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Dielectric relaxation in carbosilane dendrimers with cyanobiphenyl end groups

Trahasch, B. and Frey, H. and Lorenz, K. and Stühn, B. (1999):
Dielectric relaxation in carbosilane dendrimers with cyanobiphenyl end groups.
277, In: Colloid and Polymer Science, (12), pp. 1186-1192, [Article]

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.

Item Type: Article
Erschienen: 1999
Creators: Trahasch, B. and Frey, H. and Lorenz, K. and Stühn, B.
Title: Dielectric relaxation in carbosilane dendrimers with cyanobiphenyl end groups
Language: English
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.

Journal or Publication Title: Colloid and Polymer Science
Volume: 277
Number: 12
Divisions: 05 Department of Physics > Institute for condensed matter physics
05 Department of Physics
Date Deposited: 27 Feb 2010 13:01
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