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Trimesic Acid-Based Star Mesogens with Flexible Spacer: Synthesis and Mesophase Characterization
A.
Shanavas A,
T.
Narasimhaswamy B and
A. Sultan
Nasar A C
A
Department of Polymer Science, University of Madras, Guindy Campus, Chennai-600025, India. B
Polymer Laboratory, CSIR-Central Leather Research Institute, Adyar, Chennai-600020, India. C
Corresponding author. Email: drasultannasar@yahoo.com
Australian Journal of Chemistry
65(10)
1426-1435 http://dx.doi.org/10.1071/CH12258
Submitted: 16 April 2012 Accepted: 14 June 2012 Published:
19
July
2012
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Abstract
A series of trimesic acid-based star mesogens containing an octamethylenoxy spacer and two-ring containing side arms with terminal alkoxy groups were synthesised by a divergent approach. A structurally similar mesogen containing a three-ring side arm was also synthesised. All the mesogens and intermediates were characterised thoroughly using FT-IR, 1H NMR, 13C NMR spectroscopy, and elemental analysis techniques. The mesophase characteristics were identified by hot stage optical polarising microscopy (HOPM) and differential scanning calorimetry (DSC), while X-ray was used to confirm the existence of a smectic A (SA) phase. The HOPM and DSC results revealed the presence of rich polymesomorphism in the star mesogens. The dominance of a SA phase in the series is attributed to the steric repulsion associated with steric asymmetry. The change of the side arm from two rings to three rings was found to increase the mesophase stability. 
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