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The Influence of External Electric Field on Local Orientations and Phase Transitions in Polymer Liquid Crystals (PLCs)
Author(s) -
Brostow Witold,
Hibner Kazimierz,
Walasek Janusz
Publication year - 2001
Publication title -
macromolecular theory and simulations
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 56
eISSN - 1521-3919
pISSN - 1022-1344
DOI - 10.1002/1521-3919(20010401)10:4<304::aid-mats304>3.0.co;2-e
Subject(s) - liquid crystal , mesogen , dipole , electric field , phase transition , condensed matter physics , chemical physics , polymer , phase (matter) , materials science , chemistry , liquid crystalline , physics , organic chemistry , quantum mechanics , composite material
The starting point is our previous study of influence of the internal molecular mean field of dipole‐dipole interactions on local orientation and phase transitions in polymer liquid crystal (PLC) systems of longitudinal chains. [1, 2] Electric dipoles are created by LC mesogen moieties. The longitudinal PLC is a macromolecule of consecutively copolymerized LC and flexible polymer sequences. We now amplify the model by inclusion of dipole‐external electric field interactions. We find that the external fields can seriously modify the local orientational order of the system and affect phase transition parameters dependent on that order. In particular, the external fields induce the formation of disoriented nematic phases with negative values of the second order orientation parameter 〈P 2 〉 for LC sequences in the longitudinal PLCs while the first order parameter 〈P 1 〉 is positive. However, some rapid decreases in 〈P 1 〉 are observed at points of positive‐to‐negative transitions of 〈P 2 〉; thus the LC disorientation manifests itself. The limiting case of the monomer liquid crystal (MLC) systems is included also.