Perex
Abstrakt:
Text
The list of required parameters for ferroelectric multicomponent
mixtures suitable for applications is long. Properties such as: low
melting temperature, low viscosity and broad temperature range of liquid
crystalline phase existence as well as parameters important for
electrooptic modes like tilt angle or helical pitch can be easily
optimized. However preparation of multicomponent mixture should be
preceded by miscibility studies in bicomponent systems, in order to
select appropriate components. The compounds used for preparation of
application mixture can differ in phase sequence and it is not necessary
that all of them form ferroelectric phase or even liquid crystalline one
[1, 2]. The most favourable are mixtures formed by optimization of
eutectic composition. In order to prepare multicomponent mixture
non-chiral compounds can also be used [3].
The aim of this work was to check how the structure of dopants
(from non-chiral pyrimidines and terphenyls through chiral biphenyls to
chiral quterphenyls) and their amount influence the phase situation and
helical pitch of ferroelectric phase in binary mixtures. As base
compounds three ring esters 6F2OBi and 1H6Bi(3F), differing in the type
of terminal non-chiral chain and substitution in rigid core, were
selected. Base compounds differ also in the dependence of helical pitch
upon temperature: 6F2OBi forms only right-handed helix whereas 1H6Bi(3F)
forms both left- and right-handed helix. Results of miscibility and
helical pitch studies will be presented.
[1] K. Kurp, M. Czerwiński, M. Tykarska, Liquid Crystals 42, 248 (2015)
[2] A. Bubnov, M. Tykarska, V. Hamplova, K. Kurp, Phase Transitions
2016; DOI:10.1080/01411594.2015.1087523
[3] K. Kurp, M. Tykarska, Liquid Crystals 43, 1359 (2016)
This work was supported by the COST Action IC1208.