Evidence for metal interaction in gold metallized polycarbonate films: An x-ray photoelectron spectroscopy investigation

The interfacial interactions between in situ thermally evaporated Au and polycarbonate (PC) film, a technologically important polymeric material, is studied by x-ray photoelectron spectroscopy (XPS). Angle resolved XPS is performed to investigate the Au reactivity if any, in forming the metal-polymer interface. The spectral evidence from the above suggests that the metal interacts predominantly with the carbonyl carbon of the monomeric unit with only minor interactions with the phenyl carbons without any complex formation. In contrast to previous findings of Au to be inert at the M-polymer interfaces, this work emphasizes the salient charge transfer type interactions of Au (as electron injector) at the C=O as the primary interaction site, distributing a net charge density to C=O with the formation of a Au-CO π-back bond. The conclusions are supported by the observed new $C 1s$ feature at 282.6 eV and the $O 1s$ and $Au 4f7/2$ XPS spectral changes. The growth mode of Au on PC was proceeded by the metal monolayer deposition with cluster growth on the already weakly bonded Au onto the C=O carbon of the polymeric backbone.