The even–odd effect in liquid crystals. A simple model

Abstract

We have developed a model of molecules composed of rigid segments and hydrocarbon chains which interact via van der Waals forces, and it has been used to study the even–odd effect in the nematic–isotropic transition in liquid crystals. Because it is mathematically simpler than other models which have examined this effect, analytical results can be obtained in a molecular field approximation. It shows explicitly the reasons for certain peculiarities observed and identifies the causes of the even–odd effect in the transition temperature and rigid segment order parameter. Finally, the transition temperatures calculated agree more closely with experiment than those obtained by other theories.