Publication Title

Physical Review E

Publication Date

11-23-2004

Document Type

Article

DOI

10.1103/PhysRevE.70.051706

Keywords

short-range order, disodium-Cromoglycate, light-scattering, orientational order, water-systems, na-23 Nmr, Lyomesophases, spectroscopy, Mesophases, resonance

Disciplines

Physics

Abstract

We have studied isotropic-to-nematic pretransitional fluctuations in an aqueous solution of disodium cromoglycate (cromolyn) by static and dynamic light scattering. Cromolyn is a representative of lyotropic chromonic liquid crystals with building units being elongated rods formed by aggregates of disk-like molecules. By combining light-scattering and viscosity measurements we have determined the correlation length and relaxation time of the orientational order-parameter fluctuations and estimated the size of the cromolyn aggregates. The pretransitional behavior of light scattering does not completely follow the classic Landau-de Gennes model. This feature is most probably associated with the variable length of cromolyn aggregates. We have observed a dramatic increase of the shear viscosity near the transition to the nematic phase, the fact which correlates with the idea of growing supramolecular aggregates. The steep temperature dependence of the viscosity is accompanied by a practically temperature-independent translational diffusion coefficient.

Comments

Copyright 2004 American Physical Society. Available on publisher's site at http://dx.doi.org/10.1103/PhysRevE.70.051706


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