Optical Properties of Polymer Stabilized Cholesteric Liquid Crystals

Polymer Stabilized Cholesteric Liquid Crystals (PSCLC) were prepared from homogeneous mixtures including various contents of a nematic liquid crystal (E7), a chiral dopant (R1011), a photoinitiator (Darocur 1173) and a difunctional acrylate monomer (HDDA). Helical pitch measurements were carried out on several chiral dopant/LC blends and compared to mixtures including monomer. Similar helical pitch values were found for samples with and without monomer. The electric field-induced diffraction gratings in the cholesteric liquid crystal phase were efficiently stabilized by polymerization of the monomer. Isothermal photocalorimetry measurements were performed to follow the photopolymerization process. The averaged acrylate double bond conversion is of the order of 72%. Preliminary results on the electro-optical properties of PSCLC samples are presented and briefly discussed.