Effects of nematic coupling on the phase behaviour of nematogen mixtures

The phase behaviour of binary nematogen mixtures of side‐chain liquid crystal crosslinked polymers and low molecular weight liquid crystals is investigated with particular emphasis on the effects of nematic coupling. The cross nematic quadrupole parameter ν12 is assumed to be proportional to the geo...

Full description

Saved in:
Bibliographic Details
Published in:Polymer international 2001-04, Vol.50 (4), p.469-474
Main Authors: Benmouna, Farida, Maschke, Ulrich, Coqueret, Xavier, Benmouna, Mustapha
Format: Article
Language:English
Subjects:
Applied sciences
binary nematogen mixtures
crosslinking
Exact sciences and technology
interaction parameter
low molecular weight liquid crystal
nematic coupling
Organic polymers
Physicochemistry of polymers
Properties and characterization
side-chain liquid crystal polymer
Thermal and thermodynamic properties
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The phase behaviour of binary nematogen mixtures of side‐chain liquid crystal crosslinked polymers and low molecular weight liquid crystals is investigated with particular emphasis on the effects of nematic coupling. The cross nematic quadrupole parameter ν12 is assumed to be proportional to the geometric average of ν11 and ν22 characteristic of single nematogens. In the weak coupling limit, the proportionality constant is lower than 1, and the phase diagram exhibits a reduced miscibility of the nematogens. In the case of strong coupling, the proportionality constant exceeds 1 resulting in higher miscibility. This is characterized by a nematic order that extends to temperatures above the upper nematic–isotropic transition temperature. A wide region of miscibility emerges showing a single nematic phase. Nematogens having similar nematic–isotropic transition temperatures exhibit different phase properties from systems with widely separated transition temperatures. Effects of the polymer volume fraction at crosslinking, rubber elasticity parameters of the network, and the Flory–Huggins interaction parameter on the equilibrium phase diagram of these systems are discussed. © 2001 Society of Chemical Industry
ISSN:0959-8103
1097-0126
DOI:10.1002/pi.659