The pretransitional equilibrium properties of isotropic liquids in the proximity of the isotropic-nematic phase transition are well known and successfully modeled. Much less is known about the dynamic behavior, and in particular about the pretransitional viscosity. In this work we combine two techniques [dynamic light scattering (DLS) and electric birefringence spectroscopy (EBS)] offering complementary insights into both static and dynamic pretransitional behavior of the homologous nCB family (n-alkyl cyanobiphenyl). EBS explores the single molecule flipping dynamics retarded by a paranematic potential barrier and enables extracting the associated transport coefficient, which is found to be of Arrhenius type in the whole temperature range explored. DLS reflects the collective dynamics of correlated domains and depends on the viscous damping of the orientational order. Such a viscosity displays Arrhenius behavior only sufficiently far from the transition temperature, with deviations growing as a power law of the appropriate reduced temperature with exponents around 0.1

Jimenez, M., Mantegazza, F., Gallazzi, L., Zanchetta, G., Bellini, T. (2006). Optical and electro-optical derivation of the pretransitional behavior of orientational and shear viscosities in the isotropic phase of liquid crystals. PHYSICAL REVIEW E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS, 74(1), 011707.1-011707.10 [10.1103/PhysRevE.74.011707].

Optical and electro-optical derivation of the pretransitional behavior of orientational and shear viscosities in the isotropic phase of liquid crystals

MANTEGAZZA, FRANCESCO;
2006

Abstract

The pretransitional equilibrium properties of isotropic liquids in the proximity of the isotropic-nematic phase transition are well known and successfully modeled. Much less is known about the dynamic behavior, and in particular about the pretransitional viscosity. In this work we combine two techniques [dynamic light scattering (DLS) and electric birefringence spectroscopy (EBS)] offering complementary insights into both static and dynamic pretransitional behavior of the homologous nCB family (n-alkyl cyanobiphenyl). EBS explores the single molecule flipping dynamics retarded by a paranematic potential barrier and enables extracting the associated transport coefficient, which is found to be of Arrhenius type in the whole temperature range explored. DLS reflects the collective dynamics of correlated domains and depends on the viscous damping of the orientational order. Such a viscosity displays Arrhenius behavior only sufficiently far from the transition temperature, with deviations growing as a power law of the appropriate reduced temperature with exponents around 0.1
Articolo in rivista - Articolo scientifico
liquid crystals
English
lug-2006
74
1
011707.1
011707.10
011707
none
Jimenez, M., Mantegazza, F., Gallazzi, L., Zanchetta, G., Bellini, T. (2006). Optical and electro-optical derivation of the pretransitional behavior of orientational and shear viscosities in the isotropic phase of liquid crystals. PHYSICAL REVIEW E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS, 74(1), 011707.1-011707.10 [10.1103/PhysRevE.74.011707].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/1705
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