How Much is Too Much : Testing the Boundaries of Hydrogen Bonded Liquid Crystal/Inhibitor Networks

Abstract

A liquid crystal is state of matter that simultaneously displays properties of both a liquid and a solid. Liquid Crystals have applications in liquid crystal displays (LCD’s) and optical imaging. Liquid crystals or “mesogens” are created when molecules have both core (ex. aromatic) and chain (ex. Alkyl group) structures. This allows the molecule to form a semi-ordered phase in between a solid and a liquid. In this experiment, liquid crystallinity was induced thermally to form rod-like semi-ordered phases. The bisacid donor tetraethyleneglycoxy-bis-4-naphthoic acid (4EOBNA) was used as the primary hydrogen bonding donor. 1,2-di(4-pyridyl)ethylene (2RP) was used as primary hydrogen bonding acceptor. Inducing liquid crystallinity creates mesogenic properties that can display network properties. When heated and cooled, molecules melt and are free to align based on the hydrogen bonds that are formed. This system allows us to tune liquid crystallinity with both temperature and amount of hydrogen bonding present. Disruption of the balance between core and chain components in a liquid crystal can lead to loss of liquid crystallinity. This project investigates the impact of varying the mole percent of hydrogen bond acceptor (2RP) to flexible hydrogen bond donor (4EOBNA) by using differential scanning calorimetry and polarizing light microscopy. This study uses means of “controlled contamination” with the inhibitor tetrakis (4-pyridoxymethane) (4PD) to show how the mole percent of this inhibitor affects the mesogenic properties of these complexes. Additionally, studying the mesogenic properties of these complexes will give us a better understanding of liquid crystal design for potential application use.