Nonequilibrium nematic-isotropic interface

Abstract

Liquid crystals have been very fruitful systems to study equilibrium phase transitions. Recently, they have become an important system to study dynamics of rst-order phase transitions. The moving nonequilibrium nematic-isotropic interface is a model system to study growth of stable states into metastable states and displays a myriad of dynamical instabilities that, far from equilibrium, drive the system to a scenario of spatio-temporal chaos. We present a mean-eld theory for the time evolution of a planar nonequilibrium nematicisotropic interface for pure liquid crystals using a time dependent Ginzburg-Landau equation, which is one of the simplest approaches to dissipative dynamics. We obtain a theoretical expression for the growth kinetics of the nematic phase into a metastable isotropic phase and compare it with our experimental results. In a directional solidi cation arrangement we study instabilities of the nematic-isotropic interface of the liquid crystal 8CB doped with water and hexachloroethane. The observed instabilities are similar to cellular instabilities that appear during growth of crystal-melt interfaces of binary mixtures. We then compare our results with known theories of morphological instabilities during crystal growth.

Self-assembly via branching morphologies in nematic liquid-crystal nanocomposites

“…When coupled to the diffusive dynamics of NPs, this transition can lead to morphological instabilities of the phase boundary. Such instabilities have been reported during directional growth of pure and doped LC systems [4][5][6][7][8]. They are triggered by a diffusive instability of the thermal field or the impurities, respectively, which differ in their length and time scales.…”