Fabrication and characterization of polymer stabilized cholesteric liquid crystal cells with chiral monomers derived from borneol

Abstract

Polymer stabilized cholesteric texture (PSCT) liquid crystal cells were fabricated using the commercially available host liquid crystal ZLI‐2293/CB15 and functional monomers 4,4′‐bis[6‐(acryloyxy)hexyloxy]biphenyl (BAHB) and bornyl 4‐[4‐(6‐acryloyloxyhexyloxy)phenylazo] benzoate. Monomers synthesized in this investigation were identified using FTIR, ¹H NMR and elemental analysis. Optical properties of the PSCT cells were studied, including variations in the reflected band, the pitch, and the helical twisting power. The dependence of the variation of liquid crystal texture on UV irradiation, temperature, and voltage were estimated. A schematic molecular orientation of the cells was used to describe the phenomena obtained on application of a voltage. Due to the thick film gap, surface stabilization from the polymer matrixes on the substrates was found to be unable to fix the focal‐conic texture, even when the cell was slowly released from the applied field. The liquid crystal molecules returned to a planar texture in few seconds. The real images of reflected band colours, and the reversible changes between the turbid and transparent states corresponding to OFF (30 V) and ON (100 V) applied electric fields were evaluated.

Acknowledgements

The authors would like to thank the National Science Council (NSC) of the Republic of China (Taiwan) for financial support of this research under Contract No. NSC 92‐2216‐E006‐005.

Notes

^aAdded chiral monomer A6B.

^bBefore UV irradiation.

^cAfter UV irradiation.

^aAfter polymerization.

^bBefore UV irradiation.

^cAfter UV irradiation.