화학공학소재연구정보센터
Molecular Crystals and Liquid Crystals, Vol.637, No.1, 28-36, 2016
The effect of molecular rigidity and flexibility on the mesomorphism of azoesters
An Azoester novel homologous series RO-C6H4-COO-C6H4-N=N-C6H4-OC4H9(n) (para) of liquid crystalline (LC) materials are synthesized and studied with a view to understanding and establishing the effects of molecular structure on liquid crystal behavior with reference to lateral, terminal, or central group or groups on the basis of molecular rigidity and/or flexibility. The novel homologous series consists of thirteen (C-1 to C-18) homologues. C-1 to C-5 homologues are nonmesogenic and the rest of the homologues are enantiotropically mesogenic. C-8 to C-18 homologues are smectogenic plus nematogenic and the remaining two C-6 and C-7 homologues are only nematogenic without exhibition of smectic property. Analytical, thermal and spectral data confirms the molecular structures. Textures and transition temperatures of homologues were determined by an optical polarizingmicroscope (POM) equipped with a heating stage. Textures of a nematic phases are threaded or Schlieren and that of a smectic phase are of the type of A or C. The average thermal stabilities for smectic and nematic are 111.3 degrees C and 124.7 degrees C, respectively. The smectic and nematicmesophase lengths from 10.0 degrees C to 28.0 degrees C and 7.0 degrees C to 16.0 degrees C, respectively. The transition temperatures are compared with known series.