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Dielectric and IR spectroscopy of the macromolecular reaction of anhydridization in a functionalized side-chain liquid crystalline copolymer containing acrylic acid groups

Zhukov, S. ; Stühn, B. ; Borisova, T. ; Barmatov, E. ; Barmatova, M. ; Shibaev, V. ; Kremer, F. ; Pissis, P. (2001):
Dielectric and IR spectroscopy of the macromolecular reaction of anhydridization in a functionalized side-chain liquid crystalline copolymer containing acrylic acid groups.
In: Macromolecules, 34 (11), pp. 3615-3625. [Article]

Abstract

The anhydrization reaction has been investigated in functionalized side-chain random liquid crystalline (LC) copolymers containing cyanobiphenyl mesogenic and acrylic acid (38 mol %) groups. Heat treatment of the LC copolymer at 130 degreesC for 5-200 h is accompanied by formation of intra- and intermolecular anhydrides and network structures causing an increase of the glass transition and clearing temperatures. The influence of annealing on the reorientational dynamics of the copolymers was investigated by broad-band dielectric relaxation spectroscopy. The local dynamics of the side group involving spacer motion (gamma relaxation) and mesogen rotation about the long axis (beta relaxation) do not depend on the annealing time. At the same time a considerable (more than 2 orders of magnitude) decrease in the relaxation rates of the cooperative delta and alpha processes was observed due to a gradual increase in the main-chain rigidity during the annealing. The molecular mechanism of all relaxation processes detected is discussed.

Item Type: Article
Erschienen: 2001
Creators: Zhukov, S. ; Stühn, B. ; Borisova, T. ; Barmatov, E. ; Barmatova, M. ; Shibaev, V. ; Kremer, F. ; Pissis, P.
Title: Dielectric and IR spectroscopy of the macromolecular reaction of anhydridization in a functionalized side-chain liquid crystalline copolymer containing acrylic acid groups
Language: English
Abstract:

The anhydrization reaction has been investigated in functionalized side-chain random liquid crystalline (LC) copolymers containing cyanobiphenyl mesogenic and acrylic acid (38 mol %) groups. Heat treatment of the LC copolymer at 130 degreesC for 5-200 h is accompanied by formation of intra- and intermolecular anhydrides and network structures causing an increase of the glass transition and clearing temperatures. The influence of annealing on the reorientational dynamics of the copolymers was investigated by broad-band dielectric relaxation spectroscopy. The local dynamics of the side group involving spacer motion (gamma relaxation) and mesogen rotation about the long axis (beta relaxation) do not depend on the annealing time. At the same time a considerable (more than 2 orders of magnitude) decrease in the relaxation rates of the cooperative delta and alpha processes was observed due to a gradual increase in the main-chain rigidity during the annealing. The molecular mechanism of all relaxation processes detected is discussed.

Journal or Publication Title: Macromolecules
Volume of the journal: 34
Issue Number: 11
Divisions: 05 Department of Physics > Institute for condensed matter physics (2021 merged in Institute for Condensed Matter Physics)
05 Department of Physics
Date Deposited: 27 Feb 2010 13:15
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