COPPER-ION BINDING TO N-PHENYLPHTHALAMIC ACID STUDIED BY C-13 NUCLEAR-MAGNETIC-RESONANCE AND ELECTRON-PARAMAGNETIC-RESONANCE - MODEL INTERACTION OF POLYAMIC ACID WITH COPPER

The interaction of copper with N-phenylphthalamic acid (PPA) cured at various temperatures was investigated by C-13 NMR and EPR spectroscopi es, as the model system of polyamic acid on copper. EPR spectra prove that copper is dissolved into the PPA-N-methylpyrrolidone solution, pr oducing paramagnetic Cu2+ ions. The C-13 NMR resonances of the phthali c group of PPA are selectively broadened due to the paramagnetic inter action between the C-13 nuclei and Cu2+ ions, showing binding of Cu2to the carboxylate group. Cu2+ ion has no effect on the amide and phen yl groups. Cu2+ ion exchanges rapidly between the carboxylate groups a t an exchange rate > 10(3) s(-1) at 23 degrees C. PPA is imidized to N -phenylphthalimide (PPI) at 150 degrees C; accompanied by the dissocia tion of Cu2+. Paramagnetic effects from the Cu2+ ions is not exerted o n PPI. The results obtained are compared with the interfacial interact ion between polyamic acid and copper.