Eur. Phys. J. E 2, 303-309
The effect of a polymer network on smectic phase structure as probed by polarization measurements on a ferroelectric liquid crystal
I. Dierking - M.A. Osipov - S.T. Lagerwall
Department of Physics, Division of Microelectronics and
Nanoscience, Chalmers University of Technology, S-41296 Göteborg,
Sweden
dierking@hrz2.hrz.tu-darmstadt.de
Received 27 September 1999 and Received in final form 14 January 2000
Abstract
We have studied the effect of a polymer network, formed from an
achiral monomer in a chiral SmC* and SmA* liquid crystal by
measuring the resulting changes in the temperature dependence of
the spontaneous polarization. When the polymerization is performed
well into the SmC* phase, an increase of the spontaneous
polarization with respect to the original values of the liquid
crystal mixture is observed in the vicinity of the SmC*-SmA*
transition for increasing polymer concentration. When the
polymerization is carried out in the SmA* phase, the polarization
at the corresponding reduced temperatures is decreased. This
behaviour is due to a local stabilization of the respective phase,
in which the polymerization is carried out, caused by the elastic
interaction of the polymer network with the liquid crystal. In the
network-dominated regions the average tilt angle is approximately
preserved after a transition to another phase (SmA* or SmC*) and
this effect accounts for the corresponding change in polarization
observed in the experiment. The results are interpreted in a simple
semi-phenomenological description based on the effective
stabilizing potential of the quadrupole symmetry.
PACS
61.30.-v Liquid crystals
- 77.80.-e Ferroelectricity and antiferroelectricity
- 61.41.+e Polymers, elastomers, and plastics
Copyright EDP Sciences, Società Italiana di Fisica, Springer-Verlag
