Experimental evidence of enhanced transport in supernematics

TL;DR

This study provides experimental and simulation evidence that reentrant nematic liquid crystals exhibit enhanced molecular mobility near phase transitions, revealing history-dependent high mobility states and clarifying ongoing debates.

Contribution

It offers the first combined experimental and simulation analysis of molecular dynamics in reentrant nematics, highlighting the occurrence of high mobility states and their dependence on thermal history.

Findings

Maximum in molecular mobility observed near reentrant nematic transition

High mobility states are history-dependent due to metastable mesophases

Experimental results support simulation findings on enhanced transport

Abstract

Deviations of molecular shapes from spherical symmetry may give rise to a variety of novel phenomena, including their dynamic behavior. It has recently been predicted [Mazza \textit{et al}. Phys. Rev. Lett. \textbf{105}, 227802 (2010)] that liquid crystals in the reentrant nematic phases may show unexpectedly high rates of translational displacements. Using broadband dielectric spectroscopy and a single-component thermotropic liquid crystal we explore molecular dynamics in the vicinity of the reentrant nematic transition and find the formation of a maximum in the mobilities upon changing temperature. The occurrence of the high mobility states are found to be history-dependent due to the formation of metastable mesophases on heating. The experimental results are further supported by computer simulation. Our results contribute to the clarification of an ongoing controversy on the dynamics of reentrant nematics.