Multiscale dynamics of pretransitional fluctuations in the isotropic phase of a lyotropic liquid crystal

C. E. Bertrand, K. L. Linegar, A. F. Kostko, and M. A. Anisimov
Phys. Rev. E 79, 041704 – Published 29 April 2009

Abstract

Using an improved static and dynamic light-scattering technique, we have observed multiscale relaxation of the pretransitional fluctuations in the isotropic phase of a cromolyn aqueous solution, a lyotropic liquid crystal where rods are formed by aggregates of disklike molecules. We have detected the onset of cromolyn aggregation about 12°C above the transition temperature. The onset is manifested by the emergence of strong scattering due to the fluctuations of local anisotropy and by the split of the diffusion dynamics into two distinctly different modes, one associated with the relatively fast diffusion of monomer-size particles and the other one with the much slower diffusion of the cromolyn aggregates. A third observed dynamic mode is associated with the pretransitional slowing down of fluctuations of the local anisotropy. This mode behaves differently in polarized and depolarized light scattering, due to a coupling between fluctuations of the local-anisotropy and velocity fluctuations.

    • Received 23 July 2008

    DOI:https://doi.org/10.1103/PhysRevE.79.041704

    ©2009 American Physical Society

    Authors & Affiliations

    C. E. Bertrand1,2, K. L. Linegar1, A. F. Kostko3,4, and M. A. Anisimov1,2,*

    • 1Department of Chemical and Biomolecular Engineering and Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA
    • 2Department of Chemical Engineering, The Petroleum Institute, Abu Dhabi, P.O. Box 2533, United Arab Emirates
    • 3Department of Physics, St. Petersburg State University of Refrigeration and Food Engineering, St. Petersburg 191002, Russia
    • 4Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond, Virginia 23284, USA

    • *Corresponding author; anisimov@umd.edu

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    Issue

    Vol. 79, Iss. 4 — April 2009

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