Title:	Role of molecular dipoles in liquid crystals
Authors:	Madhusudana, N.V.
Keywords:	antiparallel short-range order, biaxial smectic A phase cone phase polar molecules polar short-range order smectic C liquid crystals
Issue Date:	2004
Publisher:	Taylor & Francis
Citation:	Molecular Crystals and Liquid Crystals, 2004, Vol.409, p371-387
Abstract:	A vast majority of compounds exhibiting liquid crystalline phases have polar molecules. The nematic director is apolar, even when the molecules have cyano or nitro end-groups, as neighbouring molecules tend to have an antiparallel short-range order. This leads to a partial bilayer structure in the smectic A phase of rod-like molecules as also many interesting phase transitions. The latter can be understood on the basis of a change over to a polar short-range order as the density of the medium is increased. If the molecules have bent-cores and cyano end-groups, a partial bilayer biaxial smectic A phase is also found, implying the formation of quartets with an apolar structure. Lateral dipolar components lead to a tilting of molecules in smectic phases. This can be understood on the basis of the off-axis locations of such dipoles. A mean field theory of smectic C liquid crystals based on this mechanism gives results which reflect experimental trends. In appropriate cases, the possibility of occurrence of a cone-phase consisting of double-tilt cylinders is also pointed out.
Description:	Restricted Access
URI:	http://hdl.handle.net/2289/2102
ISSN:	1542-1406 1563-5287 (Online)
Alternative Location:	http://dx.doi.org/10.1080/15421400490433721
Copyright:	2004 Taylor & Francis
Appears in Collections:	Research Papers (SCM)

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