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Molecular mobility in halogen‐containing side‐chain liquid‐crystalline polymers studied by dielectric spectroscopy
Author(s) -
Georgoussis George,
Nikonorova Natalia A,
Barmatov Eugeniy B,
Pissis Polycarpos
Publication year - 2000
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/1097-0126(200009)49:9<975::aid-pi414>3.0.co;2-i
Subject(s) - thermotropic crystal , materials science , relaxation (psychology) , polymer , dielectric , side chain , cooperativity , arrhenius equation , dielectric spectroscopy , polymer chemistry , chemistry , activation energy , liquid crystalline , composite material , psychology , social psychology , biochemistry , optoelectronics , electrode , electrochemistry
Molecular mobility in polymethacrylate‐based thermotropic side‐chain liquid‐crystalline polymers (SCLCPs) of the chemical structure CH 2 C(CH 3 )COO(CH 2 ) 5 COOC 6 H 4 OOCC 6 H 4 X (where X = F, Cl, Br, I) has been investigated by means of broadband dielectric relaxation spectroscopy (DRS, 10 −2 –10 6 Hz) and thermally stimulated depolarization current (TSDC; −180 to 30 °C) techniques. The α process, with a significant contribution being provided by the segmental main‐chain motions, has been studied in detail. The temperature dependence of the relaxation rate of the α process shows a crossover at a characteristic temperature T c from the Arrhenius type at high temperatures to the Vogel–Tammann–Fulcher–Hesse type at lower temperatures. The magnitude and the shape of the α relaxation show characteristic changes in the liquid‐crystalline phases, in particular close to T c . These results are discussed in the framework of cooperativity and of the influence of the liquid‐crystalline layers. © 2000 Society of Chemical Industry