Electro‐optical cells using a cellulose derivative and cholesteric liquid crystals

Abstract

A cellulose derivative/liquid crystal composite‐type electro‐optical cell using a commercial cholesteric liquid crystal (CLC) was investigated. The electro‐optical properties of the system were examined, i.e. the dependence on applied voltage of the reflected wavelength and the minimum and maximum transmissions. A thin film of the CLC was dispersed with a cross‐linked cellulose film of 25 µm thickness. In the voltage dependence of the reflected wavelength it was verified that there is a hysteresis in the reflected wavelength. The variation of the reflected wavelength with temperature was also determined. The results are analysed in the framework of similar systems described in the literature for CLC dispersed in a polymer matrix.

Keywords:

• cellulose derivative
• cholesteric liquid crystal
• electro‐optical cell
• temperature effect
• pitch

Acknowledgements

This work was partly supported by projects POCTI/CTM/56382/2004 and by the Portuguese Science Foundation (FCT) through Pluriannual contracts with CENIMAT. S. Kundu thanks the Portuguese Science Foundation (FCT) for the granted fellowship SFRH/BPD/34096/2006.