Molecular Crystals and Liquid Crystals, Vol.409, 401-408, 2004
Correlation between order parameter of liquid crystal mixture and dichroic ratio of its guest-host system
Good correlation was found between the order parameter S of liquid crystal, (LC) host-mixture and the dichroic ratio of its guest-host system. We investigated temperature dependence of the S value of several LC substances, focusing on its index beta. The index beta was determined by measuring the temperature dependence of refractive index. LC substances with a cyano terminal group have smaller beta values than those with an alkoxy or a fluoro-substituted terminal. This means that the S value is expected to be larger for the cyano substances than the alkoxy or fluoro substances at a fixed reduced-temperature. There exists good correlation between the calculated S value of a host LC mixture and the measured dichroic ratio of its guest-host system. This enables us to design highly ordered LC mixtures for high contrast guest-host LC displays based on beta values of LC substances.