The interactions of copper overlayers with four different polyimides [pyromellitic dianhydride-oxydianiline (PMDA-ODA), benzophenonetetracarboxylic dianhydride-diaminobenzophenone (BTDA-DABP); oxydiphthalic anhydride-oxydianiline (ODPA-ODA); and pyromellitic dianhydride-phenylene diamine (PMDA-PDA)] have been studied by x-ray photoelectron spectroscopy. Emergent etherlike functionalities on polyimides without innate ether groups suggest a copper-induced partial reduction of carbonyl groups. A surface behavior diagram of the carbon chemistry confirms this reaction by indicating a partial conversion of carbonyl moieties to etherlike moieties.