Resumen de Synthesis and Physical Properties of Liquid Crystals: An Interdisciplinary Experiment
Gerald R. Van Hecke, Kerry K. Karukstis, Hanhan Li, Hansford C. Hendargo, Andrew J. Cosand, Marja M. Fox
This experiment features an investigative approach designed for the introductory science or engineering major and integrates concepts in the fields of chemistry, biology, and physics. Derived from faculty research interests, this novel experiment gives students the opportunity to draw conclusions from tests performed to illustrate the connection between molecular structure and macroscopic properties. The chemical synthesis of the compounds studied further enhances the connection between molecular structure and macroscopic physical properties. The results of two separate physical measurements, refractometry and absorption spectroscopy, are combined to calculate a microscopic, but very practical, property of chiral nematic liquids—the pitch of the helix formed in the liquid crystalline phase. This pitch depends on temperature and composition of the sample exhibiting the liquid crystalline phase, specifically the chiral nematic (or cholesteric) phase. An additional simple measurement using polarized light and a quarter wave-plate can determine the handedness of the helix.
