Europhys. Lett.
Volume 47, Number 4, August 1999
Page(s) 442 - 448
Section Condensed matter: structure, mechanical and thermal properties
Published online 01 September 2002
DOI: 10.1209/epl/i1999-00407-y

Europhys. Lett, 47 (4), pp. 442-448 (1999)

Equilibrium textures in main-chain liquid crystalline polymers

F. Elias, S. M. Clarke, R. Peck and E. M. Terentjev

Cavendish Laboratory, University of Cambridge
Madingley Road, Cambridge CB3 0HE, UK

(received 17 March 1999; accepted in final form 10 June 1999)

PACS. 61.30-v - Liquid crystals.
PACS. 61.41+e - Polymers, elastomers, and plastics.
PACS. 61.30Eb - Experimental determinations of smectic, nematic, cholesteric, and other structures.


We analyse the Schlieren textures formed by the nematic director in a thermotropic main-chain liquid crystalline polymer. After an initial coarsening, the textures reach a stable time-independent state which appears to be an equilibrium function of temperature and material parameters, with a characteristic length scale $\xi$of order $2 \, \mu\hbox{m}$. In particular, we study the evolution of this domain size when the temperature approaches the nematic-isotropic transition $T_{\rm ni}$. The texture size $\xi$increases towards $T_{\rm ni}$, but decreases reversibly when the temperature decreases back into the nematic phase. We discuss possible theoretical models that may explain such an equilibrium polydomain state of nematic director and the dependence of its size on the nematic order parameter.


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