SURFACE-CHEMISTRY OF POLYIMIDE PRECURSORS ON CU(111)

We have investigated the bonding of the monomers pyromellitic dianhydride (PMDA) and oxydianiline (ODA) as well as model compounds, succinic anhydride, phthalic anhydride, and benzoic acid, on Cu(111) in ultrahigh vacuum. Unenhanced surface Raman spectroscopy was used to identify the adsorbed species. ODA was unreactive at 110 K; the surface vibrational features were identical to those in the condensed multilayer. In contrast, PMDA chemisorbed dissociatively to form a bidentate surface carboxylate. Succinic anhydride physisorbed at 110 K, whereas benzoic acid and phthalic anhydride both adsorbed dissociatively forming bridging surface carboxylates as was observed for PMDA. The surface Raman spectrum of PMDA showed resonance enhancement.