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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 19: Glasses and Glass Transition 1 (joint session DY/CPP)

CPP 19.2: Talk

Wednesday, March 24, 2021, 09:50–10:10, DYc

Glassy dynamics, glass transition and electrical conductivity of Guanidinium based ILCs: Influence of the cation headgroup configuration — •Mohamed A Kolmangadi, Arda Yildirim, and Andreas Schönhals — Bundesantalt für Materialforschung und -prüfung (BAM), Berlin, Germany

Molecular mobility and conductivity of four bent shaped tetramethylated guanidinium based ionic liquid crystals (ILCs) with varying head group configuration (cyclic or acyclic) and alkyl chain length is investigated by a combination of broadband dielectric spectroscopy (BDS) and specific heat spectroscopy (SHS). BDS investigation reveals two relaxation processes: a localized γ process and α1 process corresponding to the glassy dynamics. SHS investigations show one calorimetrically active α2 relaxation process also corresponding to the glassy dynamics of the system. The temperature dependencies of the relaxation rates of two different glassy dynamics are similar for the cyclic ILC while for the acyclic counterpart they are different. Possible molecular assignments for the α1 and α2 relaxation are discussed in detail. Alongside relaxation processes, a significant conductivity contribution was observed for all ILCs, where the absolute value of DC conductivity increases by 4 orders of magnitude at the transition from the crystalline to the hexagonal columnar phase. The increase is traced to the change in the underlying conduction mechanism from the delocalized electrical conduction in the Cry phase to ionic conduction in the quasi 1D ion columns formed in the hexagonal columnar mesophase.