtained. On the other hand, the hydrophilicity of the PDMS surface increased noticeably after the APPJ treatment, but 24 h after treatment almost 80% hydrophobicity was recovered and the adhesive strength was markedly reduced with time after the APPJ treatment. However, the application of an acrylic adhesive layer on the just-APPJ-treated PDMS surface retained the adhesive strength, limiting the extent of hydrophobic recovery. The STSM Grant by COST ACTION MP1101 ‘Biomedical Applications of Atmospheric Pressure Plasma Technology’ and financial support from the Innovaciones DisRas S L Company is gratefully acknowledged.

Threshold ionization mass spectrometry (TIMS) has been used to measure the excited molecular oxygen states O2 (1Δg) and during plasma-assisted chemical vapour deposition of tin oxide (SnO2) thin films. The latter, composed of nanosized features, was deposited by feeding in a mixture of Ar, O2 and tetramethyltin (Sn(CH3)4 or TMT) in a capacitively coupled RF discharge reactor. Langmuir probe measurements were performed along with TIMS to measure the electron temperature and density. The correlations between these two diagnostic methods have been investigated. The observed densities of O2 (1Δg) and in the γ mode of the discharge are maximum at a low electron temperature and high density. Furthermore, these results have been shown to be correlated to the trend of the electronic conductivity of the deposited SnO2 thin films.

We report the self-organized nanostructures of hydrogen-free amorphous carbon (a-C) with controllable characteristic length scales obtained by using ion beam assisted deposition. By selecting various temperature regimes, two kinds of nanostructure, mounds and ripples, are successfully formed. For the growth temperature of 200 °C, the fractal analysis of the surface shows that the lateral characteristic length for mounding structures increases with increasing ion energy. But for ripple structures formed in the relatively high temperature region, the ripple wavelengths are found to show a nonlinear dependence on the ion energy. Further, at certain temperatures there exist energy thresholds for stopping the formation of ripple structures. These results demonstrate that the characteristic scales of nanostructures for a-C can be significantly controlled through the tuning ion energy in a well-defined manner.