Liquid crystals (LCs) are fluids, composed of anisotropic molecules, which possess some degree of orientational or positional order. Molecules having a plank-like or bent-core shape and, thus, lacking cylindrical symmetry give rise to the possibility of forming optically biaxial nematic and smectic phases. In spite of vigorous search for the past two decades, the thermotropic biaxial nematic phase had remained elusive until its discovery in 2004 in bent-core mesogens by Kumar, et al. Researchers, mostly outside the US, have recently succeeded in synthesizing new and unique mesogens that, from preliminary results, appear excellent candidates for the study of biaxiality. These include several photosensitive bent-core compounds and a new class of materials, known as the tetrapodes (having plank-like aggregate shape), synthesized by our collaborators in the UK, Germany and India. This SGER proposal by three interdisciplinary researchers seeks support for a time-critical effort to study these LC materials using fluorescence confocal and polarizing microscopy, synchrotron x-ray diffraction, and deuterium NMR techniques, with the following specific objectives: 1) The nature and the structure of liquid crystal phases and their dependence on molecular structure will be studied in the 5- and 6-ring rigid bentcore molecules with different terminal groups and the tetrapodic compounds; 2) The biaxial order parameter, its temperature dependence, the effect of biaxiality on elasticity and viscosities of LC phases will be determined; 3) transformative electro-optics technology due to the possibility of building much faster and multistate switching devices at low applied voltages. Results of the proposed study should lead us to the development of a transformative display technology and low cost fabrication of devices such as tunable biaxial retardation films.
The proposed research will have tremendous impact on industry via the emergence of a new display technology and other applications of these new materials. Undergraduate and graduate students and postdocs will be trained in physics and chemistry, and lead to the creation of a revolutionary technology of these new biaxial LC materials that have the potential of changing the face of display industry and impact the fields of photonics, telecommunications, and cyber infrastructure. Junior researchers will have opportunities to interact and forge long-term professional contacts with members of our collaborators' research groups in other countries
