| The objective of this research was to determine the molecular structure of interphases formed by curing the polyamic acid (PAA) of pyromellitic dianhydride (PMDA) and oxydianiline (ODA), an epoxy/amine adhesive, and an epoxy/anhydride adhesive against metal substrates such as silver, gold, and copper. A novel technique known as surface-enhanced Raman scattering (SERS), was developed and utilized along with reflection-absorption infrared spectroscopy (RAIR) and X-ray photoelectron spectroscopy (XPS) to characterize the polymer/metal interphases.;SERS is a phenomenon in which the Raman scattering cross section of molecules adjacent to the roughened surfaces of some metals is enhanced as much as 10;Results obtained from the polyimide/metal system indicated that acid groups of PMDA/ODA reacted with metal ions from the substrates to form metal carboxylate salts. Formation of carboxylates inhibited the curing of PAA, resulting in a unique structure in the interphase which was chemically different from that in the bulk polymer. The extent of carboxylate formation at the interphase depended strongly on the nature of metal. The structure of polyimides (e.g., chain flexibility) also had a strong effect on the interfacial structure.;In the case of epoxy/metal system, the curing agent tended to segregate to the substrate surface. No strong chemical interaction occurred between the amine curing agent (4,4;In some cases, organosulfur compounds such as 4,4;The fundamental information in this research can be used to tailor the molecular structure of polymer/metal interphases and lead to produce improved polymer-to-metal adhesion. It was also demonstrated that SERS is a powerful technique for non-destructive characterization of polymer/metal interphases. |
