The molecular structure of interfaces formed by curing the polyamic acid of pyromellitic dianhydride (PMDA) and oxydianiline (ODA) against copper and gold substrates was determined using surface‐enhanced Raman scattering (SERS) and reflection‐absorption infrared spectroscopy (RAIR). It was found that acid groups of the polyamic acid reacted with metal ions on the substrates to form carboxylate salts when the polyamic acid was spin‐coated onto metal substrates. Formation of carboxylates on the copper surface extended several hundred angstroms into the polyamic acid films, while only trace levels of carboxylate were formed on the gold surface. Formation of carboxylate salts suppressed the curing of polyamic acid on copper substrates. However, the degree of curing of the polyamic acid was high on gold surfaces. These results were compared to our previous work concerned with the molecular structure of interfaces between PMDA/ODA polyimides and silver substrates. The extent of carboxylate formation on silver was intermediate between those on copper and gold. Results obtained from SERS and RAIR also indicated that cured polyimide films above the partially cured layers were oriented edge‐on, with the PMDA moieties perpendicular to the metal surface and the ODA moieties mostly parallel to the surface.
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Young et al. (1993) studied this question.
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