화학공학소재연구정보센터
Molecular Crystals and Liquid Crystals, Vol.630, No.1, 69-78, 2016
Mesomorphism dependence on molecular flexibility
A novel ester homologous series of liquid crystals with a highly polar laterally substituted -OCH3 group is synthesized and studied with a view to understanding and establishing the effects of molecular structure involving lateral substitution on liquid crystal behavior. The novel series ROC6H4COOC6H3OCH3(ortho)CH=CHCOOC2H5 consists of 12 homologs of which C-7, C-8, C-10 are nematogenic and C-12, C-14, C-16 homologs are smectogenic. The rest of the homologs are nonliquid crystals. The textures of nematic phase are threaded and the smectic phase is of the type A or C. Transition temperatures and the textures of mesophases were determined by an optical polarizing microscope equipped with a heating stage. Analytical and spectral data support the molecular structures. The N-I and Sm-I transition curves behave in normal manner without exhibition of an odd-even effect. Average thermal stability for smectic and nematic are 127.3 degrees C and 129 degrees C, respectively. The total mesophase length ranges from 17 degrees C to 57 degrees C and series is of a middle ordered melting type with transition temperatures varying between 82 degrees C and 148 degrees C. The liquid crystal properties of present novel series are compared with, structurally similar known homologous series.