Effect of Chirality on Physical Properties

As noted earlier, the incorporation of chiral groups in the liquid crystal moieties can have the effect of inducing non-linear properties, which include thermochromism, ferroelectricity, antiferroelectricity, electrostriction, and flexoelectricity. In a now classical study, Hult [82] demonstrated that it was possible for supermolecular material 34 to exhibit two-state ferroelectric switching. The remarkable material he investigated, shown in Fig. 30, was found to exhibit two hitherto unclassified mesophases between the smectic 

A phase and the smectic C phase. At a temperature of 105 °c, just in the smectic C phase, ferroelectric switching was achieved with a tilt angle of 26°. The mesogenic units were based upon the famous MHPOBC ferroelectric material which had a switch angle of approximately 25°. Thus this result demonstrated that the dendrimer is really acting as a collection of low-molar-mass liquid crystals. 

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