Title:	High pressure investigations on the phase behaviour of discotic liquid crystals
Authors:	Rao, Shankar D.S. Prasad, Krishna S. Bamezai, R.K. Kumar, Sandeep
Keywords:	high pressure discotic liquid crystals columnar phase PT diagram
Issue Date:	2003
Publisher:	Taylor & Francis
Citation:	Molecular Crystals and Liquid Crystals, 2003, Vol.397, p143-159
Abstract:	Liquid crystals made of disc shaped molecules, now referred to as discotic liquid crystals, were discovered [1] in 1977 and represent a new class of thermotropic liquid crystals. Since the discovery, there are only a few studies [2–9] concerning the effect of pressure on these materials. Here we report highpressure investigations on the columnar phase of several triphenylene compounds. We selected the compounds such that for one set of materials the number of peripheral substituents, x, was fixed and the length of the alkoxy chains, n, was varied, while for the second set n was fixed and x varied. We observe that with increase in either n or x, the slope of the pressure-temperature phase boundary, i.e., (dT/dP)1bar shows a strong decrease. The magnitude of the transition enthalpy and the calculated transition volume across the columnar-isotropic transition show a strong decrease with increasing n or x. To explain these features we propose an argument based on the ratio of the volume of the triphenylene core to the total volume of the molecule.
Description:	Restricted Access.
URI:	http://hdl.handle.net/2289/4637
ISSN:	1542-1406 1563-5287 (Online)
Alternative Location:	http://dx.doi.org/10.1080/15421400390214086
Copyright:	2003 Taylor & Francis
Appears in Collections:	Research Papers (SCM)

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