PA31 End chain length effect on the layer structure in bent-shaped dimer liquid crystals

Abstract

Layer structure of dimer liquid crystals having two mesogenic groups linked by an alkylene spacer was studied by the one and two dimensional x-ray measurement. Although it is reported that the structure changes from a single layer through a frustrated layer to bilayer with increasing the terminal chain length (Fig1), the transition from a frustrated layer to a bilayer have not been determined yet. The purpose of our study is to determine this transition. From one dimensional x-ray measurement, It is clearly found that the compounds with m=8 and 16 exhibit the frustrated-layer and bilayer smectic phases, respectively. In contrast the compounds with m=10〜14, the profiles suggest intermediate structure ; both the peaks corresponding to each structure are observed, and peak intensity for frustrated structure one. gradually decreases, and that for bilayer one increase with the increase of the end chain.