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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]

Broadband dielectricspectroscopy (BDS) is employed to study themolecular dynamics of hydroxyl- (OH-) and amino- (NH2-)terminated polypropylene glycols (PPGs) of varying molecular weight.Besides the dynamic glass transition (α relaxation), a normalmode process and a secondary γ-relaxation is observed, the latterbeing assigned to librational fluctuations of the polar COC moiety.Additionally a further process is found and proven in two independentexperiments (annealing PPGs at high temperatures and physical aging)to originate from residual H2O impurities in the sampleand is therefore not related to the dynamics of PPG. It is occasionally,albeit incorrectly, discussed in the literature as Johari–Goldsten(JG) relaxation.Furthermore, aging in the systems under study is analyzed and foundto follow the Nagel–Leheny equation. [ABSTRACT FROM AUTHOR]

We examined the behavior of poly(mercaptopropyl)methylsiloxane (PMMS), characterized by a polymer chain backbone of alternate silicon and oxygen atoms substituted by a polar pendant group able to form hydrogen bonds (-SH moiety), by means of infrared (FTIR) and dielectric (BDS) spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and rheology. We observed that the examined PMMS forms relatively efficient hydrogen bonds leading to the association of chains in the form of ordered lamellar-like hydrogen-bonded nanodomains. Moreover, the recorded mechanical and dielectric spectra revealed the presence of two relaxation processes. A direct comparison of collected data and relaxation times extracted from two experimental techniques, BDS and rheology, indicates that they monitor different types of the mobility of PMMS macromolecules. Our mechanical measurements revealed the presence of Rouse modes connected to the chain dynamics (slow process) and segmental relaxation (a faster process), whereas in the dielectric loss spectra we observed two relaxation processes related most likely to either the association-dissociation phenomenon within lamellar-like self-assemblies or the sub-Rouse mode (α'-slower process) and segmental (α-faster process) dynamics. Data presented herein allow a better understanding of the peculiar dynamical properties of polysiloxanes and associating polymers having strongly polar pendant moieties., Competing Interests: The authors declare no competing financial interest., (© 2020 American Chemical Society.)