New copper(II) complexes of polyampholyte and polyelectrolyte polymers: Solid-state NMR, FTIR, XRPD and thermal analyses

Novel solid copper(II) complexes were obtained from the polyampholyte poly(EGDE-MAA-IM) and the polyelectrolyte poly(EGDE-MAA) polymers with copper salts at different concentration levels.The materials were characterized employing solid-state Nuclear Magnetic Resonance (NMR), Fourier Transform infrared (FTIR), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) and thermogravimetry (TG).The reticulation induced by MAA in these materials against the poly(EGDE-IM) gel was analyzed by DSC. The coordination behavior of the carboxylic acid of MAA, compared to that provided by the imidazole ring, was studied through solid-state 13C NMR and changes in the FTIR spectra. The non-homogenous character of the doped and undoped materials was analyzed by the glass transition temperature (Tg), 2D 1H-13C WISE NMR and proton spin-lattice relaxation time in the rotating frame (TH1ρ). In particular, the TH1ρ and TH1 values in the complexes decreased with the Cu(II) concentration, showing the high sensitivity of both parameters to the presence of a paramagnetic ion. Finally, the thermogravimetric studies indicated that the presence of the imidazole ring was decisive for the stability of the Cu(II) complexes and for the undoped polymers.