ISSN:
0323-7648
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Glasses from cationic polyelectrolytes of the type “ionenes” are considered as being a new class of materials. Below their glass transition the quaternized ammonium groups in the polymer backbone are essentially static, due to their strong Coulomb interactions. At the glass transition temperature (Tg) the N+ cations become mobile. However, both the low molecular weight counterions and the organic chain segments linking the cations are already mobile below Tg. Therefore, in contrast to other polymers, the glass transition in ionenes is characterized by the relaxation of the cationic centers. Ionic conductivity in the glassy state is based on thermally activated anion transport. In this paper, the influence of the coordination of Mn2+ in the [MnBr4]2- -anions on the solid state properties is investigated by electron paramagnetic resonance (EPR) and by dielectric spectroscopy. The local structure of the magnetically active Mn2+ centers in the ionene glass is found to have a tetragonally distorted symmetry at low temperatures, which is transferred into Td symmetry of [MnBr4]2- via a distorted octahedral transition state [MnBr42--Br22-] gives rise to an additional dielectric relaxation and to an unusually high activation energy for the anion transport.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/actp.1994.010450318
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