RUI: New oxadiazole containing liquid crystals: Effects of structural changes on the biaxial nematic phase

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TECHNICAL SUMMARYThis RUI award to the University of Puget Sound from the Solid State and Materials Chemistry Program of the Division of Materials Research will allow for an in depth analysis of how structural changes in a series of oxadiazole and oxazole containing liquid crystals (LCs) impact the formation and stability of the biaxial nematic (Nb) phase. This unique LC phase, that was discovered in oxadiazole derivatives in 2004, may allow for faster electro-optic switching in LC displays. However, the original compounds show the Nb phase at impractically high temperatures. The awardee, Eric Scharrer, and his undergraduate students have demonstrated in preliminary work that the incorporation of lateral methyl groups into oxadiazole containing derivatives is a successful way to lower the nematic onset temperatures. The proposed research will involve systematically changing the position of various lateral groups (alkyl and halogen) to probe the effects of both steric and electronic factors on the biaxial nematic phase. Synthesis of the target compounds (by undergraduates and a community college instructor), and initial phase analysis, using polarizing microscopy and differential scanning calorimetry, will be carried out at the University of Puget Sound. In order to determine the degree of biaxiality present in each of the derivatives, the PI and his students will travel to the University of North Carolina to carry out more sophisticated analysis (conoscopic microscopy and 2H NMR spectroscopy). An overarching goal of the research is to generate derivatives that show the Nb phase at relatively low temperatures, which will facilitate the exploration of device applications of these compounds by physicists and engineers. NON-TECHNICAL SUMMARYLiquid crystal displays (LCD) are widely found in a variety of applications including laptop computers, cell phones, and flat screen televisions. Compounds that exhibit the liquid crystal phase are an integral component of these displays; molecules in this phase are reoriented by an electric field producing changes in contrast, thus allowing the production of images. The aim of the research funded by this grant is the investigation of a particular type of liquid crystal phase, the biaxial nematic phase. Specifically, the goal is to prepare new compounds that show improved stability of this phase. The biaxial nematic phase is of tremendous interest because assembly of an LCD using a compound possessing this phase may lead to significantly faster response times. Undergraduate students at the University of Puget Sound will be directly involved in all aspects of preparation and characterization of this technologically important class of materials. The experience they gain will be excellent preparation for graduate studies in Chemistry or a related field, or direct employment in the industrial sector. The grant also provides a summer stipend that will allow an instructor from Tacoma Community College (which has a diverse student population) to be involved in the research process. This experience will allow her to more effectively convey to her students how Chemistry plays an important role in technology. In addition, the PI will visit the community college to deliver presentations on liquid crystals and other materials science topics.