Premium
Synthesis and Characterization of Thermotropic Liquid Crystalline Main‐Chain Polyurethanes from High‐Aspect Ratio Mesogenic Diols
Author(s) -
Padmavathy Tallury,
Sudhakar Sundarraj,
Srinivasan Kalathur S. V.
Publication year - 2001
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(20010801)202:12<2538::aid-macp2538>3.0.co;2-t
Subject(s) - thermotropic crystal , mesogen , polymer chemistry , differential scanning calorimetry , thermogravimetric analysis , monomer , liquid crystal , chemistry , diol , thermal stability , copolyester , benzoic acid , materials science , polymer , organic chemistry , polyester , liquid crystalline , physics , optoelectronics , thermodynamics
A series of novel tetrad high aspect ratio mesogenic diol monomers 4‐{[4‐( n ‐hydroxyalkoxy)phenylimino]methyl}benzoic acid 4‐{[4‐( n ‐hydroxyalkoxy)phenylimino]methyl}phenyl ester ( 3 a – e ) were prepared with varying alkoxy spacer length ( n = 2, 4, 6, 8, 10) by reacting 4‐formylbenzoic acid 4‐formylphenyl ester and 4‐( n ‐hydroxyalkoxy)anilines. Two series of thermotropic main‐chain liquid crystalline polyurethanes (LCPUs) 4 a – e and 5 a – e were obtained by the polyaddition of 3 a – e with hexamethylene diisocyanate (HMDI) and 4,4′‐methylene bis(cyclohexylisocyanate) (H 12 MDI) in DMF respectively. Structural elucidation was carried out by elemental analysis, FT‐IR, 1 H NMR and 13 C NMR spectroscopy. Inherent viscosity of the polymers measured in methanesulfonic acid at 26°C was in the range of 0.13–0.65 dL/g. Mesomorphic properties were studied by differential scanning calorimetry and hot stage polarizing optical microscopy and the thermal stability was determined by thermogravimetric analysis. The monomeric diols and the polyurethanes exhibited nematic texture.