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Dynamic Light Scattering in 5CB Confined in Disordered Porous Media

Published online by Cambridge University Press:  10 February 2011

Fouad M. Aliev  and
Vladimir V. Nadtotchi
Fouad M. Aliev
Affiliation:
Department of Physics and Materials Research Center, PO BOX 23343, University of Puerto Rico, San Juan, PR 00931-3343, USA
Vladimir V. Nadtotchi
Affiliation:
Department of Physics and Materials Research Center, PO BOX 23343, University of Puerto Rico, San Juan, PR 00931-3343, USA
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Abstract

We performed dynamic and static light scattering measurements in nematic LC (5CB) confined in silica porous glasses with average pore sizes of 1000 A˚ (volume fraction of pores 40%) and 100 A˚ (27%). The experiments show significant changes in physical properties of confined LC. Nematic-isotropic phase transition temperature TNI is depressed by 0.6°C in 1000 A˚ pores compared to that bulk value and this phase transition was not detected at all in 100 A˚ pores. We found that even about 20°C below bulk melting temperature the relaxational processes in confined LC were not frozen. Slow relaxation process which does not exist in the bulk LC and wide spectrum of relaxation times (10−8 –)s appear in both 100 A˚ and 1000 A˚. In 100 A˚ pores slow relaxation exists even at T corresponding to the bulk isotropic phase. Our data can not be described using the standard form of dynamical scaling variable (t/r) but they obey activated dynamical scaling with the scaling variable x = lnt/lnr.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 407: Symposium M – Disordered Materials and Interfaces-Fractals, structure and Dynamics , 1995 , 125
Copyright
Copyright © Materials Research Society 1996

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References

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