Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 22: Poster: Charged Soft Matter

CPP 22.16: Poster

Mittwoch, 28. März 2012, 11:00–13:00, Poster A

Quasilinear electro-optic effect in ferroelectric polymer-dispersed nematic liquid crystals due to remanent polarization — •Lars Hollänedr, Werner Wirges, and Reimund Gerhard — Universität Potsdam, Institut für Physik und Astronomie, Potsdam

Polymer-dispersed liquid crystal (PDLC) films were prepared using ferroelectric poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) and nematic 4-cyano-4-n-hexylbiphenyl (6CB). Inside the composite material the liquid crystal 6CB was separated in discrete micrometer-sized droplets with nearly spherical shape. The transparency change due to an applied external electric field was measured for non-poled and poled samples.

Usually the change in transmittance of nematic PDLC-films depends only on the absolute value of the electric field and not on the polarity. But after the poling of the PDLC device the remanent polarization of the P(VDF-TrFE) creates an internal electric field, which acts as an offset. It is assumed that due to the internal field the preferred orientation of the nematic liquid crystal inside the droplets is changed from a radial to an axial one. This pre-alignment in field direction causes a quasilinear transmittance behavior as well as a general increase of transparency.