Vacuum Ultraviolet Photolysis of Hydrocarbon Polymers

✍ Scribed by Florina-Elena Truica-Marasescu; Michael R. Wertheimer

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 292 KB
• Volume: 206
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.200400510

✦ Synopsis

Abstract

Summary: The wavelength‐dependent vacuum ultraviolet (VUV) photolysis of several polymers, low density polyethylene (LDPE), biaxially oriented poly(propylene) (BOPP), atactic polystyrene (PS), and poly(methyl methacrylate) (PMMA), was studied by irradiation in vacuum with the well‐characterized emissions from four different resonant or excimer VUV sources. These lamps comprise radiofrequency (r.f.) discharges in different noble gases, such as krypton, xenon (at low pressures, producing near‐monochromatic resonant line radiations), xenon excimer (at “high” pressure), and a deuterium/argon mixture (producing a broad‐band emission). VUV‐induced mass loss (ablation or etching) was monitored in situ by quartz crystal microbalance measurements. Following irradiation, samples were analysed by ATR‐FTIR and XPS, to evaluate near‐surface structural changes (e.g., creation of unsaturation, cross‐linking) resulting from the VUV‐initiated bond scissions and radical‐creation reactions. PMMA was the most readily ablatable polymer, whereas the mass loss of BOPP was higher than that of LDPE, regardless of the irradiation wavelength, λ. All polymers were found to form double bonds, with the exception of PS, which is rather stable, probably due to energy dissipation by fluorescence.

Formation of double bonds in a) vinyl‐, b) vinylidene‐, and c) vinylene‐like unsaturated groups, as a function of the radiation dose, D, for KrL (▪), XeL (▴), and D~2~Ar‐irradiated (•) PMMA.

magnified imageFormation of double bonds in a) vinyl‐, b) vinylidene‐, and c) vinylene‐like unsaturated groups, as a function of the radiation dose, D, for KrL (▪), XeL (▴), and D~2~Ar‐irradiated (•) PMMA.