Chemistry, diffusion and cluster formation at metal-polymer interfaces

This paper shows how structure and formation of metal-polymer interfaces depend strongly on the preparation process and the interfacial chemistry. Emphasis is placed on results obtained from transmission electron microscopy (TEM), X-ray photo electron spectroscopy (XPS), radiotracer measurements and computer simulations on the early stages of interface formation during noble-metal deposition onto fully cured polymers. Noble metal atoms deposited onto polymers diffuse on and inside the polymer and tend to agglomerate to clusters. XPS results show that no significant diffusion occurs from larger clusters and is therefore also not expected from a continuous metal film. Thus the extent of diffusion into the polymer appears to be determined only by the initial stage of the deposition process and increases strongly at low deposition rates and elevated temperatures, where a large fraction of isolated metal atoms is able to diffuse into the polymer before being trapped by other atoms at or near the surface. Our results point to a strong interplay between chemical interaction, diffusion and agglomeration.