Glassy dynamics of rod-like liquid crystals: the influence of molecular structure

Abstract

discussed. The linearized derivative-based analysis of data made it possible to 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. Despite decades of studies the complex dynamics of vitrifying liquids remains a puzzling phenomenon. Hence, studies in experimental model-systems which made it possible to reduce the complexity associated with canonical glass formers, namely low molecular supercooled liquids and polymers, may be of particular importance. This idea has proved its significance in studies on colloidal liquids 4 , enabling strong restrictions of orientational degrees of freedom or on orientationally disordered glassy crystals (ODIC) where the translational freezing is coupled to the orientational disorder. To the category of mesophases. of hard ellipsoids of revolution, which mime rod-like nematic liquid crystals (NLC), pointed out several significant model-features of such systems, namely subsequent orientational and translational freezing. 9,10 These feature obtained crystalline n-octylcyanobiphenyl (8CB) and n-octyloxycyanobiphenyl (8OCB) is identify dynamic crossovers linked to different Vogel-Fulcher-Tammann (VFT) 1-3 5-8 9-13 heterogeneities in the fluidlike (isotropic) surrounding, (iii) the unique appearance of two mode coupling, ergodic-non-ergodic crossovers, linked to GLASSY DYNAMICS OF ROD-LIKE LIQUID CRYSTALS: The mode-coupling theory (MCT) analysis of a fluid composed Abstract. The evolution of dielectric relaxation times in rod-like liquid experimental model-systems can be encountered rod-like compounds which on cooling usually firstly freeze in partially ordered liquid crystalline (i) the glassy dynamics in the isotropic phase, (ii) the significance of ordered S.