Trahasch, B. ; Frey, H. ; Lorenz, K. ; Stühn, B. (1999)
Dielectric relaxation in carbosilane dendrimers with cyanobiphenyl end groups.
In: Colloid and Polymer Science, 277 (12)
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
Carbosilane dendrimers of generation 1 and 2 are functionalized with mesogenic end groups (cyanobiphenyl) via spacers of 5 and 11 carbons. The dielectric relaxation is measured over broad frequency (1 Hz-l GHz) and temperature (170-470 K) ranges. Two relaxation regimes are observed and characterized as delta and beta relaxation. The delta relaxation is nearly a single Debye process and varies strongly with temperature. The SE to SA transition observed for the dendrimers with long spacers causes a jump in the relaxation rate of the delta process. The beta process displays an Arrhenius-type temperature dependence with an activation energy of 35 kJ/mol. The relaxation time depends on spacer length. The dielectric relaxation reflects the mutual distortion of the dendrimer scaffold and the smectic layers.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 1999 |
| Autor(en): | Trahasch, B. ; Frey, H. ; Lorenz, K. ; Stühn, B. |
| Art des Eintrags: | Bibliographie |
| Titel: | Dielectric relaxation in carbosilane dendrimers with cyanobiphenyl end groups |
| Sprache: | Englisch |
| Publikationsjahr: | Dezember 1999 |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Colloid and Polymer Science |
| Jahrgang/Volume einer Zeitschrift: | 277 |
| (Heft-)Nummer: | 12 |
| Kurzbeschreibung (Abstract): | Carbosilane dendrimers of generation 1 and 2 are functionalized with mesogenic end groups (cyanobiphenyl) via spacers of 5 and 11 carbons. The dielectric relaxation is measured over broad frequency (1 Hz-l GHz) and temperature (170-470 K) ranges. Two relaxation regimes are observed and characterized as delta and beta relaxation. The delta relaxation is nearly a single Debye process and varies strongly with temperature. The SE to SA transition observed for the dendrimers with long spacers causes a jump in the relaxation rate of the delta process. The beta process displays an Arrhenius-type temperature dependence with an activation energy of 35 kJ/mol. The relaxation time depends on spacer length. The dielectric relaxation reflects the mutual distortion of the dendrimer scaffold and the smectic layers. |
| Fachbereich(e)/-gebiet(e): | 05 Fachbereich Physik > Institut für Festkörperphysik (2021 umbenannt in Institut für Physik Kondensierter Materie (IPKM)) 05 Fachbereich Physik |
| Hinterlegungsdatum: | 27 Feb 2010 13:01 |
| Letzte Änderung: | 05 Mär 2013 09:32 |
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