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Dielectric Spectroscopy and Low Temperature Molecular Dynamics of Thermotropic Side‐Chain Polymethacrylates with Side Halogen Terminal Groups
Author(s) -
Nikonorova Natalia,
Borisova Tamara,
Shibaev Valeriy,
Barmatov Evgueni,
Georgoussis George,
Pissis Polycarpos
Publication year - 2001
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(20010501)202:8<1313::aid-macp1313>3.0.co;2-l
Subject(s) - thermotropic crystal , mesogen , chemistry , side chain , halogen , arrhenius plot , polymer chemistry , polymer , dielectric , relaxation (psychology) , glass transition , molecular dynamics , arrhenius equation , crystallography , materials science , activation energy , computational chemistry , organic chemistry , alkyl , psychology , social psychology , liquid crystalline , optoelectronics
Local forms of molecular mobility of LC side‐chain halogen‐containing polymers (P‐Hal) where Hal is F, Cl, Br, or J, with caproyloxyphenyl benzoate mesogenic groups were studied by dielectric relaxation spectroscopy (DRS) and by thermally stimulated depolarization currents (TSDC) techniques. For all halogen‐containing polymers investigated herein three relaxation ranges of dipole polarization were detected at temperatures below T g , β, γ 1 and γ 2 processes in the order of decreasing temperature. The molecular mechanisms of these processes correspond to the mesogen motion about the long axis, to the spacer motion, and to the mobility of the mesogen end part, respectively. For all P‐Hal, the kinetic characteristics for each of the β, γ 1 and γ 2 processes can be described by a single curve in the Arrhenius plot, log f max = φ (1/T). In other words, the local molecular mobility in the series P‐F, P‐Cl, P‐Br, and P‐J does not change with halogen type.