Photoetching and modification of poly(tetrafluoroethylene-co-hexafluoropropylene) polymer surfaces with vacuum UV radiation

• Published in: Polymer degradation and stability 2003-03, Vol.79 (3), p.399-404
• Main Authors: Chen, J.X., Tracy, D., Zheng, S., Xiaolu, L., Brown, S., VanDerveer, W., Entenberg, A., Vukanovic, V., Takacs, G.A., Egitto, F.D., Matienzo, L.J., Emmi, F.
• Format: Article
• Language: English
• Subjects: Applied sciences; Crosslinking and degradation; Exact sciences and technology; FEP; Photodegradation; Physicochemistry of polymers; Polymers and radiations; Radiation; Surface modification; VUV
• ISSN: 0141-3910; 1873-2321
• DOI: 10.1016/S0141-3910(02)00339-7

Films of poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) were exposed to radiation from 6.7 × 10 4 Pa He and Ar dc arc plasmas that were made to rotate inside of a graphite tube by the application of an auxiliary magnetic field. The films were covered with optical filters having different cut-off wavelengths to vary the vacuum ultraviolet (VUV) radiation that modified the fluoropolymer surface. With arc currents of 7 A and sample temperatures up to 110 °C, the photoetch rate of FEP was ca. 50% higher than for PTFE. Consistent with results for PTFE, treated FEP showed the following: (1) contact angles that started to decrease in the wavelength region between 173 and 160 nm and continued to decrease with shorter wavelengths; (2) surface roughening; (3) defluorination of the surface with a slight increase in the atomic%C and formation of C–C bonds in the top 3–5 nm of the surface as detected by XPS analysis; and (4) incorporation of oxygen, presumably from reaction with oxygen in air.