| dc.description.abstract | Commercially available organic polymer films were treated with radiation from 6·7 × 104 Pa He and Ar plasmas that were made to rotate inside a graphite tube by the application of an auxiliary magnetic field. To investigate modification with vacuum ultraviolet (VUV) photons, the films were covered with LiF, CaF2, fused silica, KBr and crown glass optical filters having different cut-off wavelengths. The weight loss for polytetrafluoroethylene (PTFE) was found to be linear with exposure time and dependent upon cut-off wavelength, inert gas, exposure temperature and arc current. Photoetch rates up to 105 nm min−1 were observed for PTFE using unfiltered radiation from a He arc with a current of 7 A and temperatures up to 240°C. Kapton-H® showed nearly linear weight loss, although there was some curvature at longer exposure times. Upilex-S® and -R® showed rapid initial weight loss that increased with decreasing wavelength and then negligible loss with increasing time of exposure. XPS analysis of treated samples revealed defluorination for PTFE and formation of SiO2, probably resulting from photo-oxidation of a Si, O, C-containing additive, on Upilex-S which prevented further photoetching. Receding contact angles of the polymers decreased rapidly with exposure time to minimum saturation values. In agreement with known photoabsorption spectra, modification for PTFE was induced with wavelengths between 160 and 200 nm while λ > 160 nm affected Kapton and Upilex surfaces. Surface roughening was observed with exposure to VUV radiation. | en_US |
