Phase Transition Isotropic Liquid-Nematic in Films with Two Free Surfaces

Abstract

The nematic layer growing from the isotropic liquid of a free suspended film has been investigated. The selected substances possess different dielectric anisotropy, molecular orientation of the interfaces, latent heat of the N-I phase transition, a kind of phase under the nematic. It is found that the nematic layers of the two interfaces nematic-air arise and grow at very slow cooling independently if the thickness of the free film is ≥8 μm. After the upper nematic layer of some substances reaches ∼5 μm thickness, the formation of drops begins under the layer on the interface nematic-isotropic liquid. For substances in which the molecules lie approximately in the interface N-I at the same experimental conditions the drops are not seen. It is found that the transition I-N does not depend on the kind of phase under the nematic if the nematic temperature region is not too small.