ORIENTATIONAL ORDERING IN MELTS OF CONFOR MATIONALLY LABILE MESOGENS

A simple model of a homogeneous melt of anisotropically interacting di mers (thermotropic system) with rotation-isomeric mechanism of flexibi lity was considered, For such systems; a theory of liquid-crystalline ordering was developed within the framework of the Maier-Saupe approxi mation and numerical calculations of phase characteristics were carrie d out, When two discrete conformations are allowed (extended, with a v alence angle pi, and folded, with a valence angle pi - alpha, alpha no t equal 0), undercooling of the extended isomers takes place in the is otropic phase, When the liquid-crystalline state is formed, because of the conformational lability of the system, redistribution in favor of mon extended conformations takes place, and the jumpwise variation of the order parameter that accompanies the phase transition increases i n comparison with that in nonlabile systems.