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Suppressed Transition and Dynamic self-asembly of ionic superdiscs in cylindrical nanochannels

  • Liquid crystalline mesophases in nanoconfinement exhibit intriguing phase transition behaviors and relaxation dynamics. Here, we investigate the molecular mobility and electrical conductivity of a columnar ionic liquid crystal confined in self-ordered nanoporous alumina oxide membranes of pore size ranging from 180 nm down to 25 nm. We use nano-broadband dielectric spectroscopy (BDS) and calorimetry to study the dynamics and phase behavior. Calorimetric investigation reveals a complete suppression of the columnar – isotropic transition, while the plastic crystalline – columnar transition temperature decreases with inverse pore size and deviates from the Gibbs – Thomson equation. For the bulk case, BDS detects two relaxation modes in the crystalline phase, the γ relaxation and the α1 relaxation, and two relaxation modes in the columnar phase, the α2 and α3 relaxation. All relaxation modes slow down for the confined case compared to the bulk. However, a new relaxation mode reflectingLiquid crystalline mesophases in nanoconfinement exhibit intriguing phase transition behaviors and relaxation dynamics. Here, we investigate the molecular mobility and electrical conductivity of a columnar ionic liquid crystal confined in self-ordered nanoporous alumina oxide membranes of pore size ranging from 180 nm down to 25 nm. We use nano-broadband dielectric spectroscopy (BDS) and calorimetry to study the dynamics and phase behavior. Calorimetric investigation reveals a complete suppression of the columnar – isotropic transition, while the plastic crystalline – columnar transition temperature decreases with inverse pore size and deviates from the Gibbs – Thomson equation. For the bulk case, BDS detects two relaxation modes in the crystalline phase, the γ relaxation and the α1 relaxation, and two relaxation modes in the columnar phase, the α2 and α3 relaxation. All relaxation modes slow down for the confined case compared to the bulk. However, a new relaxation mode reflecting the interfacial layer emerges for the 80 and 25 nm. We discuss the possible molecular origins of the different relaxation modes observed. For the bulk ILC, a clear jump of 4 orders of magnitude in the absolute values of DC conductivity occurs at the transition from the plastic crystalline to hexagonal columnar phase, for the confined ILC, this transition is smooth. DC conductivity is reduced for the confined case, except for the 25nm, where the values are similar to the bulk.zeige mehrzeige weniger

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Metadaten
Autor*innen:Mohamed Aejaz Kolmangadi
Koautor*innen:Andreas Schönhals
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2023
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:Conductivity; Ionic Liquid crystals; Nanoconfinement
Themenfelder/Aktivitätsfelder der BAM:Material
Material / Nano
Veranstaltung:APS March Meeting 2023
Veranstaltungsort:Las Vegas, NV, USA
Beginndatum der Veranstaltung:05.03.2023
Enddatum der Veranstaltung:10.03.2023
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:20.04.2023
Referierte Publikation:Nein
Eingeladener Vortrag:Nein
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