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Molecular Mobility and Ionic Conductivity of Ionic Liquid Crystals Forming a Hexagonal Columnar Mesophase

  • For the first time, the molecular mobility of two linear-shaped tetramethylated guanidinium triflates ionic liquid crystals (ILCs) having different length of alkyl chains was investigated by a combination of broadband dielectric spectroscopy (BDS) and specific heat spectroscopy (SHS). By self-assembly, these ILCs can form a hexagonal ordered mesophase besides plastic crystalline phases and the isotropic state. SHS was carried out by differential AC-chip calorimetry at higher frequencies and temperature modulated DSC at lower frequencies. Two relaxation processes were found by BDS for both samples. At low temperatures, a γ-processes is observed which is assigned to specific localized fluctuations. At higher temperatures, α1-processes take place. α2 processes were also detected by SHS but with a completely different temperature dependence of the relaxation times. Different molecular assignments of α1- and α2-processes are suggested. At even higher temperatures, conductivity wasFor the first time, the molecular mobility of two linear-shaped tetramethylated guanidinium triflates ionic liquid crystals (ILCs) having different length of alkyl chains was investigated by a combination of broadband dielectric spectroscopy (BDS) and specific heat spectroscopy (SHS). By self-assembly, these ILCs can form a hexagonal ordered mesophase besides plastic crystalline phases and the isotropic state. SHS was carried out by differential AC-chip calorimetry at higher frequencies and temperature modulated DSC at lower frequencies. Two relaxation processes were found by BDS for both samples. At low temperatures, a γ-processes is observed which is assigned to specific localized fluctuations. At higher temperatures, α1-processes take place. α2 processes were also detected by SHS but with a completely different temperature dependence of the relaxation times. Different molecular assignments of α1- and α2-processes are suggested. At even higher temperatures, conductivity was detected by BDS. An increase in the DC conductivity by four orders of magnitude at the phase transition from the plastic crystalline to the hexagonal columnar mesophase is found. This result is traced to a change in the charge transport mechanism from a delocalized electron hopping in the stacked aromatic systems (in the plastic phase) to one dominated by an ionic conduction in the quasi-1D ion channels formed along the supermolecular columns in the ILC hexagonal mesophases.zeige mehrzeige weniger

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  • Yildirim_Molecular Mobility and Ionic Conductivity of Ionic Liquid Crystals Forming a Hexagonal Columnar Mesophase_BDS 2018_Brussels_Publica.pdf
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Metadaten
Autor*innen:Arda Yildirim
Koautor*innen:Paulina Szymoniak, Kathrin Sentker, Patrick Huber, Andreas Schönhals
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2018
Organisationseinheit der BAM:6 Materialchemie
6 Materialchemie / 6.6 Physik und chemische Analytik der Polymere
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten
Freie Schlagwörter:Ionic Liquid Crystals
Themenfelder/Aktivitätsfelder der BAM:Material
Veranstaltung:10th Conference on Broadband Dielectric Spectroscopy and its Applications
Veranstaltungsort:Brussles, Belgium
Beginndatum der Veranstaltung:26.08.2018
Enddatum der Veranstaltung:31.08.2018
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:12.09.2018
Referierte Publikation:Nein
Eingeladener Vortrag:Nein
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