On the appearance of the antiferroelectric phase

Abstract

As the origin of the appearance of the antiferroelectric phase, the importance of dimerization of molecules in adjacent layers is pointed out on the bases of some experimental results. In thermotropic main chain polymer liquid crystals, the appearance of the antiferroelectric molecular orientation shows the odd-even effect concerning the number of spacer methylene unit. The same kind of odd-even effect was observed in low molecular weight liquid crystals, when the number of carbon atom, n, in chiral end is changed; the antiferroelectric phase tends to appear when n is even. The phase diagram in enamtiomeric mixtures of an antiferroelectric liquid crystal and the layer thicknesses in these mixtures also suggest the pairng of the molecules. The image of a scanning tunnelling microscope is also shown; the core parts of molecules align in a zigzag fashion.