Chemical structures of the ferroelectric LCE, comprised of a siloxane polymer backbone, (left), a chiral mesogen,(top), and the crosslinker molecule, (bottom).

The LCE is assembled in a stepwise manner, first the biphenol LC component is attached to the siloxane polymer, next the chiral component is connected to the mesogen, and finally, the crosslinker molecule is attached. To form the LCE, the film is photo-crosslinked

ref:Martin Rößle: Synthese von flüssigkristallinen Polysiloxanen und Charakterisierung der smektischen Phasen. 2004 dissertation

Smectic ferroelectric LCE

The LC polymer is built up in a multi-step process. First the mesogen is covalently connected to the siloxane polymer through the double bond on the mesogen.(S1) Next, the chiral molecule is attached to the end of the mesogen(S2). The crosslinker is then attached to mesogen moeities that do not have chiral tail (S3). Finally a small amount of pentene react with any Si-H groups on the polymer that remain unreacted with mesogen.

1. mesogen connected to siloxane polymer

   Siloxane polymer with mesogen covalently linked

2. siloxane polymer | mesogen with either chiral molecule or acrylate crosslinker molecule
Nitrobenzoate derivative chiral molecule

(click on name to see the chemical structure)
The LCE may be prepared using different variants of the chiral mesogen: a nitroxy-benzoate derivative or a chloro-alkane derivative, with procedures for preparing a two chiral mesogens. The choro-alkane is commercially available from TCI America CAS# [32653-34-2]. Likewise, either of the two crosslinker molecules crosslinker molecules may be used to prepare the film.

For more information on how different chemical constituent influence the material properties, please go to the Zentel section of the online references, and refer to the year 2000 Macromolecules articles.