Dynamic Glass Transition and Electrical ConductivityBehavior Dominated by Proton Hopping Mechanism Studied in the Familyof Hyperbranched Bis-MPA Polyesters.

Dielectric and infrared spectroscopieswere employed to study inter-and intramolecular glass-transition dynamics in the series of hyperbranchedpolyesters of the second, third, and fourth generations. Our studyshows that conductivity relaxation becomes increasingly faster thanstructural relaxation as the glass transition temperature Tgis approached, signifying decoupling betweentranslational motions of charges and reorientation of molecules. Dependingon the polymer’s generation conductivity relaxation times canbe up to few orders of magnitude faster than structural dynamics.Because of extensive hydrogen bonding network, the most significantcontribution to the total ionic conductivity comes from proton transferalong hydrogen bonds. Decoupling phenomenon was accompanied by narrowingthe dispersion of the conductivity relaxation with decreasing temperaturethat reaches almost exponential decay in the glassy state. Finally,by analyzing the absorption spectra in terms of integral intensity,we have demonstrated significant role of H-bonded moieties in thecourse of vitrification of investigated materials. [ABSTRACT FROM AUTHOR]