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Effect of Different Layer Thicknesses and Boundary Conditions of Confined Liquid Crystal on Dynamics of Director Relaxation: Dynamic Light Scattering Investigations

Published online by Cambridge University Press:  01 February 2011

Sarmistha Basu  and
Fouad M. Aliev
Sarmistha Basu
Affiliation:
Department of Physics, University of Puerto Rico, San Juan, PR 00931–2343, USA
Fouad M. Aliev
Affiliation:
Department of Physics, University of Puerto Rico, San Juan, PR 00931–2343, USA
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Abstract

Dynamic light scattering (DLS) has been used to study the influence of boundary conditions (planar-axial and homeotropic-radial) and layer thickness of liquid crystal (8CB) confined to cylindrical pores on phase transitions and relaxation of director orientational fluctuations. For confined 8CB in the nematic phase two well-defined relaxation processes were observed for both axial and radial orientations of the liquid crystal. The first relaxation is qualitatively associated with bulk-like nematic director fluctuations. The second relaxation (with relaxation time slower than the first one) is most likely due to the fluctuations in the layers nearest the wall surface. In samples with radial boundary conditions, we observed the onset of smectic-A phase order formation on the pore wall even though the rest of the liquid crystal could be in the nematic phase. The influence of pore wall-liquid crystal interactions on the properties of the confined 8CB was stronger for radial boundary conditions of confined liquid crystal, than in the case of axial orientation‥ The separation between the first and the second (slow) process was clearer for thinner layers and the amplitude of the slow process was greater for thinner layers. This suggests that the slow process was related to surface relaxation of director fluctuations.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 790: Symposium P – Dynamics in Small Confining Systems–2003 , 2003 , P7.12
Copyright
Copyright © Materials Research Society 2004

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