Growth laws for the phase ordering dynamics of the B1 phase of a bent-core liquid crystal.

Abstract

We have experimentally investigated the dynamics of the phase ordering process of bent-core molecules at isothermal conditions, forming the liquid crystalline "banana" B1 phase from the isotropic melt. In contrast to the fractal growth patterns observed for other "banana" liquid crystal phases, the B1 phase exhibits dendritic-like growth, which at short times shows similar growth structures as observed for conventional smectic bâtonnet growth. Analysis with respect to growth laws of the form L(t) approximately tn shows that the growth process follows the theoretically predicted Allen-Cahn dynamics with n=1/2 for zero difference in the free energy between the high- and the low-temperature phase, while the growth exponent approaches n-->1 for increasing supercooling. From the experimentally obtained data, we estimate the ratio between volume and curvature driven contributions to the phase ordering process as a function of supercooling and suggest a phenomenologically determined relationship of log DeltaF approximately DeltaT for the difference in free energy between the high- and the low-temperature phase as the quench depth is varied.