A study on the finding new lyotropic biaxial mixtures and investigation of their uniaxial-to- biaxial phase transitions

Abstract

During my collaboration with Prof. Neto's research group as a visiting professor in the Institute of Physics (IF)/University of São Paulo, we will mainly concentrate on the production of new lyotropic mixtures presenting biaxial nematic phase. For this purpose, we will use totally 16 different amphiphilic molecules: DL- and L-forms of amino acid based esters (e.g. DL- or L-alaninehydrochloride dodecylester) and amides (e.g. potassium N-dodecanoyl-DL- or L-alaninate), where since DL-forms give achiral nematic phases, L-forms produce cholesteric phases. All these molecules will be synthesized in Turkey before my visit to the IF. Then, new lyotropic mixtures exhibiting biaxial nematic phase will be produced by using these amphiphilic molecules. The uniaxial-to-biaxial phase transition temperatures will be determined via laser conoscopy which is very useful for the determination of the phase transitions. The textures of uniaxial and biaxial phases will be characterized under polarising optical microscope. Combining the texture analysis with laser conoscopy measurements (birefringences of the nematic phases), the phase diagrams of each nematic systems will be constructed. The modification in the micellar shape anisotropy along the phase transition borders will be determined from the small-angle x-ray scattering. In addition, some linear and non-linear optical techniques such as dynamic light scattering and Z-scan will be applied to the new mixtures which will be obtained in the frame of this collaboratin.We hope that all these results may use to prepare publication(s) to be published in the international journals and international congress(es). (AU)