VIBRATIONAL SPECTROSCOPIC CHARACTERIZATION OF PROTONIC CONDUCTING POLYETHYLENEIMINE-ALPHA-ZIRCONIUM AND GAMMA-ZIRCONIUM PHOSPHATE NANOCOMPOSITES

New hybrid inorganic-organic nanocomposite systems have been obtained by intercalation of polyethyleneimine (PEI, 5 x 10(4) Da) into alpha- and gamma-structured zirconium phosphates. The composites can be formu lated as alpha-Zr(HPO4)(2) . 2.7(PEI). 1.8H(2)O and gamma-Zr(PO4)(H2PO 4). 1.03(PEI). 3.3H(2)O, when dried at room temperature and 75% RH. Th e corresponding interlayer distances are 2.0 and 2.5 nm, respectively. The ac conductivity of the gamma-nanocomposite at 100 degrees C and 8 2% RH, is significantly higher (2.6 x 10(-5) S/cm) than that of the al pha-intercalate (4.8 x 10(-7) S/cm). Vibrational spectroscopies (IR an d incoherent inelastic neutron scattering) have shown that increasing the temperature induces progressive proton transfer from the host laye r surfaces to the guest, with successive formation of protonated NH2and NH3+ groups (arising from secondary and primary amine groups respe ctively). Proton transfer is, however, more complete in alpha-ZrP-PEI.