Photoemission study of the copper/poly(ethylene terephthalate) interface

The metallization of poly(ethylene terephthalate) (PET) by copper has been studied by photoelectron spectroscopy (x-ray and vacuum ultraviolet). The results are interpreted in the light of a valence-effective-Hamiltonian band-structure calculation on the PET polymeric chain and by comparison with earlier work on copper oxides. The theoretical valence-band density of states is in very good agreement with the photoelectron spectra of PET and allows us to present a detailed interpretation of the valence electronic structure of PET. Upon metallization, we find that, for low coverages (5×{}10¹⁴ Cu atoms/cm²) copper binds preferentially to the oxygen from the carbonyl (---C---O) and the ether (---C---O---) groups of the PET. At coverages near 7.5×{}10¹⁴ Cu atoms/cm², the additional copper remains metallic and gives rise to a three-dimensional islandlike growth mode. The low reactivity towards PET stands in sharp contrast to the case of other transition metals, like Ti and Cr.