An x-ray photoemission spectroscopy study of chemical interactions at silver/plasma modified polyethylene interfaces: Correlations with adhesion

Abstract

Plasma treatment is a convenient way to modify the surface (∼25–50 Å) of a polymer for improved adhesion of vacuum deposited metals. X‐ray photoemissionanalysis of plasma modified polyethylene (PE) indicates no detectable chemical effects for argon plasmas, whereas oxygen and nitrogen plasmas create new chemical species which alter the chemical reactivity of the PE surface for vacuum depositedAg. The adhesion strength of vacuum depositedAg on PE is shown to increase in the following order: untreated<argon plasma<oxygen plasma<nitrogen plasmatreated PE. Changes in chemical bonding and nucleation of submonolayer vacuum depositedAg on plasmatreated PE correlate with Ag/PE adhesion. Changes in the PE core levels after submonolayer deposition of Ag are interpreted as due to the formation of Ag–O–C and Ag–N–C species on oxygen and nitrogen plasmatreated PE, respectively. In contrast, no chemical bonding effects are observed on untreated or argon plasmatreated PE. The Ag valence‐band structure suggests that the plasma induced species act as nucleation and chemical bonding sites resulting in a much smaller average cluster size for vacuum depositedAg. Interfacial analysis of peeled thin films of vacuum depositedAg on PE suggests the locus of failure changes from interfacial adhesive failure for untreated and argon plasmatreated PE to cohesive failure of the PE for oxygen and nitrogen plasmatreated PE.