Pressure-Induced Reactivity in the Emeraldine Salt and Base Forms of Polyaniline Probed by FTIR and Raman
journal contributionposted on 26.11.2014 by Marcelo M. Nobrega, Matteo Ceppatelli, Marcia L. A. Temperini, Roberto Bini
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This report presents the influence of the morphology on the pressure-induced reactivity of the doped (PANI-ES) and dedoped (PANI-EB) forms of polyaniline using Raman and FTIR techniques. Our PANI-EB FTIR spectroscopy data showed an intensity exchange among characteristic bands of the quinoid and benzoic segments above 9 GPa, suggesting a specific coupling reaction between adjacent quinoid rings. The reaction kinetic was followed, and the results showed a dependence of the rate constant with pressure, as well as the activation volume, presented an inversion from negative to positive at 13 GPa, suggesting that steric factors have a role in the reactivity of the species. Raman spectra of PANI-ES showed a broadening and a blue shift of the bands as the pressure increases preceding the almost complete amorphization of the polymer; after decompression, some minor spectral changes were observed, suggesting the occurrence of the dedoping and cross-linking reactions in less extension than PANI-EB.