Presentation on theme: "Fluid Phases of Bent-Core Molecules - Novel Physics and Applications Samuel N. Sprunt, Kent State University, DMR 0606160 Giant flexoelectricity observed."— Presentation transcript:
Fluid Phases of Bent-Core Molecules - Novel Physics and Applications Samuel N. Sprunt, Kent State University, DMR Giant flexoelectricity observed in a Bent-core Nematic Liquid Crystal We discovered and are further characterizing an unexpectedly giant flexoelectric effect in the orientationally-ordered (nematic) phase of a bent-core liquid crystal, using both electromechanical (bottom figure on right) and light scattering methods. Such a large effect presents significant promise for new electromechanical energy conversion technologies – e.g., wearable, renewable personal power generation (US patent pending). The flexoelectric effect in a bent-core nematic compound (ClPbis10B) is ~1000 times larger than in conventional “rod-shaped” liquid crystals (like 5CB). Novel apparatus for direct measurement of flexoelectricity developed with support from this grant. Elastic bending of material “Flexo” “Electric” Induced polarization
Fluid Phases of Bent-Core Molecules - Novel Physics and Applications Samuel N. Sprunt, Kent State University, DMR Search for a new form of orientational order The traditional and most prevalent form of liquid crystal orientational order – the nematic state – is characterized by optical anisotropy. But it is theoretically possible for molecular liquids to develop orientational order while remaining optically isotropic. Such order has been termed “tetrahedratic”. We have been searching for the tetrahedratic state in bent-core liquid crystals and have recently discovered – and are following up on – evidence of a transition between optically isotropic phases (above the nematic state) that may be a “smoking gun” for tetrahedratic order. Related work on this project was performed at the NSF-funded National High Magnetic Field Laboratory, and was selected to be a 2006 NHMFL Research Highlight. Out of over 400 research reports, only 30 were selected as highlights. Evidence of a possible “tetrahedratic” phase between nematic and fully isotropic phases in a bent-core liquid crystal. Heat capacity data taken by graduate student Krishna Neupane in the laboratory of collaborator Prof. G. Iannacchione at WPI.
Graduate Student Training and Development Dr. Wiant (third from left) is congratulated at his graduation by his advisor, Prof. Gleeson, Dean of Arts and Sciences J. Feezel, and KSU President L. Lefton. In 2007, Wiant was the first US student ever to be awarded the Otto Lehmann Award by the Universität Karlsruhe and the Otto Lehmann Foundation, in recognition of an “outstanding doctoral dissertation in the field of liquid crystal technology”. Graduate students Dave Wiant and Krishna Neupane in a new facility for high-field magneto- optical measurements on soft materials developed at the NSF-funded NHMFL in Florida. The facility was set up and first operated by Wiant and Neupane, who are supported by this grant. Fluid Phases of Bent-Core Molecules - Novel Physics and Applications Samuel N. Sprunt, Kent State University, DMR
Top left: Grant-supported graduate student John Harden describes optical properties of liquid crystals to a visiting team of Operation Physics (grades 4-8) science teachers. Top right: Undergraduate KSU Physics major and REU student Richelle Teeling explains her grant-related work on liquid crystal-based electromechanical energy conversion to local junior high school students. Bottom: Thank You letter from Mr. Thomas Caston, graduating senior from Walsh High School, after completing a 3 week internship in Prof. Jakli’s lab. Highlights from outreach activities
Fluid Phases of Bent-Core Molecules - Novel Physics and Applications Samuel N. Sprunt, Kent State University, DMR This project has resulted in either new or strengthened KSU collaborations with leading national and international institutions in liquid crystal and soft materials science. Significant Collaborations