Reactivity of vapor-deposited metal atoms with nitrogen-containing polymers and organic surfaces studied by in situ XPS

The reactivity of vapor-deposited Fe, Ni, Cu and Au atoms with nylon 6 ([NH(CH2)5CO]n), a nitrogen ion beam-modified polyethylene substrate (N-PE) and a nitrile-terminated self-assembled monolayer (CN-SAM) have been investigated using in situ X-ray photoelectron spectroscopy (XPS). On nylon 6, Fe deposition produced FeO and FeN bonded species as well as an amorphous carbonaceous film at the metal/polymer interface. Metal–nitrogen bond formation was also observed during Ni and Cu deposition on nylon 6, although the CO functionality remained intact, and no evidence was found for the production of either CuO or NiO species. Deposition of Fe and Ni on N-PE and the CN-SAM also resulted in the production of metal–nitrogen bonds. In contrast, Cu exhibited little or no reactivity with N-PE and failed to activate CN bond cleavage in the CN-SAM, while the deposition of Au produced a purely metallic overlayer on all three substrates. The relative reactivity of different polymer functional groups in the present study was found to be largely determined by their respective bond strengths, while the overall metal reactivity trend (Fe>Ni>Cu>Au) can be correlated with the strength of metal–oxygen and metal–nitrogen bonds that can potentially form during metallization.