GLASSY DYNAMICS OF ROD-LIKE LIQUID CRYSTALS: THE INFLUENCE OF MOLECULAR STRUCTURE

摘要

The evolution of dielectric relaxation times in rod-like liquid crystalline n-octylcyanobiphenyl (8CB) and n-octyloxycyanobiphenyl (8OCB) is discussed. The linearized derivative-based analysis of data made it possible to identify dynamic crossovers linked to different Vogel-Fulcher-Tammann (VFT) equations. It is noteworthy that in the isotropic phase the dynamics can also be well portrayed by the critical-like relation but within the mode-coupling theory (MCT) for 8CB and the dynamical scaling model (DSM) for 8OCB. For both compounds the evolution of relaxation times in the Smectic A phase seems to follow the DSM description. Results obtained clearly indicate the dominant influence of heterogeneities on glassy dynamics in both liquid crystalline compounds.