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

Citation
S. Zhukov et al., Dielectric and IR spectroscopy of the macromolecular reaction of anhydridization in a functionalized side-chain liquid crystalline copolymer containing acrylic acid groups, MACROMOLEC, 34(11), 2001, pp. 3615-3625
Citations number
53
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
MACROMOLECULES
ISSN journal
00249297 → ACNP
Volume
34
Issue
11
Year of publication
2001
Pages
3615 - 3625
Database
ISI
SICI code
0024-9297(20010522)34:11<3615:DAISOT>2.0.ZU;2-W
Abstract
The anhydrization reaction has been investigated in functionalized side-cha in random liquid crystalline (LC) copolymers containing cyanobiphenyl mesog enic 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 inte rmolecular anhydrides and network structures causing an increase of the gla ss transition and clearing temperatures. The influence of annealing on the reorientational dynamics of the copolymers was investigated by broad-band d ielectric relaxation spectroscopy. The local dynamics of the side group inv olving spacer motion (gamma relaxation) and mesogen rotation about the long axis (beta relaxation) do not depend on the annealing time. At the same ti me a considerable (more than 2 orders of magnitude) decrease in the relaxat ion rates of the cooperative delta and alpha processes was observed due to a gradual increase in the main-chain rigidity during the annealing. The mol ecular mechanism of all relaxation processes detected is discussed.