Induced twist grain boundary phase in the binary mixtures of cholesteryl caprylate and nonyloxybenzoic acid

Binary mixtures of cholesteryl caprylate (ChC) and nonyloxybenzoic acid (NOBA) having different mole ratios have been studied using differential scanning calorimeter (DSC) and polarizing microscope (PM). ChC has monotropic chiral nematic (N*) mesophase in the cooling cycle whereas, NOBA has enantiotropic nematic (N) and smectic C (SmC) mesophases. Transition temperatures and enthalpies of these mixtures have been determined with the help of DSC, whereas different mesophases have been identified by their typical textures as viewed under polarizing microscope. Addition of NOBA in ChC induces smectic A (SmA) and twist grain boundary A (TGBA) phases between two critical concentrations.