The importance of the electric interaction for stabilizing the antiferroelectric smectic liquid-crystalline phase

The importance of the interlayer molecular interaction to stabilize the antiferroelectric smectic C A * (S * C A ) phase is shown using dimer molecules in which chiral mesogenic units are connected by a polymethylene chain. According to the conformational effect of the polymethylene chain, two mesogenic units tend to align parallel or anticlinically for even or odd carbon number, respectively. In a dimer molecule with a longer chain length, however, another interaction overcomes the conformational effect and stabilizes the S * C A phase. This observation suggests the importance of the electric, possibly the dipole-dipole, interaction between mesogens in S * C A .