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Ion and Chain Mobility in a Tetrazole Proton-Conducting Polymer

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journal contribution
posted on 03.04.2014, 00:00 by R. Casalini, B. L. Chaloux, C. M. Roland, H. L. Ricks-Laskoski
The morphology, relaxation properties, and conductivity of the statistical copolymer polystyrenic (alkoxy 1H-tetrazole-co-alkoxy nitrile), an anhydrous proton conductor, were measured. The material phase-separates into hard and soft domains, the latter corresponding to a phase richer in the pendant tetrazole groups. Using dielectric and mechanical spectroscopies, two relaxation processes were observed, the slower associated with local segmental dynamics of the backbone and the higher-frequency process involving motion of the tetrazole moieties. The latter is coupled to the ionic conductivity, which means that below the principal glass transition of the material (∼313 K) the conductive mechanism remains active. Thus, the usual compromise in proton exchange membranes between mechanical stability and ion conductivity can be avoided.